Understanding Plastic Chair Mold Production
Plastic chair molds are among the most technically demanding products in the injection mold industry. This article walks you through the complete production process.
Phase 1: Design and Engineering
Product Design Review
- Ergonomic assessment
- Structural analysis (FEA)
- Weight optimization
- Aesthetic refinement
Mold Design
- 3D mold design with CAD
- Mold flow analysis
- Cooling simulation
- Ejection system design
Phase 2: Material Preparation
Steel Selection
Common steels for chair molds:- P20: Cost-effective, good for moderate runs
- 718H: Pre-hardened, excellent polishability
- S136: Corrosion resistant, mirror finish capability
Steel Procurement and Inspection
- Verify steel certificates
- Check hardness
- Inspect for defects
Phase 3: Rough Machining
CNC Machining
- Remove bulk material
- Create basic geometry
- Leave 0.3-0.5mm for finish machining
Deep Hole Drilling
- Cooling channel drilling
- Ejector pin holes
- Guide pin holes
Phase 4: Heat Treatment
For Tool Steel
- Vacuum hardening
- Stress relief
- Dimensional stabilization
Phase 5: Finish Machining
High-Speed CNC
- Achieve final dimensions
- Surface finish preparation
- Tolerance: ±0.02mm typical
EDM (Electrical Discharge Machining)
- Complex geometries
- Fine details
- Textures
Phase 6: Surface Treatment
Polishing
- Progressive polishing grades
- Mirror finish for visible areas
- Texture application
Coating (Optional)
- Chrome plating for wear resistance
- Nitriding for hardness
- PVD coating for special applications
Phase 7: Assembly
Component Assembly
- Core and cavity fitting
- Slider and lifter installation
- Cooling system assembly
- Ejection system assembly
Hot Runner Installation
- Manifold mounting
- Nozzle alignment
- Wiring and temperature control
Phase 8: Trial and Optimization
First Trial (T1)
- Initial sampling
- Identify issues
- Measure dimensions
Optimization
- Adjust processing parameters
- Fine-tune cooling
- Modify if necessary
Final Trial (T2/T3)
- Confirm all specifications
- Production speed test
- Quality consistency check
Gas-Assist Technology for Chairs
Many modern chair molds use gas-assist injection:
Benefits:
- Reduced material usage (often 15-30%, design dependent)
- Lighter products
- Eliminated sink marks
- Shorter cycle times
Requirements:
- Specialized nozzle design
- Nitrogen supply system
- Modified process control
Quality Inspection
Dimensional Inspection
- CMM measurement
- Profile projection
- 3D scanning comparison
Functional Testing
- Mold opening/closing
- Ejection smoothness
- Cycle time verification
Conclusion
Chair mold production is a complex process requiring expertise at every stage. Understanding this process helps you better communicate with your mold manufacturer and ensure optimal results.
