Injection molding remains the most successful and widely used method for molding plastic materials. Injection molding is different from compression molding, because the entire molding process takes place in one machine.
Prior to the mid-1980s, plastic molding compound contained asbestos as a filler material because it added strength and heat resistance to molded products. Even though injection and compression molding processes are different, exposure to asbestos was nearly identical to the compression molding process; bags and barrels of plastic molding compound were opened and dumped into a large hopper, creating a cloud of asbestos dust which the workers inhaled.
After the granular plastic molding compound entered the hopper, it was fed into a large cylinder and heated. A plunger forced the plastic molding compound from the hopper into the heating unit, where it melted. The molten plastic compound is fed through a nozzle and into the mold cavity to form the molded product. Air or water circulated around the mold so that its contents cooled and cured quickly. When the mold cooled and the plastic hardened, the mold was opened and the plastic pieces were removed by a molder. An air hose removed dust and debris from the mold, and this process created asbestos dust the molder inhaled.
Once the asbestos-containing molded plastic reached the finishing department, it was placed into the tumbling machine where workers were exposed to asbestos dust. The same finishing process was used in the compression molding process. The tumbling machine removed any imperfections and excess plastic from the finished molded pieces. After the cycle was complete, the tumbling machine operator removed the molded plastic pieces and sent them to another finishing department employee to remove additional excess plastic by hand. The tumbling machine operator used an air hose to blow out excess dust and debris that collected in the machine from the tumbling process. This process generated a visible cloud of dust that the tumbling machine operator inhaled.
When the tumbling process did not completely remove the rough edges left behind from the mold, additional filing of the molded pieces was required. Workers in the finishing department hand-filed, sanded and polished the finished pieces. Hand-filing and sanding created even more dust that these workers inhaled. Finally, the end product was packaged and shipped.
If you or a loved one has been diagnosed with mesothelioma, lung cancer or another asbestos-related disease because you worked with or around asbestos-containing plastic molding compound, please contact us today.