There will be scratches on the inner surface of the aluminum tube

The inner surface of the aluminum tube will be scratched because:

The lubricant is not suitable or the ratio is incorrect.

The extrusion needle temperature is too low.

The extrusion needle is stained with metal and has not been cleaned off. The metal needs to be cleaned off.

The quality of the extrusion needle surface is not good enough and needs to be polished and repaired.

The extrusion speed of the extrusion needle is uneven or too fast, which needs to be adjusted.

The lubricant contains water or metal chips and grit, which need to be removed.

The extrusion needle is not evenly oiled.

The interval between oiling the extrusion needle and extrusion is too long, and the lubricating oil is evaporated or burned dry.

The extrusion speed of the hard alloy mill is too high.