{ "slug": "minimum-wall-thickness", "title": "Minimum Wall Thickness for CNC Machined Parts", "description": "Minimum and recommended wall thickness for aluminium, steel, stainless, titanium, copper and plastics — plus wall height limits and fixturing for thin walls.", "lang": "en", "tables": [ { "caption": "Minimum and recommended wall thickness by material", "columns": [ "Material", "Absolute minimum", "Recommended", "What happens if it is too thin" ], "rows": [ { "Material": "Aluminium (6061, 7075)", "Absolute minimum": "0.5 mm", "Recommended": "1.0 mm", "What happens if it is too thin": "Chatter during finishing, the wall pushes away from the cutter, the dimension goes out of tolerance." }, { "Material": "Steel (1045, 4140)", "Absolute minimum": "0.8 mm", "Recommended": "1.5 mm", "What happens if it is too thin": "Tool deflection at 0.5 mm is severe with steel and walls bow inward. Harder steels amplify this." }, { "Material": "Stainless steel (304, 316)", "Absolute minimum": "0.9 mm", "Recommended": "1.5 mm", "What happens if it is too thin": "Stainless work-hardens rapidly. Thin walls overheat, warp and may crack, and tool wear accelerates." }, { "Material": "Titanium (Ti-6Al-4V)", "Absolute minimum": "1.0 mm", "Recommended": "1.5 mm", "What happens if it is too thin": "Titanium has low thermal conductivity, so heat builds up in thin sections and causes thermal warping." }, { "Material": "Copper and brass", "Absolute minimum": "0.5 mm", "Recommended": "0.8 mm", "What happens if it is too thin": "The soft material helps and copper can go quite thin, but very thin copper walls are fragile during handling and assembly." }, { "Material": "Engineering plastics (Delrin, Nylon, PEEK)", "Absolute minimum": "0.4 mm", "Recommended": "0.8 mm", "What happens if it is too thin": "Plastics deflect under cutting force and thin walls flex away from the tool, producing burrs and poor accuracy." } ] }, { "caption": "How Tall a Wall Can Be", "columns": [ "Rule", "Guideline", "Why it matters" ], "rows": [ { "Rule": "", "Guideline": "Wall thickness at least 1/5 of the adjacent feature height", "Why it matters": "A tall thin wall behaves like a cantilever beam." }, { "Rule": "", "Guideline": "Maximum unsupported height = 8× wall thickness in aluminium, 5× in steel", "Why it matters": "Beyond this ratio the wall vibrates during machining." }, { "Rule": "", "Guideline": "Keep walls within 20% of each other on the same part", "Why it matters": "Uneven walls cause differential cooling in heat treatment and uneven stresses." }, { "Rule": "", "Guideline": "Gradual transitions between thick and thin sections", "Why it matters": "Abrupt thickness changes create stress concentrators. Add a fillet or taper." }, { "Rule": "", "Guideline": "Rib thickness = 0.6× wall thickness, rib height at or below 5× rib thickness", "Why it matters": "Thick ribs create sink marks on the opposite surface." } ] }, { "caption": "What a Tight Wall Costs", "columns": [ "Design feature", "Standard specification", "Tight or difficult specification", "Cost multiplier" ], "rows": [ { "Design feature": "Wall thickness (aluminium)", "Standard specification": "at least 1.0 mm", "Tight or difficult specification": "0.5–0.8 mm", "Cost multiplier": "1.3–1.8×" }, { "Design feature": "Wall thickness (steel)", "Standard specification": "at least 1.5 mm", "Tight or difficult specification": "0.8–1.2 mm", "Cost multiplier": "1.4–2.0×" }, { "Design feature": "Internal fillet radius", "Standard specification": "R3–R6 mm", "Tight or difficult specification": "R0.5 mm or smaller", "Cost multiplier": "1.8–3.0×" }, { "Design feature": "Floor radius in pocket", "Standard specification": "R1–R3 mm", "Tight or difficult specification": "R0 (sharp)", "Cost multiplier": "3.0–5.0×" }, { "Design feature": "Edge break", "Standard specification": "0.5 mm chamfer (default)", "Tight or difficult specification": "Sharp edges, no break", "Cost multiplier": "1.0×, but higher handling risk" }, { "Design feature": "External radius", "Standard specification": "Sharp or 0.5 mm break", "Tight or difficult specification": "Large cosmetic radius, R5 and above", "Cost multiplier": "1.1–1.3×" }, { "Design feature": "Deep pocket aspect ratio", "Standard specification": "depth at or below 4× width", "Tight or difficult specification": "depth above 6× width", "Cost multiplier": "1.5–2.5×" }, { "Design feature": "Tall thin wall", "Standard specification": "height at or below 5× thickness", "Tight or difficult specification": "height above 8× thickness", "Cost multiplier": "1.5–2.0×" } ] }, { "caption": "How to Hold a Thin Wall While Machining", "columns": [ "Fixturing method", "Minimum wall thickness", "Material compatibility", "Typical deflection", "Best use" ], "rows": [ { "Fixturing method": "Hard jaws (standard)", "Minimum wall thickness": "at least 6 mm", "Material compatibility": "All metals", "Typical deflection": "0.1–0.3 mm", "Best use": "Thick parts only" }, { "Fixturing method": "Soft jaws (machinable)", "Minimum wall thickness": "at least 1.5 mm", "Material compatibility": "All metals", "Typical deflection": "0.02–0.05 mm", "Best use": "General thin walls" }, { "Fixturing method": "Vacuum chuck", "Minimum wall thickness": "at least 0.3 mm (foil)", "Material compatibility": "Non-porous, any metal", "Typical deflection": "0.01–0.03 mm", "Best use": "Flat sheet, light cuts" }, { "Fixturing method": "Magnetic chuck", "Minimum wall thickness": "at least 1 mm", "Material compatibility": "Ferromagnetic only", "Typical deflection": "0.02–0.08 mm", "Best use": "Steel ground plates" }, { "Fixturing method": "Wax potting", "Minimum wall thickness": "at least 0.5 mm", "Material compatibility": "All metals, avoid thermal exposure", "Typical deflection": "0.01–0.05 mm", "Best use": "Thin-wall roughing" }, { "Fixturing method": "Low-melt alloy", "Minimum wall thickness": "at least 0.5 mm", "Material compatibility": "All metals, check thermal history", "Typical deflection": "0.005–0.02 mm", "Best use": "Complex thin-wall cavities" }, { "Fixturing method": "Sacrificial tabs or bosses", "Minimum wall thickness": "Any, by design", "Material compatibility": "All metals", "Typical deflection": "Effectively zero", "Best use": "The best general answer" } ] } ] }