Machinable plastics give designers lightweight parts without the high tooling costs of metal. When you mill, turn, or drill these polymers, you must know which grade fits your job, how to hold it, and how to keep the chips cool. This article explains the most useful machinable plastics, compares their properties, and offers shop-floor tips you can apply right away.
Inhaltsübersicht
- Why machinable plastic matters
- Rank plastics by machine-ability
- Compare strength, weight, and cost
- Plan feeds, speeds, and chips
- Fixture and support soft stock
- Avoid heat and burr problems
- Finish and polish for function
- Match plastics to industry needs
- Estimate budget and lead times
- Need a free quote?
- Quick recap for your shop
WHY MACHINABLE PLASTIC MATTERS
Shops use machinable plastic when they need parts fast, light, and corrosion-proof. Unlike 3D printing, cutting plastic keeps the original resin properties intact. You can hit tight tolerances for jigs, gears, and optical mounts without the long cure or shrink windows of casting.
RANK PLASTICS BY MACHINE-ABILITY
The table below lists ten common polymers and scores how easily they cut on standard CNC mills or lathes.
| Plastik | Machine-ability score (1–10) | Key trait in cutting | Typical tool material |
|---|---|---|---|
| POM (Acetal / Delrin) | 10 | Chips break clean | Uncoated carbide |
| ABS | 9 | Low melt smear | Polished HSS |
| Nylon PA6 | 8 | Minimal stress marks | Single-flute O-bit |
| Polycarbonat (PC) | 7 | Requires coolant | Diamond-like carbon |
| PEEK | 6 | High cutting force | Carbide or PCD |
| UHMW-PE | 5 | Stringy chips | Sharp HSS |
| PTFE (Teflon) | 4 | Cold flow risk | Zero-rake insert |
| Polypropylen (PP) | 4 | Gummy surface | Coated carbide |
| PVC Rigid | 3 | Edge chip if hot | Low RPM HSS |
| Phenolic G-10 | 2 | Abrasive glass fiber | Diamond grit tool |
COMPARE STRENGTH, WEIGHT, AND COST
Choosing a plastic is a balance of mechanical needs and budget. The chart shows how four top polymers trade strength against density and price.
Relative Tensile Strength vs Density vs Cost
Strength | PEEK ██████████
| PC ████████
| PA6 ███████
| ABS █████
Density | ABS ███
| PA6 ████
| PC █████
| PEEK ██████
Cost/kg | ABS $$
| PA6 $$
| PC $$$
| PEEK $$$$$
PLAN FEEDS, SPEEDS, AND CHIPS
Light cuts keep heat down and stop melt. Use these starting values, then fine-tune.
| Material | Spindle (rpm) for 6 mm tool | Feed rate (mm/min) | Chip load (mm/tooth) | Coolant |
|---|---|---|---|---|
| POM | 16 000 | 2 560 | 0.04 | Air blast |
| Nylon PA6 | 14 000 | 1 960 | 0.035 | Mist |
| PC | 12 000 | 1 440 | 0.03 | Flood 5 % |
| PEEK | 9 000 | 1 080 | 0.03 | Flood 8 % |
FIXTURE AND SUPPORT SOFT STOCK
Thin sheets bend under cutter pressure. Choose a holding plan that spreads load.
- Vacuum table — fast changeover, no clamp dents.
- Low-tack tape — best for panels under 2 mm.
- Custom pallets — repeat jobs, multi-part runs.
- Soft-jaw vise — blocks thicker than 15 mm.
AVOID HEAT AND BURR PROBLEMS
Heat is enemy #1. Keep chips moving and edges sharp.
| Problem | Symptom | Aktion |
|---|---|---|
| Melt smear | Gloss bands on cut | Lower rpm 20 %, raise feed |
| Long stringers | Tangled chip nest | Add chip-breaker tool or peck cycle |
| Burrs on exit | Frayed edge | Increase chip load, hand de-burr |
| Stress cracks | White lines near holes | Reduce clamp pressure, use step drill |
FINISH AND POLISH FOR FUNCTION
After cutting, you may need tighter Ra or optical clarity.
- Tumble — batch edge break, Ra down to 1 µm.
- Flame polish — clear PC or PMMA edges.
- Vapor smooth — nylon SLS prototypes.
- Hand buff with fine rouge — POM gear teeth.
MATCH PLASTICS TO INDUSTRY NEEDS
The next table shows where each plastic excels in real tasks.
| Industrie | Ideal plastic | Why it wins |
|---|---|---|
| Aerospace fixtures | PEEK | High temp, low creep |
| Food automation | POM | FDA grade, easy clean |
| Medizinische Geräte | PC clear | Impact plus clarity |
| Packaging lines | UHMW-PE | Low friction slide |
| Consumer audio | ABS | Good paint adhesion |
ESTIMATE BUDGET AND LEAD TIMES
Use this quick view to schedule your order.
| Lot size | Setup hours | Cycle time per part | Indicative cost | Lead time |
|---|---|---|---|---|
| Prototype 1-5 | 2 h | 25 min | $90 each | 3 days |
| Short 20-50 | 2 h | 15 min | $32 each | 1 week |
| Mid 200 | 3 h | 10 min | $15 each | 2 weeks |
| High >1k | 4 h pallet | 6 min | $8 each | 3-4 weeks |
NEED A FREE QUOTE?
Our shop mills plastics and metals on 3- to 5-axis centers and can combine CNC, sheet-metal, and injection options in one contract. Send your drawing for a fast, single-source quote.
QUICK RECAP FOR YOUR SHOP
- Pick a plastic that balances strength, price, and machine-ability.
- Use razor-sharp tools, modest rpm, and generous chip loads.
- Clamp with care—support thin walls to avoid warp.
- Manage heat with air or mist, not aggressive flood on hygroscopic grades.
- Finish edges by tumble or flame if cosmetics matter.
Follow these pointers and your machinable plastic parts will leave the spindle cool, clean, and right on size.
