What is the difference between direct and indirect aluminum extrusion?

The difference between direct extrusion and indirect extrusion is between the direction of metal flow and the direction of extrusion shaft movement, as well as the resulting differences in process characteristics and application scenarios. 

Definition and rationale

direct extrusion: the direction of metal flow is the same as that of extrusion shaft. This method is simple and flexible, but there is relative sliding between the metal and the extrusion cylinder wall, resulting in high friction, high energy consumption and uneven metal flow.

indirect extrusion: the direction of metal flow is opposite to the direction of motion of the extrusion shaft. This method has the advantages of small extrusion force, low energy consumption and uniform metal flow, but the operation is complex and the equipment requirements are high.

Process characteristics

direct extrusion:

Advantages: simple operation, great flexibility, excellent surface quality of products.

Disadvantages: high friction, high energy consumption, uneven metal flow, and fast die wear.

indirect extrusion:

Advantages: small extrusion force, low energy consumption, uniform metal flow, suitable for extrusion of high strength alloys.

Disadvantages: complex operation, high equipment requirements and poor product surface quality.

Application scenarios

direct extrusion: it is applicable to the production of products with conventional shape and rough processing requirements, such as pipes, bars, profiles, etc.

indirect extrusion: it is applicable to the production of products with complex shape or high precision requirements, such as aircraft, automotive parts, electronic device shells, etc.

Comparison of advantages and disadvantages

direct extrusion:

Advantages: simple operation, great flexibility, excellent surface quality of products.

Disadvantages: high friction, high energy consumption, uneven metal flow and fast die wear.

indirect extrusion:

Advantages: small extrusion force, low energy consumption, uniform metal flow, suitable for extrusion of high strength alloys.

Disadvantages: complex operation, high equipment requirements and poor product surface quality.

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