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Views: 0 Author: Site Editor Publish Time: 2024-11-11 Origin: Site
TPU is a class of thermoplastic elastomers (TPEs), offering a unique balance of elasticity, transparency, and resistance to abrasion, oils, and chemicals.
Polyether-based TPU: Better hydrolysis resistance (good for water exposure)
Polyester-based TPU: Higher mechanical strength and oil resistance
Polycaprolactone-based TPU: Excellent low-temperature flexibility
TPU injection molding involves melting TPU pellets and injecting them into a mold to form a product. TPU behaves like rubber but processes like plastic, which allows for efficient mass production with complex geometries.
Material Drying: TPU must be dried before molding to avoid bubbles or poor surface finish (usually at 80–110°C for 2–4 hours).
Melting & Injection: TPU is melted (typically 190–230°C) and injected into the mold under pressure.
Cooling & Ejection: TPU cools rapidly, forming a flexible part. Parts are then ejected from the mold.
Post-processing: May include trimming, overmolding, or assembly.
| Parameter | Value |
|---|---|
| Drying Temperature | 80–110°C for 2–4 hrs |
| Melt Temperature | 190–230°C |
| Mold Temperature | 25–60°C |
| Injection Pressure | 70–140 MPa |
| Screw Speed | Moderate (to avoid degradation) |
Note: TPU is hygroscopic (absorbs moisture), so drying before molding is crucial to prevent defects.
| Industry | Applications |
|---|---|
| Footwear | Soles, cushioning inserts, sports shoes |
| Electronics | Phone cases, cable insulation, wearables |
| Automotive | Bushings, air ducts, vibration dampers |
| Medical | Tubing, grips, seals (biocompatible grades) |
| Industrial | Gaskets, hoses, seals, wheels, belts |
| Property | TPU Characteristics |
|---|---|
| Hardness | Shore 60A – 85D |
| Tensile Strength | 30–50 MPa |
| Elongation at Break | Up to 700% |
| Abrasion Resistance | Excellent |
| Chemical Resistance | Good (especially to oils, greases, solvents) |
| Flexibility | High, even at low temperatures |
| UV Resistance | Moderate (can be improved with stabilizers) |
Rubber-like flexibility with thermoplastic processability
Excellent wear and tear resistance
Elastic memory (returns to shape after deformation)
Good chemical, oil, and abrasion resistance
Compatible with overmolding on rigid plastics (e.g., ABS, PC)
| Issue | Description |
|---|---|
| Moisture Sensitivity | Requires pre-drying to prevent bubbles |
| Shrinkage | Higher than rigid plastics; requires compensation in mold design |
| Deformation | Softness can cause part distortion after ejection |
| Flow Issues | TPU has high viscosity; thin walls or long flow paths need careful design |
| Tool Wear | Can be abrasive to molds over time, depending on additives |
Rounded corners and uniform wall thickness help avoid stress points.
Ejection system must be gentle to avoid tearing or deforming the part.
Ventilation is important to prevent air traps.
TPU is ideal for two-shot or overmolding with rigid substrates like PC or ABS.
| Property | TPU | TPE | Rubber | Silicone |
|---|---|---|---|---|
| Elasticity | Excellent | Excellent | Excellent | Excellent |
| Chemical Resistance | Good | Good | Moderate | Excellent |
| Temperature Resistance | Moderate | Moderate | High | Very High |
| Processing | Easy | Easy | Difficult | Moderate |
| Recyclability | Yes | Yes | No | No |
| Defect | Cause | Solution |
|---|---|---|
| Bubbles / Voids | Moisture | Dry the TPU properly |
| Short Shots | Poor flow | Increase temp or injection pressure |
| Warping | Uneven cooling | Balance cooling system, adjust mold temperature |
| Flash | Low viscosity or overpacking | Reduce pressure, improve clamp |
| Burn Marks | Trapped air | Improve venting, lower melt temp |
Choose TPU injection molding if your part needs:
Flexibility and stretchability
Abrasion and impact resistance
Rubber-like feel with plastic processing benefits
Biocompatibility (for medical-grade applications)
Welcome to contact SWY MOULD for more mould project. email at shine@swymould.com or phone with +86 15757668880.
