polymer processing

Safety is everyone's responsibility in the workplace. Safety is most often related to good maintenance and good housekeeping. Safety needs to be an attitude that if 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 bars when pumps are running. 5. Retract injection. unit before entering the bar space. 6. The front gate should have an electrical, hydraulic and mechanical safety device preventing clamp from closing when the front gate is open. 7...

The ninth step in validating a injection mold with the overall process shown in injection mold validation flow chart is Design of Experiments . The steps before: 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) Purpose: The purpose of the Design of Experiments (DOX or DOE) is to identify the optimum mold process and the mold process window. A solid statistical understanding of DOX is necessary. There are many different types of software that can be used to assist you in performing design of experiments properly. Use the software that you are most comfortable with. The DOE can require a large amount of time to perform depending on the number of variables selected to test. In some cases a properly conducted DOX can require 2-3 days to perform as well as additional time to measure part attributes. I...

The eight step in validating a injection mold with the overall process shown in injection mold validation flow chart is Commissioning (multi-cavity analysis) . The steps before: 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 Purpose: The purpose of commissioning is to ensure that all cavities in the mold deliver the same quality, i.e., there is no difference between cavities in the mold on the critical dimensions. The time required to perform this analysis is a function of the number of cavities and number of critical dimensions. The time on the injection molding machine is minimal compared to the time required to measure the parts. However, by performing this analysis it will significantly reduce the number of parts required to test and measure for future experiments on the multi-cavity tool. A solid understanding of creating and inter...

The seventh step in validating a injection mold with the overall process shown in injection mold validation flow chart is Gate Freeze Test . The steps before: 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 Purpose: The purpose of the gate freeze test is to identify the hold conditions necessary to freeze the gate. The extent and duration of hold pressure has a large effect on the dimensional stability and outer appearance of the molded part. If the hold time is too short, the gate will not have had enough time to freeze off and sink marks could appear on the part. This is especially true of larger parts and when higher hold pressures are employed. After the mold gates "freeze", hold pressure has no effect and should be terminated at that point. It is typically better to be a little high on the hold pressure timer setting. This will cause a sli...