#Product Trends
SPINWORX® application example - BORBET
Self-rotating for improved process reliability
Minor infeed, high feedrates. At first glance, this does not sound too exciting. However, the material to be machined is quite challenging. In the past, great variations in terms of hardness and strength have challenged those responsible for tool making at BORBET time and again, as it was very difficult to achieve the desired process reliability for roughing. This has changed drastically with the use of SPINWORX®, the self-rotating indexable insert from POKOLM.
Challenging material
Light alloy and passion – this is the company philosophy of the leading manufacturer of premium light alloy wheels. While BORBET Hallenberg focuses on sophisticated design or aerodynamic bene-fits, tool making was faced with supposedly much more trivial tasks. During milling of the casting dies, the indexable inserts had to be turned particularly frequently due to the material (1.2367 ESU, hardened and tempered). According to Matthias Mause, responsible for the cutting tools in mould manufacturing at BORBET, this material regularly causes problems: “This material is subject to large variations with regard to toughness and machinability, in part due to manufacturing tolerances. As a result, we were unable in the past to accurately determine the operational life of the tools. Conse-quently, we could not leave the machines unsupervised for extended periods. Furthermore, one em-ployee was always needed, as the indexable inserts had to be turned after a certain period. On the one hand, a lot of time needed to be invested, and on the other, one had to be very careful about how much rotation was required or whether a complete replacement was necessary due to damage to the blade.” For this reason, tests with indexable inserts from other manufacturers were performed initially. However, this did not result in any improvement.
SPINWORX ® provides the solution
In the middle of 2015, SPINWORX® with the self-rotating cutting insert was used for the first time. This tool had been known to Matthias Mause and Markus Reuter, head of tool making, but it had not been available with the required plate diameter of 7 mm up to that point. This concept was also met with some scepticism in Hallenberg. Markus Reuter comments: “Like many of my colleagues in ma-chining, we initially found it hard to believe that this would work. You learn that the blade must be fixed without play. However, SPINWORX® quickly convinced us otherwise. Wear is much lower and process reliability has been greatly increased.”
Process reliability is the primary objective
Process reliability is so important as one employee operates several machines and is thus not able to monitor machining continuously. While wear at a cutting insert had so far been too high, the carrier tool was sometimes also known to break. Since using SPINWORX®, such incidents have no longer occurred, and process reliability has significantly increased. Infeed at BORBET might be low, but the feedrate is high. The cutting data in detail: Vc = 314 m/min, Vf = 8,000 mm/min, fz 0.33 mm/tooth und ap 0.42 mm. Naturally, with this low infeed, the finished surface is almost achieved after roughing, and semi-finishing can be started immediately. Although the Hallenberg site is also competing with exter-nal providers and machining has to be economical, the cutting data have not yet been increased compared to the fixed indexable insert. Martin Mittelberg, application engineer at Pokolm, also re-gards this as a necessity: “Of course you always want to achieve ever increasing material removal rates. However, the upper limit had already been reached with the fixed insert. So there is no need to explore limits now which might put process reliability as well as longer service life at risk.”
The achieved process reliability can amongst others be attributed to the smooth and even running, which noticeably reduces vibrations in the machine and on the spindle at the same time. Markus Reu-ter on the other hand also sees advantages in the manufacturing process, which no longer needs to be interrupted: “The time for roughing of a moulded part is approx. three to five hours, depending on the size and geometry. The interruption for turning the indexable insert has up to now taken about 10 minutes. So in addition to the improved process reliability, we can talk about an additional 10 percent time saving, and we no longer need to provide any sister tools.”
SPINWORX® has already been on the market for eight years. POKOLM has thus powerfully proven that the concept of the rotating insert is working. Particularly tool and mould making will not be able to dispense with round inserts. Compared to high-feedrate cutters, it is possible to work very closely on contours, not creating any problems with the residual material. If you then also gain process relia-bility like BORBET did, it quickly becomes clear that a blade does not need to be fixed.
Focus on the BORBET GmbH
The family-owned company from the Sauerland region has evolved since 1962 to become one of the leading manufacturers of light-alloy wheels worldwide, and employs a 4,600 strong workforce across nine different locations. The Hochsauerland site has 960 employees, 25 of which work in tool making. All in all, the company trains 100 apprentices (commercial and industrial) at its sites in Germany and Austria. In addition to the six German branches, the BORBET GROUP includes subsidiaries with pro-duction sites in South Africa, the USA and Austria.
Incidental facts
Although idle times could be minimised significantly, roughing at BORBET does not yet occur without human intervention. The material is too “jumpy” for that.
By the by
Markus Reuter: “In summary, I see SPINWORX® as a clear improvement with regard to operational life and process reliability.”
