Some materials get specified because they’re exotic and high-performance. Others get specified because they’re dependable, cost-effective, and get the job done without drama. Delrin and PTFE fall into the second category — and that’s exactly why they’re two of the most frequently requested materials in precision plastic machining. Delrin PTFE machining projects come across our shop floor constantly, from mechanical components that need strength and stiffness to seals and bearings that need to move without friction.
At Reading Advanced Machining, we’ve machined both materials for decades across industries including medical, telecom, food and beverage, and industrial manufacturing. They’re often mentioned in the same breath because they’re both considered “workhorse” engineering plastics, but they solve very different problems. Here’s how to tell them apart and know which one your application actually needs.
Delrin is DuPont’s trademarked name for acetal homopolymer, a type of polyoxymethylene (POM) plastic known for combining high strength, stiffness, and low friction in a single material. It’s often described as one of the best plastic substitutes for metal in mechanical applications, and it shows up constantly in gears, bushings, bearings, valve components, and consumer electronics housings.
What makes Delrin especially useful for precision parts is its dimensional stability. It resists moisture absorption, which means machined parts hold their tolerances over time rather than swelling or shifting with humidity. It also has good fatigue resistance, so components that flex repeatedly — like small gears or snap-fit housings — tend to hold up well over their service life. As this acetal machining overview notes, Delrin also performs reliably across a wide temperature range, and it’s relatively easy to machine compared to many other engineering plastics, which keeps lead times and costs down.
Delrin does have some limitations worth knowing. It has limited chemical resistance compared to plastics like PTFE, and under constant load it can be prone to creep — a gradual, permanent deformation — so it’s not always the right choice for parts under sustained heavy stress.
PTFE, widely known by the brand name Teflon, occupies a different niche entirely. Its defining trait is an extraordinarily low coefficient of friction — one of the lowest of any solid material — which makes it the material of choice for seals, gaskets, bearings, and sliding components that need to move smoothly without added lubrication.
PTFE is also remarkably chemically resistant. It holds up against nearly all industrial acids, solvents, and bases, and it’s the only common engineering plastic with essentially zero water absorption, which helps it maintain dimensional accuracy in wet or humid environments. Its usable temperature range is unusually wide, remaining stable from deep-freeze conditions to several hundred degrees Fahrenheit, which is why it turns up in both cryogenic and high-heat applications.
The tradeoff with PTFE is machinability. It’s a much softer material than Delrin, and it’s prone to a phenomenon called cold flow, where the material slowly deforms under constant mechanical pressure. That softness also makes it more challenging to hold tight tolerances and produce clean edges without experience machining the material — sharp tooling, proper work-holding, and a careful hand all matter more with PTFE than with most other engineering plastics.
The decision between these two materials usually comes down to what the part needs to do mechanically. If a component needs to be rigid, load-bearing, and dimensionally precise — like a gear, bushing, or structural mechanical part — Delrin is typically the better and more cost-effective choice. If the part needs to slide, seal, or resist aggressive chemicals with minimal friction, PTFE is usually worth the added machining complexity and cost.
It’s also worth noting that these materials sometimes work best together. A common approach in Delrin PTFE machining projects is specifying a Delrin blend reinforced with PTFE fibers, which combines Delrin’s strength and rigidity with some of PTFE’s low-friction benefits — a useful middle ground for bearings and wear components that need both.
Industries like food and beverage processing frequently rely on both materials, since Delrin and PTFE are available in FDA-compliant grades suited to components like augers, rollers, and chute liners in food processing equipment, where hygiene, wear resistance, and chemical exposure all matter simultaneously.
Specifying the right material is only half the equation — how it’s machined matters just as much. Delrin’s ease of machining can create a false sense of security if tooling and cutting parameters aren’t dialed in for tight-tolerance work, and PTFE’s softness means an inexperienced shop can end up with parts that are out of spec before they even leave the machine.
At Reading Advanced Machining, we stock both Delrin, PTFE, and dozens of other specialty plastics and machine them daily for customers who need parts that perform exactly as specified. If you’re not sure which grade or material fits your application, our team has the material knowledge to help you decide before you commit to a design.
Whether you need the strength and stability of Delrin or the low-friction, chemical-resistant performance of PTFE, choosing the right material — and the right machining partner — makes all the difference. Request a quote and let our team help you find the right fit for your next component.
