Views:1 Author:JIA HUA ALUMINIUM CO., LTD Publish Time: 2020-06-13 Origin:Site
Follow the direct of the aluminum profiles, it will have some line on the surface of aluminum profiles during extrusion. We call it die mark. It looks like you use hard object scratch the surface of aluminum extrusion profiles. Below is the picture. It is obvious to see die line on the surface. It will influence the appearance of aluminium extrusion. And it can't be cover the coating.
How it come?
The cause of scratches are come from the extrusion mould, processing of extrusion and material.
The Smoothness, heating process and working belt length of the mould will affect the die line. It will easy to get the die mark if the working belt is not be polished or polish effect is not that good.
The working belt of the mould will be hurt or the Nitride layer will fall after a long time production. It need to be re-nitriding or polished again. That’s the reason why we need to maintain the mould.
Sometimes, the heating of mould is too long, it also will make the working belt anodized. Or make the part of mould have annealing that reduced the strength. Also, it will come out the same result if the temperature is too high.
In addition, The longer the working belt of the die, the longer the friction time during the extrusion process, which will make the working belt stick to aluminum, causing the surface of the extruded aluminum material to become thicker, and even produce mold marks.
Processing of extrusion
The higher the extrusion temperature, the higher the aluminum alloy stick, which will increase the chance of die mark on the surface. In the mean time, it also will come out the line if the speed is too fast.
When extruding 5××× alloy and 7××× alloy pipes, due to the high alloy content of the material, it is easy to precipitate a small amount of hard compound phase at the exit of the working belt of the extrusion die, resulting in the surface of the product Mold marks, which are irregular and discontinuous in most cases.
The causality diagram produced by the mold marks is shown in below picture