The right tool for the job

The right tool for the job

GTL produces an internationally renowned range of quality tools which covers almost every torque application throughout a multitude of industries. However, occasionally our customers find that the need arises for a niche tool which isn't quite catered for in our catalogue, and we are always delighted to work with them to find a solution.

One recent example of this occurred when Toyota Motor Manufacturing UK got in touch with us last year. The team had previously used our weld stud test tools, and they wanted to discuss an idea they had had concerning testing welded studs in car dashboards. David Broadhead, our Technical Sales Manager, had several meetings at Toyota's Burnaston site in Derbyshire to discuss using our Rotary Torque Unit as a solution. An RTU is a torque limiter which can be used with power and hand tools that don't have an in-built torque limiting facility.

Toyota uses automatic stud welders on its assembly lines, but when these go down manual welders are used instead. The problem facing Toyota was that if a stud sheared off because of poor weld during final assembly, it created major problems in replacing it at this stage, mainly because of access issues.

They had previously tried various methods but decided the best way forward for them would be to apply approximately 12-14 N.m. of torque dynamically to the stud with a power tool, which would have our RTU fitted on the end of it.

Initially they tried our standard RTU unit which slips free in both directions, but they decided they would need a unit to slip free in a clockwise mode only. If the stud was still intact after the correct test torque was applied, the RTU then needed to be able to lock in an anti-clockwise direction so the tool could be reversed and unscrewed ready for the next stud to be tested. This method would therefore speed up the whole process.

The task of producing an RTU specifically for this purpose was taken up by GTL's engineering department, and Peter Shafe, Research and Development Manager, set his team to work on what was quite a complicated task.

GTL currently produces RTUs with a torque range of up to 10 N.m. but Toyota needed up to 12. Peter says "to begin with, we looked at our existing design to see if we could extend the range. We decided to try new springs, did the calculations, and our spring manufacturers provided five different springs to test. We also needed to look at design issues, for example ensuring threaded components didn't come loose during operation."

As Toyota had requested a one way RTU, this would involve either a clutch or a non-symmetrical cam. Peter looked at both of these options in our current RTU, but realised there was no space within it to put in a clutch. The team then looked at changing the cam profile to make it non-symmetrical.

The cam was designed, manufactured, hardened and then tested, but it was stretched in every area. The spring was at the top limit, the cam was outside the experience level, and the speed that it needed to run at was too high. So the team decided completely to rethink how to make this work.

They took a look at the screwdriver components. These springs were more suited to a higher torque so closer to the required values, and the internal components were already set up; GTL produces one way screwdrivers so it was easier to produce a one way action for the clutch. A new cam was then designed, made and hardened. After considerable testing, consistent readings were produced, although this was not an easy procedure because as it was a new product there was nothing to compare it against!

GTL's engineering and production departments worked closely together to maintain a smooth process which was geared all the way through to meeting Toyota's requirements, and ensuring that approval was given for each stage before moving on to the next one. In the engineering department, design engineer Adam Gilham did all of the main design work and most of the testing, mechanical engineer Matt Conacher worked in redoing the cam designs, and toolmaker Rob Dillon made all the prototype cams. The production department had to check that they could make the new parts needed, including the end fitting, new body, adjuster and locking mechanism, and make sure Toyota's scheduled delivery date would be met.

A few prototypes were made of the final proposal, which has a torque range of 9-14 N.m. thus easily fulfilling Toyota's requirements. They were tested extensively and an example tool was sent to Toyota for a trial. It worked very well, at which point GTL was given the go-ahead to supply 50 off of the bespoke RTU, and it's possible that there could be further potential for it at other worldwide Toyota locations. The whole process was complete within four months and, in spite of a compressed delivery schedule, attention to detail was consistently maintained on the quality of the product. The RTUs have now been delivered to Toyota. The cover pic shows Clive assembling the RTUs and the pic to the right shows Adam laser marking them.

GTL was delighted to work closely with Toyota; it was a very successful project, with the teams co-operating from the outset to solve any possible issues before they arose. Initially Toyota sent GTL a video showing how the RTU was going to be used, which meant that we could understand how its application would work and include extra features in the design which would help its utility.

We enjoy working with customers to ensure that they arrive at a perfect tool solution which ticks every single box. We find it mutually beneficial in that it gives us opportunities to exercise our flair for creative engineering while fulfilling our customers' exact needs. So if you have a project you think we can help you with, get in touch!

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