self-lubricating
dimensionally stable
temperature
tight tolerances
Delrin CNC Machining: What You Need to Know
Delrin is the go-to plastic for parts that slide, spin, or wear. It is stiff, strong, and self-lubricating. It holds tighter tolerances than almost any other plastic. And it machines like butter.
The full name is polyoxymethylene (POM). You may also hear it called acetal. Delrin is the DuPont brand name. No matter what you call it, the material is the same: a semi-crystalline engineering thermoplastic with a friction coefficient of just 0.20.
Delrin absorbs only 0.22% moisture. That is 10 times less than nylon 6/6. This means your Delrin parts hold their dimensions even in humid shops, outdoor enclosures, and food processing plants. No swelling. No warping. No surprises.
At RivCut, we keep Delrin 150, Delrin AF, and Delrin 100 in stock. Upload your CAD file and get a quote in minutes. Most Delrin parts cost $65–$250 and ship in 5–7 business days.
Delrin Material Properties
Here are the numbers that matter for CNC machined Delrin parts.
| Property | Value | Why It Matters |
|---|---|---|
| Tensile Strength | 10 ksi (69 MPa) | Strong for a plastic — handles structural loads |
| Yield Strength | 8.8 ksi (61 MPa) | Resists permanent deformation under load |
| Elongation at Break | 25% | Bends before it breaks — good toughness |
| Hardness | Rockwell M80 | Hard surface resists denting and wear |
| Friction Coefficient | 0.20 | Self-lubricating — no grease needed |
| Moisture Absorption | 0.22% | Best dimensional stability of any plastic |
| Density | 0.051 lb/in³ (1.41 g/cm³) | 82% lighter than steel, 48% lighter than aluminum |
| Max Continuous Temp | 180°F (82°C) | Good for room-temp and mildly warm applications |
| Thermal Conductivity | 0.37 W/mK | Low — acts as a thermal insulator |
Delrin Grades We Machine
Not all Delrin is the same. Each grade is tuned for a different job. Here are the three grades RivCut keeps in stock.
| Grade | Key Feature | Best For | Cost |
|---|---|---|---|
| Delrin 150 | Standard general-purpose acetal | Gears, bushings, rollers, structural parts | $ |
| Delrin AF | PTFE-filled — even lower friction | Sliding parts, wear pads, high-cycle bearings | $$ |
| Delrin 100 | Higher impact resistance | Parts that take shock loads, snaps, clips | $ |
Delrin 150 is the standard. Pick this if you are not sure which grade to use. It covers 80% of Delrin applications.
Delrin AF has PTFE (Teflon) mixed into the resin. This drops the friction coefficient even lower and cuts wear in half. Use it for bearings that run dry, sliding gates, and any surface that rubs against metal.
Delrin 100 has more impact strength than Delrin 150. Choose it for snap-fit clips, spring latches, and parts that get dropped or hit.
Delrin vs Other CNC Plastics
Delrin is not the only plastic we machine. Here is how it compares to the alternatives so you can pick the right one.
| Property | Delrin (POM) | Nylon 6/6 | PEEK | UHMW-PE |
|---|---|---|---|---|
| Tensile Strength | 10 ksi | 12 ksi | 16 ksi | 5.8 ksi |
| Friction | 0.20 | 0.30 | 0.35 | 0.15 |
| Moisture Absorption | 0.22% | 2.5% | 0.50% | 0.01% |
| Max Temp | 180°F | 220°F | 480°F | 180°F |
| Dimensional Stability | Excellent | Poor (swells) | Very Good | Good |
| Machinability | Excellent | Good | Good | Fair (gummy) |
| Cost per Part | $65–$250 | $60–$200 | $150–$600 | $50–$150 |
| Best For | Gears, bearings, precision sliding parts | Impact-resistant structural parts | High-temp, chemical, metal replacement | Wear strips, guide rails, liners |
Choose Delrin when you need low friction, tight tolerances, and dimensional stability. It is the best all-around engineering plastic for precision moving parts.
Choose PEEK when you need temperatures above 180°F or chemical resistance. PEEK costs 10–20x more but works where Delrin cannot.
Choose nylon 6/6 when you need more impact resistance and do not care about moisture swelling.
Choose UHMW-PE when you need the lowest possible friction and your part does not need tight tolerances.
Get a Delrin Part Quote in Minutes
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Upload CAD for Instant QuoteIndustries That Use CNC Machined Delrin
Delrin shows up everywhere a part needs to slide, spin, or wear without lubrication. Here are the top industries.
Medical Devices
FDA food-safe Delrin 150 for surgical instrument handles, drug delivery mechanisms, and lab automation components. Low friction for smooth action. Autoclavable for sterilization.
Robotics & Automation
Delrin gears, cam followers, and guide blocks for robotic arms and pick-and-place machines. Self-lubricating means no grease contamination. Tight tolerances for repeatable motion.
Food Processing & Packaging
Conveyor rollers, chain guides, and wear strips in Delrin 150. FDA compliant. Resists cleaning chemicals. Low moisture absorption means no bacteria-hiding swelling.
