When designing a part and selecting a plastic to use in manufacturing it, we have previously blogged about the many questions to consider. For example, what are your desired mechanical properties, electrical resistance, and chemical resistance? And, do you have application-specific needs such as a flame rating or biocompatibility?
In developing an electronic enclosure, you may have to answer many of these questions, leaving you wondering where to begin. While there are many, many grades of plastic, here are a few of the types commonly used in electronic enclosures to begin your search.
ABS: ABS has excellent impact strength and electrical resistance at a modest price point. It shows resistance to many chemicals, and can be combined with other grades such as PC or nylon when common ABS doesn’t provide everything you need. It can also have additives mixed in to improve certain characteristics such as flame rating, impact resistance, or flow. ABS is easily colorable, but it is not transparent. When compared to other engineered materials, ABS can have a lower strength in thin wall thicknesses.
PC: Polycarbonate, or PC, has extraordinary impact strength. It is transparent and easily colorable. PC is commonly used to make light pipes, which transport an internal LED to the outside surface. Though PC is stronger and more temperature resistant than ABS, it can be subject to damage by many oil or alcohol-based chemicals. Another consideration is that PC contains BPA, a chemical that may be concerning in some applications.
ABS/PC: Can’t decide between ABS or PC? You don’t have to. An alloy combines the best of both: the strength and heat resistance of PC, but the flexibility of ABS. It is easily colorable and can receive many additives such as flame retardants and impact modifiers. This is commonly used in enclosures that are cleaned often with a variety of cleaning agents.
PPE+PS: A common blend between PPO and Polystyrene, this material is excellent for chemical and electrical resistance. It is used in many electrical applications, such as relays and transformer housings. While there are colors available, the most common version grade is black.
PBT: PBT is a thermoplastic polyester with excellent electrical and mechanical properties, and with resistance to chemicals and stress. PBT is a common choice for high temperature applications. However, it is crystalline in nature and its shrink rate does not allow a designer to easily switch to other material classes such as ABS or PC.
Acrylic: Acrylic is used selectively in electronic enclosures, when a transparent material is used but the designer wants to avoid PC. Though some grades can have modifiers to improve performance, acrylic generally has poor impact resistance.
Picking the Right Plastic
Using the right material for your plastic injection molding project is critical to achieving your desired results. We have decades of experience helping customers choose the ideal formula. Have questions about your upcoming project? We’re happy to share our thoughts. Give us a shout.