3 design considerations for cylindrical components18th Jul 2022
Cylindrical components are typically machined on a lathe through a process called ‘turning’ rather than milled on a milling machine.
If we look at this a bit deeper, you see that this is a simplified statement. It is possible to mill cylindrical components (although you can’t ‘turn’ non-cylindrical components), and there are often milling processes required on a turned component. For example, a cylindrical component may have other features that need to be machined that cannot be accessed by a lathe.
Again, let’s look deeper. ‘Mill-turn’ machines are lathes that can also perform milling functions, meaning that some components can be manufactured entirely on a lathe.
But how a component is manufactured, be it on a lathe, a mill-turn machine, or a milling machine, is generally only of interest to those who have a good understanding of machining – what matters most is that the component is manufactured to the right specification, it arrives on time, and is the right price.
The relevance of the manufacturing method comes down to machining efficiency. A supplier will consider the most efficient way to manufacture a design, and how to get the best cost for its customers. When it comes to cylindrical components, there are some very specific considerations which will enhance component function, improve machining efficiency, and help keep costs in check.
Here are my top 3 considerations when it comes to designing your cylindrical component.
1. Thickness of wall sections
If a cylindrical component is designed with thin wall sections, there is a risk of the component being crushed or warped when held by the chuck, or when the component is released.
The chuck is what holds the workpiece in the machine and must grip tightly to ensure the component doesn’t move while being machined. If the wall section is thin, the force needed to hold the workpiece in place can cause distortion to the component, making it hard to maintain the circularity.
Similarly, when machining a component with a thin wall section, vibration may occur along the work piece. This is an issue because it makes it difficult to hold tolerances and a consistent surface finish.
There are ways to manufacture cylindrical components with very thin walls, but it is important to bear in mind that a design with a thin wall will require a longer set up and increase the machining time. Both of these factors mean that the cost will be higher, so it is best to design wall sections with a reasonable thickness if the application allows.
2. Length of cylinder
Another design feature that can cause surface finish issues and difficulties in maintaining tolerance is related to the length of the component.
At the chuck end, the material will be held tightly, however, the further away from the chuck, the greater the amplification of the rotation, which will cause a ‘wobble’. A longer piece of material will also flex more during machining. Both of these factors will cause inaccuracies and the vibration will mean that the surface finish is compromised.
One solution to this is to use a centre. This is when a small recess is machined in the end of the component, so that it can be held steady at both ends. For most applications this causes no issues, but it is worth considering when designing a component.
Machining without a centre is possible, but to achieve a suitable surface finish, a different solution would be sought, generally necessitating a longer set up and machining time, which would in turn increase the cost.
3. Orientation of features on either end
It can be challenging to ensure an exact orientation of features on each end of a cylindrical component. If it is imperative that they match for the application, it is possible, but it will increase machining and set up times and therefore cost.
If the features do not need to match exactly, you can specify this by writing ‘orientation not important’ on your design. This gives more freedom to the manufacturer to produce the component in the most efficient way possible.
When designing a cylindrical component, you don’t need to worry about how the part will be made. What is essential is that you choose a machining expert who can offer machining design advice and be able to determine how best to manufacture your component, balancing form, function, efficiency and cost.
Partner with Penta
Penta is an experienced machining company with strong expertise in both turning and milling. We also have a mill turn machine which combines tool rotating and workpiece rotating functionality – the ultimate milling/turning hybrid. This can improve the speed, efficiency and accuracy of machining more complex parts.
If you would like to discuss how Penta can help you with your upcoming project, give our friendly and experienced estimating team a call on 023 9266 8334.