BASED IN
SHENZHEN CHINA
AND THE USA
SHENZHEN CHINA
AND THE USA
Product Design Services
- Plastic Part Design
- Medical Device Design
- Fixtures
- Machined Metal Components
- 3D CAD SolidWorks
- 2D Drawings
- Tolerance Analysis
- Design for Manufacturability
- Assemblies
- Mold Flow Analysis
1. Draft Angles (for Easy Part Ejection)
Plastic shrinks onto the mold surface during cooling, creating friction during ejection. Draft angles prevent this issue.
General Guidelines:
2. Shut-Offs (for Creating Interlocking Features Without Side Actions)
Shut-offs help eliminate expensive side actions in the mold by allowing one half of the mold to block plastic flow in the other.
Angle Considerations:
3. Wall Thickness (Uniformity to Prevent Sink & Warp)
4. General Wall Thickness Guidelines for Common Plastics
The plastic’s Melt Flow Rate (MFR) should be considered when designing wall thicknesses. Some applications may require thinner or thicker walls than these guidelines.
5. Rib Design
Ribs add stiffness but can cause sink marks and molding defects if improperly designed.
Rib thickness guidelines based on main wall thickness:
ABS: 40-60%
PP: 50-70%
PC: 40-60%
Nylon (PA): 50-70%
POM (Acetal): 50-70%
6. Texture and Surface Finishes
Methods of Applying Texture:
Texture Standards:
7. Mold Flow Analysis
8. There are many other considerations based on the product application.
Plastic shrinks onto the mold surface during cooling, creating friction during ejection. Draft angles prevent this issue.
General Guidelines:
- Standard draft: 1° to 3° per side.
- High-texture surfaces: 3° to 5° (deeper textures require more draft).
2. Shut-Offs (for Creating Interlocking Features Without Side Actions)
Shut-offs help eliminate expensive side actions in the mold by allowing one half of the mold to block plastic flow in the other.
Angle Considerations:
- Minimum shut-off angle: 2° (however, this is small and may lead to wear and flashing).
- Preferred shut-off angle: 3° to 7° (reduces wear on the mold).
3. Wall Thickness (Uniformity to Prevent Sink & Warp)
- Uneven thickness leads to differential shrinkage, causing warpage, sink marks, and dimensional stability challenges.
- Maintain uniform wall thickness. If thickness changes are needed, use a gradual transition.
4. General Wall Thickness Guidelines for Common Plastics
The plastic’s Melt Flow Rate (MFR) should be considered when designing wall thicknesses. Some applications may require thinner or thicker walls than these guidelines.
- ABS: 1.5 to 4.5 mm (0.060 to 0.177 inches)
- Polypropylene (PP): 1.0 to 4.5 mm (0.040 to 0.177 inches)
- Polycarbonate (PC): 1.2 to 5.0 mm (0.047 to 0.197 inches)
- Nylon (PA): 1.0 to 3.5 mm (0.040 to 0.138 inches)
- Polyethylene (PE), including HDPE and LDPE: 1.2 to 6.0 mm (0.047 to 0.236 inches)
- Acetal (POM): 1.0 to 3.5 mm (0.040 to 0.138 inches)
5. Rib Design
Ribs add stiffness but can cause sink marks and molding defects if improperly designed.
Rib thickness guidelines based on main wall thickness:
ABS: 40-60%
PP: 50-70%
PC: 40-60%
Nylon (PA): 50-70%
POM (Acetal): 50-70%
6. Texture and Surface Finishes
Methods of Applying Texture:
- Chemical etching
- Laser engraving
- Blasting
- Polishing
Texture Standards:
- Mold-Tech (MT)
- SPI Mold Finishes
- VDI 3400
7. Mold Flow Analysis
- If the product design progresses to the design freeze phase without a mold flow analysis, there is a risk that the design will need to be modified for DFM when transferring to the mold manufacturing phase.
- Performing a basic mold flow analysis during the product design phase will mitigate this potential problem.
8. There are many other considerations based on the product application.