European Plastics News

>> Tuesday, 13 October 2009

European Plastics News is the only monthly pan-European plastics industry magazine, delivering an international perspective on the key technical and business issues impacting on the plastics industry throughout the region.

Qualify for Your Three Free Trial Issues! The journalists, who have an unrivalled combination of plastics and editorial experience, travel the length and breadth of Europe and beyond, meeting key plastics processors, suppliers, innovators and opinion formers. Their reports and comments make EPN essential reading for decision makers throughout Europe's plastics industry who are demanding international viewpoint on an increasingly global market. You will receive 3 RISK-FREE issues of European Plastics News. You can choose to continue to receive 9 additional issues (12 issues total) for just £240; otherwise, keep the 3 FREE trial issues and owe nothing by returning the bill marked "cancel".

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Plastic pipes

>> Wednesday, 23 September 2009

The pipe sector is one of the most challenging construction sectors today. Economic pressures have led to fewer construction projects in many major markets, while specifiers have been increasingly expected to balance higher performance with reduced cost.

Today's plastics provide the opportunity to overcome these challenges. The economic and environmental benefits achieved by plastic pipe are an outcome of features including:

Zero corrosion — Plastics resist corrosion from water and many chemicals, reducing wear and tear and increasing longevity.
Increased flexibility — Easy to install, even at low temperatures.
Durable and tough material — Plastic pipes give a high resistance to fracture and fatigue
Leak-free joint fusion — Buttwelding, socket welding, electro-fusion fittings
Light weight materials — The light weight of plastic contributes to reducing man hours and the need for heavy equipment, such as cranes. Plastics are also easier to transport and store.
Easier installation and rehabilitation — The flexibility of plastics means that several components can be combined in one, making them easy to manufacture and install.
Higher flow-rate properties — These are sustained for the life of the pipe.
Greater lifetime expectancy — Plastics provide durable and tough solutions, meaning maintenance can be kept to a minimum.
Hygienic and clean delivery — Plastics are a hygienic choice particularly for water delivery systems.
Environmentally sound products — Plastic pipes are easy to install, meaning less environmental disruption. After use, plastic pipes can be re-used, recycled or even turned into a source of energy.
Cost-effective components — Plastic components are often more economical to produce than other materials in custom-made forms.
Industry-tailored options — Plastic pipes can easily be industry-tailored through color coding.

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Plastics & Rubber Weekly

>> Thursday, 3 September 2009

Qualify for Your Three Free Trial Issues! PRW is a genuinely vital source of information for its plastics and rubber readership, wherever they are in their supply chain. In terms of timeliness, independence and coverage, there is no equivalent to PRW’s news section in this industry. Every week, PRW also publishes an in-depth feature on the key sectors and processes in the UK plastics industry, along with regular updates on technology, regulation and personnel changes. You will receive 3 RISK-FREE issues of PRW. You can choose to continue to receive 49 additional issues (52 issues total) for just 240; otherwise, keep the 3 FREE trial issues and owe nothing by returning the bill marked “cancel”.
Request Free!

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2. Dry cycle mold - Validation procedure for injection molds

>> Tuesday, 1 September 2009

The second step in validating an injection mold according to injection mold validation flow chart is dry cycle mold. The steps before are:

1. Mold certification

Purpose:
The purpose of the dry cycle mold is to evaluate the mold mechanical actions for any gross problems prior to injecting plastic into the mold. The machine operator at the mold builder or molder should know how to adjust the settings on the injection unit to cycle the mold without injecting plastic into the tool. If at anytime during the dry cycle procedure there is a possibility that damage is being done to the tool or if the mold is not operating as designed, pull the mold from the press and have it examined by an experienced mold builder.

This stage is often carried out prior to the customer being invited to the mold builder for the debug. If there are any machine/mold operation issues it is preferable for the mold builder to remedy this before customer attendance, saving unnecessary travel. If there is a serious mold design flaw (as opposed to a mold assembly issue) it will then be necessary to attend to discuss next steps.

All the steps during the procedure that involve intimate contact with the injection molding machine are to be done by a qualified injection molding machine operator.

Procedure:
1. Put mold in press. Ensure that the cooling circuits are attached to the mold and that water is circulating through the mold. Also, if there is a hot runner manifold have the controller installed and temperature heaters turned on.
2. Verify water is flowing through the mold at resin manufacturer’s recommended mid-range; check with flow meter indicator or measure flow rate by having the returns empty into a bucket. Ensure heaters are working in the hot runner system by reading the thermocouple outputs.
3. Close the mold at a slow rate and pressure to verify that the mechanical, pneumatic or hydraulic actions of the mold have responded and are moving as designed. Listen for any suspect noises of possible binding of slides or galling.
4. Clamp up on the mold at a low tonnage. Be sure to have mold protection time, pressure and rate properly set so that no major damage can be done to the mold.
5. When the mold is in the press, open the mold at a slow rate to ensure that the mechanical, pneumatic or hydraulic slides are responding and moving as designed. Listen for any suspect noises of possible binding or galling. The slides should move with little resistance.
6. After mold is completely open, cycle the ejector plate manually at a low pressure and low rate, while visually inspecting to verify the ejector plate is performing as designed.
7. Cycle the mold without injecting plastic. Typically this is done by transferring from fill/pack stage to hold stage by position and setting the feed stroke and transfer position to the same position while having the hydraulic pressure set to 0 bar. Keep the clamp open/close rates and pressures to a minimum. Set the hold time to zero. Set cool time to a minimum machine value to decrease the cycle of the mold.
8. Evaluate the mold while it is cycling for any gross mechanical problems. Study the movements of the mold for possible binding or galling of slides, ejector pins and leader pins.
9. Increase the rate and pressure of mold open/close slowly until it replicates the speed and pressures expected during production or sampling. Also do the same with the ejection action.
10. Increase the tonnage slowly until it replicates the tonnage necessary to keep the mold closed during the injection stage of the molding process.
11. Continue cycling the mold until you determine that mechanically there are no fundamental flaws with the production or design of the mold.

The further steps are required in validating a injection mold according to injection mold validation flow chart:

3. Process stability test
4. Gage repeatability & reproducibility (R&R) test
5. Mold viscosity test
6. Balance of fill analysis
7. Gate freeze test
8. Commissioning (multi-cavity analysis)
9. Design of experiments
10. Qualification (process capability study)
11. Mold metal Adjustments - centering process
12. Verification (30-day run)

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Head tooling – extrusion blow molding

>> Wednesday, 19 August 2009

Mandrel and die dimensions are estimated based on container dimensional data, container symmetry, blow-up ratio, targeted container weight, neck finish requirements and the type of material (degree of parison swell) that will be used to produce the container.

An initial blow-up ratio must be calculated using the container design dimensions and the required parison diameter.
The required parison diameter will depend on the relative size of the container, the container design (handle or no handle) and the container neck finish requirements. Initial blow-up ratios may be calculated using the following equation.

Blow up ratio = Bd / Nd

where:
Bd = Bottle diameter, in
Nd = Minimum neck diameter, in

The blow-up ratio is compared with the maximum recommended blow-up ratio of the selected material.
Blow up ratios of 2 or 3 to 1 are considered normal when molding commodity resins such as polyethylene.
A blow-up ratio as high as 4:1 is a practical upper limit.
The blow up ratio for large containers with a small neck, is generally extended to 7:1 so that the parison fits within the neck and so that there is no mold parting line mark on the neck finish.
Blow up ratios for a containers with a handles are generally in the 3 or 5 to 1 range as the die diameter must be larger to allow the handle to be blown.

