The CNC programming department in the mold factory establishes clear machining processes and standards. Implementing standardized operations during production improves efficiency and reduces errors.
1. Front Mold Core
1.1 Hot Sprue Position
- Dimensions with assembly requirements must be machined to precise specifications.
- Flat surfaces: The CNC program must match the exact dimensions. Operators shall check using a dial gauge according to the drawing’s tolerance.
- Side surfaces: The program must include a compensation, leaving 0.02 mm stock on each side for trial fitting. Operators should use pin gauges for a tight fit, ensuring a single-side tolerance between 0.015 mm and 0.005 mm. All other dimensions must match the 3D drawing exactly.
1.2 Insert Lock Position
- Side surfaces must be machined according to exact dimensions.
- Depth (Z value) must also match the drawing dimensions, measured with a dial gauge, with a depth tolerance of ±0.01 mm.
1.3 Cavity Dimensions
- All cavities in finish machining should leave 0.02 mm per side (unless otherwise specified).
- If EDM texture is required, leave 0.15 mm per side for EDM processing.
1.4 Through Holes / Interference Fit Holes
- Normally, the front mold core is machined to final size, while the rear mold core leaves machining allowance.
1.5 Side Lock Position
- Bottom depth (Z value) must be machined to exact size.
- Side surfaces should leave 0.02 mm per side for trial fitting, using pin gauges for a tight fit, with single-side tolerance between 0.015 mm and 0.005 mm.
2. Rear Mold Core
2.1 Slide Groove
- Depth (Z value) must match drawing dimensions and be checked with a dial gauge.
- Side surfaces should leave 0.02 mm per side for trial fitting with block gauges, ensuring tolerance of 0.015 mm to 0.005 mm per side.
2.2 Insert Lock Position
- Side surfaces and bottom depth (Z value) must match dimensions exactly, with depth tolerance ±0.01 mm.
2.3 Mold Frame Holes (Core Hidden Position)
- Finishing program must leave 0.02 mm per side for operator fitting.
- Operators measure to drawing specs and machine single-side 0.005 mm–0.01 mm oversize for easier assembly.
2.4 Cavity Dimensions
- All cavities should leave 0.02 mm finishing allowance (unless otherwise specified).
2.5 Through Holes / Interference Fit Holes
- Normally, rear mold leaves +0.02 mm to 0 mm stock.
- Mating areas with slide units must be machined to exact size, while other areas may keep allowance.
3. Mold Core Protrusions (CORE)
3.1 Rough Machining
- Leave 0.5 mm per side.
- For mold frame inserts, leave 10 mm straight stock at the bottom for stability checking.
- For special-shaped cores requiring heat treatment, leave 10 mm straight at the base for centering after hardening.
3.2 Cavity Dimensions
- During finishing, leave 0.02 mm for cavities (unless otherwise specified).
- Through/interference positions leave +0.02 mm to 0 mm.
3.3 Core Outer Shape Finishing
- Program must leave 0.02 mm per side for operator measurement.
- Final tolerance: 0 to –0.005 mm per side for easy assembly.
3.4 Irregular Core Insert Centering
- See detailed notes in later section.
