Key strengths of Febi Bilstein, a supplier of high-quality replacement automotive parts to OEM quality standards, is its manufacturing knowledge backed by the ‘Made in Germany’ seal of approval.

The capabilities of Febi, based in Ennepetal, are focused on the production of advanced products. To meet its requirement for the highest levels of quality, the company not only invests continually in modern equipment, but also constantly improves its machining methods and tooling — hence Febi’s working partnership with tooling company Horn.

The latter has a UK subsidiary in Ringwood (www.phorn.co.uk) and recently introduced the S100 grooving/parting-off insert, with an internal coolant supply that allows it to provide four-times the tool life previously available.

The Bilstein group is a family-owned independent group of companies with the brands Febi, SWAG and Blueprint; it is a leading specialist in the automotive after-market, with some 1,450 employees and a range of over 47,000 different spare parts for passenger cars and commercial vehicles.

Febi Bilstein at Ennepetal has a total of 1,120 employees and a production area of 10,000 sq m, where thousands of car and commercial vehicle replacement parts are manufactured annually.

Many of these are safety-relevant parts. The annual production quantity per part number is between 500 and 200,000, with the scope of manufacture covering almost the complete production chain, from material procurement and analysis through tooling, machining, hardening and assembly to computerised documentation.

Shaft machining

In Febi’s manufacturing department, employees work on spare parts such as chain tensioners, axle bolts, wheel hubs, wishbones and most wear parts on an vehicle. The materials processed are mostly C45, 42CrMo4V, cast iron and aluminium, usually supplied as bar or forged section. A wide variety of shafts is produced, and several tools from Horn are used.

These include Type S224 for roughing, Type 312 for recessing and S100 for grooving. Shafts are machined from bar on Gildemeister CTX 1250 TC 4As, which have a main spindle, a counter-spindle and full milling capability.

The material used for shaft production is tempered 42CrMoS4, which has a strength of 980-1,200N/mm2, making it tough and difficult to machine. Type S100 inserts without internal cooling were previously used for grooving operations, with a cutting width of 4mm for shaft diameters of 50-90mm and 3mm for diameters of 20-50mm.

The results using non-internally cooled S100 inserts were, according to production manager Christian Erlenkötter, “satisfactory to good”.

However, when Horn introduced its S100 with internal cooling, sales representative Michael Ehmann contacted Febi to say that the new product was likely to offer significant benefits.

Mr Erlenkötter decided to carry out tests to explore its potential and ordered test tools, along with a VDI-40 holder to suit a Sauter Trifix turret. The results were a quadrupling of service life and a halving of tooling costs.

“The VDI-40 holder uses the turret’s standard KSS port and, in this case, coolant at a pressure of 25 bar. This insert features the AS45 carbide grade; together with the EN geometry and a chip-groove, there is effective cooling at the cutting zone.

"The coolant jet impinges directly on the cutting edge and improves the machining conditions considerably. Furthermore, the focused application of coolant aids chip removal and greatly reduces the risk of swarf congestion; it also reduces the formation of built-up edge and premature cutting-edge wear.

“Although the tooling system with the new holder is slightly more expensive than that previously used, overall tool costs have been halved. In addition, the quadrupled tool life reduces tool changes and thus increases the up-time of the machine.”

Machine setter Michael Krüsel also highlights the ease with which inserts can be changed. “Clamping of the prismatic inserts using a clamping screw has proved to be totally reliable, even for cutting depths up to 45mm.”

Mr Erlenkötter sees considerable potential for the S100 insert. “We are still in the evaluation phase with a test tool, and we are still using the cutting parameters developed for inserts without internal cooling.

"However, as the optimisation process continues, I expect to see higher cutting parameters and further cost savings. For us, this first application of the new S100 with internal cooling is a precursor of many similar applications on other parts and other machines.”