Figure shows a typical blow molded container with dimension and design nomenclature for reference


In order to properly estimate and ‘size’ mandrel and die geometry for the blow mold(s), and to effectively control the process, a thorough understanding of parison swell and draw down phenomena is required. Parison swell is a combination of diameter swell and weight swell. It is a difficult blow molding property to estimate and to control. The parison diameter swell is a complex function of the weight swell, the rate of swell, and the melt strength.

Parison swell behavior varies significantly depending on material type, material processing conditions, machine processing parameters, basic die design (diverging vs. converging), container geometry (required parison diameter), container weight (shuttle process) and type of blow molding process. Some of the wheel type blow molding processes clamp (pinch off) and hold the parison at both ends during the blowing sequence in the process. The parison swell effects are normally more readily controlled on the wheel process compared with the shuttle process.

Parison swell data for a given material is often not available for mandrel and die calculations. The alternative is to proceed in a stepwise approximation towards the desired mandrel and die dimensions, and through trial and error, towards the targeted container weight with the aid of an interchangeable set of dies.

Internal die design dimensions including approach angles and land lengths vary significantly with blow molding machine capabilities and machinery manufacturers experience. Calculations for these dimensions are beyond the scope of this document and will not be discussed here.

However, as a rule of thumb, when blow molding commodity materials (PE, PP), a die land length of at least 8 times the annulus gap (die gap) is typical.

A simplified approach for calculating and estimating mandrel and die dimensions is presented here to serve as a general guide. The following equations may be applied in cases where the container geometry is symmetrical and there is no handle on the container.

Case A
When the neck size of a container or the smallest diameter of the container is the controlling feature (as when the parison must be contained within the smallest diameter) , the following approximations may be used to calculate the dimensions of the mandrel and die. Use of these equations assume a free-falling parison and they can be used with most PE blow molding materials.

Dd = 0.5 N d (Equation 1)

Pd = ( D d2 - 2Bdt + 2t2)1/2 (Equation 2)

where:
Dd = Diameter of die bushing, in
Nd = Minimum neck diameter, in
Pd = Mandrel diameter, in
Bd = Bottle diameter, in
t = Bottle thickness at Bd, in

Case B
When the container weight is specified instead of the wall thickness for a process using inside-the-neck blowing, the following equations may be applied:

(The equation may be applied for a free-falling parison, and is applicable to most irregularly shaped containers.)

Pd = (Dd 2 - 2 (W/T2) Ld)1/2 (Equation 3)

where:
Pd = Mandrel diameter, in
Dd = Diameter of die bushing, in
W = Weight of container, g
L = Length of container, in
d = Density of material, g/cc
T = Wall thickness, in

Case C
When a parison is partially controlled by tension, i.e., the rotary wheel blow molding process, the following relationships may be used. The assumption here is that the parison is not free-falling.

Dd = 0.9 N d (Equation 4)

Pd = ( Dd 2 - 3.6 Bd t + 3.6 t 2)1/2 (Equation 5)

Pd = ( Dd 2 - 3.6 ( W / T 2 ) Ld) 1 / 2 (Equation 6)

where:
Pd = Mandrel diameter, in
Nd = Minimum neck diameter, in
Dd = Diameter of die bushing, in
W = Weight of container, g
L = Length of container, in
d = Density of material, g/cc
T = Wall thickness, in
Bd = Bottle diameter, in
t = Bottle thickness at Bd, in

Case D
Estimating head tooling dimensions for containers with handles requires an empirical method based on container size and geometry. When the container has a molded handle use the following equations to determine the estimated dimensions for the head tooling die and mandrel.

The die diameter can be estimated using equation 7 with the container dimension data.

D = ( 0.8 Z ) / 3 (Equation 7)

Where:
Z = Maximum container width or diameter
D = Diameter of die bushing, in.

The die diameter, D, is then substituted in equation 3, equation 5 or equation 6 depending on available container data and the blow molding process that will be used.

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PET drying

A fault with the dryer will lead to hydrolysis of the material in the barrel of the machine. This will cause lowered I.V. of the material. Lowered I.V. is the major cause of bad quality in preforms and bottles. More than 60% of all PET processing related faults can be traced back to the dryer.
Maintaining the dryer in optimum condition will allow the molding machine to perform at maximum efficiency and quality.

Check the basics!
Airflow - The most important parameter, there should be nothing causing a restriction in the process and regeneration air flow.
Temperature - Process Temperature should be in the region of 145~170ºC Depending on the resin supplier and the drying time. Also check the Regeneration Temperature which should be around 200~230ºC depending on the maker.
Time - Calculate (or measure) the time the material is in the hopper, this should be at least 3½ hours.
Dewpoint - Correct dewpoint may vary according to the manufacturer of the dryer, consult the maker's manual before assuming an error exists.

How Do I Do This?
Airflow - Most common problem is a blocked process filter, but also check blowers are operating correctly and the delivery hoses have not been squashed.
Temperature - Confirm process air temperature is correct on the display panel. The regeneration air temperature is not so easy to check since most regeneration controllers are hidden away in the electrical panel.
Time - If you know the capacity of the hopper in liters, you can calculate the PET quantity using a figure of 0.84kg/L as the bulk density. Compare this figure (kilograms of PET) against the current consumption of PET by the machine in kg/hr. If you are not sure, the safest method is to switch off the hopper loader and check the time necessary for the material to be consumed.
Dewpoint - Use a commercially available dewpoint meter to sample the air coming from the desiccant chamber. Typical vales may be anything between -20ºC and -50ºC. Check the manual for correct specification. In machines with more than one desiccant chamber, be sure to check all of them.
Check the correct function of all heaters on a regular basis using a clip-on ammeter. If one or more has broken, the others will be taking extra load.
Always check the calibration of instrumentation and thermocouples before assuming a problem exists

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Calculating the consumption of polymer

What Is It?
A simple calculation that tells you the consumption of poly(ethylene terephthalate), PET by an injection molding machine.

The Calculation Is...

kg / hr = W x C x S

Where;
W = Weight of the container in kg. (e.g. 45 grams = 0.045 kg)
C = Number of injection cavities
S = Number of injection cycles per hour (shots)
(3,600 / Cycle Time (sec) for one set of preforms)

Example

A machine with a cycle time of 14 seconds making a 35 gram bottle
W = 0.035
C = 8
S = (3,600 / 14) = 257.1
kg / hr = 0.035 x 8 x 257.1 = 72 kg / hr

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1. Mold certification - Validation procedure for injection molds

>> Sunday, 16 August 2009

The first step in validating an injection mold according to injection mold validation flow chart is mold certification.

Purpose:
The purpose of the mold certification is to ensure the mold is built according to specification before the mold validation procedures begin, e.g., critical dimensions on the first mold set are cut "Steel Safe", core/cavity stack up dimensions are correct, cavity to cavity spacing is correct, cooling circuit layout, etc. The tool builder is required to provide verification of all critical metal tolerances on core and cavity ‘fits’ to be +/- 0,005 mm. The critical part dimension metal tolerances must be less than 10% of the plastics part dimension tolerances. In many cases, it will be necessary to go tighter than 10%. The mold certification should be performed at the tool builder while the mold is being fabricated to expedite any needed adjustments to the mold. Mold certification needs to be agreed upon when the mold order is placed. A copy of the mold certification should be included with the final mold validation report.

