1. The mould cavity or working belt has sundries, and the hardness of the mould working belt is low, so that the surface of the working belt is injured when it is extruded and scratches the profile.
2. When the forked bar sends the profile to the pendulum bed, the profile damage is caused by the fast speed.
3, the surface of the ingot is attached to the impurity or the segregation of the ingot. There are a lot of things out of the ingot surface segregation and ingot without homogenization treatment or homogenization treatment effect is not good, hard metal particles in ingot memory of a certain amount, in the extrusion process of metal flowing through the work zone, these metal particles segregation or hard to damage in the attachment of the work or work surface with the final to scratch the surface of profile;
4. There are hard inclusions in the exposed metal or graphite strip on the material orbits or in the pendulum bed. When they are exposed to the profile, the scratches are caused on the surface of the profile.