The effect of small variations in input parameters – such as material and tooling properties – are often seen only during the final inspection of products. When a machine tool is being used to produce high value components, this can lead to a conservative approach to the manufacturing process, with the cutting tools, for example, being changed more frequently than necessary.
What if a system could be developed that allows data pertaining to the machining process to be collected in real time at the time of cutting, so process variations can be diagnosed and managed?
That, in a nutshell, is the aim of the Intelligent Tooling project, being managed by the Centre for Process Innovation (CPI). And one of the tools which the project is bringing to bear is flexible electronics.
Dr Peter Tune, a business manager at CPI, has until recently been involved with the project. “I’ve been involved with the project for about two years; initially in the drafting process and then bringing companies together to create a consortium. We are now in the middle of a two year project which is end user driven. A key partner is BAE Systems, which is particularly interested in matters relating to machining and tooling.”
In Dr Tune’s opinion, what happens at the ‘sharp end’ of the machining process is an industry wide problem. “Say there’s a lathe spinning at several thousand RPM,” he suggested. “There is very little known about what happens at the point of contact between the tool and the metal. The parts being machined are often difficult to cut, so machinists err on the side of caution, changing the tool tip every 10 to 30 minutes.
“That’s expensive,” he remarked. “It could be that if more reliable data was available, you could get a few more minutes of use out of the tool tip – and that could save millions in tooling costs.”
So the CPI project – which also involves Element Six, the Advanced Manufacturing Research Centre (AMRC), Advanced Manufacturing, Printed Electronics, National Physical Laboratory and DMG Mori Seiki – is looking to introduce sensing techniques at that ‘sharp end’. “Nobody has solved this challenge,” Dr Tune said, “but with the advances being made in printed and flexible electronics technology, we now have the opportunity to embed some kind of sensing technology in the hostile environment found on small parts.”
CPI is contributing its printed electronics expertise, but other partners bring other strengths. “Element 6, for example, is a provider of tooling materials,” said Dr Tune. “AMRC, part of the High Value Manufacturing Catapult, is bringing modelling skills to the project.”
There are two parts to the project: the electronics/printable electronics element; and the tooling and materials. “It’s industry driven and moves forward depending on the partners’ feedback. Although it’s a publically funded project, there is a large degree of confidentiality,” he continued.
The project, in essence, is about measuring something at the cutting edge and giving real time feedback. “It’s all about the connection between sensor technology and the outside world,” Dr Tune said. “And it focuses on the tool insert.”
The Intelligent Tooling project has just passed the halfway point, but the partners are somewhat reluctant to discuss the finer details. “Although it’s a partially public funded project,” Dr Tune explained, “it’s being conducted under confidentiality, to a large extent.” The public funding element has come from InnovateUK.
As with similar projects, developments are happening in parallel through work packages. “We have already defined the sensor design,” Dr Tune reported, “and have produced some sensors, although I can’t reveal what we are using.” He said the electronics element of the project is well advanced, with progress made through the use of ‘off the shelf’ technology. “The difference will come from the sensor design.”
“We have also addressed the modelling aspects; we know what it is we will be printing and we know the design. Our next challenge is to prepare full working prototypes.”
The environment in which the sensor will operate is not friendly. So why printable electronics in a hostile environment? “It’s cost effective for large areas, applicable to curved surfaces and lightweight.
“The ambition has always been to work close to the cutting face; to get the sensor onto the tool insert and to make it work. But that brings operating challenges,” Dr Tune said. “There are solvents and swarf; there’s a lot going on. Temperatures can range from a few hundred degrees to more than 1000°C, depending on what’s being machined.”
The sensor is measuring three key parameters: temperature; vibration; and stress. Modelling allows the system to consider secondary interactions, with the information used to quantify tool health. “It’s all about using the data to determine the health of the tool. The sensor will tell how hard the tool is being worked; for example, the higher the temperature, the harder it’s being worked and this could tell the operator to back off. We also want to measure tool wear; is there 50% left or 20%?”
One of the goals of the project is to develop technology that can be embedded on the tool’s surface. “There are size constraints,” said Dr Tune, “but that isn’t something that worries us; the scale at which we can deliver a solution isn’t a problem.”
The hostile environment has required some trade offs; while there is some electronics on the tool, wireless communication will relay data to the processing element – which is ‘some distance’ away, where temperatures are closer to ambient – with software providing a link to the host machine. “The really clever bit is the sensor design and the technique of producing the sensor,” Dr Tune asserted.
While the concept of embedding sensors on machine tools would seem to be an area which has already been explored, Dr Tune says this isn’t the case. “We have done our due diligence. While it’s a challenge recognised by industry and there are some people active in the field, there is nothing that we see that gives a working solution. What we are doing is way beyond academic research; we’re working with industrial partners on real applications and the project is generally at TRL 5 to 6 – the demonstration level.”
The project is ‘on target and on budget’ and the partners should be able to move to a demonstration in the near future. “We’re not looking to offer a turnkey solution,” Dr Tune concluded. “We only want to demonstrate the capability. However, if things go the way we hope, there will be a second phase because we have a strong consortium which is supply chain focused and there is sufficient market pull.”
