Introduction to Aluminium Extrusion Dies

Introduction to Extrusion Dies

The design and manufacturing of extrusion dies involve numerous steps, including material selection, design, manufacturing, and die repair. Their cost accounts for approximately 35% of the total cost of profile extrusion production.

In profile processing, there are generally two main extrusion methods: sprue-combination die extrusion and pin-punch extrusion. The former is simpler to process and has lower costs, while the latter is more expensive and has a smaller application range. In actual profile processing, sprue-combination dies are more widely used.

1 Working Conditions of Extrusion Dies

Extrusion forming of large-section, complex profiles is quite challenging, placing high demands on the structure and shape of the extrusion dies. This is especially true for profiles with complex cross-sectional shapes, significant differences in wall thickness, large cross-sectional areas and circumscribed circles, and multi-cavity hollow profiles, where the working conditions of the extrusion dies become even more severe.

Therefore, the requirements for extrusion dies are high, mainly in the following aspects:

First, they must operate under high temperature and high pressure conditions;

Second, they must possess good wear resistance;

Third, they must possess high strength and toughness to prevent stress concentration and die failure during operation.

2 Classification of Extrusion Dies

There are many types of extrusion dies, which can be classified according to different criteria. The main basis for classification is the die structure and the cross-sectional shape of the compression zone of the die orifice.

The flow-dividing combination mold is currently the most widely used mold type. The structure of a planar flow-dividing combination mold mainly consists of four parts: an upper mold, a lower mold, locating pins, and connecting screws. Its working principle is that under a certain extrusion pressure, the molten metal is divided into a flow through the diversion holes, flows through the welding chamber for collection and bonding, and finally flows out through the mold core and mold hole, forming a profile product with the required geometry.

The flow-dividing combination mold is composed of upper and lower molds. The upper mold has diversion holes, diversion bridges, and a mold core, while the lower mold has a welding chamber and a mold hole. Working zones are provided on both the mold core and the mold hole.

For flow-dividing combination molds, the number of welds on the product is the same as the number of metal streams. Therefore, flow-dividing molds are only suitable for metals with good high-temperature welding properties, such as lead, magnesium, zinc, and their alloys, and not for metals with poor welding properties, such as hard aluminum.

3 Extrusion Die Maintenance

Die maintenance and storage are crucial aspects. From the moment a die leaves the factory, a record must be created detailing its information, including order and acceptance details, process parameters, technical condition during use, wear, and repair history.

During regular use, the vacuum and cooling systems should be cleaned as needed based on usage intensity. If scratches or minor corrosion appear on the die surface, it should be promptly polished with fine sandpaper (1000 grit or higher). Severe damage should be repaired immediately.

When not in use, the die should be stored in a clean, dry, and well-ventilated place to prevent corrosion. For dies not used for extended periods, measures such as oil sealing should be taken to prevent damage.

Furthermore, die repair and maintenance must be performed by skilled workers; carelessness is strictly prohibited.