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Before a die can go into production or through any manufacturing process, you need a design that is technically achievable or which is physically possible to extrude. Without a fully functioning design you can expect expensive errors to crop up throughout the manufacturing process, not to mention the time consumed in achieving your final workable design.
It’s surprising how many people believe their design will work and put it through the manufacturing process only to find certain parts of the design have failed. That’s why 3D printed prototype/samples are an excellent place for you to begin, it’s the most cost effective way of testing whether your design is going to work and a way of making alterations before having to pay the cost of a die and set up charges.
There are a lot of things to take into consideration when designing a die for extrusion, although each die design will be different, there are a set of general rules which govern the basics of die design.
Many extruders prefer to work with designs which are easier to produce, simple, similar wall thickness and symmetrical. It makes the production of the die more cost efficient for the extruder and gives the tool a longer life. Productivity also comes into play when extruders are evaluating new designs.
In this article, we are going to look into aluminium extrusion design and 5 common mistakes when designing a profile for extrusion.
1. Wall thickness
A common problem when designing a die for extrusion is wall thickness, often people design a profile which has thin walls or substantial variations in wall thickness which creates problems with metal flow during the extrusion process.
Other factors which influence wall thickness are the extrusion force and speed. Typically speaking, wall thickness depends on the general shape of the profile and whether it is solid or hollow. It is much harder to maintain flatness on a profile that has a thin wall and CCD (circumscribing circle diameter). Extrusion container size and ram pressure are also factors that can affect profile designs.
Having a wall thickness which is uniform throughout the profile also makes it easier to extrude.
2. Tolerances
There are many factors that affect tolerances, such as wall thickness, dimensions, size, profile type –solid or hollow, alloy used, overall profile shape and that’s just to name a few.
Productivity and price can be affected when tolerances are tighter and therefore should be considered when designing your die.
Profiles which are designed with no understanding of dimensional limitations of the extrusion process will be rejected or can cause many errors throughout the process.
Extrusion profile tolerances are generally controlled by BS EN 755-9. Utilising this tolerance document in your design will ensure that it can be extruded successfully.
Tolerances should always be considered in the design phase, if you are concerned about your tolerances or design, please contact one of our design experts.
3. Shapes and Corners
To assist in the flow of aluminium through the die, sharp corners should be avoided. Corners should ideally be radiused to assist extrusion flow. Blend radii should ideally be used to ease the flow from one mass area to the next, as this can help prevent witness lines along the surface of the profile.
4. Mating components
There will be times when you will need to design an extrusion which features mating components.
Extrusions can be designed to slide, hinge or clip together, such as a clip fit for a two-part electronic enclosure. Simple designs are the most cost effective as they are easier to extrude so by having these mating components, it will reduce the assembly time significantly. You will need to think through the final assembly needs during your design phase to ensure that your design is extrudable and will fit with your mating components.
To understand more about designing for mating components, contact a member of our team who will help you achieve your extruded profile requirement.
5. Symmetry
The more unsymmetrical or unbalanced a shape, the less likely it is to remain straight or hold its shape accurately. It should be symmetrical where possible – There are often situations where this is impractical but with a little design assistance the profile can be made easier to extrude so you can achieve good tolerance and shapes.