Precision and dynamics lead to an efficient complete package


The OMB company in Flawil successfully covered the capacities of 2.5 machining centers with the first VERSA 825, installed in 2018. Over time, the 5-axis machine with 32 pallet positions became an absolutely key machine. Since March 2021,OMB has been producing on Fehlmann's new flagship. The VERSA 945. Thanks to the larger travels, maximum precision and increased dynamics, OMB has been able to continuously expand its product portfolio, and with the enormously reduced non-productive times, it is playing in a new league. 
 


At the beginning of 2018, Markus Wick, Managing Director of OMB Maschinenfabrik AG, occupied himself with the investment in a new 5-axis machining center. In conjunction with the move from Bütschwil to Flawil, the company also wanted to renew its machine park. This new 5-axis machining center was to replace two machines, one with a 10-pallet magazine and one with a double pallet changer.

In other words, Markus Wick was also looking for a machine with a high degree of autonomy: “My goal was to vastly expand unmanned production with at least 30 pallet spaces and to be flexible. However, I could not find the solution I had in mind. Either the price was off the charts or the delivery times were too long. The problem was that we would not have been able to shut down the machines at our old location if the machine was not operational by October 2018. To make a long story short, the overall package with Fehlmann convinced me."

Starting with the delivery time, the portal design, the automation with 32 pallet positions and the control system, as OMB relies exclusively on Heidenhain for cubic parts. In the meantime, the VERSA 825 had become an absolutely key machine in Flawil due to its reliability, precision and high availability, replacing 2.5 machines. This satisfaction led Markus Wick to repeatedly confront Adrian Tobler, Technical Consulting and Sales at Fehlmann, with the question of a possible new or further development with longer travels and thus a more universal application.

At some point, it was revealed that Fehlmann was working on just such a project, so OMB was the first company awarded the contract for VERSA 945. Production has been running on it since March 2021 and the range of workpieces has already expanded significantly as a result. With a 650 mm swing circle (Versa 825 has 560 mm), an even larger machining area with corresponding travels, longer components are currently being machined in 5-axis, either with work-and-turn process or on 400 x 500 mm pallets. A major advantage in Flawil is that the 400 x 400 mm pallets, including zero point clamping systems and fixtures, of the VERSA 825 and another 5-axis machine are compatible with the VERSA 945.

Significant differences reduce non-productive time
Fehlmann calls the VERSA 945 a flagship not only because of the extended travels. With the new development, a lot has also changed in terms of precision and dynamics. With high-precision ground ball screw drives and double nuts, Fehlmann has opted for a drive concept that also enables short-stroke applications, e.g. trochoidal milling. There are hardly any drawbacks in comparison with linear motors, thanks to the corresponding acceleration and rapid traverse of 50 m/min in all axes. Markus Wick can confirm these facts: "We took a part from the VERSA 825 with the same fixtures and NC programs to the VERSA 945 and only changed the post processor to make the swivel axis turn to the other side. Without any optimization, we were significantly faster on the VERSA 945."

The time savings primarily reflected the fact that the machining of many details on all sides meant the 4th and 5th axis required numerous rotations and that the rotary axes were significantly faster. For Adrian Tobler, however, these non-productive times contribute quite significantly to such enormous time savings: "The cutting speeds and feeds are now at a similar level for all comparable machines. In contrast, there are still significant differences in non-productive times, such as tool changing and rotation. Fehlmann, therefore, continues to rely on fast double grippers when changing tools with the VERSA 945, as well as on swiveling on both sides with the rotary-swivel bridge." This double-sided swiveling means that fewer compensating movements have to occur. This results in precise surfaces, especially for simultaneous parts. Surfaces have always been an issue at OMB. As a result, there have already been significant investments in programming and balanced tools, in addition to current milling techniques, such as trochoidal milling. 

In Flawil, the precision requirements are 80 percent at 2/100mm and 20 percent at 1/100mm. Even with-out an accuracy package, the VERSA 945 is capable of these tolerances. On the contrary, a second zero point is set on other machines for work-and-turn machining. 
However, Markus Wick considers it particularly important that the entire package works: “In aluminum machining, metal removal rates play a large role, so we're pushing the performance limits of this machine. We are well-positioned with the high rigidity of the tool axes, the rotary swivel table (swivel bridge with counter bearing), and also the Fehlmann spindle (HSK-A63, 18,000 min-1, 120 Nm). Both the machine and Fehlmann's service are excellent." 
Nevertheless, there are still space issues. However, once the existing older machines have been sorted out, the VERSA 945 is also being considered for expansion with automation.  

OMB Gärtner GmbH in the spotlight
OMB developed the world's first high-pressure cleaners branded WAP. Following a strategic reorietation, the company now specializes exclusively in classic contract manufacturing. Core competencies include: CAD-CAM programming, turning, milling, drilling, assembly of subassemblies and turbines. The customer base includes medical and pharmaceutical technology (container construction, analysis equipment), machine tool construction, machinery for food production, general machine construction, turbine technology, as well as analysis equipment, turbochargers and diesel injection systems. 

By the way
The VERSA 945 was deliberately designed with a ball screw drive, because the larger and heavier the moving axes, the less efficient the linear motor. Due to the size and acceleration capabilities of the VERSA 945, the normal forces generated by the motor magnets would significantly reduce the lifespan of the linear guide.

Interesting facts on the side
Batch sizes at OMB range from 10 to 300 parts. However, annual quantities are being ordered more and more frequently. As a result, the production of repeat parts is increasing enormously. 
The Versa 825 has been in operation for 2.5 years and, although it is only run in 1-shift operation, 9,668 spindle hours have been registered thus far.
 

OMB Maschinenfabrik AG
CH-9230 Flawil
Phone +41 (71) 982 72 72
www.omb-maschinenfabrik.ch 
 


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