Our material selection for August is plastic resin, Acetal.

If you know anything about acetal, you’ll know it can be complicated.  Even if we had a full day, we still wouldn’t have enough time to discuss the copycat versions and changes which have occurred for acetal over the years.  But we haven’t.  So, we’ll keep it simple!


Acetal is the commonly known name for the family of thermoplastics with the chemical name “PolyOxyMethylene”, or POM.

Originated by those pioneers of innovation over at Dupont, Delrin® Acetal is as well respected as it is renowned across the globe.  By far the “crème de le crème” of resins. Predominantly available in two types, each offering their own pros and cons; the original: Homopolymer acetal (POM-H) and the slightly cheaper alternative: Copolymer acetal (POM-C).

Both Delrin® Acetal resins offer similarities; Homopolymer generally excels in its physical properties, whereas Copolymer can be a little softer, a little cheaper, making it better suited for specific applications.  Each have good dimensional stability and sliding properties, often used in automotive applications, specifically fuel systems. A popular material selection for plastic gears as well as pump components.

Known for its engineering properties rather than as a commodity plastic, acetal offers lots of advantages; it’s easy to machine and gives a lovely glossy, super-cool finish.  Making it great for prototypes … but it comes at a price.

It’s comparatively expensive, which is one of the reasons our design team work closely with customers to determine their ideal material “wish-list” first.   Asking questions to narrow the search:  Will your end product need to withstand extreme temperatures?  Offer good colourability?  Stability?  Flexibility vs Rigidity?  Sliding properties?  You get the idea.

But that way we can suggest alternatives and give you options, so you get the injection moulded product you want. The quantity and quality you expect. When you want it. At the price you can afford.


We’ve even designed and moulded a “Sample Material Card” so you can see, touch and feel the material itself.  This will give you a much better idea of its suitability for your product.

We help you navigate the material selection process, giving you options so you can make an informed decision. Every time.

If you’ve got an idea for a fabulous new product get in touch with our product design and development team on 01425 613131 or email hello@becgroup.com, they’ll soon tell you if acetal is your best option.  For now though, here are the pros and cons:


· Stiffness with high mechanical strength and resistance to creep
· Low thermal expansion
· Low water absorption
· Excellent chemical resistance
· Good wear resistance
· Low coefficient of friction (often used fo gears, bearings and sliding parts)
· Resistance to ESC
· Easier to machine
· Filled grades available (glass etc)


· Can emit hazardous fumes when burnt
· Very high shrinkage allowance needed on tooling
· Can be affected by UV
· Burns easily, not flame retardant
· Difficult to bond (the drawback of a slippery material)
· Comparatively expensive

Not many people know….  we use acetal for a well-known household vacuum cleaning project as well as to plastic injection mould 10,000 filter mesh mouldings a year for Vitalograph, manufacturer of respiratory diagnostic devices.  Not only a leading specialist contract research organisation in respiratory clinical trials, but also supplier of quality medical devices to over 80 countries worldwide.