This is related to your material area and the output power of the equipment: the high-frequency hot bonding machine is designed to make molecules move inside the material to achieve the purpose of dissolution, so the power is large enough to weld. If it was originally 4KW, you can try it with 5KW, or raise the frequency a little (27. 12/40.68MHz) and lengthen the pressing time. The above is for your reference and I hope it will help you.