Wander through the rows of CNC cutting and milling machinery, past the brazing set-up positioned in the corner and beyond the quality assurance apparatus arranged along the back wall, through a big blue door and sat beside a furnace is a single Markforged Metal X.
We are inside a facility which is pioneering a new approach to Polycrystalline Diamond (PCD) cutting tool production and represents the only Guhring production centre out of 72 to be applying additive manufacturing technology like this. The site is in Aston, UK, just down the road from Birmingham and, in early March, hosted a presentation and tour for dozens of engineers looking to learn from an AM user that has hit the ground running.
Markforged, and its UK reseller Mark3D, are said to be very impressed with how quickly Guhring UK has managed to not only identify applications but develop and deliver them to several customers. So enthused is one Mark3D employee that he interrupts a slideshow presentation to emphasise that Guhring UK is ‘leading the way in their market’ with ‘nobody else on the planet’ using the tech in the same way.
Starting with a Markforged Design system, Guhring UK was first printing composite bodies of cutting tools that they would go on to manufacture with CNC machinery to assess form and fit, so that there were no unwanted collisions after they had positioned the tips. Not long after, Mark3D introduced Guhring UK to the Metal X machine, which they quickly deployed for the manufacture of cutting tools that were sent to select customers to retrieve some feedback.
“There was one application that we did for a company abroad which they wanted to turn around in a week,” Alan Pearce, PCD Production Supervisor at Guhring UK tells TCT. “What we did was print the head, raise the PCD, ground the shank and shrunk it into a holder, so it became a monoblock tool, and we sent it to the customer. It worked fine and we turned that around in just over a week, from design to shipping. From the design of the tool, it was just a few modifications to the body, like some grinding on the shank; we do a plastic version to make sure everything is okay; then we do a steel body [with the Metal X]; sinter to harden the body; and then braze and wire grind just like a normal steel body tool or carbide tool. The fact we could do it so quick, that’s a massive advantage.”
The typical turnaround period for Guhring’s PCD tooling is a couple of weeks, sometimes more, but after a successful first implementation of additive, the company has wasted no time in moving onto the next part, and the next part. Twelve months after adopting AM, the company is unveiling its H13 tool steel milling cutter with a weight reduction of 60%, a time reduction of 66% and a tooling costs saving of 75%. It is the key draw as engineers from across the UK take their seats in the Aston facility.
It's special what these guys get up to.
This part is most suitable for application in the automotive industry to cut aluminium pieces and can be printed, washed, sintered and sandblasted within a few days, before the PCD tips are then brazed and the tool is ground with a clocking ring. The part has 125-micron layers, is printed with modular support structures that fall away during the wash and are said to feature smooth surface finishes in the inside pockets. Guhring has also designed the cutting tool with an internal triangular webbing which, along with the thickness of the walls, contributes to that 60% weight reduction. This lighter weight is said to put less strain, stress and force on a CNC machine’s grippers and spindles, while also allowing for faster tool changes and, subsequently, a reduction in cycle times. Meanwhile, thanks to some optimised cooling channels, which work to supply coolant and flush away chips as the cutting happens, the lifespan of the tool has increased too.
“One of the things they're finding, because they can be very, very directional with the coolant holes, is the tip life is going up,” explains Mark3D UK Managing Director Ian Weston. “Before, the coolant is just a wash or, at best, a sparked hole somewhere in the area. Now, if you want to run it down the side of that tool, we can have letterbox shaped vents kinked straight at the cutting face. All of a sudden, the coolant is exactly where it needs to be. There's a lot of progress being made with internal geometry and that’s stuff you can’t make any other way.”
The message from Weston during his presentation is the same as it was to Guhring when the company first began to apply 3D printing: “Don’t think about printing everything, just focus on the awkward stuff.” What he shows the packed room next is something once considered an awkward design to tackle, indeed it was impossible to manufacture through conventional means, but with AM they found a way. As he clicks to the next slide, ‘phenomenal,’ is Weston’s assessment, ‘really special.’
Guhring tool in action
Guhring cutting tool in action.
It is an ejector drill that has been designed to make sure that, as the tools cuts away, the chips come backwards out of the cutting area to significantly reduce the risk of swarf being left behind on the piece that is being cut. To direct cutting chips away from the cutting area, the coolant channels have been designed to come along the sidewalls of the tool and twist at a 90-degree angle to squirt coolant at the bottom to divert the chips away.
“When it cuts, it forces the chips through the centre of the drill. And the chips come out at the bottom around the body,” describes Weston. “As an engineer, I love it, that's what it's all about. It's special what these guys get up to here. Now, I'm not allowed to tell you much more, but this is something that has been very, very well received.”
“3D printing is the only way to do this part,” Pearce adds later. “With the coolant holes design, it would be impossible to do with manual CNC machines. You need to print this part.”
Print this part is what Guhring UK is doing as it continues to embrace the advantages AM brings to the company. An anecdote told on the way around Guhring UK’s facility is that of all the engineering staff in Aston, it was the intern, who has since been taken on full time, that was most sceptical of 3D printing’s ability to produce the cutting tool’s required by the likes of BMW, Jaguar Land Rover, Airbus and BAE Systems. The scepticism, quite like the metal chips that fly out as Guhring’s 3D printed cutting tools get going at over 10,000 RPM, has been washed away.
The introduction of AM has not only allowed Guhring to negotiate complex designs to improve performance, but it has allowed prototype parts to be produced quickly and taken in physical form to production meetings, as well enable Guhring to scrap minimum order quantities on certain parts and free up capacity on its conventional manufacturing machinery. And, as a company with more than 70 production facilities around the world, there’s surely more to come.
“The more and more tooling that we're doing, the more and more we're learning,” finishes Pearce. “We're looking at more and different applications so we can use the printer to print tools, to give us a better chip flow, to give us a better coolant flow, all the time. The Guhring plants throughout the world all try to replicate each other. That’s how we first started. We were replicating a plant in Germany. If 3D printing takes off, that will be the case as well.”
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