Frequently Asked Questions
With Additive Manufacture growing in popularity, why should I consider CNC machining?
3D Printing or Additive Manufacture can achieve some great results, especially if time is very limited but does that make it the best choice?
There are several points to consider:
Part size vs part complexity
If your part is large and simple (in relation to its size) then certainly consider CNC machining as a method of manufacture, as quite simply cost is related to the amount of material being removed.
If your part is small and intricate, then additive manufacture may well be better suited.
There is no concrete hard and fast rule - there are some features that are very challenging to produce with machining but can be realised easily through additive manufacture. Likewise, there are important design considerations for additively manufactured parts that must be taken into account, such as the placement of support material and tight tolerances that may be difficult to produce.
Then there is the big issue of surface finish. 3D Printed parts by their nature will be made in layers and on curved surfaces these can appear as steps. To achieve a good surface finish this needs to be hand dressed out before painting or tooling.
CNC machining, however, works in a minimum of three simultaneous axes with the result being a smooth, accurate surface straight from the machine.
Thirdly, how critical are your material requirements? Materials are usually process specific for 3D Printing, whereas the list of options for CNC Machining are huge.
Another important consideration is part quantity. Additive manufacture can produce prototype or low quantity runs very quickly, with little or no tooling. However, this process is less suited to larger quantities due to the time spent on expensive-to-run machinery.
CNC machining allows you to produce finished prototype parts without post processing, which can make this a cost effective option if it suits your finish requirements. Low runs and larger quantities become even more viable due to the set-up time being utilised across the numbers (we have machined up to 100,000 parts).
You need to have an understanding of which method of manufacture you intend to use and design the part to suit, although obviously there will be design features which you cannot change as they perform critical functions.
A good designer will often have a method of manufacture in mind as they design a model, so they optimise the part for that particular process. We can help you with this by suggesting how it could be optimised for the given process. This preparation is crucial to avoid delays in production.
CNC machining is a viable option
A CNC prototype therefore has a lot to offer, especially if the goal is for an excellent surface finish. In addition, CNC machining can be cost competitive, frequently allowing a ‘finished’ part to be delivered for the same price as a ‘raw’ 3D printed part.
Our advice is don't rule out CNC machining as an option! For further support and advice please pick up the phone and talk to us.
Read more expert articles in our FAQ section where we discuss topics on materials, methods and products.
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