Manufacturing 101: Injection Molding
Injection molding is the process of heating plastic pellets (resin) into a liquid form, injecting it under high pressure into a mold, and then letting the liquid cool into a solid before opening the mold and pulling out the piece. As you can see in the photo, plastic dice are molded in multiples. The mold is designed around a specific number of cavities, based on the total production volume required. When the group of dice is removed from the mold, they are all connected by the plastic that fills the main distribution ports of the mold, called the “sprue”. After the dice are removed from the sprue, this scrap plastic can sometimes be ground up again and reused for other molding requirements. The small area where the plastic fills the cavity that forms the dice is called the “gate”. You’ll see in the photo that injection molding allows for a high degree of creativity in mixing colors, in this case clear and blue acrylic. This can create a swirl effect in the dice.