Reason analysis affecting the surface quality of aluminum profile

with the need of social development,aluminum alloy profile in various industries also gradually increased, involving the 

scope is more and more wide,customer demand is becoming more and more strict,the producers have to strengthen their 

production skills,today I will extrusion profile surface quality,summarize their production experience to share with you.

In our normal production process, frequent surface quality problems are: scratches, black and bright lines, rough, cracks.

1.Scratches

                                               A                                                                       B

This kind of scratch (Figure A) is the height of the welded steel bar and choke block exceeds the height of the working belt

of the mold after mold maintenance, and there is scratch during extrusion.

The solution is shown in Figure B. The steel bar choke block beyond the working belt is polished to be lower than the

working belt, and the distance below it is faster or slower through the flow rateNeed to control. The block is generally

closer to the working belt, the better, the farther the effect or gradually reduce.

                                                                                        C

Figure C scratches are intermittent scratches in production and irregular irregular occurrences in extrusion. The first such 

scratches are caused by unqualified aluminum bar material composition and excessive impurities; the second is caused 

by the wear of the extrusion pad and the extrusion cylinder. There is too much gap in the extrusion cylinder, resulting in 

too much impurity aluminum on the cylinder wall.

Squeezes into the mold causing scratches. The third type is the extrusion center is not correct, causing such scratches to 

occur continuously on one side.

The solution:

(1) Check the composition of the aluminum rod to ensure that the aluminum rod is qualified.

(2) Check the extrusion pad and extrusion cylinder, and replace it in time if there is a problem.

(3) Adjust the extrusion center, the extrusion force is uniform, and avoid the eccentric position into the alumina causing 

scratches.

2.Black and bright lines

                                                       D                                                             F

The black lines in Figure D and Figure F all appear in the extrusion process, which affects the subsequent processing, 

especially the oxidized products. After processing, the black lines are more serious and even lead to scrapping. The problem 

of Figure D appears, first of all, the treatment is started from the polishing of the mold, the polishing is not thorough, there 

is dust, dust accumulation on the surface of the work belt, and even the bump gap, such problems will occur. Figure F shows 

uneven discharge temperature caused by mold flow rate, or poor welding in the head and tail area.

Solution: First, strengthen the polishing personnel to improve their skills, and clean the dust and oil in the mold welding room 

when polishing. The polishing technique should pay attention to, horizontal polishing, eliminate longitudinal polishing, easy 

to appear longitudinal scratches, and the scratch comes with the material. When polishing from coarse sand to fine sand, and

 then use the back of the fine emery cloth to throw once. The surface of the polished working belt is mirror-smooth.

3.Rough

Profile roughness is divided into rough drawing and rough surface, rough drawing is because the extrusion speed is too fast, 

the exit temperature is burned, resulting in the profile surface stretch, and the profile surface is accompanied by feel. The reason 

for the roughness of the surface is that the mold working belt is not polished fine, and the discharge is rough.

Solution: When the profile is drawn, the outlet temperature is too high, the outlet temperature can be measured, the extrusion 

speed can be adjusted appropriately or the cool rod production, the operator should always pay attention to the discharge situation 

and develop good habits. Rough discharge can only start from the mold, and strengthen the inspection after polishing to ensure 

that the machine is qualified. In addition, the mold heating time is too long will also appear rough surface, so it is necessary to 

reasonably control the heating time and make a good record.

4.Cracks

                                                     G                                                            H

As shown in Figure G, the cracking situation belongs to the third point of severe roughness. The cracking of the outer surface is generally 

caused by high bar temperature and fast speed. During the extrusion process, the cracking situation of the internal cavity of the profile 

will also appear as shown in Figure H.

Solution: First of all, the extrusion speed is reduced, and the exit temperature is first lowered to meet the required process requirements, 

generally controlled at 510-530 degrees. At the same time, the temperature of the outer skin of the aluminum rod can be reduced by using 

more aluminum rods for cooling rod production, and high temperature overburning can be avoided in the later period of extrusion.

In summary, the factors that affect the surface quality of aluminum extrusion are molds, aluminum rods, and extrusion processes, and we 

want to solve the surface quality separately The surface is not good, so it is necessary to solve the comprehensive system in order to do 

a good job of the surface quality of the profile.