Injection mold validation procedure

>> Tuesday, 11 August 2009

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.

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.

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.

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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