Precision CNC machining determines cavity dimensional accuracy, assembly clearance and final casting quality. Poor machining control leads to core offset, uneven wall thickness and assembly interference. This article introduces Xinfeng mould CNC machining sequence, tolerance allocation and inspection standards.
Cavity rough machining: leave 0.4–0.6 mm finishing allowance, control machining vibration to avoid residual stress. Roughing tool path keeps 0.25–0.35 mm depth per cut.
Semi-finish machining: leave 0.12–0.20 mm allowance for final polishing. Check cavity deformation after semi-finishing, especially for large mold inserts over 400 mm.
Finish machining: cavity profile tolerance ±0.03 mm; core pin position tolerance ±0.025 mm. Machining temperature controlled at 22±2℃ to reduce thermal expansion error.
Draft angle machining tolerance: ±0.1°, directly affects ejection drag marks.
Fillet machining: continuous milling for large fillet R≥3.0; small fillet manually polished after CNC. Fillet radius tolerance ±0.05 mm.
Parting surface flatness within 0.02 mm per 500 mm length, to guarantee parting line clearance ≤0.03 mm and prevent flash.
H13 material machining after roughing: stress relief tempering before finish machining to release cutting residual stress, avoiding cavity deformation after final machining.
CMM inspection after finish machining: full 3D scanning of cavity, core pins, cooling holes and vent slots, generate dimensional deviation report.
Electrode design for EDM: used for deep narrow rib cavities where milling tool cannot reach. EDM surface must be polished to Ra0.8 before nitriding.
Machining marking: each insert engraved with part number, serial number and heat treatment batch for full traceability.
Q1: What finishing allowance is reserved after mold semi-finish machining? A1: 0.12–0.20 mm finishing allowance left before polishing. Q2: What is flatness requirement of mold parting surface? A2: Parting surface flatness controlled within 0.02 mm per 500 mm length. Q3: Why stress relief tempering after H13 rough machining? A3: Release cutting residual stress and prevent cavity deformation after finish machining.
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