Christophe Meier stands by his WFL and loads a new CNC program into his Siemens controller. He can be sure that he has made no programming errors that would lead to a collision, since his program was simulated during data entry from A-Z and finally checked for collisions. “The fact that simulation takes place directly during the program data feed is one of the big advantages of TopSolid’Cam,” says Christoph Meier. He adds: “Turning with several tool holders is extremely well resolved in this CNC programming system, and this characteristic contributed significantly to our choosing the software."

Christophe Meier is production manager at Gewinde Ziegler, a company based at Horriwil in the canton of Solothurn, north-west Switzerland. He is the main man in charge of setting up new pre-heat treatment machining. The company specializes in thread grinding, and it celebrated its 75th anniversary in 2007. The mainstay of its business - accounting for 50% of its turnover - is the threaded spindle drive activity (Figure 1). Threaded spindle drives carry out similar tasks to ball screws, but instead of ball bearings use small threaded rods that rotate around the threaded spindle and carry the nut back and forth.

Gewinde Ziegler AG has been offering this type of product for 25 years. By dint of quality and precision the company has made an excellent name for itself, and its threaded spindle drives are marketed worldwide by the global corporation INA-Schäffler KG. Threaded spindle drives are high-tech products that are used in automotive technology, the aerospace industry and machine engineering of special tools. For example, they are an integral part of the tilt mechanism on high-speed tilting trains, such as the German ICE and ICN. These drives, transferring high power free of any play, replace hydraulic cylinders when these characteristics are required.

Reto Ziegler has run the company for 10 years. The success of the threaded spindles division, with an average growth of 20% per annum, led him to set up a separate pre-heat treatment machining facility. “We wanted to offer greater flexibility and be able to offer shorter turnaround times. The best way of doing this is to expand our manufacturing range,” says the dynamic boss. So it was that a great deal of investment was made in 2006 and 2007, with the manufacturing premises extended to include a new annex and new machines procured. At the end of 2006, Hermle was able to deliver a 5-axis milling machine and in 2007 the company acquired two multi-function machines: a Doosan Puma and a WFL M40-G mill-turn machine. They also invested in one of the largest grinding machines. The two machining centres are fitted with a main and a secondary spindle, tool revolver and milling spindle, with each machine offering 9-axis control and requiring very precise programming. These machines were the trigger for our procurement of a CNC programming system.

When it became clear that they wished to procure a WFL machine, Reto Ziegler made enquiries with the specialists at WFL Millturn Technologies in Linz about which systems were suited to the programming of these machines. WFL recommended the software that they too used for their client programming: TopSolid’Cam from the French software manufacturer, Missler Software based in Evry, and the mature post-processor from Comdata, Vienna. Gewinde Ziegler then began their evaluation of the programming system to use. Several systems were considered, and out of the 3 bidders under consideration the choice went to NCDATA AG, from Schlieren (Switzerland), the Swiss and German representative of Missler Software products. For Reto Ziegler, the mature technology of TopSolid’Cam, both for 5-axis programming and for the programming of mill-turn centres, was the decisive factor. Christoph Meier, the first user, comments: “Complex machines for 6-sided machining make enormous demands on programming. For me, it was the concurrent simulation, even with two simultaneously running tool holders, during the programming process that was the main criterion for recommending TopSolid'Cam to my boss. An application that monitors crashes on the controller does not serve the same purpose,” he goes on to say.

The system was ordered in December 2006, and in February 2007 the employee training took place at NCDATA in Schlieren. First of all, and at the same time serving as an introduction to a technology still unfamiliar to this company, the Hermle C40 (the 5-axis milling machine) had to be programmed with TopSolid’Cam. A previous version of the post-processor and the machine kinematics was already available for training purposes, with fine-tuning on the post-processor planned for March. Christoph Meier and his programming colleague, Marco Kopp, straightaway could see that reliable program simulation required consistently correct 3D data, a key element for this being dimensionally-stable tools. The training was therefore expanded to include the use of TopSolid’Tool for tool management.  Since the programming system builds on parametrically-associated CAD software, the 3D volume models of the tools are generated during run-time from the digital data. A single template per tool type therefore suffices to generate the 3D tools, so keeping the time and expenditure for this to a minimum.

Christoph Meier’s programming office is on the first floor above the workshop, from where he can oversee the machine pool of Hermle, Okuma, Doosan and WFL for which he takes care of the technical programming. On average, he spends 2 days per week on programming and develops in this time 5 or 6 sophisticated CNC programs. In the future, however, the machine setters will be producing their own programs. Marco Kopp has already assumed this duty for the 5-axis milling machine. So how is the manufacturing process now technically organized at Gewinde Ziegler?

1. The designer determines from the production plan which parts are to be manufactured first and places the data for the 3D volume model on the server in a common directory. He uses Inventor from Autodesk for the design. Internally, design and manufacturing have agreed on the development of models suitable for production, and so the design is tolerance-centred and the curve radius, edge breaks and recesses are geometrically modelled (the previously used textual information disappearing from the drawings). The following takes the example of a workpiece to be manufactured on the WFL.
2. The CNC programming deals with the volume model in the form of a SAT file and models the raw part for this with the TopSolid-3D functions.
3. The programmer now selects the model of the CNC milling machine and fixes to it by click of the mouse the raw and finished part. The small team has already developed the chuck, jaws and tools during the preparation phase and system assembly phase and can now access this digital data.
4. Next, the CNC programmer develops the turning envelope for part-cubic work pieces. The centre-boring is then done, and the roughing, finishing and micro-finishing, along with the recesses and threading using the turning tools, are programmed. This is followed by the milling and boring with the milling spindle. Once the first side is complete, the current raw part with the machined part is transferred to the other spindle and the previously described work process is repeated. There then follows an important step: synchronization. In the timing diagram, Mr. Meier can monitor the load on both tool systems (Figure 4). Using the mouse, he can drag individual operations in the timing diagram to other locations or to another tool holder, and by clicking on the timeline can add synchronization marks. This generates a CNC program that optimally exploits the advanced specifications of controller and tool machinery. Finally, there is another complete simulation of the new CNC program with collision calculation. This gives rise to a process-safe CNC program that is converted by post-processor into an executable ISO program.
5. For the documentation and for the machine setter, Mr. Meier produces tool lists and mounting plans with the help of the powerful functions of TopSolid’Cam.
6. Now the QUINX-DNC comes into play. The ISO data are loaded into the controller and the part is introduced. Since the programming system has already simulated everything, the process stage is very rapid. Christoph Meier estimates the time saving for the first run of the machine at 80% for the Hermle and 20-60% for the WFL.