The customer’s task was clearly defined: aluminium machining with a shiny surface finish. “For the required machining procedure, we had already developed a step drill in which we eroded the PCD cutting edges. After this, however, manual operations in the form of cylindrical grinding, clearing the tool body in the front and on the diameter, followed by polishing were still necessary. On top of all this, we had to send the tool to an external service provider to incorporate the chip breaker, and this took an average of two weeks. Since this slowed down our work processes considerably, we embarked on a search for a timesaving variant so that, ideally, we could complete everything in a single clamping,” says Manuel Graf, a process engineer at Günther Wirth Hartmetallwerkzeuge Betriebs-GmbH (GW) in Balzheim.
From tests to series production
The search led to laser technology. This technology promises particularly sharp or defined cutting edges. In particular, it can perform all operations such as the cylindrical margins and chip breaker, including defined rounding of the cutting edge. “To find out which manufacturer could deliver the best overall package and optimum quality, we sent one of
our series tools to three laser machine manufacturers. Each manufacturer had to send back two samples – one sharp and one with the specified cutting edge rounding,” explains Manuel Graf. The results were then tested at Günther Wirth as well as on the customer’s premises.
Following measurements and an evaluation, it quickly became clear who was in the lead. “In particular, the surfaces achieved with the lasered tools were of decisive importance. Our customer’s requirement was a workpiece with an appearance similar to mirror-finish, and this was the result that the cutting process had to achieve. The lasered tool machined on the Rollomatic machine unmistakably achieved the required quality with surface qualities of Ra = 0.1 μm,” emphasises Manuel Graf.
“For test purposes, we measured the cutting edges and cutting surfaces. The Rollomatic test tool came from the machine and the customer could use it straight away, without any reworking at all. Built-up edges form quickly during aluminium machining. For this reason, both the exactly produced cylindrical land as well as a defined cutting edge were decisive. With the LaserSmart 500, we can transfer the programming onto the tool with an accuracy level of 2 μm – reproducible at any time, naturally,” adds Rüdiger Damaschke, head of production at GW.
Sharpness – ultra-high definition
Rollomatic drew on its decades of experience in grinding machine production in developing and constructing this product. Thanks to this, the LaserSmart 500 has become a thoroughly sophisticated and reliable product. Five interpolating axes with linear and servomotors form the basis for manufacturing indexable inserts and shank tools made of ultra-hard materials such as PCD, CBN, CVD, MCD or natural diamond. Cutting edges, chip breakers, laser marking and, for the first time, cylindrical lands, can be produced in a single clamping.
The advantages of this laser process are numerous. In particular, this procedure allows PCD to be brought into the shape that it is used in. “During erosion, for example, only the PCD’s binder parts are cut; the diamond grains remain uncut. This results in radii of approximately 0.13 mm as well as breakouts on the cutting surface. Things are very different with lasering. The beam cuts through the grain and achieves much sharper cutting edges without melting or breakouts“, says Rüdiger Damaschke. Sven Peter, laser\ product manager at Rollomatic: “Sharp cutting edges are the measure of all things in specific applications. To obtain the optimum from the cutting process in question, edge rounding and contact pressure play a major role. For example, if we are dealing with extremely sharp cutting edges with a cutting radius of less than 1 μm, less pressure is possible and chatter marks that have a negative impact on the result may occur, depending on the cutting parameters. In such a case, the right cutting edge rounding is a decisive factor in achieving success”.
Time as a success factor
Since several operations can be completed in a single go with the LaserSmart 500, Manuel Graf and his team in Balzheim now have more time to develop new strategies and become more familiar with laser technology. “The example of our three-step drill with a diameter of 35 mm clearly shows the time savings. In the past, eroding on its own took 3.5 hours, then came another hour for cylindrical grinding and then the chip groove had to be incorporated by an external service provider. Now the complete machining process, with chip breaker, circular lands and contour laser takes only around 5 hours. And the cutting results are better than ever!” says Manuel Graf. The HSC holder as well as automation via a robot loader contribute to this as well. The considerable additional benefit for GW customers: if around 16,000 drillings were possible with the eroded PCD tools, the lasered variant promises a 30% increase in service life.
Ten employees in the PCD special department at GW look after the requirements of customers, mainly from the automotive industry and aluminium wheel machining. “In most cases, we deal with batch sizes of three to ten tools. Sometimes, we even deal with pieces on their own. Even though we have a small standard product range, manufacturers in search of special solutions to improve efficiency generally come to us,” says Manuel Graf. The tools are then sold via the Ceratizit Group, the majority owner of the family-run company GW, headquarters in Balzheim.
Service that thinks in advance
Rollomatic was part of GW production in Balzheim long before the LaserSmart 500 came along. “Due to the neverbefore- seen precision and high quality, we use some cylindrical grinding machines from the NP series, including an up-to-date NP5 in series production at headquarters. For this reason, we are already familiar with the quick and outstanding service,” says Rüdiger Damaschke. But with the LaserSmart 500, GW entered uncharted technological territory and was more and more dependent on solid service knowledge.
Manuel Graf: “We have been using the LaserSmart 500 since late April 2016 and we have received optimum training in the machine‘s functions. But what makes us happiest is the regular feedback from the Rollomatic engineer who often shows us solutions in areas where we haven’t even encountered problems! This means we are always one step ahead so that we don’t end up lagging behind at some stage!”
The experts at GW are more than convinced that they have purchased an up-to date and trendsetting technology with the LaserSmart 500 from Rollomatic. “In PCD, we are now creating things that were impossible in the past, particularly with regard to precision and reproducibility. But since we constantly want to expand our opportunities, we have already conducted tests with hard metal in which the drilling tool tip has been lasered. This means it no longer has to be ground manually: this benefits the run times and reproducibility. We are currently trying out CBN tools for Inconel machining. We, and in particular, our customers, will benefit from the Rollomatic laser technology here as well,” forecasts Manuel Graf. ☐ Courtesy: Rollomatic SA