• Fried Egg - PVC Magnet
  • Chocolate Chip Cookie - PVC Magnet

Plastisol Casting by Piper Platics Corp.

Since plastisol is primarily a suspension of PVC particles in a liquid plasticizer, it flows as a liquid and can be poured into a open mold. When the mold then gets heated to the proper temperature, the PVC resin swells and begins to absorb the plasticizer. After cooling the mold, a flexible, permanently plasticized solid product results.

This process is good for refrigerator magnets, key tags, and door mats; basically anything with a "flat" bottom because of the open mold.

Plastisol can also be used for slush molding or slush casting, a form of spin casting that is more complex than relatively simple open mold casting, but less expensive and less sophisticated than the injection molding used for most plastic products.

It requires metal molds that are filled with liquid plastisol. When the open mold cavities are filled, the mold is spun on a heavy duty, high speed centrifuge to force the liquid vinyl into all of the fine detail on the interior of the mold.

fried egg magnet

Then the metal mold is placed into a heating solution, usually an industrial salt heated to about 204 °C (400 °F). The liquid vinyl cooks for a few seconds. and a gel layer of plastisol forms on the inside surface of the mold.

The mold is then removed from the heating solution and the liquid that has not yet gelled is poured out. This leaves a thin skin of vinyl on the interior surface of the metal mold. The mold is then placed back into the heating solution for three to four minutes to cure.

After curing, the mold is again removed from the heating solution, cooled with water, and placed on a rack. While the vinyl part is still warm in the mold, it is very flexible and can be removed from the mold. When the parts cool, they become rigid and are ready for assembly.

The metal molds can produce an unlimited number of castings.

Unlike the flexible molds used for resin casting, metal molds are not adversely affected by heat. The metal molds allow grouping of several parts in one mold cavity and several mold cavities in one mold for faster production.  An example of a part that is made in this way is a boat bumper.

Custom Casting Services we offer: 

  • Intricate & Complex Shapes.
  • On-Site Pattern & Tool Development saves you time & money.
  • CAD/CAM, SPC/SQC to Custom Specs.
  • All Colors, Textures & Durometers.
  • FDA / USP / Automotive materials
  • Thickness from .031" to 12"