Causes and treatment methods of blistering and peeling on the surface of extruded profiles

Bubbles or peeling: convex bubbles appear on the surface of the product, often at the head and tail. Complete ones are called bubbles, and broken ones are called peeling.

1. Reasons for bubbles and peeling of extruded products:

1) The extrusion cylinder and extrusion pad are worn out of tolerance, the dimensions of the extrusion cylinder and extrusion pad are improperly matched, and the diameter difference between the two gaskets used at the same time exceeds the allowable value.

2) The extrusion cylinder and extrusion pad are too dirty, with oil, moisture, graphite, etc. stuck on them.

3) Lubricating oil contains water

4) There are too many shovel grooves on the surface of the ingot, too deep, or there are pores, blisters, loose tissue, and oil stains on the surface of the ingot.

5) When replacing the alloy, the inside of the cylinder was not cleaned.

6) The temperature of the extrusion barrel and the temperature of the extrusion ingot are too high

7) The ingot temperature and size exceed the allowable negative deviation

8) The ingot is too long, the filling is too fast, and the temperature of the ingot is uneven, causing non-drum filling. Therefore, the exhaust in the cylinder is incomplete, or the operation is improper and the exhaust process is not performed.

9) The design of the die hole is unreasonable, or the residual material is improperly cut. The residual material in the diverter hole and the diversion hole is partially brought out, and the gas in the gap enters the surface during extrusion.

Elimination method:
1. Reasonably design the matching dimensions of the extrusion cylinder and the extrusion gasket, and frequently check the size of the tool to ensure compliance with the requirements. If the extrusion cylinder has a belly, it must be repaired in time, and the extrusion pad must not exceed tolerances.

2. Keep tools and ingot surfaces clean, smooth and dry

3. When changing alloys, clean the barrel thoroughly

4. Check equipment and instruments frequently to prevent excessive temperatures and speeds

5. Strictly implement process procedures and various systems

6. Reasonably design and manufacture the tool and mold, and design the guide hole and shunt hole to have an internal slope of 1 to 3 degrees.

7. Strict operation, correct cutting of residual materials and complete exhaust