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: Rotork Case Study
Hello and welcome to this week’s Insight.
Today we’re going to take a close look at CNC machining and explore how Rotork Gears used it to prototype a system to prevent leaks from valves into an explosive atmosphere.
Now I’m sure that you can imagine that a leak in say the petrochemical industry could be disastrous. Sadly, we’ve seen the headlines of what can happen when things go wrong. So, it’s not surprising that there is very strict legislation surrounding equipment installed in a potentially explosive atmosphere. Those in the know will be aware of ATEX regulations and how hard it can be to meet those requirements.
Not only that but I’m sure you know that in the real world, valves that control or regulate the flow of fluids can and do leak. Even with the best design and highest manufacturing standards, failures still occur.
Rotork’s plan was to produce a bespoke leak housing designed to prevent any fluid leaks from a valve stem to stop emissions getting into the atmosphere.
As you can imagine for an application like this, they needed to be very sure of their design, so testing was vital.
Rotork needed a proof of concept prototype and they needed it quickly.
The solution was to upload the CAD model into Protolabs’ online quoting platform. Having the CAD is not enough in itself however as it needs to be checked for manufacturability, or in other words can CNC machining produce the design for testing and beyond that will it be suitable for mass manufacturing using injection moulding.
The two processes are very different and understanding the design limitations of each is vital if the design is to work in practice.
Using CNC machining for prototyping does have big advantages. For a start there is no need to invest in tooling upfront until you are sure of the concept and you can cost check different iterations of the design until you are happy with the result without spending too much money.
By the way it is possible to use injection moulding for prototyping and even try several iterations by modifying the mould. The trick is to find a supplier that uses aluminium tooling rather than steel – but that is another video and it was not the chosen technology here.
Anyway getting back to the story; the advantage of using software to check the CAD before moving to production is that you can quickly change the drawing, resubmit it and get a quick response back highlighting any potential issues. An engineer can also do this manually but then you are reliant on their workload to get it done quickly and he or she may have other priorities that you are not aware of; so the rapid prototyping might not be as rapid as you hoped.
Following this design analysis, the prototype produced for Rotork was right first time and early testing proved very positive.
One final interesting thing to say about the product is, it will also be able to detect and measure gas leaks using in-built electronic sensors. It will then communicate any detected leaks to a monitoring station via wireless tech.
So Rotork also needed to manufacture the plastic housing prototype for these electronics and then conduct field trials for both the valve housing and the detection system.
Both products must pass very strict testing before they can be used in such environments so accurate prototyping to test functionality is a critical stage of development. This needs to be a fast process in case the design needs modifying in the face of real-life results.
Of course, Rotork had to think about manufacturing the products, so the prototypes had to be designed with this in mind as well.
This requires a third party that understands both the rapid prototyping process and all the production techniques used in product development so that they can move the concept through testing to mass manufacture without any issues.
CNC machining and injection moulding are very different processes, so using the former to produce prototypes that will be eventually manufactured using the latter is something that needs to be understood by your supplier. Ideally your supplier should work with both technologies.
That’s it for this week. I look forward to seeing you again next Friday.
With special thanks to Natalie Constable.