Milling

A universal tool masters three applications

After many years of cooperation, the partners usually know each other very well. Each knows what it can expect from the other and what can be achieved with this alliance. Since its founding in 1987, the tool manufacturer Depo GmbH has placed its trust in the coating competence of CemeCon. And that's why the company from the area near Gütersloh in Germany is now one of the first to coat with the new SN² Supernitride class – and to use it from the very start for a new line of cutting inserts.

A longer tool life and shorter machining cycles – the pressure to reduce costs in the machining industry demands that all available savings potentials are fully utilized. That's especially important in industries in which the consecutive use of a large number of different tools for each application is required. There every manufacturer is happy to order, store and use as few tool versions as possible.

New cutting insert generation offers triple benefits

So that customers can now be provided with relief in this point, Depo developed the new XPERT cutting insert generation according to the “three-in-one” principle. From roughing milling to 3D milling to HSC milling – the patented new development covers all applications expected of an APKT, a rhombic and a polygon insert. In the process, different clearance angles of the cutting inserts from 90° to 105° achieve the various functions of the tool required in each case.

With specifications of this kind, the standard for the tool coating was accordingly high. Andreas Schaeper, National Sales Manager at Depo says, “The greatest challenge was certainly meeting the various requirements for the functions of the cutting inserts. That could only be guaranteed
with an extremely rugged, smooth and heat-resistant coating solution. That much was clear.”

The desired coating properties correspond exactly to the new Supernitrides of the SN² class. Dr. Rainer Cremer, Executive Director Technical Unit at CemeCon explains, “That's why Depo is one of the first of our customers to use the advantages of SN². And the results are quite good. With the new line of cutting inserts, enormous increases in the tool life and top surface quality now offer Depo customers ideal properties for even more economical production.”

Source: FACTS 25 page 10

Two experts in the same boat

The way to the perfect hollow chocolate item is long: for example, precision machined moulds are needed in which the liquid chocolate attains its marked contour. That already the month of September can be the right point of time for Easter bunnies was proven by the company Pokolm Frästechnik GmbH from the town of Harsewinkel, Germany through its first place in the 7th European High Speed Machining Award 2006.

At the end of September 2006, the Austrian town of Steyr was again the meeting point of the specialists from the area of highspeed machining and precision manufacturing in order to position themselves, by way of a competition between each other, even more clearly on the market. 15 companies from the area of „hard milling“ accepted this offer – the company Pokolm Frästechnik from the East-Westphalian town of Harsewinkel was able to win recognition.

A mould insert for a chocolate Easter bunny was to be processed according to the hanmouldsded out CAD data. Franz Pokolm, owner of the company Pokolm Frästechnik: “The geometry of the work piece which was to be manufactured was certainly demanding: in the case of the Easter bunny of the confectioner Roman Hauswirth from the town of Kittsee we had to mill differently deep and shallow areas – and this of course with a surface quality and accuracy which was to be as high as possible. In the case of X38CrMoV5-1 steel having a hardness of 52 to 54 HRC, it is essential to equip the machines with the matching tools!”


Finest contours with precision tools

And in this case the tools had to be precise and durable – this at the same time being quite a challenge for the coating vendor. In view of the stringent requirements, precision tools of the utmost quality were much in demand. Together with the engineers from Pokolm, the experts from CemeCon worked out the corresponding coating solutions based on supernitride coating materials – and this with success.

Contour accuracy in the mould cavity on the entire surface amounted to +/- 0.015 mm, all surfaces exhibited a surface accuracy of 0.3 Ra. This was achieved above all through the corresponding tools – the smallest tool used in connection with the mould cavity exhibited a diameter of just 2 mm. At the separating plane, surface quality was 0.5 to 0.6 Ra and for the contour of the letters 0.8 to 1.0Ra. Franz Pokolm: “Especially the con-tour of the letters was a challenge because these were particularly fine and fragile. For these we used a milling cutter coated with a supernitride and this with a milling cutter diameter of just 1 mm”.

Important quality criteria of this award were, besides complying as best possible with the demanded manufacturing tolerances, the assessment of the visual overall impression and the surface quality of all surfaces. Moreover, the milling respectively processing strategies, the processing time until attaining the surface accuracy in the mould cavity, the separating plane and the lettering as well as the degree of innovation of the submitted proposals were assessed.

Milling at tremendous speed

From the 15 participating companies, the company Pokolm Frästechnik won the first place in the category “hard milling” taking a time of two hours, 29 minutes and 52 seconds.

“Breakdowns caused by a broken tool or a failure of the coating would have cost us the first place. But sound preparation work by the entire team regarding the challenge and to show off our abilities in a competition with other top-class vendors, fully paid off” explains Pokolm boss Franz Pokolm who received the award jointly with his son Marco.

After the cooperation for this award was concluded successfully, Pokolm and CemeCon are now jointly working already on the next challenge.

Source: FACTS 29 page 6-7