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Complete Machining and Integration of Functions in Grinding

The INDEX Group prac­tices ver­sa­til­ity — not only in its own prod­ucts, but also in their man­u­fac­ture. Grind­ing machines from Glauchau play an impor­tant role in this process.

The INDEX plants in Esslin­gen are one of the largest machine tool man­u­fac­tur­ers in the world. An impor­tant ingre­di­ent in the recipe for suc­cess is the con­stant search for improve­ment oppor­tu­ni­ties. And least of all does this stop at the company’s own processes.

A mas­ter­mind when it comes to man­u­fac­tur­ing effi­ciency at INDEX is site pro­duc­tion man­ager Mar­tin Steiner: “Our cus­tomers require spe­cial solu­tions and this results in spe­cial machine com­po­nents. Thus the cen­tral ques­tion is: how can we meet the spe­cial require­ments of these com­po­nents, which are often only real­ized in small runs, as eco­nom­i­cally as pos­si­ble?“ Mar­tin Steiner also has the answer at hand: “Due to the INDEX phi­los­o­phy of pro­vid­ing cus­tomers with com­plete machin­ing with our machines, we have long been sen­si­tized to the poten­tial of func­tion inte­gra­tion. We know the advan­tages and of course use them our­selves every day. By con­stantly ques­tion­ing exist­ing man­u­fac­tur­ing processes, new solu­tions are reg­u­larly created.“

INDEX-Werk in Esslingen
INDEX plant in Esslingen

WEMA Glauchau scores with universal machining

Uni­ver­sal­ity is the key­word when it comes to equip­ping the Esslin­gen man­u­fac­tur­ing facil­ity. This cri­te­ria is also impor­tant when pur­chas­ing a machine for quill pro­duc­tion. There­fore, Mar­tin Steiner turned to Werkzeug­maschi­nen­fab­rik (WEMA) Glauchau, a com­pany whose grind­ing machin­ing cen­ter (SBZ) WOTAN® S6 U INDEX has already owned and oper­ated successfully.

“When you have a good part­ner, you nat­u­rally ask them for a solu­tion first. Of course, you also look around at other man­u­fac­tur­ers. But the way we needed it, no one else would have imple­mented it for us. Uni­ver­sal machin­ing is really a big advan­tage of WEMA, mak­ing it the only man­u­fac­turer that has imple­mented inter­nal and exter­nal grind­ing with two sep­a­rately oper­at­ing grind­ing units.“

Arbeitsraum WOTAN® S6 U mit einer Innen- und Außenschleifeinheit
WOTAN® S6 U work­space with one inter­nal and one exter­nal grind­ing unit

Increased efficiency through automatic mold change & modern sensor technology

“The batch sizes for the pro­duc­tion of quills are between 2 and 100 pieces. Con­sid­er­able time is spent on retool­ing,“ says Mar­tin Steiner. A new sys­tem was needed to sig­nif­i­cantly increase these setup times and the pro­cess­ing spec­trum com­pared to the older grind­ing cen­ter, with the goal of reliev­ing bot­tle­neck machines upstream and down­stream through process inte­gra­tion, sig­nif­i­cantly reduc­ing flow times in-house, and cre­at­ing a low-man­power operation.

The machine con­cept of the WOTAN® S6 U was expanded to include a tool changer for this pur­pose. “For us, the inte­gra­tion of an auto­matic tool changer was a com­pletely new chal­lenge,“ recalls Ronald Krip­pen­dorf, Man­ag­ing Direc­tor of WEMA. Trans­fer posi­tions had to be defined and a break­age sen­sor sys­tem inte­grated. After all, the machine was sup­posed to auto­mat­i­cally detect tool break­age and replace the affected tool on its own.

