Injection Mold Design: Core Process & Targeted Solutions

Injection mold design is the cornerstone of high-quality plastic part production—its rationality directly impacts mold lifespan, production efficiency, and product consistency. Below is a streamlined breakdown of the design process and tailored solutions, aligned with industry best practices.

1. Design Process: From Demand to Validation

Step 1: Demand & Product Analysis (10%-15% of total time)

First, clarify core requirements: product material (e.g., PP, PMMA), dimensional tolerance (e.g., ±0.01mm for precision parts), appearance standards (mirror finish/VDI texture), and production capacity (e.g., 10k pieces/month). Analyze the part’s 3D model to identify potential issues—such as thick-walled areas prone to sink marks or undercuts requiring slider structures.

Step 2: Preliminary Structure Design

Determine mold type (two-plate/three-plate), cavity quantity (1-out-2 for low-volume, 1-out-8 for mass production), and gate location (hot runner for large parts, pin-point gate for small precision parts). Layout key components: guide pillars (for alignment), cooling circuits (initial straight-path design), and ejection systems (顶针 for flat parts, 顶管 for cylindrical parts).

Step 3: Mold Flow Simulation (MoldFlow)

Use simulation software to test melt filling, pressure distribution, and cooling efficiency. Optimize to eliminate risks: adjust gate position to avoid weld lines on stress-bearing areas, or add vents (0.01-0.02mm deep) to prevent air bubbles.

Step 4: Detail Optimization & 2D/3D Drawing Finalization

Refine critical details: set parting surface clearance ≤0.005mm, specify steel grades (S136 for corrosion resistance, P20 for general use), and define heat treatment (HRC 50-52 for mold cores). Generate 2D engineering drawings (with geometric tolerances) and 3D assembly models for manufacturing.

Step 5: Trial Mold & Iteration

Conduct a test run: check part dimensions (via coordinate measuring machine) and appearance (no flash >0.02mm). Adjust if needed—e.g., enlarge cooling holes to reduce cycle time, or modify ejection force to avoid part deformation.

2. Tailored Solutions for Common Scenarios

• Material-Adapted Design: For high-shrinkage PP (1.5%-2.5%), pre-compensate dimensions in 3D models; for heat-sensitive PMMA, use low-temperature cooling (40-50℃) to prevent yellowing.

• Efficiency-Driven Solutions: For mass production, adopt conformal cooling (3D-printed ) to cut cycle time by 20%; for precision parts, use 5-axis machining for mold cores to ensure ±0.003mm accuracy.

Effective injection mold design balances quality, efficiency, and cost—starting with thorough demand analysis and ending with data-driven iteration. It lays the groundwork for stable, high-performance injection production.