PVC and TPU are the two most common materials processed by high frequency welding machines, widely used in medical bags, automotive air bladders, tarpaulins and inflatable products. Though both can be fused by HF equipment, their welding parameters, defect risks and finished performance have huge differences.

PVC material has soft texture and low melting point. Its standard welding parameter is medium current, 0.3–0.8s welding time and short cooling time. The biggest defect of PVC welding is flash overflow on weld lines, caused by excessive pressure or too long heating time. To solve this, reduce air cylinder pressure and add a trimming edge on the welding mold.

TPU material features excellent air tightness and wear resistance, which is the top choice for automotive air lumbar and medical drainage bags. It needs higher current and longer cooling time to avoid weak welds. The most frequent TPU welding failure is product breakdown, because TPU is thinner and more sensitive to high frequency sparks. Operators need to turn up spark protection sensitivity and polish mold surfaces to remove burrs.

For factories that produce both PVC and TPU products, you do not need two separate HF machines. Adjust three core parameters when switching materials: welding current, holding pressure and cooling duration. Clean the mold surface thoroughly before switching production to prevent cross-contamination causing air leakage.

In terms of finished quality, TPU welds have better stretch resistance and air tightness, suitable for products working under 0.2–2.5Bar air pressure. PVC welds are more cost-effective for disposable tarpaulin and packaging bags with low durability requirements. Choose matched materials and adjust HF parameters accordingly to cut defective rates greatly.