{"id":11160,"date":"2026-06-02T01:48:09","date_gmt":"2026-06-02T01:48:09","guid":{"rendered":"https:\/\/nylonplastic.com\/peek-plastic-machining-guide\/"},"modified":"2026-06-11T16:08:28","modified_gmt":"2026-06-11T16:08:28","slug":"peek-plastic-machining-guide","status":"publish","type":"post","link":"https:\/\/nylonplastic.com\/ko\/peek-plastic-machining-guide\/","title":{"rendered":"PEEK Plastic Machining: Properties, Applications and CNC Guide"},"content":{"rendered":"

PEEK (polyetheretherketone) sits at the apex of engineering thermoplastics: continuous service above 250\u00b0C, tensile strength rivaling aluminum at one-sixth the weight, and chemical resistance that survives autoclaves, jet fuel, and concentrated acids. But these same properties that make PEEK invaluable in aerospace, medical implants, and oil & gas also make it one of the most challenging materials to CNC machine correctly. The heat generated during cutting does not dissipate \u2014 it builds up in the chip and workpiece, causing melting, dimensional drift, and rapid tool wear.<\/p>\n

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PEEK material properties engineering data chart<\/figcaption><\/figure>\n

This guide covers PEEK machining parameters from our production floor: grade selection, feeds and speeds for each operation, the critical annealing step that most shops skip, and the tooling choices that make the difference between a $500 scrapped part and a flight-ready component.<\/p>\n

PEEK Grades: Choosing the Right Variant for Machining<\/h2>\n

Unfilled PEEK (natural):<\/strong> The baseline. Tensile 95-100 MPa, excellent machinability (best surface finish), used for medical implants and seals. Machines similarly to brass \u2014 continuous chips, low tool wear. PEEK-GF30 (30% glass fiber):<\/strong> Stiffer (flex modulus 6 GPa vs 3.7 GPa for unfilled) but highly abrasive. Tool life drops 50-70% versus unfilled PEEK; carbide tools wear in 15-30 minutes of continuous cutting. PEEK-CF30 (30% carbon fiber):<\/strong> Highest stiffness and strength (tensile 220 MPa) but maximum abrasiveness. Requires diamond-coated tooling for production runs. Carbon fiber also makes the material electrically conductive \u2014 relevant for semiconductor applications.<\/p>\n

Feeds and Speeds for CNC PEEK<\/h2>\n\n\n\n\n\n\n\n\n\n
Operation<\/th>\nTool<\/th>\nSpeed (SFM)<\/th>\nRPM (6mm dia.)<\/th>\nFeed (mm\/min)<\/th>\nDOC (mm)<\/th>\nCoolant<\/th>\n<\/tr>\n<\/thead>\n
Roughing<\/td>\n3-flute carbide<\/td>\n150-300<\/td>\n8,000-12,000<\/td>\n600-1,200<\/td>\n1.5-3.0<\/td>\nFlood \/ high-pressure<\/td>\n<\/tr>\n
Finishing<\/td>\n3-flute carbide<\/td>\n200-400<\/td>\n10,000-15,000<\/td>\n300-600<\/td>\n0.2-0.5<\/td>\nFlood coolant<\/td>\n<\/tr>\n
Drilling<\/td>\nCarbide twist, 118 deg<\/td>\n80-150<\/td>\n3,000-6,000<\/td>\n100-200<\/td>\nPeck 2-3mm<\/td>\nThrough-coolant if 5xD+<\/td>\n<\/tr>\n
Threading<\/td>\nCarbide thread mill<\/td>\n100-150<\/td>\n5,000-8,000<\/td>\nHelical<\/td>\n0.1-0.2\/pass<\/td>\nFlood lubricant<\/td>\n<\/tr>\n
Slotting<\/td>\n3-flute carbide<\/td>\n120-200<\/td>\n6,000-10,000<\/td>\n400-800<\/td>\n0.5-1.0<\/td>\nTrochoidal path + flood<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

The Critical Annealing Step<\/h2>\n

PEEK accumulates significant internal stress during machining. The outer skin heats and expands while the core stays cool \u2014 as the part cools, this differential creates residual stresses that can cause warpage of 0.05-0.2 mm over the following days, or immediate cracking in thin-walled sections. Annealing protocol:<\/strong> Heat to 200\u00b0C (for unfilled) or 220\u00b0C (GF\/CF grades) at 1\u00b0C\/min, hold for 3 hours minimum (add 1 hour per 25 mm of thickest section), then cool at 0.5\u00b0C\/min to below 140\u00b0C before removing from oven. Skipping this step guarantees dimensional instability in tight-tolerance PEEK parts.<\/p>\n

