Copper – For 3D Printing And CNC Machining
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Our Insight video series will help you master digital manufacturing.
Every Friday we’ll post a new video – each one giving you a deeper Insight into how to design better parts. We’ll cover specific topics such as choosing the right 3D printing material, optimising your design for CNC machining, surface finishes for moulded parts, and much more besides.
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Insight: Copper – For 3D Printing And CNC Machining
Hello and welcome to Proto labs' Insight video series.
This week we’ve got a real treat for you. We are going to talk about some new technology that as the title says makes the impossible possible.
Okay so we’re not about to develop a warp drive to power us to the stars, but hey, what I’m talking about today is still pretty cool. Let’s get right into it.
Copper is a vital component of much of what we do in engineering and for some industries, such as automotive, its role is growing.
Until recently if you wanted to prototype or produce a copper part, then your best option was nearly always CNC machining. Don’t get me wrong this is still a great way to go, but it does have its limitations.
While you can use 3D printing for other metals, this was not possible for copper, or at least until now.
Let’s just stop and think about what that means. There are some things, where only copper will do the job.
And now if you want complex geometries in this material, such as internal channels or a honeycomb structure to save weight, you can design and get that part manufactured.
In the next couple of minutes, I’m going to explore the possibilities with you, but I’m also going to point out, that while this new technology opens up new design possibilities, it is not always the best answer.
Sometimes CNC machining may still be the best choice. We’ll weigh up the pros and cons of each technology, and help make an informed choice.
First let’s go back a step. Most suppliers who can provide 3D printed copper parts will use a low alloy copper material such as this.
This alloy has still got high electrical and thermal conductivity, but it is also corrosion resistant and has got great mechanical properties. It means that it can be used in environments where you would not use pure copper.
You might use it for bus bars, rocket nozzles, heat exchangers or induction coils to name but a few applications.
Suppliers who can provide copper 3D printing will be using direct metal laser sintering, let’s call it DMLS. This adds successive layers of metallic powder to your part, which is then micro welded onto the structure using a laser. The thickness of each layer is just 20 microns thick.
Using this technology, you can create virtually any shape you want. It can however be a slow process.
This is where you need to consider your options for copper.
CNC machining is more limited in the geometries that it offers, but it is far faster.
So, ask yourself the following questions:
Can the part or parts be machined?
And how many parts do I need?
If your answer to the second question is in the high hundreds or thousands, then CNC machining is probably your better solution.
For prototyping or customised parts though, 3D printing copper parts could open up a whole new world of designs.
Sadly, there are some limitations that you need to know about.
The significant heating and cooling of the metals, as the laser does its work, does create some internal stresses. This can result in miniscule movement of the part and some loss of accuracy. It means that if your tolerances are tighter than 0.1mm, the part will need some machining.
Of course, you can combine the best of both worlds. Produce your complex copper part using DMLS and then finish it using machining.
Also, for vertical or horizontal surfaces DMLS will produce a smooth surface, but other surfaces will show some stair stepping as each layer is added. If you need a smooth finish, then your part will need to be blasted, sanded or machined.
It’s important that you consider this when you are designing your part and highlight any critical features on your CAD model when you submit it to your supplier.
You also need to think about support structures when designing any metal part using 3D printing. With DMLS, scaffold like supports are needed to keep the semi molten metal in place. These supports can often be removed using a Dremel tool, but again machining may be an option for larger volumes.
So yes, you can now design that impossible copper part, but it is not a silver bullet that will solve everything.
CNC machining may still offer you the best solution and sometimes you may be able to get the best of both worlds and combine the technologies.
There are design points for both 3D printing and CNC machining that you need to be aware of. Our best tip is to talk to your supplier. Find a supplier that offers both options and you will get unbiased advice.
That’s it for this week.
Next time, I’m going to take a look at how you can reduce your lead time from development to production of new parts.
Until next week.
With special thanks to Natalie Constable.