Case Study
Simulation solves the challenges of very fast, very complex machines
Witzig & Frank GmbH
Digital simulation helps create complex machining centers that perform faster and are available to customers sooner
Multiple operations and cycle times of just seconds
Witzig & Frank GmbH develops and produces specialized machining centers for the automobile industry and its suppliers, the sanitary and fittings sector and other markets where medium and large series of parts are produced in cycle times of a few seconds. Individually designed multipath rotary transfer machines in the company’s Turmat series, for instance, integrate technologies such as lathe turning, five-axis milling, grinding, honing, bending and rolling with up to ten stations and 27 machining units. These machines are capable of working simultaneously at several levels in one workpiece and can achieve cycle times of between 1.5 and 40 seconds.
Modular multi-station machining centers in the Triflex series, with up to seven stations and just as many machining units, permit five-sided machining with cycle times between 20 and 150 seconds. Multi-spindle two station machining centers from the Twinflex series can be loaded at two locations and process, vertically or horizontally, in five axes, with machining processes taking up to 300 seconds. Although these machines are very complex, Witzig & Frank does not want them to be complex for the users. “Our vision was to make these complex machines as easy to operate as a simple machining center,” says Walter Bauer, the company’s technical manager.
Doing away with trial and error
Customers are asking Witzig & Frank for machines capable of producing high-pressure pumps for petrol and diesel fuel injection, differential housings, steering housings, gear and crank housings for motorbikes, mixer taps and other fittings and are expecting an economically viable machining scheme. Triflex and Twinflex machines are typically ready to start production in six months. A Turmat installation can take up to a year. “The key to this business is to prepare everything in advance so well that the trial time needed on the factory floor is as short as it can possibly be,” explains Bauer.
In the past, however, it was the trial run that first showed how well a machining scheme could actually perform. Until that time there was at least some uncertainty surrounding the design of the machining scheme, the expected cutting data and, finally, achievement of the agreed cycle times. All of these factors, as well as awkward contours on the workpiece or passive collisions of the large number of tools maintained in the machining stations, usually required two or three iteration loops before a machining center was accepted.
Witzig & Frank’s Application Technology Department was created in 2003 to design the machining process, including the selection and use of multi-spindle heads, tools and clamping tools, the NC programming and the commissioning of new machining centers. Today three workplaces in this department are equipped with Tecnomatix® software solutions, eMPower-Machining and eMRealNC, that allow the company to replace trial and error on physical machines with digital simulation. eM-RealNC allows the user to model the common NC controllers from leading manufacturers. In contrast to simulation tools that are part of NC programming systems or among their accessories, eM-RealNC begins work after postprocessing, with the work done in the code of the machine instructions actually generated. eMPower Machining is used to construct, simulate, analyze and optimize integrated production lines and flexible machining cells. The software calculates the production operations and cycle times, generating corresponding NC tool paths. Department manager Pascal Schnebelt explains, “We achieved the breakthrough in the application of our simulation tools in 2004. Without simulation, we could no longer come close to the necessary cycle times.”
Shorter machine cycle times increase customer benefits
The clamp-to-clamp times of Witzig & Frank’s very fast machines are barely one second; visual collision checking is scarcely possible. Expensive crashes and damage are not the only consequences of this. Since the clearance from difficult contours cannot be exactly determined, the paths taken around obstacles must follow a wide arc. “The simulations provided by the Tecnomatix solutions allow us to achieve optimum routes with the smallest possible safety clearances,” Bauer says. “In general this has allowed us to reduce cycle times in our machines by between five and 10 percent.” When one realizes how important even the smallest improvements in cycle times are in the manufacturing of large series, it is hard to overestimate the value of this to Witzig & Frank’s customers.
Digital simulation not only benefits Witzig & Frank in the design of its machines, it has also streamlined the production process for the machines themselves. The company can now be certain of achieving the desired result on a single set-up cycle. “Tecnomatix can shorten the lead times in our own production facility by between 10 and 20 per cent,” Bauer reports. Reduced capital commitment and lower costs for rework and for spare parts are additional financial advantages of digital simulation.
More uses for simulation in the future
In addition to using simulation for its own purposes, Witzig & Frank now offers digital simulation as a service to its customers: “On-going production processes can be optimized without halting production, and then only very short downtimes are needed to adapt the process,” reports Schnebelt.
In the future, the use of the Tecnomatix simulation solutions at Witzig & Frank will be further developed as well as integrated into the process chain at an earlier stage. “We want to handle all specific projects with the Tecnomatix solutions as early as the quotation phase,” says Bauer. “Our experience suggests that projects that have been secured through digital simulations have a greater probability of successful implementation.” In addition, a new project planning department led by Schnebelt, bringing in workers who are trained in Tecnomatix operation, will support the sales department in the development of complete production solutions and will maintain responsibility through to successful handover.
The application of the Tecnomatix solutions in various sectors will also be expanded. For example, tool plans can be prepared with eMPower-Machining, with all the necessary information already available. (This requires the addition of functionality for outputting drawings to the program. Witzig & Frank plans to continue the effective collaboration it has had with Siemens PLM Software in the past to see this happen.) Similarly, application of the simulation software at the machines themselves is yet to be developed. During the setup procedure, a separate PC can be used to correct cutting speeds, tool lengths and dimensions in the NC program. Dimensions can be changed independently of the position of the workpiece in the machine – a considerable simplification. A further simplification will be the option of running a partial module from the eM-RealNC software on the NC controller. All this was part of Bauer’s vision from the beginning.
Real controller data
Cooperation between Siemens PLM Software and Siemens A&D in a research project within the “Integrated Virtual Product Creation” (iViP) program is giving the users of eM-RealNC the option of using a virtual NC kernel of the Siemens 840 D, which is used as an alternative to Fanuc on Witzig & Frank’s machining centers. Bauer believes “this will raise agreement of the simulation results with the actual values of the mechanical machining, for which the present figure is between 95 and 97 percent, towards 100 percent.” As a result of the still-growing complexity of the machines – for instance through the use of multi-spindle heads on turret heads, which already have more than eight spindles – he also sees an improvement in user-friendliness as an important goal. His vision is that “complex machines must be as easy to operate as single-spindle devices.” Tecnomatix solutions are being used to make this happen.
Download the PDF:
Challenges:
- Reduce design, production and set-up time for new machines
- Enable faster machine performance
Keys To Success:
- Digital simulation is used to optimize toolpaths
- Trial runs of actual machines have been replaced by computer simulation of digital models
- Digital simulation is offered as another service for customers
Results:
- Machine cycle times down by 5 to 10 percent
- Production lead times lower by 10 to 20 percent
- Reduced capital commitment due to fast shipment
- Lower costs for rework and spare parts
- New machines are ready to go after only a single set-up cycle
Industry:
- Machinery & Industrial
Client's Primary Business:
Witzig & Frank GmbH develops and produces machine tools consisting of standard modules for metal cutting and metal forming manufacture of a wide range of work pieces.
Business Initiatives:
- Production Efficiency
Solutions/Services:
- Tecnomatix
Client Location:
Offenburg
Germany
"We want to handle all specific projects with the Tecnomatix solutions as early as the quotation phase."
Walter Bauer
Technical Manager
Witzig & Frank GmbH