Reasons and solutions for the welding of plastic mold injection products

In the plastic mold injection molding process, when there are holes, inserts, and thickness variations of the product in the multi-gate or cavity, the plastic melt will flow in both directions above the mold. When the melt meets, a weld line is formed in the article.

According to the different production methods, the fuse wire can be divided into hot melt wire and cold melt wire. From the apparent point of view, the weld line has a curved shape, and also approximates a straight line. From the thickness of the product, the weld line has a surface on the outer surface, and there is also a V-shaped groove mark deep into the surface layer, and even some Through the entire wall thickness section.
Equipment aspect
If the plasticization is poor and the melt temperature is not uniform, the molding cycle can be appropriately extended to make the plasticization more complete, and if necessary, the machine with a large plasticizing capacity can be replaced.

2. Mold aspect
1. If the mold temperature is too low, the mold temperature should be increased appropriately or the local temperature at the weld line should be purposefully increased.

2. You can enlarge or reduce the gate section and change the gate position. The gate is opened to prevent the melt from flowing around the inserts and holes. The gate where the injection molding occurs should try to correct, migrate or add the block buffer. Try to use wood or use less gates.

3. Raw materials
1. The raw materials should be dried and minimize the liquid additives in the formulation.

2. Add appropriate lubricants and stabilizers to plastics with poor fluidity or high heat sensitivity. If necessary, use plastics with good fluidity or high heat resistance.

4. Process aspects
1. Increase the injection pressure and prolong the injection time.

2, adjust the injection speed, high speed can make the melt less than the temperature to reach the confluence of the low speed allows the air in the cavity to have time to discharge.

3, adjust the temperature of the barrel and nozzle, the temperature is high, the strength of the plastic is small, and the fluidity is smooth and the weld line becomes thinner.