tries, but most particularly for the medical industry. There were several complications that arose when Dynomax increased its medical precision-molding production, specifically cracking, weld lines, and short shots. These are all caused by a combina- tion of similar issues resulting from dif- ficulties in filling the last place the mold fills with plastic. It is the most difficult area to fill for several reasons: First, air and molding gas are often trapped in this area, creating air pockets or shot shorts in the final molded part. Second, when the plastic enters the mold tool, it is at its highest temperature. However, as it fills in throughout the tool, the temperature cools at a very high rate, making the last place to fill (and the area where the plastic comes together) the most difficult. Lastly, the raw material itself can present a challenge.
Another step Dynomax took to improve their precision micro-molding process was to invest in new
technological equipment.
It is very difficult to fill a high per- centage of glass-filled material through thin-wall areas. When filling a mold with 30-40% glass-filled LCP in the areas that are only .003”, it is possible for the glass particles within the material to be larger than the width of the wall. To solve these issues, Dynomax had to make certain adjustments. Simple fixes could be done to solve a few of the problems: better ventilation to keep air pockets from forming in the mold; using a custom formulated grade of material with smaller glass fibers to account for the thin walls; making adjustments to mold tools. Unfortunately, these solu- tions were not enough to fix every issue.
Dynomax began using mold flow analysis software with every new injection mold tool they designed and manufac- tured. Using this software, they were able to run a mold flow simulation prior to building the mold tool in order to determine