Variation observed during the process stability test, balance of fill analysis, and commissioning (multi-cavity analysis) are often a result of variation observed in the mold metal dimensions. Some molds, such as a four-face stack mold with a part thickness of approximately 0,80 mm are extremely sensitive to such variation, and may not pass the process stability test as a result. It is important for this step to be completed first so any correlation between variation observed during the remaining tests can be determined without pulling the mold from the press and disassembling it. Ensuring consistent cavity to cavity mold metal dimensions before running the mold will significantly decrease the time required to complete the validation procedure.

Data obtained from the mold certification for critical dimensions can be plotted on a control chart along with the critical part dimension obtained during the to determine if the two correlate to each other. A correlation between part dimension and steel dimension variation between cavities can be seen in figure: Correlation between steel and part dimensions
Correlation between steel and part dimensionsTable: Steel certification summary

Steel certification summarysummarize the metal certification data for this stack-up in figure: Critical core/cavity stack-up metal dimensionsCritical core/cavity stack-up metal dimensionsThe mold builder did not achieve their pre-determined mold metal tolerances. In some instances this may be acceptable. As shown for the outside diameter (dimension No. 5). A more constructive method to view the metal certification data is to control chart (X-MR) the data. The mold builder should know their measurement variation when performing metal certification. If not, they should perform a Gage repeatability & reproducibility (R&R) test. Ideally, the mold builder will machine the dimensions in control and be well within the agreed upon specifications.

The further steps are required in validating a injection mold according to injection mold validation flow chart:

2. Dry cycle mold
3. Process stability test
4. Gage repeatability & reproducibility (R&R) test
5. Mold viscosity test
6. Balance of fill analysis
7. Gate freeze test
8. Commissioning (multi-cavity analysis)
9. Design of experiments
10. Qualification (process capability study)
11. Mold metal Adjustments - centering process
12. Verification (30-day run)

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Reinforced Plastics – Free Subscription!

>> Tuesday, 11 August 2009

Free magazines, eBooks, publications, newsletter review from the polymer processing industry. Celebrating over 50 years of service to the composites industry worldwide.
For over 50 years Reinforced Plastics has been the first choice of moulders, fabricators and end-users as a comprehensive source of impartial and informed comment on the global composites industry. Their unique partnership with all the main industry players enables them to empower their readers with up-to-the-minute news on all aspects of the industry. They are totally committed to being the best in the business and maintaining the support of their readers and advertisers in the continuing challenges of their industry.

Geographic Eligibility: Select International

Offered Free by: Elsevier Limited

Request Free!

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Modern Plastics Worldwide – Free Subscription!

Modern Plastics WorldwideFree magazines, eBooks, publications, newsletter review from the polymer processing industry. Modern Plastics Worldwide is the only plastics publication dedicated to covering global business management issues, key technologies, and the latest manufacturing management trends for the international plastics industry.
Topics range across all processes, including injection, extrusion, blowmolding, thermoforming, blown film, cast film, and compounding. Modern Plastics Worldwide also covers the latest technology developments in materials, design, equipment, processing, and applications from a business strategy perspective, marketing information on new markets, industry trends, economic influences, forecasts and more.
Geographic Eligibility: USA, Canada, Mexico, Selected International (Print or Digital version)

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Canon Plastics Group - the Voice of an Industry

Canon Communications LLC is a strategic partner to the plastics industry. Both of our publications, Injection Molding Magazine and Modern Plastics Worldwide, address the plastics industry from a unique viewpoint. Each one offers in-depth coverage of its subject matter that a generalist publication just can’t accomplish. Each viewpoint helps readers stay on top of the fast-paced plastics industry. Together, Canon’s two plastics magazines add up to comprehensive coverage that gives industry professionals a 360° look at running a successful business. This is carried over online with our plastics industry community site, plasticstoday.com.

Corporate Information
Founded in 1978, Canon Communications has grown from a one-magazine publishing firm to a diversified multimedia communications company. While the company continues to grow and steadily expand its scope of markets, Canon remains committed to providing the most relevant, vital information to professionals in all areas of the complex industries it serves.
Canon now publishes more than a dozen magazines, all of which serve as authoritative sources of information in their respective industries. In addition to plastics, the packaging, medical manufacturing, and design industries are among the well-served business communities that rely on Canon's wide variety of publications for the latest in industry news, innovations, and market trends. Offering unique insight into each industry sector its magazines target, Canon publications are renowned for their unparalleled commitment to quality.

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Injection Molding Magazine – Free Subscription!

Free magazines, eBooks, publications, newsletter review from the polymer processing industry. IMM is the only publication devoted exclusively to the injection molding marketplace, consisting of custom and captive molders, contract manufacturers, OEM companies, part designers, moldmakers, and key members of the supply channel. Readers prefer IMM's editorial content as it provides them with "how-to" advice that contributes to their success.
Geographic Eligibility: USA, Canada, Mexico (Print Edition Only), Selected International (Digital Edition Only)

Request Free!

Canon Plastics Group - the Voice of an Industry

Canon Communications LLC is a strategic partner to the plastics industry. Both of our publications, Injection Molding Magazine and Modern Plastics Worldwide, address the plastics industry from a unique viewpoint. Each one offers in-depth coverage of its subject matter that a generalist publication just can’t accomplish. Each viewpoint helps readers stay on top of the fast-paced plastics industry. Together, Canon’s two plastics magazines add up to comprehensive coverage that gives industry professionals a 360° look at running a successful business. This is carried over online with our plastics industry community site, plasticstoday.com.

Corporate Information
Founded in 1978, Canon Communications has grown from a one-magazine publishing firm to a diversified multimedia communications company. While the company continues to grow and steadily expand its scope of markets, Canon remains committed to providing the most relevant, vital information to professionals in all areas of the complex industries it serves.
Canon now publishes more than a dozen magazines, all of which serve as authoritative sources of information in their respective industries. In addition to plastics, the packaging, medical manufacturing, and design industries are among the well-served business communities that rely on Canon's wide variety of publications for the latest in industry news, innovations, and market trends. Offering unique insight into each industry sector its magazines target, Canon publications are renowned for their unparalleled commitment to quality.

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Injection mold validation procedure

To validate an injection mold, there are numerous items one must take into consideration before the mold is completed and work is ready to begin. First, it is advisable to hold a mold design review meeting with all involved parties prior to tool manufacture. Invite the mold builder, hot runner supplier, steel supplier, press supplier, resin supplier, and a strategic molder for the design review. Involving everyone early on in the process and keeping them informed throughout the building of the mold avoids needless complications.

