Most on-site technicians adjust spin welding machines purely by trial and error - randomly changing rotation speed, pressure, and welding time. As a result, problems such as weak welding, water leakage, misalignment, excessive flash, and angle deviation frequently occur. The root cause is that they have not fully understood the complete standardized operating process of spin welding machines.
Aotuo Machinery servo spin welding machine adopts a five-step closed-loop process throughout the entire operation:
Workpiece clamping → Downward pressing and fitting → High-speed friction melting → Precise positioning and stop rotation → Pressure holding and cooling solidification
Every step directly determines the welding yield rate.
Step 1: Precise Clamping and Positioning
The upper and lower molds securely hold the two plastic workpieces separately. Concentricity must be maintained with zero deviation. For circular workpieces, any eccentric positioning will cause vibration during rotation, uneven weld seam width, and direct product rejection due to water leakage.
The positioning spin welding machine should preset the stopping angle in advance to ensure accurate alignment of product patterns, slots, and assembly marks. For non-standard circular parts, anti-misalignment positioning grooves should be added to eliminate manual loading errors.
Step 2: Stable Axial Pressing
The cylinder moves downward at a uniform speed, allowing the upper and lower workpieces to fit tightly together with evenly distributed and stable pressure.
Insufficient pressure results in poor contact between surfaces and inadequate friction heat generation. Excessive pressure may cause deformation, and thin-wall circular parts can collapse directly, causing loss of concentricity.
The standard industry air pressure range is 0.5–0.8 MPa. Lower pressure is recommended for thin-wall small parts, while higher pressure is suitable for thick-wall large components.
Step 3: High-Speed Rotational Friction Melting
The spindle drives the upper workpiece to rotate at high speed. Continuous friction between the contact surfaces generates heat rapidly, bringing the plastic material to its melting temperature.
For different materials:
- PP/PE require relatively higher rotation speeds.
- Nylon/PET require relatively lower rotation speeds.
The friction time must be precisely matched to the wall thickness.
The melting process follows:
Solid-state friction heating → Surface softening → Complete melting and material flow
A uniform molten layer is formed at the welding interface, which becomes the core factor determining welding strength.
Step 4: Instant and Precise Rotation Stop
After reaching the preset melting depth and friction duration, the spindle stops immediately through rapid braking.
For servo-controlled models, the angle deviation can be controlled within ≤0.1°, while traditional pneumatic machines are more likely to experience angle drift.
The faster the rotation stops, the tighter the molecular fusion and the smoother the weld seam. Delayed stopping may cause plastic material turbulence, excessive flash accumulation, and appearance defects.
Step 5: Pressure Holding and Cooling Solidification
Constant pressure is maintained without releasing the workpiece. Through natural air cooling, the molten material quickly solidifies, allowing the polymer molecules to firmly interlock and form a strong welded structure.
Premature pressure release or mold opening is strictly prohibited. If the workpiece is released before complete solidification, high-temperature joints may crack, leak, or become misaligned.
Cooling time should be equal to or longer than the friction time. In winter or low-temperature environments, the cooling time should be extended by approximately 20%.
The entire process cycle takes only 10–15 seconds, providing much higher production efficiency than traditional hot plate welding and ultrasonic welding.
All common defects - including water leakage, weak welding, angle deviation, and excessive flash - are directly related to imbalance in these five key process parameters.
By fully understanding the process logic, operators can quickly optimize welding parameters for different products without relying on experienced technicians.
