How Open Molding Works
For larger parts, the simplest open molding process is hand lay-up. Using this process, precut fiber pieces are placed on the mold and resin is applied. Our team at MFG West then manually rolls all of the entrapped air out of fiberglass, leaving a finished, smooth part.
When producing more intricate parts, we use the spray-up or chopping process. The fiberglass chop and resin flow are pushed through the chopper unit and air pressure sends the resin mixture onto the mold through a spraying motion. As in hand lay-up, our MFG West team manually rolls out air bubbles to get the finished, smooth part.
At MFG West, open molding begins with a release agent which is spray coated on the mold to ensure that the part will discharge from the mold smoothly. The mold then is gel coated with a pigmented polymer to give the part the specified color finish. Next, fiberglass is added to the part, either by the hand lay-up or spray-up process. The required thickness of the part determines how many layers of the fiberglass material will be used. Once the fiberglass cures, another layer of gel coat is added, if needed, for the end product application of the part.