Once all the suppliers have been identified it is vital that they are all given training on the injection mold validation procedure, IMVP. The training should be done well in advance of the first mold qualification, if you have a pilot tool stage this is an ideal time. It could be done whilst the production tools are being manufactured. It is strongly advised the tool builder is made aware of the requirements of mold certification (steel measurements) before tool manufacture is commenced.
It is recommended the entire mold validation be performed on the production injection molding machine.
Well before the mold is ready to be validated, begin to identify resources and equipment to measure the molded parts accurately and efficiently. A majority of the time to qualify molds is based upon how fast the parts can be measured after proper conditioning. In addition, identify the best means to capture the measurement data and analyze the results. Working these issues beforehand can dramatically reduce the amount of time required to follow this process. For an alpha injection mold (first production mold of a series) one should target two weeks to fully qualify the mold. For repeat molds of the same design (beta molds), the target should be three days.

Purpose:
The purpose of the injection mold validation procedure is to identify a capable mold-process which will achieve key part dimensions and tolerances. It is also the purpose of the injection mold validation procedure to establish a mold processing-window for the injection mold. This document provides a detailed description of the steps which will deliver the types of results a validation process is designed for.
The injection mold validation procedure will determine the molding process conditions necessary to give production personnel maximized process capability and also process adjustment range while maintaining a capable, controlled process, and while molding parts to specifications.

Safety:
Equipment is operated and tests performed only by trained and qualified personnel.

Comply with safety requirements as defined by ANSI/SPI B 151.1-1990. A copy of the "Horizontal Injection Molding Machines-Safety Requirements, Care, and Use" can be obtained from:

American National Standards Institute
1430 Broadway, New York, NY 10018
(212) 642-4900

Comply with quality assurance and good manufacturing practice as defined by ANSI.

Procedures:
The following steps are required in validating an injection mold according to injection mold validation flow chart.

1. Mold certification
2. Dry cycle mold
3. Process stability test
4. Gage repeatability & reproducibility (R&R) test
5. Mold viscosity test
6. Balance of fill analysis
7. Gate freeze test
8. Commissioning (multi-cavity analysis)
9. Design of experiments (DOX)
10. Qualification (process capability study)
11. Mold metal Adjustments - centering process
12. Verification (30-day run)

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Injection mold validation flow chart

The following steps are required in validating a injection mold according to injection mold validation flow chart.

1. Mold certification
2. Dry cycle mold
3. Process stability test
4. Gage repeatability & reproducibility (R&R) test
5. Mold viscosity test
6. Balance of fill analysis
7. Gate freeze test
8. Commissioning (multi-cavity analysis)
9. Design of experiments
10. Qualification (process capability study)
11. Mold metal Adjustments - centering process
12. Verification (30-day run)

injection mold validation flow chart

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It's K time 2010

Companies from the world’s plastics and rubber industry put their faith in K 2010 in Düsseldorf. Some 3,000 exhibitors will step out at the No. 1 event for the industry from 27 October to 3 November 2010. No other trade fair in the industry compares with K 2010 for the panorama it will provide on offerings from all over the globe. The extensive palette on display is once again assured by exhibitors’ international reach. Companies from every continent have signed up to showcase their innovations in the following categories:
- Raw materials, auxiliaries,
- Semi-finished products, technical parts and reinforced plastics,
- Machinery and equipment for the plastics and rubber industry.
Once again, suppliers from Germany, Italy, Austria, Switzerland and the USA as well as Asian manufacturers from China, Taiwan and India will be out in force. Among them will be not only the global market leaders but also a wealth of exciting newcomers.

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Safety precautions for extrusion blow molding

>> Sunday, 12 April 2009

Safety is everyone's responsibility in the workplace. Safety is most often related to good maintenance practice and good housekeeping. Safety needs to be an attitude that is always present in your daily activities. Employees should not be hesitant to voice safety concerns in the workplace. Management is just as committed to safety as the operators on the floor; the primary difference is that the operators are usually the closest to unsafe conditions; keep management advised of unsafe conditions.

The following list includes items which should be maintained to assure a safe working environment:

1. Floor and machine should be kept free of oil.
2. Floor and machine should be kept free of pellets.
3. Never reach over or under machine guards.
4. Never climb between the tie bars when hydraulic pumps are running.
5. Never disconnect or by-pass safety switches on guards.
6. In order to prevent mechanical hazards such as limbs being drawn into or trapped in the machinery, operators should not wear personal effects such as bracelets, watches, rings or chains during work shifts engaged in operating the blow molding machine.
7. Process only materials that are specified for use with the blow molding machine by the machine manufacturer.
8. Always wear adequate noise protection.
9. Use caution and wear protective gloves when making adjustments on hot die head components and manifolds.
10. Catwalks or platforms with railing should be present if hoppers such as drying hoppers stand tall enough whereby access requires climbing onto machine.
11. Know location of portable fire extinguishers; there should be an extinguisher no farther than 75 feet.
12. All electrical outlets should be marked as to the line voltage.
13. Never reach into the throat of an operating granulator. Unplug granulators before working on.
14. Always wear suitable foot and eye protection; safety glasses should be worn and steel toed shoes are recommended; soft soled shoes should not be worn.
15. Doe not operate any equipment unless suitable training has been completed.
16. All employees should be advised of any chemicals in the facility which are considered hazardous; read further about "Right To Know" laws for each particular state.
17. First aid kits should be available.
18. Advise operators that blow molding resin pressure can reach 4,000 psi and that hydraulic line pressure can reach 2500 psi. Clamp tonnage developed equals 2000 lbs of force for each ton; operators be advised.
19. Be conscious of sharp square corners on mold components and cavity parting line edges.
20. Razor knives also require extreme caution as their use results in many cuts.
21. NEVER use steel tools on the mold cores, cavities or parting line... Use brass, copper or aluminum. Brass can scratch highly polished steel, so use caution.
22. Do not stick fingers or rods into the barrel/screw feed throat area.
23. Examine air hoses and electrical cords to verify condition is proper; do not use cords with damaged insulation. Be especially observant when working near nozzle heater bands as these wires are easily
24. damaged.
25. Use only swivel type safety eyebolts; screw eyebolts far enough in such that thread engagement is 1.5 times the diameter.
26. Never stand directly below a mold suspended in air.
27. Avoid back injuries; lift properly with the back upright and straight; know your limitations and do not exceed them; use proper tools and get help when needed.

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Acetaldehyde A.A. in poly(ethylene terephthalate) processing

>> Wednesday, 1 April 2009

Acetaldehyde A.A. is an organic chemical compound with the formula CH3CHO. Is a colorless gas at room temperature and has a strong fruity smell. It occurs naturally in many fruits and other foodstuffs is used as a flavor enhancer for certain products and is produced by plants as part of their normal metabolism.

Acetaldehyde is also generated during the production and injection processing of poly(ethylene terephthalate), PET material. It can cause an off-taste in bottled water.
Generally, most acetaldehyde problems originate in the barrel during the injection process. All PET resins have some residual acetaldehyde after being manufactured, the quantity will vary according to the grade. Acetaldehyde is only generated while the PET resin is in its melt condition, therefore it can only be controlled by adjustments in the barrel (90%) and hot runner (10%) of the machine. The generation of acetaldehyde is not linked to moisture content of the material, although in the process of being dried, acetaldehyde can also be driven off. Therefore, correct drying is also important for acetaldehyde control.Possible causes listed in order of likelihood and / or ease of correction:

1. Barrel / hot runner heater overridingAcetaldehyde A.A. in poly(ethylene terephthalate) processing

Confirming that all heating zones are operating correctly will reduce problems such as: increased A.A. and lowered I.V. black specks, flashing, silver streaks etc. Check that:

  • Thermocouples are seated correctly and are free of any damage.
  • All heaters are drawing correct amperage using a clip-on ammeter. The actual temperature of each heating zone using an electronic or infra red thermometer.
  • All SSR's are switching correctly when commanded by the heat controller.
  • Wire connections are tight.

