{"id":6868,"date":"2026-05-15T08:38:50","date_gmt":"2026-05-15T08:38:50","guid":{"rendered":"https:\/\/rapidcision.com\/?p=6868"},"modified":"2026-05-16T08:42:39","modified_gmt":"2026-05-16T08:42:39","slug":"blog-cnc-machining-aerospace-composites","status":"publish","type":"post","link":"https:\/\/rapidcision.com\/de\/blog-cnc-machining-aerospace-composites\/","title":{"rendered":"CNC-Bearbeitung von Verbundwerkstoffen f\u00fcr die Luft- und Raumfahrt: Delamination, Werkzeuge und Prozessleitfaden"},"content":{"rendered":"

CNC Machining Aerospace Composites: Delamination, Tooling & Process Guide<\/b><\/h1>\n

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Author: Marcus Chen, Quality Director, Rapid Precision<\/b><\/p>\n

Marcus Chen has 16 years in aerospace and precision manufacturing quality, with direct experience qualifying composite machining processes for AS9100D-certified aerospace programmes including CFRP structural components and GFRP radome panels.<\/span><\/p>\n

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For aerospace structural engineers specifying CNC machining operations on carbon fibre reinforced polymer (CFRP) components, the failure mode that ends careers and programmes is delamination \u2014 the interlaminar separation of composite plies caused by cutting forces, heat, or vibration that splits the laminate at the resin-matrix interface. A single delamination event on a $5,000 CFRP blank scraps the part and delays the programme. At scale, delamination rates of 2\u20135% across a production run of complex composite aerostructures cost $50,000\u2013$500,000 in scrap, rework, and programme schedule impact.<\/span><\/p>\n

Composite machining is fundamentally different from metal machining in two critical ways: composites are anisotropic (properties vary with fibre direction), and composites cannot be plastically deformed \u2014 they fail by fracture and delamination rather than by chip formation. Every machining decision \u2014 tool geometry, cutting speed, feed rate, cutting direction relative to fibre orientation, coolant strategy, and fixturing \u2014 directly affects delamination risk. The process that works on 0\u00b0\/90\u00b0 cross-ply laminate may cause delamination on quasi-isotropic laminates with the same nominal dimensions.<\/span><\/p>\n

This guide covers the delamination mechanism, tooling selection, cutting parameters by composite type, fibre orientation effects, NDT inspection requirements, and the AS9100D process framework that Rapid Precision uses for aerospace composite programmes.<\/span><\/p>\n

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Composite Types for Aerospace CNC Machining<\/b><\/h2>\n\n\n\n\n\n\n\n\n\n\n
Composite<\/b><\/th>\nFibre<\/b><\/th>\nMatrix<\/b><\/th>\nMachinability<\/b><\/th>\nPrimary Aerospace Applications<\/b><\/th>\nKey Machining Risk<\/b><\/th>\n<\/tr>\n<\/thead>\n
CFRP (standard)<\/span><\/td>\nCarbon fibre<\/span><\/td>\nEpoxy<\/span><\/td>\nDifficult \u2014 highly abrasive CF, brittle fracture<\/span><\/td>\nPrimary structure: wing spars, fuselage frames, empennage<\/span><\/td>\nDelamination, fibre pullout, tool wear (carbide fails fast)<\/span><\/td>\n<\/tr>\n
CFRP (woven)<\/span><\/td>\nWoven carbon fabric<\/span><\/td>\nEpoxy<\/span><\/td>\nDifficult \u2014 bidirectional cutting loads<\/span><\/td>\nSkins, fairings, access panels<\/span><\/td>\nDelamination at fabric interfaces, fraying at cut edges<\/span><\/td>\n<\/tr>\n
GFRP (glass fibre RP)<\/span><\/td>\nE-glass \/ S-glass<\/span><\/td>\nEpoxy \/ polyester<\/span><\/td>\nModerate \u2014 less abrasive than CF<\/span><\/td>\nRadomes, antenna fairings, non-structural panels<\/span><\/td>\nFibre pullout, delamination at stack exit<\/span><\/td>\n<\/tr>\n
CFRP\/Ti hybrid (CFRP-titanium)<\/span><\/td>\nCarbon + titanium layers<\/span><\/td>\nEpoxy + Ti<\/span><\/td>\nVery difficult \u2014 dual material transition in single stack<\/span><\/td>\nAdvanced wing structures, door surround structure<\/span><\/td>\nGalvanic corrosion on tool, delamination at CF-Ti interface<\/span><\/td>\n<\/tr>\n
Thermoplastic CFRP (PEEK matrix)<\/span><\/td>\nCarbon fibre<\/span><\/td>\nPEEK<\/span><\/td>\nChallenging \u2014 high matrix toughness, gummy matrix<\/span><\/td>\nNext-gen aerostructures, brackets, clips<\/span><\/td>\nMatrix melting if heat not managed \u2014 gummy deposits on tool<\/span><\/td>\n<\/tr>\n
Nomex\/carbon honeycomb sandwich<\/span><\/td>\nCarbon face skins + Nomex core<\/span><\/td>\nEpoxy<\/span><\/td>\nModerate \u2014 core crushing risk<\/span><\/td>\nFlight control panels, cabin floors, nacelle components<\/span><\/td>\nCore crushing under clamping force; delamination at face-core bond<\/span><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

