At the aluminum extrusion production process, some time there are some rough scratches on aluminum profiles, it will affect the beauty of aluminium extrusion profiles surface and the value of aluminum profile. Here some information collected from our engineers’ experience and aluminum industry knowledge from internet.  First at all, observe the aluminum extrusion profile scratch shape, the position, the depth. 

 

1. If the scratches recessed from aluminum profile surface mostly due to the extrusion die which sticking foreign matter (other material) or the hollow groove machining of aluminum extrusion die is very rough.

2. If the convex corner scratches on the corner of aluminum profile due to aluminum extrusion die cracks.

3. If aluminum extrusion profile scratch is transverse lines, it due to the hard protrusion on the handing table system to finish saw, or scratched by aluminum profiles loading, unloading and transportation.

1) If aluminum profile scratch lines (the lines are deep) show on four faces of profiles, check the plunger pump (ram pump) displacement, the aluminum extrusion press pressure may be not stable. If the ram pump is all right, then check the prefill valve.  Other aluminum extrusion factory said, the dummy block may cause this problem, but we have not met this problem at our client’s factories.

2) If aluminum profile scratch is white line (the lines are light) and is on the bottom side of aluminium profile, that may cause by aluminum profile handing table system. When the run-out saw cut the aluminium profile, the handing table may shake and aluminum profiles may lightly hit the handing table. So adjust the balance of handing table system.

4. If aluminum profile scratch is vertical white lines, check the aluminum billet temperature, then the aluminum extrusion die temperature and extrusion die surface quality, and then aluminium billet quality.

Here some suggestions to resolve the problem of “scratch” from aluminum extrusion profile:

1. Check the aluminum extrusion press working condition, aluminum extrusion technical production process likes aluminum billet temperature, aluminum extrusion container temperature, extrusion die temperature, aluminum extrusion speed, aluminum extrusion die surface quality and aluminum billet quality.

2. Aluminum Extrusion die working area should be smooth and clean, even the hollow groove of extrusion die also need to be smooth.

3. Before load the extrusion die to the aluminum extrusion press, check carefully the extrusion die to avoid the small cracks on the die. The die design also needs to take care of the corner radius.

4. Check the aluminum profile handing table, cooling table and finish storage table to avoid of the hard protrusions.

5. Place the soft parting sticks between aluminum profiles, also try to cover a layer of felt belt on the basket steel.

6. If the aluminum profile scratch is very light, can use the aluminum profile polishing machine to eliminate it, but needs the anodizing process to get a layer of oxidation film to protect the new surface.

 

According to the hydraulic action standard, Aluminum extrusion press has two kinds of action standard: one is single action, the other is double action. Double action aluminum extrusion press is good at making seamless aluminum pipe for resisting high temperature at industry aluminum profile.  Almost of China aluminum extrusion plants adopts single action aluminum extrusion press. Here some information of double action aluminum extrusion press:

 

Here is some information point-like scratch on the aluminum alloy of 2A11, 2A12, 7A04 to make aluminum pipe/aluminum tube.

1. Piercing mandrel needle of aluminum extrusion press working area need to keep clean, smooth and hardness. After the needle machined, try to do some treatment of polishing, nitriding or boriding, After the needle be used a certain time, do this treatment again.

2. Correct the needle of aluminum extrusion press regularly, after finished the aluminum pipe extrusion, fix and polish the needle, remove the aluminum thoroughly; When correct the needle, need to notice the uniformity to avoid getting the taper on the needle working area.

3. Paint some lubricant on the front end of needle when aluminum extrusion.

4. Aluminum billet homogenizing can avoid chip breaking problem when piercing.

5. If adopt semi-piercing, use the piercing needle to push out the waste, oxide or the Segregation layer which on the inner hole of aluminum billet, increase inner hold surface quality.

6. Adopt suitable extrusion speed and temperature.

 

This information are adapted according to my own aluminum extrusion press knowledge, if there is any mistake created by my translation or my knowledge, welcome to correct it.