Aluminium extrusions are manufactured using a hydraulic power-press. An alloyed aluminium ingot is cut into standard lengths, heated up to 500 degrees Centigrade and then forced through a die under high pressure by a hydraulic ram. The material is shaped to the desired cross-section when it passes through the die.
At ProfilGruppen, we have three separate presses, each of which can press up to eight extrusions at the same time. After pressing, the extrusions are cooled with air and/or water depending on the alloy. After this, the extrusions are straightened in hydraulic stretching equipment and cut into suitable lengths. Finally if specified, the strength of the extrusions is increased by thermal aging, where the material’s natural hardening process is accelerated by heating for five to eight hours at approximately 180 degrees Centigrade.
The press opening indicates the maximum limit of what can pass through the press, an extrusion design must therefore be kept to within these outer limits. In addition, a tool is required that can press the required extrusion in an efficient and accurate manner. Extremely large or small extrusions often require special consideration during component and tool design with regard to material thickness etc.
Description of the manufacture of extrusions:
- Intake of aluminium ingot, 205mm or 255mm diameter (8” or 10” diameter). Maximum extrusion width is about 120% of the ingot diameter, i.e. an 205mm ingot can provide an extrusion of 240 mm.
- A saw cuts the aluminium ingot into a unique length for each extrusion. The length of the ingot varies between 0.4 and 1.4 metres.
- The furnace heats up the aluminium ingot to more than 500 degrees.
- Loading the aluminium ingot.
- The press cylinder increases the pressure from 1.3-1.8 MPa to about 50-60 Mpa which at the point of extrusion provides a maximum pressure of 3200 tonnes.
- The magazine is loaded with the aluminium ingot before the pressing phase.
- The tool holder supports the die that the ingot is to be pressed through.
- The extrusion is collected on an outfeed table where it is cooled with water and/or air.