Niche · Niche Process
Thin Wall Molding
Wall thickness 0.4-1.0mm, cycle time 3-8 seconds, fast cycle, material savings, low unit cost – the top choice for smart terminals, disposable containers, and laptop housings.
What is Thin Wall Molding
The industry generally defines “thin wall” as wall thickness ≤ 1.0mm and flow ratio L/T ≥ 100. The challenge with such parts is that the plastic flow distance is extremely long but the cross-section is very small – requiring ultra-high injection speed (800-2000 mm/s) + high holding pressure (120-180 MPa) + precise mold thermal balance to fill the cavity before the plastic freezes.
Three Key Advantages
- Short Cycle Time: 3-8 seconds per shot (standard parts 15-30 seconds), increasing productivity by 3-5 times
- Low Material Consumption: Halving wall thickness = halving material per part = 30-50% reduction in material cost
- Lightweight: A key weight reduction method in consumer electronics
Equipment and Process Requirements
- High-Speed Injection Molding Machine: Hydraulic accumulator or electric servo, injection speed ≥ 800 mm/s
- High-Rigidity Mold: S136 / H13 + reinforced cavity to avoid deformation under high pressure
- Hot Runner: Essential, reduces flow distance and waste
- Enhanced Venting: Thin walls have poor venting efficiency, requiring multiple vent grooves + vacuum assist
- Stable Mold Temperature: Oil temperature controller with ±2°C accuracy to avoid warpage from uneven cooling
Suitable Materials
- Thin-wall specific PP (high flow MFI > 50, e.g., BX3920, HP648T)
- High flow ABS / PC+ABS (commonly used for phone cases)
- High flow PA6 / PA66 (connector housings)
- Transparent PC / PMMA (laptop keycaps, display bezels)
Typical Applications
- Phone / tablet back covers (wall thickness 0.6-0.8mm)
- Laptop D-cover (0.8-1.0mm)
- Disposable food containers, pill boxes (0.4-0.6mm)
- Battery housings (0.5-0.8mm)
- Earbuds / TWS charging case bodies (0.6-0.9mm)
Common Defects and Countermeasures
- Short Shot: Increase injection speed, raise mold temperature, enlarge runner, switch to high-flow grade
- Warpage: Balance cooling (add cooling channels), adjust holding time, pre-compensate critical dimensions
- Burn Marks / Gas Traps: Add vent grooves, reduce injection speed at end of fill, use vacuum assist
- Flash: Check clamping force (thin-wall parts require 30%+ higher clamping force than standard), repair parting line