These can be categorized according to the method of applying pressure to the billet as summarized below. As described by the graph, at the start of the extrusion, the required pressure starts to increase rapidly to its peak value known as the breakthrough pressure. Once the flow is initiated, the pressure decreases, and steady-state extrusion proceeds. When the loaded billet is almost consumed, the extrusion pressure reaches a minimum value followed by a sharp rise as the remaining is compacted.
From the graph, the required pressure only rises to the steady-state extrusion pressure. Indirect extrusion proves to be a more energy-efficient process than direct extrusion. Despite this advantage, indirect extrusion fails to be a replacement for direct extrusion.
This is because of the requirement for using a hollow ram which is weaker compared to a solid press. This limits the loads that can be applied to compress the billet. Hence, this process is only applicable for producing extrudates with small cross-sections. The hydrostatic extrusion offers the best-of-both-worlds from direct and indirect extrusion.
This process solves the problem of the high frictional forces experienced in direct extrusion and the limitation on the cross-sectional area of the indirect process. However, they also suffer from disadvantages such as lower throughput due to the longer preparation per extrusion cycle and sealing difficulties at high pressures. Lower throughput is the consequence of the additional billet tapering process and the necessary injection and removal of fluid for every cycle.
In some setups, instead of removing the fluid, the discard is retained to prevent the sudden release of the extrusion fluid. This discard is usually tougher due to cold working and will require additional compression to extrude. Sealing difficulties are from the tighter seal between the chamber and ram, and the seal between the billet and die. Aluminum extrusion is usually done under elevated pressures to increase the tendency of the metal to plastically flow.
The series, meanwhile, offers the highest strength of the alloys most widely used in construction materials. The series alloys are easy to weld and lose less strength in areas affected by heat than the series. The series alloys are commonly used in automotive parts , aircraft containers, bicycle frames, and speedboats. Aluminum extrusion offers a range of unique benefits, particularly in comparison to die casting, another popular method for shaping metal.
In die casting, molten metal is injected into a mold, which is known as the die. For easy visualization of the process, picture pouring batter into a tin in order to make a cake; the batter is the molten metal, the tin is the die, and the final product — the cake — is the complex shape produced.
These intricate shapes can include complex cross-sections. Extrusion also allows for the working of very brittle materials, since the material only deals with shear and compressive stresses. While die casting serves as a versatile, reliable process for many applications and industries, extrusion is much more cost-effective due to the lower tooling costs involved.
Plus, parts made with the extrusion process can be just as strong and rigid as those created using die casting. Heat Treatment, Finishing, and Fabrication Once extrusion is completed, profiles can be heat treated to enhance their properties. Then, after heat treatment, they can receive various surface finishes to enhance their appearance and corrosion protection. Alloys in the , , and series can be heat treated to enhance their ultimate tensile strength and yield stress.
To achieve these enhancements, profiles are put into ovens where their aging process is accelerated and they are brought to the T5 or T6 tempers. How do their properties change? As an example, untreated aluminum T4 has a tensile strength of MPa psi.
Heat-treated aluminum T6 has a tensile strength of MPa psi. It is important for the customer to understand the strength needs of their project to ensure the right choice of alloy and temper. Aluminum profiles can undergo a number of different finishing operations. Extrusions can be finished and fabricated in various ways. The two main reasons to consider these is that they can enhance the appearance of the aluminum and can also enhance its corrosion properties. But there are other benefits as well.
Other finishing processes such as painting , powder coating , sandblasting , and sublimation to create a wood look , can be undergone as well. Fabrication options allow you to achieve the final dimensions that you are looking for in your extrusions. For example, the fins on extruded aluminum heatsinks can be cross machined to create a pin design, or screw holes can be drilled into a structural piece.
Regardless of your requirements, there is a wide range of operations that can be performed on aluminum profiles to create the perfect fit for your project. Aluminum extrusion is a process for creating parts with specific cross-sectional profiles by pushing heated alloy material through a die. Shapes created can be solid, hollow, and semi-hollow; and they can be simple or they can be complex. The process of extrusion is an interesting one, resulting in foot long profiles that can then be heat treated, finished, and fabricated to customer specifications.
Aluminum extrusions can be designed to fit a wide range of products used in various industries. But product designers often have difficulty achieving optimal extrusion profile design and reducing manufacturing costs. In this guide, we provide 11 tips to help you optimize your designs for the extrusion process.
But, that has to be a very particular case. Auto Desk is a big company, and in many situations, someone will insist on using it. Value engineering: what benefit are you getting by paying more, and does the project require it?
For a Hackaday article to cover the complexity of this process this well is excellent, well done to the author. This is what I do for a living- die and punch maker though, and not for extrusion, but for forging titanium aerospace parts. I know someone who did pro video work. Inside then Alcoa now Arconic aluminum extrusion plant, some very high tech is used and they like to keep it in house. We were a high value target during the cold war, as lots of helicopter blades were produced here.
Now they have the biggest lithium-aluminum alloy plant in the world. Stronger-lighter than normal alloys.
Probably still are. So how are hollow channels formed? Are there several die with different profiles stacked together with the ones towards the end smooshing it all together? He touches on the topic of a floating die but it would be neat to see more details of how the center die is supported. I assume airfoil like shapes holding the center up in molten alum.
For those yearning for more information, check out AEC. This is a fantastic repository of knowledge regarding aluminum extrusions. There is work underay on novel Mg alloys which use Mg-Y and Mg-Zn-Y to increase ducitility during straining processes. Please be kind and respectful to help make the comments section excellent. Comment Policy. This site uses Akismet to reduce spam.
Learn how your comment data is processed. By using our website and services, you expressly agree to the placement of our performance, functionality and advertising cookies. Learn more. The Die The basic process for extruding aluminum is, outwardly, as simple to understand as the extrusion process used by a 3D-printer: heat material and force it through a die with the desired shape and size.
A die with a distinctive profile. Source: Phoenix International Die design is perhaps the most critical part of the extrusion process. The Squeeze There are a number of different ways to approach the extrusion process, each with its own pros and cons. Stretching and Aging But even with quenching, the extrusions that come out of the die onto the long outfeed tables are far from complete.
Report comment. The costs to create this stuff are quickly clear now I hope. I was surprised how in the video, they stretched the extrusions to get them back into spec. Some types of pasta are made the same way, but without stretching or aging…. Well, until layoffs hit me…soon.
Yep that just about sums it up.
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