sishie
How am i going to have a standard parameter setting in one machine
Injection moulding
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replied to: sishie
pmestl
Replied to: How am i going to have a standard parameter setting in...
Where this may not be the answer you wish to hear, it is reality for most of us as you may already suspect. Since the environment around us changes and most polymers tend to behave differently with age and humidity, standard settings are not likely. Knowing your machines and molds are under continual wear is another issues that can influence standards.
Using the same machine and same source for your polymer are a start to maintaining reasonably close standards. Remember even the same polymer source will vary the product slightly. Some polymers can collect mositure while in storage, pre-drying may be needed to ensure consistent moisture content increasing the potential for near standard parameters.
Document your settings (bore temperatures, screw turn rates, hold times, temperature of chilled water and the ambient conditions. Verify the sorrounding temperature and humidity, drafts from blowers, fans, open windows or bay doors can introduce stability issues with temperature and humidity. The bore, screw and mold must be clean. Start with an air shot with each set up to varify the temperature leaving the sprue, shear is an important effect in the molding process, make sure the temperature for the bore accounts for the increased temperature leaving the sprue.
The subtle shifts in parameters is part of what makes plastic molding unique. The polymer and the implications of molding it are mathematically documented as a science, but it still requires human intervention to make the math fit the real world. Plastic polymers are visco-elastic, understanding the tolerance of the polymer will greatly enfluence the standards you can use. Being at the higher or lower end of
Finally, as you may know continually degrading parameters are an indication of wear on the machine or mold.
Amazon has a few good books on the engineering science of plastic polymer molding that could help you, but they are the science and not the reality.
Our commercial WEB site also offers a free on-line magazine that discusses the intracies of plastic polymer molding. Now and then we discuss how to deal with variances beyond the science.
PMESTL
Using the same machine and same source for your polymer are a start to maintaining reasonably close standards. Remember even the same polymer source will vary the product slightly. Some polymers can collect mositure while in storage, pre-drying may be needed to ensure consistent moisture content increasing the potential for near standard parameters.
Document your settings (bore temperatures, screw turn rates, hold times, temperature of chilled water and the ambient conditions. Verify the sorrounding temperature and humidity, drafts from blowers, fans, open windows or bay doors can introduce stability issues with temperature and humidity. The bore, screw and mold must be clean. Start with an air shot with each set up to varify the temperature leaving the sprue, shear is an important effect in the molding process, make sure the temperature for the bore accounts for the increased temperature leaving the sprue.
The subtle shifts in parameters is part of what makes plastic molding unique. The polymer and the implications of molding it are mathematically documented as a science, but it still requires human intervention to make the math fit the real world. Plastic polymers are visco-elastic, understanding the tolerance of the polymer will greatly enfluence the standards you can use. Being at the higher or lower end of
Finally, as you may know continually degrading parameters are an indication of wear on the machine or mold.
Amazon has a few good books on the engineering science of plastic polymer molding that could help you, but they are the science and not the reality.
Our commercial WEB site also offers a free on-line magazine that discusses the intracies of plastic polymer molding. Now and then we discuss how to deal with variances beyond the science.
PMESTL