Machinable plastics
Acetal (Delrin) Machining
CDS machines acetal parts for detailed geometry and sliding interfaces. Low moisture absorption can make acetal useful for close-running fits, with grade, heat and load determining the application.
Acetal is the generic material family. A Delrin callout identifies a branded homopolymer requirement whose exact grade and availability need confirmation.
Machined detail and sliding fit
Acetal’s stiffness, sliding characteristics and low moisture absorption can be useful for guides, roller sleeves, bushings, gears and inserts. A detailed bore or locating feature still has to work with the mating material and operating conditions.
- Moisture and dimensions
- Acetal generally absorbs less moisture than nylon, which can help with moisture-sensitive fits. Absorption is not zero; temperature, stress and machining history also affect dimensions.
- Sliding and wear
- The mating surface, speed, contact load, lubrication and contaminants affect friction and wear. Dry-running suitability belongs to the complete interface and exact grade.
- Load over time
- Sustained compression can cause creep. Initial stiffness alone cannot establish the long-term position of a bore, shoulder or loaded insert.
- Impact and jams
- Repeated shock, cold impact, notches and thin sections can change the result. Stiffness and toughness are separate considerations.
The sliding surface and the fit do different jobs
- Mating partIts material, surface and motion affect the contact.
- Running clearanceThe gap must accommodate the intended temperature, moisture state and load.
- Supporting bodySection thickness and support affect how the feature holds position.
POM-C, POM-H and Delrin callouts
Acetal, or POM, is the generic family. POM-C is copolymer; POM-H is homopolymer. Delrin is a registered trade name for an acetal homopolymer family, rather than a synonym for every acetal.
- POM-C
- Copolymer generally offers the chemical-resistance advantage. The exact medium, temperature and load still govern compatibility.
- POM-H
- Homopolymer is generally somewhat harder, stronger and more heat resistant. The exact grade and finished geometry remain important.
Fillers and lubricants can alter sliding, mechanical and machining behavior. If a drawing calls for Delrin, the full grade and any permission to substitute need to remain explicit. Confirm branded supply with CDS.
Acetal names describe different levels of the specification
- Acetal / POMThe generic material family.
- POM-CAcetal copolymer.
- POM-HAcetal homopolymer, including the Delrin branded family.
Dimensions, cleaning and the finished component
Bores, slots, profiles and changes in section can respond to thermal expansion and released internal stress. Stock condition, material removal and inspection temperature affect the machining plan and required fit. Plastic machining tolerance factors explains these relationships.
Chemicals and cleaners bring their own requirements: concentration, exposure duration, heat and simultaneous load all matter. Chlorine, alkalis, hot water, steam and aggressive cleaning need exact-grade review. Food-contact and detectable requirements also need grade-specific documentation.
Your Acetal (Delrin) machining quote
Share your drawing and revision, or the available records for an existing part. CDS quotes machining against your specified material and finished-part requirements.
- Part requirements: Bores, shoulders, slots and profiles, with customer-specified datums, dimensions, tolerances and finish.
- Specified material: POM-C or POM-H, full grade and any required Delrin brand, filler, color or permitted substitute.
- Order and records: Quantity or useful quantity tiers, requested date and required material, inspection or traceability documents. Identify any specified tests for confirmation with the quote.