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The Delamination Mechanism: Why It Happens and How to Prevent It<\/b><\/h2>\n

Delamination in composite machining occurs when cutting forces \u2014 principally the thrust force perpendicular to the laminate plane \u2014 exceed the interlaminar shear strength of the composite at a ply interface. In drilling, the critical zone is the exit surface, where the drill pushes the final plies forward before breaking through (‘push-out delamination’). In edge trimming and routing, delamination occurs at the cut surface when the tool deflects into the laminate rather than cutting clean fibres.<\/span><\/p>\n\n\n\n\n\n\n\n\n\n
Delamination Type<\/b><\/th>\nMachining Operation<\/b><\/th>\nPrimary Cause<\/b><\/th>\nPrevention Strategy<\/b><\/th>\n<\/tr>\n<\/thead>\n
Push-out (exit)<\/span><\/td>\nDrilling, countersinking<\/span><\/td>\nAxial thrust force at drill exit exceeds interlaminar shear strength<\/span><\/td>\nReduce feed rate at exit, use backup plate, split-point drill geometry<\/span><\/td>\n<\/tr>\n
Peel-up (entry)<\/span><\/td>\nDrilling (early zone)<\/span><\/td>\nUpward-peeling force from conventional helix drill<\/span><\/td>\nUse low-helix or brad-point drill; reduce feed on entry passes<\/span><\/td>\n<\/tr>\n
Edge delamination<\/span><\/td>\nRouting, trimming<\/span><\/td>\nRadial cutting force peels surface plies away from edge<\/span><\/td>\nClimb milling direction; sharp PCD or diamond-coated router bits; reduce DOC<\/span><\/td>\n<\/tr>\n
Thermal damage<\/span><\/td>\nRouting, drilling, grinding<\/span><\/td>\nHeat exceeds matrix glass transition temperature (Tg) \u2014 typically 120\u2013180\u00b0C for epoxy<\/span><\/td>\nDry machining (no wet coolant that can penetrate laminate); air blast; sharp tools to minimise friction heat<\/span><\/td>\n<\/tr>\n
Core crushing<\/span><\/td>\nDrilling honeycomb sandwich<\/span><\/td>\nInsufficient support under honeycomb core during drilling<\/span><\/td>\nSupport fixture underneath sandwich panel; drill skin and core separately where possible<\/span><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

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At Rapid Precision, all aerospace composite machining is qualified under our <\/span>AS9100D quality system<\/span><\/a> with delamination inspection per ASTM E2966 and NDT requirements defined in the customer’s CMM plan.<\/span><\/p>\n

