Shenzhen Alu Rapid Prototype Precision Co., Ltd.

PLA (Polylactic Acid) is an environmentally friendly, biodegradable thermoplastic derived from renewable resources like corn starch or sugarcane, making it a great choice for sustainable manufacturing. Below is a concise guide to creating an injection mold for PLA, tailored to its properties and eco-friendly nature:

1. Understand PLA’s Properties for Molding

Melting Point: 150–160°C (302–320°F), lower than traditional plastics like ABS.

Shrinkage: 0.3–0.7%, which must be accounted for in mold design.

Viscosity: Moderate flow, requiring precise gating and venting.

Cooling Sensitivity: PLA cools quickly but can warp if cooling is uneven, so efficient mold cooling is critical.

Eco-Friendly Note: PLA’s biodegradability means it degrades faster under heat or moisture, so avoid prolonged exposure to high temperatures during molding.

Part Design (using CAD software like SolidWorks or Fusion 360):

Maintain uniform wall thickness (1–3 mm) for even cooling.

Include draft angles (1–2°) for easy part ejection.

Avoid sharp corners to minimize stress and defects.

Mold Design:

Cavity and Core: Design the mold cavity (negative of the part) and core with tight tolerances (±0.01 mm for precision).

Gating System: Use a sprue and runners with a fan or edge gate for smooth PLA flow. Hot runner systems can reduce waste, aligning with PLA’s eco-friendly benefits.

Cooling Channels: Incorporate channels for water cooling (mold temp: 20–40°C) to prevent warping and ensure consistent PLA solidification.

Ejector Pins: Add pins or plates for gentle part removal to avoid damaging delicate PLA parts.

Venting: Include vents (0.02–0.05 mm deep) to release trapped air and prevent burn marks.

Simulation: Use mold flow analysis software (e.g., Moldflow) to optimize fill time, pressure, and cooling for PLA.

3. Choose Mold Material

Prototype Molds: Aluminum or soft steel (e.g., P20) for low-volume runs. Aluminum is cheaper, easier to machine, and sufficient for PLA’s low abrasiveness.

Production Molds: Hardened steel (e.g., H13, S136) for high-volume production due to durability.

Eco-Tip: Opt for recyclable or locally sourced mold materials to align with PLA’s sustainability.

4. Optimize and Maintain

Optimization: Fine-tune injection speed, cooling time, or gate size based on test results.

Maintenance: Clean the mold regularly to remove PLA residue, which can degrade if overheated. Use minimal mold release agents to avoid contamination.

Storage: Store molds in a dry, cool environment to prevent corrosion and maintain PLA’s eco-friendly integrity.

Eco-Tip: Use energy-efficient molding machines and optimize cycle times to reduce energy consumption.

PLA-Specific Tips

Use hot runners for high-volume runs to minimize material waste, supporting PLA’s eco-friendly profile.

Avoid overheating PLA to prevent degradation, which can cause brittleness or yellowing.

Ensure proper ventilation in the workspace, as PLA can release mild fumes when heated.

Cost and Time

Cost: Aluminum prototype molds: $1,000–$5,000; steel production molds: $10,000–$100,000, depending on complexity.

Lead Time: Prototypes: 2–4 weeks; production molds: 8–12 weeks.