Design Rules for Machining PEEK<\/h2>\n
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  1. Tool selection: carbide minimum, diamond preferred:<\/strong> For unfilled PEEK, sharp polished carbide (AlTiN or TiAlN coated) runs 30-60 minutes before dulling. For GF\/CF grades, CVD diamond-coated carbide extends tool life 5-10x. PCD (polycrystalline diamond) inserts reach 10-20x carbide life in production environments. The premium on diamond tooling pays back after 50-100 parts.<\/li>\n
  2. Rigid fixturing with thermal compensation:<\/strong> PEEK expands at 47-55 x 10^-6 \/ \u00b0C \u2014 roughly 2x aluminum and 5x steel. A 100 mm part machined at 40\u00b0C (warm from cutting) shrinks 0.15-0.20 mm when measured at 20\u00b0C. Machine to nominal + thermal allowance, or machine in temperature-controlled coolant to keep the part at 20\u00b12\u00b0C.<\/li>\n
  3. Chip evacuation is everything:<\/strong> PEEK chips are tough, stringy, and do not break easily. They wrap around tools and re-cut, causing surface defects. Use high-pressure through-tool coolant (70+ bar) for deep holes, or peck drilling cycles with full retraction. For milling, compressed air at 6+ bar directed at the cut zone clears chips effectively for unfilled grades.<\/li>\n
  4. Minimum wall thickness 1.0 mm:<\/strong> Below 1.0 mm, PEEK walls deflect under cutting pressure and produce chatter marks. For unsupported walls over 15 mm tall, increase minimum to 2.0 mm. Thin floors below 0.5 mm risk blowing through \u2014 the material softens at the cutting zone before the tool completes the pass.<\/li>\n
  5. Threads: coarse pitch, never tap:<\/strong> Thread mill all PEEK threads. Taps bind and tear the material, producing rough, weak threads. Minimum thread size: M2 (M3 preferred). Depth limit: 2x diameter. Coarse pitch reduces the number of thin thread crests that crack under load. For structural threads, use helical inserts \u2014 the PEEK holds the insert; the insert holds the bolt.<\/li>\n
  6. Post-machining inspection after full cool-down:<\/strong> Wait 24 hours after machining (or 4 hours after annealing) before final inspection. PEEK creeps slightly as residual stress relaxes \u2014 a part that measures in-tolerance fresh off the machine may be 0.03-0.08 mm out the next morning. For critical aerospace and medical parts, this waiting period is mandatory.<\/li>\n<\/ol>\n<\/div>\n

    Industry Application Matrix<\/h2>\n\n\n\n\n\n\n\n\n
    \uc0b0\uc5c5<\/th>\nTypical Parts<\/th>\nMaterial\/Grade<\/th>\nKey Requirement<\/th>\n<\/tr>\n<\/thead>\n
    \ud56d\uacf5\uc6b0\uc8fc<\/td>\nBrackets, bushings, seals, cable management<\/td>\nPEEK-CF30 or unfilled<\/td>\nFST (flame\/smoke\/toxicity) certified; -55 to +260\u00b0C range<\/td>\n<\/tr>\n
    Medical Implants<\/td>\nSpinal cages, dental abutments, trauma plates<\/td>\nUnfilled implant-grade PEEK<\/td>\nISO 10993 biocompatibility; radiolucent for imaging<\/td>\n<\/tr>\n
    Oil & Gas<\/td>\nSeals, backup rings, electrical connectors<\/td>\nUnfilled or PEEK-GF30<\/td>\nNORSOK M-710; H2S, CO2, and methanol resistance<\/td>\n<\/tr>\n
    Semiconductor<\/td>\nWafer handling, test sockets, chamber components<\/td>\nPEEK-CF30 (ESD-safe)<\/td>\nLow outgassing; static dissipative (under 10^6 ohm\/sq)<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

    Cost Decision Framework<\/h2>\n
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    Material cost:<\/strong> Unfilled PEEK rod\/plate: $80-150\/kg. PEEK-GF30: $90-170\/kg. PEEK-CF30: $120-250\/kg. This is 20-40x the cost of aluminum and 8-15x the cost of PA66. A single 100x100x25 mm plate costs $30-60 in material alone.<\/p>\n

    Machining cost:<\/strong> PEEK machines at ~50% of aluminum speed due to lower feeds and frequent tool changes. Diamond tooling adds $80-200 per tool but saves 5-10 tool changes per shift. Annealing adds 4-6 hours to lead time and $15-40 in oven cost per batch.<\/p>\n

    Decision rule:<\/strong> Machined PEEK only makes economic sense when: (a) quantity is 1-200 pcs (injection molding PEEK requires $25K-50K mold + $80-150\/kg resin), (b) the part needs the combination of 250\u00b0C+ service, chemical resistance, and biocompatibility that no cheaper material offers, or (c) the cost of failure exceeds 100x the material premium \u2014 as in aerospace, medical implants, and deep-sea oil equipment.<\/p>\n<\/div>\n

