Mold Best Assurance Company Limited
In one situation I experienced, the tool was properly cleaned, sprayed with rust preventative, and pulled from the press; but the water leak was not noticed, allowing the water to accumulate inside the clearance holes. With the tool sitting in storage, the water leaked into the diamond-polished cavity and caused major damage.
In this column, I will discuss best practices for cleaning and maintaining the mold in the press to reduce downtime from part scrap and tooling issues. Last month I covered design of water lines and moving components to reduce maintenance issues.
Processing conditions are the key to success with LFRTs. It is possible to make good parts from LFRT materials using a general purpose injection machine and properly designed tools as long as the right processing conditions are used. However, even with the proper equipment and tool design...
Good part and tool design practices will also go a long way toward maintaining the fiber length of LFRTs. Eliminating sharp corners around the edges of the part (including ribs, bosses, and other features) avoids unnecessary stresses in the molded part and reduces fiber attrition, as well.
One commonly asked question regarding LFRT processing is whether it is possible to use existing injection molding equipment to mold these materials. In the vast majority of cases, equipment used to mold short fiber compounds can also be used to mold LFRTs.
Long fiber reinforced thermoplastics (LFRTs) are being used in injection molding applications that demand a high level of mechanical property performance. While LFRT technology is capable of excellent strength, stiffness...
Not only injection mold temperature determines melt temperature as it moves quickly through the mold. The melt temperature itself as it starts its journey through the injection mold (self-evidently) is the reference point. Speed of injection, particularly in thin sections, is of huge influence, as it will determine the degree of shear heating.
Many engineering materials like PBT (Polybutylene terephthalate) have a tendency of out-gassing. The best practices that I have to date are: Add 10mm wide vents spaced 30mm from each other all the way around parting line. Always follow the recommendations of the material company for vent depth.
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