    2. Melt temperature settings too high
    Running the machine with the lowest practical melt temperature will reduce the risk of hydrolysis causing lowered I.V., and will limit degradation of the material that can lead to increased A.A. levels and other faults.
    Using a melt temperature that is too low can cause problems such as:

  • Damage to screw tip.
  • Broken low shear bolts.
  • Very long screw charge time.
  • Increased crystallization - crystals do not get melted properly so they become "seed crystals".
  • Poor mixing of the material.

    3. Injection velocity too high
    Keeping the injection velocity low will reduce the shear that occurs in the material. Shear is a major factor affecting overheating of the material and I.V. reduction, therefore reducing velocity will protect the PET resin from excessive damage.
    When working with hot preform method, the injection velocity will also make a significant difference to the material distribution in the finished container. Filling slower means that the preform will be hotter when the mold opens and its temperature balance will also have changed. Typically, the shoulder area will become relatively hotter than the base area giving more stretch at the top of the preform.
    Excessive injection velocity can also disturb the alignment of the injection core, especially if the design is long and thin.
    Reducing the injection velocity will also have the effect of making the holding time shorter since the V/P time will increase.

    4. Screw rpm too high
    The speed of screw rotation will be reduced. This will prevent excessive shear and associated frictional heating from ocurring. The end result will be better control of acetaldehyde and protection of the material I.V.

    5. Insufficient temperature / airflow in dryer
    A fault with the dryer will lead to hydrolysis of the material in the barrel of the machine. This will cause lowered I.V. of the material. Lowered I.V. is the major cause of bad quality in preforms and bottles. More than 60% of all PET processing related faults can be traced back to the dryer.
    Maintaining the dryer in optimum condition will allow the molding machine to perform at maximum efficiency and quality.

    Airflow - The most important parameter, there should be nothing causing a restriction in the process and regeneration air flow.
    Temperature - Process Temperature should be in the region of 145~170ºC Depending on the resin supplier and the drying time. Also check the Regeneration Temperature which should be around 200~230ºC depending on the maker.
    Time - Calculate (or measure) the time the material is in the hopper, this should be at least 3½ - 4 hours.
    Dewpoint - Correct dewpoint may vary according to the manufacturer of the dryer, consult the maker's manual before assuming an error exists.

    6. Incorrect choice of raw material
    One way to alleviate this is to use a copolymer. Comonomers such as CHDM or isophthalic acid lower the melting temperature and reduces the degree of crystallinity of PET. Thus the resin can be formed at lower temperatures and/or with lower force.

    7. Worn / damaged injection screw
    If the injection screw is worn, damaged or of an old design, it may not be plasticizing the material correctly and may be creating excessive shear.
  • Read more...

    Which poly(ethylene terephthalate), PET resin is the best one?

    >> Thursday, 19 March 2009

    Poly(ethylene terephthalate), PET resins have several basic differences follow this notes and find the one which is the best for your application.
    1. Intrinsic Viscosity, I.V. - ranging from 0.72 up to 0.85 for injection stretch blow molding.
    2. Polymer Type - Homopolymer or Copolymer
    3. Residual Acetaldehyde A.A Level - Normal or Reduced
    4. Cosmetic Grades - Able to resist crystallization.

    1. Intrinsic Viscosity, I.V.Poly(ethylene terephthalate), PET

    PET material for bottles is available in I.V. levels from 0.72 up to 0.85. Lower I.V. is more suited to fine details but will give lower strength in the final container and will have more tendency to flash. High I.V. material will give a stronger bottle but it may be impossible to form fine details in the preform or bottle.
    Low I.V. materials tend to be better if you need to blow an intricate shape but will result in a container having less strength and will become more difficult to control in the stretch blow process.
    A higher I.V. material will give better overall strength and it will be more easy to control. However, it will be more difficult to stretch into corners meaning that logos and textures will not be so well defined. In severe cases, it may also lead to pearlescence in the finished container.
    Some of these difference can be adjusted out by raising or lowering the preform processing temperature.

    2. Polymer Type
    Most bottles can be blown from either polymer type, differences will only tend to show up when the container design becomes a little marginal. For example, homopolymer will crystallize more easily than copolymer so it may not be suitable for thick preforms. On the other hand, if you require some crystal growth (for heat resistance) then a homopolymer may be the best choice.
    Copolymers also have a lower melting temperature than homopolymers and since it is a golden rule of PET processing to keep the melt temperature as low as possible to reduce degradation, then a copolymer again looks more favorable.
    As a rule, copolymers tend to be a little more expensive than homopolymers but this can be offset by their (generally) beneficial characteristics.

    3. Residual Acetaldehyde A.A. Level
    If you are producing a container for mineral water or certain soft drinks, then you probably should choose one of the grades having a reduced level of A.A. These often include the letter 'W' in their grade number to indicate suitability for water containers. These materials are generally a little more expensive than the standard type so if you are producing a non-food container (or a non-sensitive foodstuff container) then it is advisable to go for the cheaper option.

    4. Cosmetic Grades
    These grades have been specifically manufactured to be virtually non-crystallizable. As a result of the differences in manufacture and the relatively low demand, these can also be extremely expensive, as much as four times the price of "normal" PET. However, exceptional results can be achieved even with very thick preforms (6~10mm).

    How do know if I have selected a good material?
    Although it is possible to generalize about PET grades as shown above, the actual results on the machine can sometimes be different to those expected. Therefore it is advisable to do a practical test with a sample of the material.
    Different containers react to material type in different ways. If a material works well with one container, then it does not always guarantee that it will be good with all other containers. If a company has several machines and different mold designs, then it should sample the new material on all molds before committing to a bulk supply of the sample material.

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    W - Polymer Processing Glossary of Terms

    >> Sunday, 22 February 2009

    Weld Line - The point on a part where two plastic flow fronts meet during injection.
    Witness Line - A visible line on part due to two molding surfaces coming together. Witness lines always occur at parting lines.

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    V - Polymer Processing Glossary of Terms

    Variation - A change in the value of a measured characteristic.
    Vent - A shallow channel in the mold to allow air to escape from the cavity during injection.
    Virgin Material - Plastic material that has not been subject to use or processing other than that required for its initial manufacture.
    Viscosity - Internal friction or resistance to flow of a melt or liquid. The constant ratio of shearing stress to shearing rate. It is a measure of the materials resistance to flow.

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    U - Polymer Processing Glossary of Terms

    Ultimate strength - Term used to describe the maximum unit stress a material can withstand before breaking when subjected to a load in compression, tension or shear.
    Undercut - An indentation or protuberance on a part that impedes the removal of core and/or cavity.

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    T - Polymer Processing Glossary of Terms

    Tensile strength - The resistance of a material to longitudinal tension stress.
    Thermal conductivity - Ability of a material to conduct heat.
    Thermal degradation - Deterioration of material by heat.
    Thermal diffusivity - The ability of a material to transfer heat per unit time and area.
    Thermoplastic - Capable of being repeatedly softened by heat and hardened by cooling.
    Thermoset - A material that will undergo or has undergone a chemical reaction by the action of heat, catalysts, ultraviolet light,etc.
    Three-plate mold - Mold with two parting lines, one for part and the other to free trapped cold runner.
    Two-plate mold - Mold with one parting line used to free both part and runner.