    Common Defects and Solutions<\/h2>\n\n\n\n\n\n\n\n\n
    Defect<\/th>\nAppearance<\/th>\nRoot Cause<\/th>\nSolution<\/th>\n<\/tr>\n<\/thead>\n
    Surface melting \/ smearing<\/td>\nGlossy, melted patches on machined surface<\/td>\nInsufficient cooling; feed too slow for RPM<\/td>\nIncrease flood coolant flow; raise feed 20% or reduce RPM to keep chip thickness adequate<\/td>\n<\/tr>\n
    Dimensional drift<\/td>\nPart measures out of tolerance 24h later<\/td>\nResidual stress from machining without annealing<\/td>\nAnneal per protocol (200\u00b0C\/3h\/slow cool); measure after cool-down<\/td>\n<\/tr>\n
    Chatter \/ poor surface<\/td>\nVisible wave pattern or roughness on surface<\/td>\nTool stickout too long; insufficient fixturing rigidity<\/td>\nReduce stickout below 4x diameter; add jack screws or vacuum fixture support<\/td>\n<\/tr>\n
    Rapid tool wear (GF\/CF)<\/td>\nCutting edge rounding after under 15 min cutting<\/td>\nGlass\/carbon fiber abrading carbide tool edge<\/td>\nSwitch to CVD diamond-coated or PCD tooling; reduce speed 15% for GF\/CF<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

    Why Choose Nylon Plastic for Your Project<\/h2>\n
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    Precision Manufacturing<\/h4>\n

    30+ CNC & injection molding cells under one roof<\/p>\n<\/div>\n

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    Download Our PEEK Plastic Machining Guide<\/h3>\n

    Free PDF reference guide with technical data, design rules, and supplier checklists.<\/p>\n

    📥 Download PEEK Machining Guide (PDF)<\/a><\/div>\n

    \uad00\ub828 \uae30\uc0ac<\/h2>\n
    \n
    Acrylic CNC Machining Guide<\/a><\/div>\n
    Glass-Filled Nylon Guide<\/a><\/div>\n
    Engineering Tolerance Guide<\/a><\/div>\n
    Gear Manufacturing Services<\/a><\/div>\n<\/div>\n

    \uc790\uc8fc \ubb3b\ub294 \uc9c8\ubb38<\/h2>\n
    \nHow does machining PEEK compare to machining aluminum?<\/strong><\/summary>\n

    PEEK machines at roughly 50% of aluminum speeds due to its lower thermal conductivity (0.25 W\/mK vs 120+ W\/mK for aluminum) \u2014 heat stays in the cut zone rather than dissipating through the chip. Feeds are 30-50% of aluminum rates. Tooling costs more: diamond-coated or PCD tools are strongly recommended versus standard carbide for aluminum. Surface finishes of Ra 0.4-0.8 \u03bcm are achievable with sharp tools \u2014 comparable to aluminum but requiring more careful parameter selection. The key difference is thermal management: aluminum carries heat away in the chip; PEEK requires the coolant to do all the work.<\/p>\n<\/details>\n

    \nDoes PEEK require annealing after machining?<\/strong><\/summary>\n

    Yes \u2014 this is not optional for tight-tolerance parts. PEEK accumulates internal stress during machining from the thermal gradient between the cutting zone (locally reaching 200\u00b0C+) and the cool core. Without annealing, parts warp 0.05-0.2 mm over 24-72 hours as stress relaxes. The standard protocol: heat to 200\u00b0C (unfilled) at 1\u00b0C\/min, hold 3 hours minimum, cool at 0.5\u00b0C\/min to below 140\u00b0C. Skipping this step virtually guarantees dimensional instability in parts with thin walls, deep pockets, or tolerances tighter than \u00b10.1 mm.<\/p>\n<\/details>\n

    \nWhat are the best cutting tools for PEEK?<\/strong><\/summary>\n

    For unfilled PEEK: Sharp polished carbide with AlTiN or TiAlN coating, 3-flute end mills for milling, 118\u00b0 point angle for drilling. For PEEK-GF30: CVD diamond-coated carbide extends tool life 5-10x over uncoated carbide. For PEEK-CF30: PCD (polycrystalline diamond) inserts or CVD diamond-coated end mills are required for production \u2014 standard carbide dulls in 10-15 minutes. Avoid TiN coatings \u2014 they have higher friction against PEEK than AlTiN\/TiAlN. Tool cost: $25-60 (carbide) vs $80-200 (diamond-coated) vs $150-400 (PCD insert).<\/p>\n<\/details>\n

    \nHow does PEEK compare to PTFE (Teflon) for machined parts?<\/strong><\/summary>\n

    PEEK is stronger, stiffer, harder, and more temperature-resistant than PTFE \u2014 but 5-10x more expensive and requires more careful machining. Tensile: PEEK 95-100 MPa vs PTFE 20-30 MPa. Max service: PEEK 250\u00b0C vs PTFE 260\u00b0C (similar). Wear: PEEK has 10x better wear resistance. PTFE’s advantage is its extremely low friction coefficient (0.05-0.10 vs 0.30-0.38 for PEEK) and zero moisture absorption. Choose PEEK for structural, load-bearing applications; PTFE for seals, bearings, and low-friction surfaces where strength is secondary. The two are complementary, not competitive \u2014 many assemblies use PEEK for the structural body and PTFE for the sealing element.<\/p>\n<\/details>\n\t\t\t

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