How­ever, not just any sys­tem was attached, but a tool change sys­tem that is already in use in series on INDEX machines. Last but not least, a series HSK-A63 motor spin­dle man­u­fac­tured by INDEX also had to be inte­grated for the tool change. “All in all, a com­plex but very instruc­tive task.“

Schleifbearbeitungszentrum WOTAN® S6 U mit integriertem INDEX-Werkzeugwechsler
WOTAN® S6 U grind­ing cen­ter with inte­grated INDEX tool changer

Significantly reduced flow times

The machine is equipped with an inde­pen­dently oper­at­ing inter­nal grind­ing unit, which is equipped with three motor spin­dles and a tail­stock, and an exter­nal grind­ing unit on which three exter­nal grind­ing wheels are posi­tioned. INDEX spec­i­fied the use of a self-cen­ter­ing guide steady rest as well as a spe­cial clamp­ing tech­nol­ogy, so that the con­cept of 5‑sided com­plete machin­ing could be imple­mented. The new WOTAN® S6 U grind­ing cen­ter thus allows com­pre­hen­sive quill and spin­dle machin­ing (inter­nal, exter­nal and face machin­ing). For the dress­ing units for inter­nal and exter­nal grind­ing, the hold­ers were man­u­fac­tured by INDEX, and this INDEX quick-change sys­tem (W‑gearing) was inte­grated into the WEMA WOTAN® S6 U upon request. The tool changer pro­vides more than 80 tools for drilling, milling, grind­ing, mea­sur­ing, and other oper­a­tions on the quill front. With this immense flex­i­bil­ity, the work­pieces are com­pletely machined on one machine and do not have to be dis­trib­uted among sev­eral machines. In addi­tion to short­en­ing changeover times, this also reduces lay­down times and flow times within pro­duc­tion. Pre­vi­ously, lay­down times of three to eight days were incurred per batch dur­ing the sub­se­quent oper­a­tion. With the com­plete machin­ing, “the sub­se­quent oper­a­tion has been com­pletely inte­grated to 100% and a shift between dif­fer­ent work­shops has been elim­i­nated“ says Steiner.

Process-reliable and high-precision grinding machining

Another major advan­tage of WEMA is the process reli­a­bil­ity of the grind­ing machin­ing cen­ter. “With our quan­ti­ties, i.e. batch sizes between 2 and 100 pieces, we do have 1–2 min­utes longer machin­ing times, but in return we have a lower-man­power- or nearly unmanned process. The impor­tant thing here is that the process reli­a­bil­ity is very high. When machin­ing quills, we mea­sure the tol­er­ances of the fit­ting holes once a day. At the begin­ning of work­ing with the new machine, we mea­sured every part but quickly real­ized: The WOTAN® does the job! The process is sta­ble! The machine holds the tol­er­ance all day long!“ describes Steiner.


High-pre­ci­sion work­piece clamp­ing and com­plete machin­ing also enable the machine to achieve pre­vi­ously unat­tain­able accu­ra­cies, such as cylin­dri­cal form devi­a­tions of less than 3 µm over a length of 1300 mm, dimen­sional tol­er­ances of ± 1 µm, and con­cen­tric­ity devi­a­tions between inner bores and lat­eral sur­faces of less than 1 µm.


Due to these con­sis­tently high accu­ra­cies in con­junc­tion with an auto­mated and autonomous process with enor­mously high process reli­a­bil­ity, the required oper­a­tor input is also tremen­dously reduced. The oper­a­tor capac­ity that is freed up can there­fore be used in par­al­lel for other machin­ing oper­a­tions on other machines.

Schleifbearbeitungszentrum WOTAN® S6 U mit Renishaw Messtaster
WOTAN® S6 U grind­ing cen­ter with Ren­ishaw probe

On the road to success with customized solutions

Above all, the require­ments for an increase in pre­ci­sion, which INDEX had set as a goal at the begin­ning of the project, could thus be clearly exceeded. Mar­tin Steiner is con­vinced: “For such and sim­i­lar tasks, we would def­i­nitely turn to WEMA again. What the Glauchau-based com­pany deliv­ers tech­ni­cally is a real specialty.“

The response that WEMA is receiv­ing from other cus­tomers to the offer­ing of its WOTAN® S6 U grind­ing machin­ing cen­ter clearly indi­cates that the mar­ket needs this con­cept. Mean­while, the WOTAN® S3 U is also avail­able with a smaller, fully inte­grated tool changer with five slots. This means that three exter­nal and seven inter­nal machin­ing tools are avail­able in just one machine for users with a more spe­cial­ized machin­ing spectrum.

v.l.: Martin Steiner (Standort Fertigungsleiter INDEX), Ronald Krippendorf (Geschäftsführer WEMA Glauchau)
from left: Mar­tin Steiner (Loca­tion Pro­duc­tion Man­ager INDEX), Ronald Krip­pen­dorf (Man­ag­ing Direc­tor WEMA Glauchau)