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Tooling Selection for Aerospace Composites<\/b><\/h2>\n\n\n\n\n\n\n\n\n\n\n
Tool Type<\/b><\/th>\nAnmeldung<\/b><\/th>\nLife vs. Carbide<\/b><\/th>\nCost Index<\/b><\/th>\nBest For<\/b><\/th>\n<\/tr>\n<\/thead>\n
Uncoated carbide<\/span><\/td>\nGFRP, thin CFRP laminates<\/span><\/td>\nBaseline<\/span><\/td>\n1.0x<\/span><\/td>\nLow-volume GFRP, prototypes where tool cost is secondary<\/span><\/td>\n<\/tr>\n
Diamond-coated carbide<\/span><\/td>\nCFRP all types<\/span><\/td>\n3\u20135\u00d7 carbide life<\/span><\/td>\n2.5\u20134x<\/span><\/td>\nStandard CFRP production \u2014 best cost-per-part economics<\/span><\/td>\n<\/tr>\n
PCD (polycrystalline diamond) \u2014 brazed<\/span><\/td>\nHigh-volume CFRP<\/span><\/td>\n10\u201325\u00d7 carbide life<\/span><\/td>\n8\u201315x<\/span><\/td>\nHigh-volume production runs where tool change downtime is the constraint<\/span><\/td>\n<\/tr>\n
CVD diamond (thick film)<\/span><\/td>\nPrecision CFRP, woven composites<\/span><\/td>\n15\u201330\u00d7 carbide life<\/span><\/td>\n12\u201320x<\/span><\/td>\nHighest precision requirements, cleanest edge quality on woven fabric<\/span><\/td>\n<\/tr>\n
Brad-point drill<\/span><\/td>\nCFRP drilling, entry-exit delamination-sensitive<\/span><\/td>\n2\u20134\u00d7 standard twist drill<\/span><\/td>\n1.5\u20132x<\/span><\/td>\nParts where entrance and exit delamination are the primary quality risk<\/span><\/td>\n<\/tr>\n
Step drill (pilot + reamer)<\/span><\/td>\nPrecision bore holes in CFRP<\/span><\/td>\n2\u20133\u00d7 standard drill<\/span><\/td>\n1.8\u20132.5x<\/span><\/td>\nPrecision holes \u00b10.025 mm in structural CFRP requiring surface integrity<\/span><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

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Cutting Parameters: CFRP vs GFRP<\/b><\/h2>\n\n\n\n\n\n\n\n\n\n\n
Parameter<\/b><\/th>\nCFRP (epoxy matrix)<\/b><\/th>\nGFRP (epoxy\/polyester)<\/b><\/th>\nNotes<\/b><\/th>\n<\/tr>\n<\/thead>\n
Cutting speed \u2014 routing<\/span><\/td>\n200\u2013800 m\/min (PCD\/CVD diamond)<\/span><\/td>\n100\u2013400 m\/min (carbide)<\/span><\/td>\nHigher speed reduces interlaminar shear; below minimum speed increases delamination risk<\/span><\/td>\n<\/tr>\n
Feed rate \u2014 routing<\/span><\/td>\n0.1\u20130.3 mm\/tooth<\/span><\/td>\n0.15\u20130.4 mm\/tooth<\/span><\/td>\nExcessive feed increases radial force \u2192 edge delamination<\/span><\/td>\n<\/tr>\n
Drill feed rate<\/span><\/td>\n0.025\u20130.075 mm\/rev main body; reduce 50% at exit<\/span><\/td>\n0.05\u20130.1 mm\/rev<\/span><\/td>\nCritical exit zone requires feed rate reduction 2\u20133 mm before breakthrough<\/span><\/td>\n<\/tr>\n
Climb vs conventional milling<\/span><\/td>\nClimb milling always preferred for edge quality<\/span><\/td>\nClimb preferred<\/span><\/td>\nClimb milling reduces tool engagement angle; less edge peel force<\/span><\/td>\n<\/tr>\n
Coolant<\/span><\/td>\nDry air blast \u2014 NO wet coolant on structural CFRP<\/span><\/td>\nDry air blast or MQL<\/span><\/td>\nWet coolant penetrates laminate via cut capillaries; compromises epoxy matrix<\/span><\/td>\n<\/tr>\n
DOC (depth of cut)<\/span><\/td>\n\u2264 0.5\u20131.5 mm per pass (routing)<\/span><\/td>\n\u2264 0.5\u20132.0 mm per pass<\/span><\/td>\nMultiple light passes reduce thrust force and delamination risk<\/span><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

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NDT Inspection Requirements for Machined Composite Parts<\/b><\/h2>\n

Composite parts machined for aerospace programmes require non-destructive testing (NDT) inspection after machining to confirm no sub-surface delamination, porosity, or matrix cracking was induced. Standard NDT methods for machined composites:<\/span><\/p>\n