Aluminum is a material that can be made to flow under pressure and this is the principle behind all types of aluminum extrusion machines. Most of these are hydraulically powered and a hydraulic ram acts upon one end of an aluminum billet so as to force it against the opposite end of an enclosed, barrel like, chamber. At this end, remote from the moving ram, there will be an “escape” hole through which the aluminum can be squeezed (like toothpaste coming out of a tube).
The “escape” hole will normally be in the form of a removable plate. This is so that one plate with a hole of a particular shape and size can be interchanged with another plate which has a different hole in it. In this way, many different shapes and sizes can be produced from a single extrusion machine.
The Shape And Size Of An Aluminum Extrusion
The produced length of an aluminum extrusion is a factor of the volume of aluminum in the original billet. Where the area of the hole is small, a longer length can be produced. However, it is standard practice to cut the extruded material into smaller, more manageable lengths after a full load has passed through the extruder.
Certain shapes are considered standards, likewise a range of dimensions can be considered as standard production extrusions. Shape is the geometric configuration across the ends of the extrusion and this follows the shape of the “escape” hole. Common standard shapes include round, square and rectangular which generally start at around ¼ inch and go up to around 6 to 8 inch.
A widely used aluminum construction shape is in the form of a sort of U-shaped channel (with 90° corners) a similar but L-shaped extrusion is also popular. Aluminum extrusion companies will have a standard range of these channel and angle extrusions.
However, there will be designers who either cannot incorporate standard shapes and/or dimensions into their finished product or, unfortunately, they decide to ignore all the more readily available standards. These people will need to procure Custom Aluminum Extrusions in order to bring their design into fruition as a finished product.
Whether it is the shape or the dimension that is non-standard, two important considerations have to be taken into account.
1. Can a die be made that is capable of producing such Custom Aluminum Extrusions?
2. Will the cost of that die and the price for setting it up in the extruder result in prohibitively high prices for the resulting Custom Aluminum Extrusions?
The answer to question 1 is an engineering exercise. Question 2 will depend on several factors; not least of which is the quantity that you require? However, in many cases, Custom Aluminum Extrusions can work out more economical than machining your shape from a standard extrusion.
Howard Precision Metals Inc. are good people to contact for Custom Aluminum Extrusions. They have the experience to offer you sensible advice and good prices. If you browse to Custom Extrusions page you can download a useful pamphlet on custom shape design.