Part one: Extrusion funnel, Aluminum alloy extrusion defect analysis and quality control method

Part one: Extrusion funnel, Aluminum alloy extrusion defect analysis and quality control method

Extrusion funnel, Aluminum alloy extrusion defect analysis and quality control method

Extrusion funnel causes and solutions

Extrusion funnel 

At the end of some extruded products, after inspection at low magnification, there is a phenomenon in horn-like in the middle of the section, which is called extrusion funnel.

You can often see either the first type of extrusion funnel or the second type of extrusion funnel.

The first type of extrusion funnel is located at the center of the extrusion and is wrinkled or funnel-shaped.

The second type of extrusion funnel is located in the radius 1/2 area of the product and is a ring-shaped or crescent-shaped crack.

Sometimes Continuous or discontinuous cracks or cracks in the layer are present at 0.5-2 mm from the surface layer of the extrusion, which is referred to as the third type of extrusion funnel.

Generally, the extrusion funnel of the forward extruded product is longer than that of the backward extrusion, and the soft alloy is longer than the hard alloy.

The extrusion funnel of the forward extruded product is mostly represented by an annular funnel, and the extrusion funnel of the backward extruded product is mostly a central funnel shape.

The metal is extruded to the back end, and the ingot skin on the dead corners or the gasket of the extrusion container and the outside inclusions accumulated are formed into twice funnel in the product; when the residual material is too short and the center of the product is insufficiently filled, which is formed to the first type extrusion funnel.                                                                     

From the end to the front, the extrusion funnel is gradually lighter and disappears completely.

The main causes of extrusion funnel

1. The residual material is too short or the product cutting end length does not meet the requirement;

2. The dummy block is not clean, with the oil;

3. In the late stage of extrusion, the extrusion speed is too fast or suddenly increases;

4. Use a deformed dummy block;

5. The temperature of the extrusion container is too high;

6. The extrusion container and the extrusion rod are misaligned;

7. The surface of the ingot is not clean, with oil, and there are defects such as segregation and overlapping.

8. The inner sleeve of the extrusion cylinder is not smooth or deformed, and the liner is not cleaned in time.

Solutions for extrusion funnel:

1. Residue and end cutting according to regulations;

2, keep the mold clean;

3. Improve the surface quality of the ingot;

4, reasonable control of extrusion temperature and speed;

5. Except for special circumstances, it is strictly forbidden to apply oil on the surface of mold;

6. The gasket is properly cooled.

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