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    S - Polymer Processing Glossary of Terms

    Shear - An action resulting from applied forces which cause or tends to cause two contiguous parts of a body to slide relative to each other in a direction parallel to their place of contact.
    Shear heating - Frictional heat generated within a plastic due to shear forces either in the extruder or in the runner system during injection.
    Shot - The yield of parts from a mold after one complete molding cycles, including scrap.
    Shot capacity - The maximum amount of material that the injection units ram or plunger can push out in one forward stroke.
    Shot size - The amount of plastic required to fill the mold.
    Shrinkage - The decrease in dimensions a plastic undergoes from molten state to a solid state. Shrinkage is compensated for by packing pressure, but some material shrinkage occurs after gate is frozen and for as much as 24 hours after it is molded.
    Sink Mark - An imperfection or depression in the surface of a part, generally cause by non-uniform shrinkage.
    SPC - Statistical Process Control. A statistical approach to controlling and improving a process.
    Sprue Bushing - Bushing which connects the nozzle of the injection unit to the molds runner system. Forms the sprue of the runner system.
    Standard deviation - A measure of the spread of a set of values about their average values, denoted by the letter s or sigma.
    Stress Crack - External or internal crack in plastic caused by tensile stresses less than that of its short time mechanical strength. The development of such cracks are accelerated by the environment (see ESC).
    Stripper Ejection - Type of ejection which stripping the molded part from the core.
    Stroke - Distance moved.
    Suck-Back - Also called Decompression. After the shot has accumulated, the nozzle retracts an additional amount to pull the plastic back to prevent drooling.
    Surface Finish - The amount of gloss or matte on a surface.

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    R - Polymer Processing Glossary of Terms

    Recovery - The injection unit building up (plasticizing) for a next shot.
    Regrind - A thermoplastic from one process or cycle (scrap, runners, etc.) ground up to be used for a future molding cycle.
    Resin - Any of a class of solid or semi-solid organic products of natural or synthetic origin. Most resins are polymers.
    Runner - Channel in mold that connects sprue to gate.
    Runnerless molds - Molds which are designed so that the runner is heated and stays molten. Runner is not ejected with part each shot.

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    P - Polymer Processing Glossary of Terms

    Parting line - Line, visible on the mold part, where mold separates to release the molded part from the cavity.
    Pearlescent pigments - A class of pigments consisting of particles that are essentially transparent crystals of a high refractive index. The optical effect is one on partial reflection from the two sides of each flake. When reflections from parallel plates reinforce each other, the result is a silvery luster, iridescent effects and metallic sheen resembling natural pearl.
    PET - Polyethylene Terephthalate, known as a thermoplastic polyester. Has the unusual ability to exist in either an amorphous or highly crystalline state.
    Plasticize - To soften a material and make it plastic or moldable, either by means of an extruder or by heat or both.
    Platen - The plates on which the mold assembly is mounted. Large metal blocks on clamping ends of molding machine used to support mold.
    Polycarbonate resins - Polymers derived from the direct reaction between aromatic and aliphatic dihydroxy compounds with phosgene or by the ester exchange reaction with appropriate phosgene- derived precursors.
    Polyethylene - A polyolefin composed of polymers of ethylene. Exists in three classes: low, medium and high density.
    Polymer - A high-molecular weight organic compound whose structure can be represented by repeated small units.
    Polymerization - A chemical reaction in which the molecules of a monomer are linked together to form large molecules whose molecular weight is a multiple of that of the original substance.
    Polypropylene - A tough, light-weight polyolefin plastic made by the polymerization of high-purity propylene gas in the presence of an organometallic catalyst at relatively low pressures and temperatures.
    Process - A set of conditions or set of causes working together to produce an outcome. In injection molding the key process variables are Time, Temperature, Pressure, and Flow Rate
    Process capability - The common variation of a process; the short term variation under controlled conditions. This variation is always present in a process and capability measured as the best the process will ever produce unless changed.
    Purging - The forcing out of resin from the extruder.

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    O - Polymer Processing Glossary of Terms

    Olefins - A group of unsaturated hydrocarbons and named after the corresponding paraffins by the addition of ene or ylene to the stem. Examples are polyethylene, polypropylene, etc.
    Orientation - The alignment of crystalline structure in polymeric materials so as to produce a highly aligned molecular structure.

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    N - Polymer Processing Glossary of Terms

    Nozzle - The hollowed metal cone nose screwed into the extrusion end of the extruder screw that mates with the mold via the mold's nozzle bushing. The nozzle allows transfer of the molten plastic from the extruder to the mold runner system and cavities.

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    M - Polymer Processing Glossary of Terms

    Matte finish - A surface which displays no gloss when observed at any angle.
    Mean - See Average
    Melt Flow Index - The amount, in grams, of a thermoplastic resin which can be forced through a 0.0825 inch orifice when subject to 2,160 grams force for ten minutes at 230°C, per ATSM D1238
    Metallizing - Applying a thin coating of metal to a non-metallic surface.
    Metering Zone - The final zone of an injection barrel or screw, at which the melt is advanced at a uniform rate to the screw tip.
    Mold - The cavity or matrix of cavities into which plastic melt is placed and takes form.
    Mold Components - Parts that make up a mold and determine how a mold will be operated.
    Mold Frame - Series of metal plates which support mold components.
    Multi-cavity Mold - A mold with two or more cavities.

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    L - Polymer Processing Glossary of Terms

    L/D ratio - Length to diameter ratio of an extruder screw.
    LDPE - Low Density Polyethylene
    Lead In - Initial clearance through an initial angle or chamfer that helps align two close mating parts.
    Linear Molecule - A long chain molecule of two-dimensional structure which may contain side chains or branches.
    lLDPE - Linear Low Density Polyethylene
    Lubricants - Prevent materials form sticking or improve processability.

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    K - Polymer Processing Glossary of Terms

    Knockout - Any part or mechanism of a mold used to eject the molded article.
    Knockout bar - A bar that ejects the molded article from the mold. It is usually activated automatically while the mold is opening.

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    J - Polymer Processing Glossary of Terms

    Jetting - A turbulent flow in the resin melt caused by an undersized gate or where a thin section becomes thicker. Can also occur when gating into and along a thick section.

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    I - Polymer Processing Glossary of Terms

    Impact strength - The ability of a material to withstand shock loading.
    Inert additive - A material added to a plastic compound, such as a filler, which may alter the properties of the finished article but which does not react chemically with any other constituents of the composition.
    Injection pressure - Pressure exerted on plastic to fill, pack, and hold mold. Comprised of Boost and Hold pressure.
    Injection ram - The ram which applies pressure to the plunger in the process of injection molding.
    In-mold decorating - The process of applying labels or decorations to plastic articles simultaneously with the molding operation.
    Interference fit - The mating of two points, lines, or surfaces, the dimensions of which cause negative clearance between them.

