When it comes to the manufacture of parts, there are many methods which can be used including reaction injection molding, structural foam molding and polyurethane injection molding or plastic injection molding.
Structural foam molding is a process where inert gas is added to a melted polymer. That melted polymer is then injected into an injection molding tool. As the tool cools, a skin forms against the mold and the action produced through foaming creates a honeycomb structure that reduces shrinkage once molding is finished.
With structural foam molding, parts produced are significantly lighter and there are many other advantages to using this process:
- Low stress: The process of structural foam molding cuts down on stress and warpage on parts.
- Strength: The honeycomb structure produced in the molding process gives parts increased strength and good stiffness-to-weight and strength-to-weight ratios.
- A good substitute: The parts produced by structural foam molding can replace many different types of materials including wood, fiberglass and concrete.
- Impact resistance: The honeycomb structure produced in the structural foam molding process also gives parts increased impact resistance.
- Good use of aluminum: Since structural molding is a low pressure process, aluminum works well for molds and there is a better heat transfer when using aluminum molds.
Another way of manufacturing parts is done through plastic injection molding. In this process involves the injection of molten materials into a mold and can be done with many materials. The process of die-casting for example involves using this process with molten metal. Materials are put into a heated barrel and then forced into a mold cavity, which eventually cools and hardens.
Reaction injection molding (RIM) involves plastics as well, but in this process two reaction injection molding materials, in this case liquids, are mixed and injected into a mold where they chemically react and later cure. Advantages to using plastic injection molding include:
- Details: In this process, injection molds are subjected to very high pressure, which results in the plastic within the molds being pressed harder into the mold. The high pressure allows a manufacturer to add many details when it comes to designing a particular part. In addition, the plastic can be formed into complex shapes to go along with detail, so parts manufacturing by injection molding can be as simple or as complex as needed.
- Strength: By adding fillers to injection molds, the density of plastic used in manufacturing is reduced and the fillers also add strength to the part once it’s been molded. For lines of work that require long-lasting, strong parts, injection molding gives them a strength not offered through other molding processes.
- Versatility: Another advantage of injection molding for manufacturing is that various types of plastic can be used at the same time. With co-injection molding, companies don’t have to stick to just one type of plastic.
- Efficiency: Once molds for a specific part have been designed and everything has been programmed, the molding process is relatively quick, which means a single mold can yield more parts on average. This makes injection molding highly efficient and very cost effective.
There are advantages to each of the different types of molding when it comes to parts manufacturing. Knowing the differences and benefits of each will help a company find the process that works best for them.