Plastic welding joins thermoplastic parts by applying heat and pressure. Unlike adhesives, welded joints are clean, strong, and do not require curing time.
In Chinese manufacturing, ultrasonic welding is the most common method (80% of applications), followed by hot plate and laser welding.
Method | Best Joint Shape | Cycle Time | Cost
--- | --- | --- | ---
Ultrasonic | Small, precise joints | 0.5-2s | ¥2-8/piece
Hot Plate | Large, complex shapes | 20-60s | ¥3-15/piece
Vibration | Medium-large parts | 3-10s | ¥5-20/piece
Laser | Medical, electronics | 0.5-3s | ¥8-30/piece
Spin | Round, cylindrical parts | 1-5s | ¥3-10/piece
Weldable: ABS, acrylic (PMMA), nylon (PA), polycarbonate (PC), polystyrene (PS), SAN, acetal (POM)
Conditionally weldable: PP, PE (requires surface treatment)
Not weldable: PTFE, PVC, polypropylene (unfilled)
Most Chinese molders have material compatibility charts — request one during the quoting phase.
Ultrasonic welding is widely available in Guangdong and Jiangsu. Many injection molding shops offer in-house welding services as a value-add.
Tip: If your part requires welding, ask the mold maker to add energy directors (small triangular ridges at the joint interface) in the tool — this eliminates the need for separate weld design and costs nothing to add.