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    H - Polymer Processing Glossary of Terms

    Hardness - The resistance of a material to compression or indentation. Among the testing methods Brinell, Rockwell, and Shore
    HDPE - High density polyethylene
    Heat deflection or distortion point - The temperature at which a standard test bar deflects 0.010 inches under a stated load of either 66 or 264 psi. Indication of maximum temperature that you can eject a part from a mold.
    Hold (2nd Stage Pressure) - Sufficient pressure applied to cavity that doesn't allow plastic to flow into or out of the cavity until the gate is frozen.
    Hopper - Feed reservoir into which material is loaded from which it falls into a mold machine's injection unit.
    Hot runner mold - Type of runnerless mold. Runner is not ejected with part each cycle

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    G - Polymer Processing Glossary of Terms

    Gate - An orifice through which the molten resin enters the cavity.
    Gate blush - A blemish or disturbance in the gate area of an injection molded article. It occurs when the melt fractures in leaving the gate due to relaxation of elastic forces.
    Gel permeation chromatography - A device used to determine the molecular weight distribution of a polymer.
    GPC - An abbreviation for Gel Permeation Chromatography.
    Guide pins - Devices to maintain proper alignment for molds.

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    F - Polymer Processing Glossary of Terms

    >> Wednesday, 18 February 2009

    Feed zone - Zone on injection screw directly below hopper. Plastic is pre-heated in this zone, not melted.
    Filler - A substance added to the plastic to make it less costly. Some fillers also improve mechanical properties.
    Finish - The ultimate surface of a plastic part.
    Flash - The thin, surplus web of material which is forced into crevices between mating surfaces during a molding operation, and which remains attached to the molded article.
    Flow lines - Wavy surface appearance caused by improper flow of the resin into the mold.
    Fluorescent - Organic dyes or pigments which may be blended into inks to provide a luminescent or fluorescent appearance typical of the "neon" colors.
    Frictional heating - See Shear Heating

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    Poland’s chemical sector privatization vision

    >> Monday, 16 February 2009

    For those who are interested in polish chemical sector and its privatization Privatization near to collapse in Poland's chemical sector - Missed the boat. From the same source by earlier Poland to privatize 19 chemical companies by 2011 - The privatization polka.

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    E - Polymer Processing Glossary of Terms

    >> Sunday, 15 February 2009

    Ejection - That part of the molding cycle in which the finished part is removed from the mold mechanically.
    Ejection system - System used to eject the molded part from the mold after it cures.
    Ejector plate - A plate which backs up the ejector pins and holds the ejector assembly together.
    Elastic deformation - The part of the deformation of as part under load which is recoverable when the load is removed.
    Elasticity - The property of a substance which enables it to return to its original shape and size after removal of a deforming force.
    Elongation - Lengthwise stretching of a material usually denoted as a % of original length.
    Environmental stress cracking (ESC) - The susceptibility of a plastic to crack or craze under the influence of certain chemicals, stresses, or other agents.
    Ethylene plastics - Plastics based on polymers or co-polymers of ethylene.
    EVA (Ethylene-Vinyl Acetate) - Co-polymers from these two monomers retain many of the properties of ethylene, but have considerably increased flexibility, elongation, and impact resistance.
    EVOH - Ethylene-vinyl alcohol co-polymers. Used for barrier to gases.

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    D - Polymer Processing Glossary of Terms

    >> Tuesday, 10 February 2009

    Daylight opening - Clearance between the two platens of the press in the open position.
    Decompression - See Suckback
    Degradation - A deleterious change in the chemical structure of a plastic.
    Degating - The removal of material left on a plastic part formed by the opening through which material was injected into the mold cavity.
    Degree of polymerization - The average number of monomer units per polymer molecule, a measure of molecular weight. In most plastics, the molecular weight must reach several thousand to attain worthwhile physical properties.
    Density - Mass per unit volume of a substance, exposed in units such as grams per cubic centimeter, pounds per cubic foot or pounds per gallon.
    Desiccant - A substance capable of absorbing water vapor from air or other gaseous material, used to maintain low humidity in a storage or test vessel.
    Draft - The degree of taper of a side wall or the angle of clearance designed to facilitate ejection of parts from the mold.
    Dry coloring - A method commonly used for coloring plastics by tumble-blending uncolored and colored particles of the plastic material with selected dyes and pigments.

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    C - Polymer Processing Glossary of Terms

    >> Monday, 9 February 2009

    CAD - Computer Aided Design. Use of computer to draw/design parts.
    Cap - Closure
    Capacity - The rated amount of volume (# parts) produced by a mold/molding machine per year.
    Capper - Machine that applies a closure to a bottle on a packing line.
    Cavitation - The number of molding stations within a mold.
    Cavity - Mold component(s) which form the exterior or external surfaces of a part.
    Centerline - A line drawn down on part drawing that represents the geometrical center of the part in that axis.
    Charge - The amount of material volume or weight required for the injection unit to plasticize for each molding cycle.
    Chemical resistance - Ability of a material to retain utility and appearance following contact with chemical agents.
    Child resistant closure (CRC) - A closure that requires dissimilar motions which may make removal by a child difficult. Subject to government regulations.
    Clamp speed - Speed at which the mold platens will open and close; controlled by operator settings.
    Clamp tonnage - Amount of force, in tons, that a machine is capable of exerting on the mold. Insufficient tonnage will allow the mold to flash at the parting line when the mold is filled under high pressure.
    Clamp plate - A plate fitted with the mold and used to fasten the mold to the molding machine's platens. The outermost plates on an injection mold.
    Clarifier - An additive that increases transparency of a plastic material.
    Clearance - Controlled distance by which one part of an object is kept separated from another part.
    Closure - A device used to seal off the opening of a container, so as to prevent loss of contents.
    Coefficient of expansion - The fractional change in length of a material for a unit change in temperature
    Cold slug well - A void located directly beneath the sprue, designed to collect unmelted plastic and to provide a means of positive ejection.
    Color concentrate - A measured amount of dye or pigment incorporated into a pre-determined amount of plastic. This pigment is then mixed into larger quantities of plastic material to be used in molding.
    Colorant - Any substance that imparts color to another material or mixture. Colorants can be either dyes or pigments
    Compression ratio - In a helical extruder screw, the ratio of volume available in the first flight at the hopper versus that available in the last flight at the end of the screw.
    Conditioning - Subjecting a material to standard environmental and/or stress history prior testing.
    Control chart - A graphical method for evaluating whether a process is or is not in a state of statistical control (stable). The decisions are made through a comparison of the values of some statistical measurement calculated from the data with control limits.
    Control limits - Limits on a control chart that serve as a basis for judging whether or not a process is in a state of statistical control (stable)
    Core (core pin) - Mold component which forms internal surface of the molded part.
    Cooling channels - Channels or passageways located within the body of the mold through which cooling medium can be circulated to control temperature on the mold surface.
    Crazing - Fine cracks which may extend in a network on or under the surface or through a layer of a plastic material.
    Creep - The dimensional change with time of a material under load, following the initial instantaneous elastic deformation.
    Crystalline polymer - Plastic whose state of molecular chains are in a uniform, regular arrangement.
    Crystallinity - A state of molecular orientation which denotes an orderly compact structure of the molecular chains forming the polymer.
    Cushion - Volume of plastic in-between screw end of barrel when shot is injected into mold.
    Cut-off - Point at which the injection unit goes from filling to packing. Cut-off point can be based on screw position, time, or pressure.
    Cycle - The complete sequence of operations in an injection molding process to complete a set of parts.
    Cycle time - Time during which one molding cycle is completed.

