One-piece Molding Sandal PU Production Line Full Solution
This professional production line adopts advanced one-piece (upper & sole) molding technology for sandals and beach shoes. It realizes glue-free integral forming, featuring high bonding strength, stable product quality and high continuous production efficiency. All equipment is matched according to mass production standards, suitable for medium and large-scale footwear factories.
Technical Document | June 2026 Haifeng Machinery
Basic Project Parameters
| Item | Specification |
|---|---|
| Raw Material & Ratio | Two-component PU: Polyol (A) : Isocyanate (B) = 100 : 40 ~ 70 Preheating temperature: 60 ~ 70℃ |
| Auxiliary Materials | Release agent, pigment, MC (mixing head cleaning), DOP (tank cleaning) |
| Casting Performance | Max flow: 70 g/s | Metering accuracy: ±0.5% |
| Control System | HMI manual/semi-automatic, multi-formula storage |
| Applicable Product | Beach shoes & sandals (one-piece upper & sole molding) |
Core Process Features
The one-piece molding process integrates shoe last, upper and sole into one set of molds. PU material is injected and cured in one step to tightly combine the sole and upper. No adhesive is needed, and the finished product has excellent structural strength, wear resistance and durability, which greatly simplifies the traditional gluing process.
Complete Production Process
| Procedure | Detailed Description | Equipment | Picture |
|---|---|---|---|
| Shoe Upper Cutting | Cut raw materials into standard upper shape | Hydraulic Cutting Machine CNC Pneumatic Cutting Machine |
 |
| Surface Roughening | Process bonding surface to improve PU adhesion | Roughening Machine |  |
| Lasting | Fix upper on shoe last for accurate positioning | Shoe Upper Lasting Machine |  |
| Mold Preparation | Clean mold, spray release agent, place last & upper | Release Agent Spraying Robot Custom Mold & Shoe Last |
 |
| PU Injection Molding | Mix A/B materials and inject into mold | Special PU Casting Machine |  |
| Mold Curing | Constant temperature curing in tunnel | Curing Tunnel |  |
| Demolding & Finishing | Take out products, trim edges, inspect & package | Mold Opening & Closing Unit Edge Trimmer Trimming & Sorting Line |
 |
One-piece sandal production process flow
Mold Opening & Demolding
Edge Trimming
Inspection & Packaging
Full Equipment List
Cutting & Preparation Equipment
| Equipment Name | Quantity | Key Specifications | Picture |
|---|---|---|---|
| Hydraulic Cutting Machine | 1 set | Cutting force 25~100T, power 3~7.5KW | |
| CNC Pneumatic Cutting Machine | 1 set | Feeding accuracy ±0.1mm, power 2.2~7.5KW |  |
| Roughening Machine | 1 set | Working width 1200mm, power ≈2.3KW | |
Molding & Curing Equipment
| Equipment Name | Quantity | Key Specifications | Picture |
|---|---|---|---|
| Special PU Casting Machine | 1 set | Max flow 70g/s, accuracy ±0.5%, power 20.55KW | |
| Curing Tunnel | 1 set | Size 2000×1150×1000mm, power 0.55KW | |
| Mold Opening & Closing Unit | 2 sets | Servo motor, power 2KW | |
| Custom Mold & Shoe Last | Several | Customized by shoe size |  |
Auxiliary Equipment
| Equipment Name | Quantity | Key Specifications | Picture |
|---|---|---|---|
| Raw Material Drying Oven | 1 set | Volume 2.5m³, max temp 90℃, power 6.55KW |  |
| Air Compressor & Tank | 1 set | Power 22KW, exhaust 3.2m³/min |  |
| Industrial Chiller | 1 set | Cooling capacity 6.02KW, power 1.91KW |  |
| Automatic Conveyor Line | 1 set | Total power 45~55KW |  |
| Cleaning & Release Agent Tank | 2 sets | Size 300×300×1000mm |  |
| Release Agent Spraying Robot | 1 set | Load 7KG, power 1KW | |
| Raw Material Mixer | 1 set | Uniform mixing of A/B components |  |
| Trimming & Sorting Line | 1 set | Edge trimming, inspection and packaging |  |
| Edge Trimmer | 1 set | Finish trimming for finished shoes |  |
Production Capacity & Efficiency
| Index | Data | Remark |
|---|---|---|
| Single Cycle Time | 6 ~ 7 minutes per pair | Including full curing |
| 8-hour Shift Output | 2050 ~ 2400 pairs | Theoretical value |
| 16-hour Daily Output | 4100 ~ 4800 pairs | Theoretical value |
| Actual Capacity | 80% ~ 90% of theoretical | Affected by operator proficiency |
Workshop & Operation Requirements
| Item | Requirement |
|---|---|
| Workshop Space | 25m × 10m flat floor |
| Ambient Condition | Temperature ≤40℃, no condensation |
| Power Supply | 3×380V ±5%, 50Hz, total power ~85KW |
| Compressed Air | 0.7 ~ 0.8 MPa, dry & oil-free |
| Cooling Water | Clean water, temp ≤15℃, flow ≥6m³/h |
| Operators | 5 ~ 6 trained workers |
Power & Resource Consumption
| Item | Parameter |
|---|---|
| Total Installed Power | About 90 KW |
| Compressed Air Consumption | 0.6 ~ 0.8 m³/min |
| Cooling Water Circulation | ≥6 m³/h, temp ≤15℃ |
Common Defects & Troubleshooting
| Defect | Root Cause | Solution |
|---|---|---|
| Poor upper-sole adhesion | Insufficient roughening / uneven release agent | Strengthen surface treatment; standardize spraying |
| Internal bubbles | Unqualified vacuum / raw material moisture | Check air tightness; seal material tank |
| Material overflow | Mold misalignment / excessive injection | Adjust mold position; calibrate metering |
| Incomplete curing | Low oven temp / short curing time | Adjust heating parameters & line speed |
Optional Upgrades & Customization
- Automatic feeding system (reduce manual labor)
- MES data management & traceability system
- Explosion-proof configuration for special workshops
- Multi-formula one-click switching function
- Voltage & frequency customization for global markets
- Fully automatic production linkage (unmanned auxiliary line)
Packaging & Transportation
- Overall Volume: Fit into 1 × 40HQ container
- Total Weight: 10 ~ 15 tons
- Export Package: Rainproof film + wooden pallet/iron frame
- Transportation: Support sea, air and combined delivery
After-Sales Service
- Provide complete technical documents: operation manual, electrical drawings, workshop layout
- Overseas engineer on-site installation, commissioning and operator training
- 12 months warranty for non-artificial quality problems, free spare parts
- Lifetime technical guidance and spare parts supply after warranty
Frequently Asked Questions
Is the one-piece molding process different from traditional gluing?
Yes. This line adopts glue-free integral molding, which provides higher strength and longer service life.
Can molds be customized for different shoe sizes?
Yes, we customize molds and lasts according to your product drawings.
Can equipment adapt to different national power grids?
We support voltage and frequency customization for global markets.
What is the main daily maintenance work?
Clean mixing head and spraying robot daily; check temperature, pressure and air pressure per shift.
Can old production lines be partially upgraded?
We provide partial renovation solutions to save procurement cost.
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