“Peeled” Differential Gearboxes

Torsen in Belgium makes its production more efficient with Skiving technology from Toyoda

Jean-Michel Saniez has been manufacturing gears and differentials for 30 years. However, Saniez has only recently been able to rejoice in the biggest development step: in 2013, the Process Development Manager at Torsen in Belgium accompanied the introduction of skiving technology. In 2013, the leading manufacturer of differential gears integrated two Toyoda GS300H Skiving machines into its production, thereby significantly increasing production efficiency.

The differential gears from the plant in Wallonia near Charleroi can be found in numerous vehicles - from the Hummer to the Audi Q7. Here, 196 employees produce around 600,000 differential gears per year. This requires several million rolling bearings, gears, sun gears, planetary gears and ring gears. Their production is demanding because it includes numerous production steps such as milling, drilling, deburring and finishing, and still requires very high precision.  This is particularly demanding when it comes to gearing, as the teeth must be found exactly when machining on several machines.

A production line of four machines includes the existing Torsen production and thus poses an additional challenge for the production quality: "If parts are machined first on one machine and then on other machines, this always leads to loss of accuracy. In order to be able to maintain the tolerances during finishing, you have to start with significantly lower tolerances," explains Saniez.

Less investment and more quality

The decision to introduce skiving technology at Torsen was made in 2013 because the number of production units had to be significantly increased. With the Toyoda GS300H, the parts are now produced in one clamping, which makes production much more efficient. The entire production process remains within one skiving machine. In order to achieve the same number of parts as before in the production line with four machines, now two Toyoda GS300H are sufficient. "This not only saves space, electricity, fixtures and an enormous amount of investment," says Saniez. "The big advantage is also that we can set up the machines much faster and have moved even further forward in terms of quality, as we no longer have the losses we have suffered from processing on several machines".

Traditional Technology Experiences Industrial Spring

More than 100 years ago, the German inventor Julius Wilhelm von Pittler applied for a patent for the "Process for cutting gears". However, this technology, later known as skiving, only became interesting for industrial applications when CNC controls enabled direct drive and precise synchronization of the cutting tools. Toyoda Machinery Europe was a pioneer in the development of CNC-controlled skivings from the beginning and, with the GS300H, offers a machine that combines gearing with the cutting possibilities of a turning and milling machine. "With this process integration, we are also responding to the trend towards more flexibility and smaller batch sizes," says Michael Steiner, Managing Director of Toyoda Machinery Europe.

Tool quality as a key issue

At Torsen in Belgium, skiving technology has proved itself successfully so that now three Toyoda GS300Hs are in production and one additional machine is available for development. Saniez and his colleagues continuously check the production efficiency and also test the skiving tools that Torsen manufactures itself.  For Saniez, the development of efficient tools is a key issue in the use of skiving technology. In numerous tests, the gearing expert and his team have been able to continuously improve the coatings, geometries and materials of tools. "We have thus increased the service life of the skiving tools to 9000 pieces and reduced the tool costs per part from 2 cents to 0.9 cents.

A successful development partner

For Saniez it is also important to compare the efficiency of skiving with the traditional manufacturing method of gear hobbing. "And we have now also achieved major savings in tooling costs."

Michael Steiner is also pleased with the successful technological development at Torsen. "Because this provides us with a trend-setting development cooperation from which other customers and partners can also benefit."  In addition to the Skiving machines, Toyoda can also pass on proven tool technology and production experience.

About Toyoda Manchinery Europe:

Toyoda Machinery Europe is the European subsidiary of the renowned Japanese machine tool manufacturer Toyoda Machinery. Toyoda offers vertical and horizontal machining centers and integrates them into existing or new manufacturing processes. Through its parent company JTEKT, the company is also part of the international Toyota Group. In addition to the demonstration center, the Krefeld site near Düsseldorf also houses service, sales, marketing, spare parts storage and spindle repair.