Automotive & Motorsport
Fuel system components, window regulator guides, and throttle body bushings. Delrin handles vibration, resists fuel, and runs dry without lubrication.
Consumer Electronics
Precision cam mechanisms, hinge bushings, and switch actuators. Delrin gives a smooth, consistent feel with zero backlash. Ideal for tactile feedback components.
Semiconductor & Cleanroom
Delrin fixtures and handling tools that do not scratch wafers or generate particles. Low outgassing. Dimensionally stable in temperature-controlled environments.
Design Tips for CNC Machined Delrin Parts
Delrin machines easily, but a few design choices can save you money and improve part quality.
1 Keep Walls at 0.040" or Thicker
Delrin is stiff but still plastic. Walls thinner than 0.040" can flex during cutting and spring back out of tolerance. Design walls at 0.060" or thicker for the best results. If you need thin walls, talk to our team about fixturing strategies.
2 Add Inside Corner Radii of 0.030"+
End mills are round. A sharp inside corner forces us to use a smaller tool and make extra passes. A 0.030" radius or larger costs nothing extra and speeds up machining. Larger radii like 0.060" are even better.
3 Watch Your Depth-to-Width Ratio
Keep pockets under 4:1 depth-to-width ratio. A pocket 2" deep and 0.5" wide needs a long, thin cutter that chatters in Delrin. Wider pockets or shallower depths give you cleaner surfaces and tighter tolerances.
4 Use Standard Thread Sizes
Delrin holds threads well, but stick to standard sizes: 4-40, 6-32, 8-32, 10-32, 1/4-20. Thread engagement should be 1.5x the bolt diameter minimum. Delrin threads strip more easily than metal, so longer engagement helps.
5 Avoid Tight Tolerances Everywhere
Delrin holds ±0.001" on critical features. But calling out tight tolerances on every dimension increases cost. Use ±0.005" for general features and save ±0.001" only where it truly matters — like bearing bores and gear teeth.
Finishes for Delrin Parts
Delrin comes out of the machine looking good. It has a natural white or black color with a smooth, slightly glossy surface. Here are your finish options.
- As-machined: Clean tool marks, 32–63 Ra surface finish. Ready to use for most applications. This is what 90% of Delrin parts get.
- Vapor polished: Smooths the surface to a near-optical finish. Good for light guides, sealing surfaces, and cosmetic parts.
- Tumbled / deburred: Removes sharp edges and burrs. Safe to handle. Standard on all parts unless noted otherwise.
- Dyed: Delrin can be dyed black, blue, red, green, and other colors. Not as durable as molded-in color but works for prototypes and low-wear parts.
- Laser engraved: Part numbers, logos, and orientation marks. Clean, permanent marking that does not wear off.
Note: Delrin does not accept paint or adhesives well due to its low surface energy. If you need painted Delrin, ask us about surface prep options like plasma treatment or chemical etching.
Tolerances for CNC Machined Delrin
Delrin holds tighter tolerances than most plastics. Its low moisture absorption and thermal stability keep parts in spec long after machining.
- General features: ±0.003" (±0.076 mm)
- Precision features: ±0.001" (±0.025 mm)
- Surface finish: 32–63 Ra standard, 16 Ra achievable
- Flatness: 0.002" per inch on machined surfaces
- Concentricity: 0.001" TIR on turned features
Why Delrin holds tolerances so well: Nylon 6/6 absorbs 2.5% moisture and swells after machining. Delrin absorbs only 0.22%. A Delrin bearing that measures 1.000" in the shop will still measure 1.000" in a humid warehouse. That is why Delrin is the top choice for precision plastic parts.
Need Delrin Parts This Week?
Rush delivery available. Upload your CAD file and see exact pricing with lead time options. Delrin machines fast — most parts ship in 5–7 days.
Upload CAD for Instant QuoteWhy RivCut for Delrin CNC Machining
We machine Delrin every day. Here is what makes RivCut the right shop for your Delrin parts.
- All three grades in stock. Delrin 150, Delrin AF, and Delrin 100. No waiting for material. We start cutting the day you order.
- Plastics-tuned toolpaths. Delrin melts if you cut too slow or feed too fast. Our machinists know the right speeds, feeds, and tool geometries to get clean cuts with no melting.
- ±0.001" on critical features. We inspect every Delrin part with calibrated equipment. Bearing bores, gear tooth profiles, and mating surfaces are measured to print.
- No minimum order. One bushing or 500 gears. Same process, same quality, same platform.
- Free DFM review. We check your design for thin walls, deep pockets, and tolerance issues before cutting starts. This catches expensive mistakes early.
- 100% made in USA. Every Delrin part is machined in our Union City, California facility. No overseas outsourcing.
The RivCut Guarantee
If your Delrin parts do not match your drawing, we remake them at no charge. Every dimension on your print is a promise we make. We back that promise with calibrated inspection equipment and a team that takes tolerance seriously.
Related Tools & Articles
Delrin CNC Machining: Common Questions
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Get Your Delrin Part Quote in Minutes
Upload your CAD file for instant pricing. Delrin 150, AF, or 100 — all in stock. Rush delivery in as few as 3 business days. 100% made in USA.
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