The Aluminum Extrusion Process
Direct and indirect extrusion processes are both done in stages. While there might be two or three slight differences, in the two processes, most of the others are identical. The decision on whether to go direct or indirect relies on the end product required. Some shapes are better made through direct extrusion while others are better through the indirect process.
Besides, each of the two processes has pros and cons. For instance, it may cost less to use the indirect process compared to the direct process. And that’s why some operation managers will go for that option. Other times, the direct extrusion option is inevitable. let’s go through the aluminum extrusion stages.
- Die openning
The die determines the final product’s shape. Die openning involves giving the die a specific shape. This means that any aluminum that passes through the die will assume its shape.
- Billet preparation
When aluminum is acquired raw, it isn’t ready for extruding. To prepare the metal, aluminum is heated to at least 750 degrees (F). But the heat is kept below 925 degrees (F) to avoid overheating the aluminum. This is enough temperature to melt the aluminum.
After that, smut is applied to both the liquid aluminum and the ram. Considering liquid metal is sticky the smut ensures the two do not stick together. As a result, the billet will move swiftly through the die without sticking on the ram.
- Billet extrusion
The billet is forced through the die by the ram. This happens under high pressure. Under these conditions, its’ very likely for oxides to be formed. This is prevented through the use of liquid nitrogen. The coolant ensures that the die doesn’t overheat to produce unnecessary oxides. Besides, the die will last longer if cooled enough. That means more aluminum will be extruded.
Aluminum extruders are equipped with a variety of extrusion press machines. The tonnage of the extrusion press machine represents the extrusion force. The common tonnage of aluminum extrusion press machine is 800T, 1000T, 1200T, 1800T, 2300T, 2800T, 3600T, 4000T, 5000T, 8000T and so on. A correct aluminum extrusion press machine to be used depends on the cross-sectional dimensions of the aluminium profile.
- The cooling process
As the extruded aluminum leaves through the die, it’s passed to a cooling table. There, aluminum comes to contact with air. Sometimes, the extruded aluminum may be exposed to water. The decision to choose between water, air, or both solely relies on the expectations of the final aluminium profiles.
- The straightening process
After the extrusion process passes the cooling process, the aluminum is released for strengthening. This is a stretching process that ensures the extruded aluminum leaves for the destination while in its hardest, strongest, and finest stage. This means that any deformities that might have occurred in previous stages are taken care of.
The next destination would be cutting the long aluminium profiles into desirable length. A circular saw is used for this process. By the time it’s done, the aluminum extrusion profiles would be ready for finishing before dispatch for sale.
- Finishing & fabrication
This is the final stage in the extrusion process. The extruded aluminum is coated and fabricated using the latest technology. At this point, the products are ready for supply to warehouses and clients. The aluminum extrusion profiles are designed as per client requirements.