Mold design is a complex and delicate work, which needs to comprehensively consider many factors such as product requirements, material characteristics, production process and cost control. The following are the key points of mold design, which are detailed in each category:

1. Product analysis and optimization
Structural rationality: ensure that the product has no sharp angles, cantilever structure, and avoid stress concentration and difficult demoulding.

Wall thickness uniformity: control the difference in wall thickness (usually ≤ 30%), prevent shrinkage, deformation (such as the thickness of the stiffener ≤ 60% of the wall thickness of the main body).

Demoulding slope: according to the material (such as ABS needs 1°~1.5°) and height (increase 0.5° every 10mm), the high gloss surface needs to have a larger slope.

Parting line positioning: Prioritize non-cosmetic surfaces to avoid affecting the assembly (e.g., placing the parting line of a phone case on the side).

2. Mold structure design
Parting surface design: to ensure the feasibility of processing, simplify the structure (such as flat or regular surface), and avoid flash (fitting accuracy≤ 0.02mm).

Gating system: Optimization of the runner section (high efficiency but high cost for circularity), gate location determined by mold flow analysis (e.g. point gate for cosmetic parts).

Cooling system: The waterway is 12~15mm away from the surface of the cavity, and the layout follows the principle of "near first and then far", and the conformal waterway is used to improve the efficiency.

Ejection system: uniform layout of ejector pins (spacing ≤ 50mm), combined with air roof assisted demoulding (deep cavity parts).

3. Material selection
Mold material: mass production molded cemented carbide (such as H13, HRC48-52), P20 for small batches; S136 for corrosion-resistant scenarios.

Molding material: consider shrinkage (e.g., PP 1.5-2.5%), fluidity (MI value) and thermal stability (e.g., high-temperature mold for PC).

4. Process feasibility
Processing and maintenance: modular design (such as insert structure), easy to replace; The depth of the exhaust groove ≤0.03mm to avoid overflow.

Life management: the hardness of the guide pillar and guide bush is above HRC60, and the slider is lubricated regularly (every 50,000 times).

Standardized design: DME/HASCO standard mold base is preferred to reduce non-standard processing.

5. Manufacturing & Assembly
Machining accuracy: the tolerance of core parts ± 0.005mm, and the fitting clearance of parting surface ≤ 0.02mm.

Assembly process: assemble in the order of "mold base→ molded parts→ejection mechanism →cooling system", and mold closing test is required before mold trial.

6. Cost control
Simplified structure: reduce the number of sliders (the cost increases by 20% for each additional slider), and replace the side core pulls with a sloped top.

Efficiency balance: 8-cavity mold saves 15% cycle time compared to 16-cavity, but equipment tonnage needs to be evaluated.

7. Safety and environmental protection
Ergonomics: rounded corner R≥0.5mm, chamfered at the end of the thimble, eyebolt hole selected according to the weight of the mold (such as M16 for 1 ton mold).

Environmental compliance: RoHS/REACH compliant, aluminum molds can be 100% recyclable.

Fill in the details
Thermal expansion compensation: the expansion coefficient of steel is 1.2×10⁻⁵/°C, and the expansion gap needs to be reserved for high-temperature molds.

Mold Flow Analysis: Use Moldflow to optimize the filling (e.g., avoid weld lines in the stress zone).

Transportation design: large molds are equipped with forklift slots, and molds above 10 tons are equipped with hoisting holes.

summary
Mold design needs to combine theoretical analysis and practical experience, and achieve the best effect through iterative optimization (usually 3-5 mold trials). Attention to detail (e.g., a 0.1mm difference in exhaust depth may determine the product yield), while using CAE tools to improve design efficiency, ultimately achieve high-quality, low-cost, long-life mold solutions.