Facts about the WOTAN® S6 U grinding machining center from WEMA Glauchau

  • Com­plete machin­ing in one clamping
  • Auto­matic tool change sys­tem with 80 seats
  • Machin­ing with geo­met­ri­cally deter­mi­nate and inde­ter­mi­nate cut­ting edge
  • Machin­ing of chuck and shaft shaped parts (steady rest guided)
  • Machin­ing of shaft-shaped parts between cen­ters (tail­stock on B2 axis)
  • Cylin­ders, cones, poly­gons, threads, eccentrics, grooves, and much more
  • Three inter­nal grind­ing spin­dles (on B2 axis), one of which includes an auto­matic clamp­ing interface
  • Three exter­nal grind­ing tools (fixed on B3 axis)
  • Exter­nal grind­ing wheels with a max­i­mum diam­e­ter of 600 mm
  • Power chuck (man­drel)
  • Auto­matic self-cen­ter­ing bezel
  • Auto­matic trans­fer of com­po­nents between peak volt­age in steady rest voltage


  • Innen­rundtisch mit bis zu 4 Innen­schleif­spin­deln und einen Reitstock
  • wech­sel­seit­iger Ein­satz von riemen­getriebenen Innen­schleif­spin­deln und Motorspindeln
  • fest­ste­hende Außen­schleifein­heit mit einer Schleif­scheibe (30°, 45° oder 90° zur Werk­stück­achse) oder
  • hydro­sta­tis­che Werkstückspindel
  • Taster zur Nullpunktmessung
  • fest­ste­hende und/​ oder angetriebene Abrichtwerkzeuge
  • In- und Post-Prozess-Messinstrumente
  • Inter­nal rotary table with up to four inter­nal grind­ing spin­dles and a tailstock
  • Alter­nat­ing use of belt-dri­ven inter­nal grind­ing spin­dles and motor spindles
  • Fixed exter­nal grind­ing unit with one grind­ing wheel (30°, 45°, or 90° to the work­piece axis) or hydro­sta­tic work­piece spindle
  • Probe for zero point measurement
  • Fixed and/​or dri­ven dress­ing tools
  • In-process and post-process mea­sure­ment tools

About Werkzeugmaschinenfabrik (WEMA) Glauchau

WEMA GLAUCHAU GmbH is a medium-sized Saxon mechan­i­cal engi­neer­ing com­pany whose roots go back to the year 1883. Grind­ing machines of the high­est qual­ity and pre­ci­sion, of which over 10,000 have been sold world­wide to date, are the company’s strengths. WEMA GLAUCHAU offers machines, tech­nolo­gies, and ser­vices from a sin­gle source, and is part of the inter­na­tion­ally oper­at­ing NILES-SIM­MONS-HEGEN­SCHEIDT Group.

About the holding company NILES-SIMMONS-HEGENSCHEIDT GmbH

The NILES-SIM­MONS-HEGEN­SCHEIDT Group (NSH) focuses its busi­ness activ­i­ties on research, devel­op­ment, man­u­fac­tur­ing, and sales of machine tools with the aim of pro­duc­ing prod­ucts of the high­est qual­ity, inno­va­tion, and energy effi­ciency. NSH Group is one of the 30 largest machine tool man­u­fac­tur­ers in the world and oper­ates in five indus­tries: Engi­neer­ing, Auto­mo­tive and Truck, Aero­space, Rail­way and Metro, and Tool and Die.

About INDEX-Werke GmbH & Co KG Hahn & Tessky

With its brands INDEX and TRAUB, the INDEX Group is today one of the world’s lead­ing man­u­fac­tur­ers of CNC lathes. With six pro­duc­tion sites and six inter­na­tional sales and ser­vice com­pa­nies as well as a broad dealer net­work, the Esslin­gen-based group of com­pa­nies is present at 80 loca­tions worldwide.


Ronald Krip­pen­dorf
Ronald Krip­pen­dorf · Man­ag­ing Director
Werkzeug­maschi­nen­fab­rik (WEMA) Glauchau

+49 3763 61–100

Rainer Gondek
Head of Mar­ket­ing INDEX-Werke GmbH & Co KG Hahn & Tessky 

+49 711 3191 1286