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Reasons and solutions for blackening and slag inclusion defects in aluminum extrusion profile billets

In order to solve the problems of black spots and slag inclusions in finished aluminum profile products, reduce the amount of scrap, and improve the yield rate, the Technology Department conducted a large number of investigations. Through long-term tracking, the following three methods are proposed to prevent blackouts and slag inclusions:

1. Production process control

1) After cutting the aluminum rod, use an air duct to blow off the dust on the aluminum rod to reduce the amount of soot brought in and reduce the source of blackening and slag inclusion;
2) The thickness of the residual pressure should be sufficient. Too thin a residual pressure will cause the dead area of the aluminum rod to be involved in the tail end of the aluminum profile, causing black drag and slag inclusion;
3) The extrusion speed of aluminum materials must be effectively controlled, especially the end must be decelerated to prevent turbulent flow from being involved in surface impurities;
4) The cylinder must be cleaned every period of production (at least every time the mold is changed);

2. Adjustment of equipment and devices

1) If the extrusion rod is not aligned, the material bladder will be worn during the movement of the extrusion rod, which will cause defects such as enlargement and deformation of the material bladder. The center of the mold base must be aligned up, down, left, and right. It is strictly prohibited to move the mold base. During production, if the top and bottom are misaligned, please contact the machine repairman for repair;
2) The size of the press cake must be regularly tested and replaced. For extruded cakes with curled edges, it will also cause blackening, slag inclusion, etc. and be scrapped;
3) If the material tank is used for a long time, deformation such as a big belly will occur, which will also cause batch scrapping. This kind of scrapping occurs very often in production and needs to be paid attention to. The dirt in the new material tank must be removed and the inner tank must be polished. Only then can it be installed on the computer.

3. Adjustment of mold design and production plan

1) For flat molds, such as PM series, it is necessary to install a deflector plate to guide the flow. This reduces the feed opening and clamps the dead zone;
2) The material port must fully surround the mold diverter hole. The squad leader should compare each set of molds installed. If the diverter hole is too large, it cannot be produced on the machine and must be converted to a larger machine;
3) When planning production, the plan should be based on the original machine used for mold making in the mold department (the same rod diameter can be used universally), and there should be no molds for small rods to produce large rods;