Plastic Injection Molds
Use plastic injection molding to quickly manufacture a large number of plastic itemsPlastic injection molding is a technique for manufacturing plastic in which molten plastic is injected into a mold at a high pressure and allowed to cool before it is removed from the mold. Plastic injection is the most common method of plastic manufacturing and can be used with a variety of plastics including nylon, polyethylene, polyvinyl chloride and styrene.
The machines that perform plastic injection are called presses and hold the mold closed while they are filled. Plastic injection molds require pressure ranging from under five tons to more than 6,000. The plastic molds are relatively expensive to make and usually only economical for production runs in the thousands of units.
The most expensive and longest-lasting plastic molds are made from some type of hardened steel. Aluminum molds are much cheaper and are economical for hundreds of thousands of runs while copper-beryllium molds are most often used for molds that generate a great deal of heat.
Three points to consider when using plastic injection molds are:
- Hot runner plastic molds have advantages over cold runner molds.
- Manufacturers offer test runs so you can get the bugs out of your plastic injection molding process.
- Not all manufacturers are equipped to handle odd-shaped projects.
Choose between cold runner plastic molds and hot runner molds
Sample different plastic injection processes to find the best one for your partMany full-service plastic mold manufacturers offer mold tryouts and limited production runs. This allows you to find defects in your molding process before tooling up for full-scale production.
Use a company experienced in plastic part design for unusual partsSome types of plastic parts do not lend themselves to the plastic molding process and may require special expertise in designing the part.
- Fill new plastic molds slowly to 99% capacity. Apply a holding pressure until gate freeze-off has occurred and increase the pressure until the parts no longer have sinks. Produce a setting sheet to repeat the desired results.
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