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    B - Polymer Processing Glossary of Terms

    >> Sunday, 8 February 2009

    Back draft - A slight undercut or tapered area in a mold tending to prevent removal of the molded part.
    Back plate - A plate used as a support for the cavity blocks, guide pins, bushing, etc. Sometimes called support plate.
    Back pressure - Pressure exerted by the injection unit's cylinder against the screw as it recovers or plasticates. Used to increase the melt homogeneity. Increases melt temperature.
    Baffle - A plug or other device inserted in a flow channel to divert cooling medium to a desired path.
    Balanced runner - A runner system designed to place all cavities at the same distance from the sprue.
    Ball check valve - An anti-back flow valve which prevents the plastic melt from flowing back over the screw during injection.
    Band heaters - Electrical heaters surrounding the barrel and nozzle of the injection unit.
    Bar chart - Histogram
    Barrel (extruder) - Hollow tube in which plastic is gradually heated and melted. Inside the barrel is a helical screw which compresses and moves the plastic from the feed throat (hopper end) to the injection nozzle (mold end). Outside the barrel are band heaters.
    Barrier - A layer of material designed to limit migration or infiltration of undesirable elements through the plastic or limit the loss of desirable elements through the plastic.
    Barrier properties - Material; permeability characteristics which limit the migration or permeability of elements.
    Blueing off - A mold making term for the process of checking the accuracy of mating of two surfaces by applying a thin coating of Prussian Blue on one surface, pressing the coated surface against the other surface, and observing the areas of intimate contact where the blue color has been transferred.
    Boost (1st Stage Pressure) - Pressure exerted on melt to fill the mold cavities.
    Burned - Showing evidence of excessive heating during processing or use of a plastic, as evidenced by blistering, discoloration, distortion or destruction of the surface.
    Bushing - The outer ring of any type of circular tube or pipe die which forms the outer surface of the tube or pipe.

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    A - Polymer Processing Glossary of Terms

    >> Saturday, 7 February 2009

    ABS (Acrylonitrile-butadiene-styrene) - Blends of copolymers or styrene-acrylonitrile copolymer with butadiene-acrylonitrile rubber.
    Accumulator - Auxiliary cylinder and piston (plunger) mounted on injection molding machine. It is used to provide extremely fast molding cycles through accumulation of molten plastic from the main extruder (reducing plastication time) and forces the plastic into the mold during filling at high speed and pressure (reducing fill time).
    Acetal resins - The molecular structure of the polymer is that of linear acetal, consisting of unbranched polyoxmethylene chains.
    Achromatic color - A neutral color (white, gray or black) that has no hue.
    Acrylic - Polymethylmethacralate
    Additives - Used to enhance processing, performance, appearance, and/or economics of the basic plastic formulation.
    Aesthetics - The sum total of the visual response (color, shape, feel, etc.) to the appearance of a part.
    Amorphous phase - Devoid of crystallinity; no definite order. The plastic is normally processed at the amorphous phase temperature.
    Annealing - A process of holding a material at a temperature near, but below, its melting point. The objective being to permit stress relaxation without distortion of shape.
    Anti-stat - An additive to dissipate static charges. Adds lubricity.
    Antioxidant - Additive that minimizes or prevents the effects of oxygen attack on the plastic (e.g. yellowing or degradation). Such additives may render the plastic brittle or to lose mechanical properties.
    ASTM - Abbreviation for American Society and Testing and Materials, said to be the largest non-governmental standards-writing body in the world.
    Average or mean - The sum of the numerical values in a sample divided by the number of observations.

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    Dynamic viscosity

    >> Saturday, 24 January 2009

    Material                     Dynamic viscosity, Pa·s
    Air (temp. 200C) 10-5
    Water (temp. 200C) 10-3
    Mercury (temp. 200C) 1,5·10-3
    Aluminum (temp. 7000C) 1,1·10-3
    Zinc (temp. 7000C) 1,7·10-3
    Iron (temp. 14000C) 6·10-3
    Blood (temp. 370C) 10-2
    Oil 10-2-100
    Honey 101
    Melted polymers 102-104
    Cake 103-105
    Cheese 107-108
    asphalt 108
    Melted glass (temp. 5000C) 1012
    Glass 1040

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    Biggest-ever agricultural film production line

    >> Sunday, 18 January 2009

    Reifenhäuser supplied in 2005 a 35 m high 3-layer blown film line. Essential components of the new wide film extrusion line are:

    - gravimetric dosing system for each extruder,
    - 2 extruders, 150 mm screw diameter,
    - 1 extruder, 200 mm screw diameter,
    - 3-layer blown film die with internal bubble cooling and 2200 mm die diameter ensuring a high production capacity,
    - high-performance air ring KRF 2200,
    - film guiding system with 4 ultrasonic sensing arms, collapsing assembly and side gusseting unit,
    - 8-ply folding station for C-type folding enabling simple handling of the oversized film widths in greenhouse construction,
    - fully automatic short-length winder FAC 4200 with bobbin magazine, adjustable for winding different film lengths and to cope with extremely short reel changing cycles,
    - REIcofol automation system for process control, including film measuring station and indication of side gusseting depth.


    The new 3-layer blown film line is designed for an extremely high production capacity of 2200 kg/h. Films of a circumference of up to 18,5 metres and thicknesses from 0,080 to 0,200 mm can be produced on this line. The immense total construction height reaches 35 metres. Coextruded 3-layer films are distinguished by specific properties, e.g. weather resistance, permeability to light, air-conditioning effects and high tear resistance. In addition, the consumption of raw materials processed on coextrusion lines is considerably reduced. A great advantage of a coextrusion line over a mono-layer line is that expensive additives can be used in the thin outer layers only. Also, exact matching of materials to requirements is much simpler. Multi-layer films with a durability of up to four years can be very economically produced as a result.

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    3D polymer's structure model

    All you have to do is one click on the picture and then experiment with available options

    Polyethylene, PE
    Polyethylene, PE


    Polypropylene, PP
    Polypropylene, PP


     Polyvinyl chloride, PVC
    Polyvinyl chloride, PVC

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    Random polypropylene copolymer

    >> Sunday, 11 January 2009

    Polypropylene is thermoplastic polymer consisting mainly of propylene come from a low pressure process based on catalysts and have generally linear polymer chain. There are three general types of polypropylene: homopolymer, random copolymer and impact or block copolymer.
    Random copolymer is produced by statistical insertion of units mainly ethylene. Through this, the glass transition temperature and melting point are lower than in homopolymer.
    Additionally we receive better mechanical properties in the temperature below zero (e.g. impact) and optical (transparency). Processing of random copolymer by injection molding considering properties mentioned above characterizes lower temperature (lower cycle time) and pressure. Application, e.g. thin wall and transparent products on the other hang thick wall, because of lower crystallization ratio (amorphous structure).

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    Polish polymer processing companies

    >> Tuesday, 6 January 2009

    The story of Ponar Zywiec

    The successor of the machine factory with more than 100 years of traditions in construction of different kinds of machines, among them also machines with hydraulic drive, has specialized in construction of injection moulding machines and hydraulic presses for plastics and rubbers for above 30 years.

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