Grob’s simultaneous milling & turning

An extremely impressive machine concept providing the option of milling and drilling without re-clamping and – above all – a high level of process safety with maximum accuracy for workpiece machining. Impressed by these benefits, the services provider HETEC located in Breidenbach, Hessen, has become a loyal GROB customer in the field of milling.

Stuttgart, AMB Trade Fair in September 2010. Hans Rink, Head of Rink Werk-zeugmaschinen and GROB Represen-tative for the Hessen region, mana-ged to persuade HETEC MD Friedhelm Herhaus to visit the GROB trade fair stand. Back then, Friedhelm Herhaus was rather sceptical about the size of GROB as a com-pany, as he couldn’t believe that he would really be taken seriously as a regional sup-plier of tool, die and machine manufactu-ring products from one of the world’s big-gest machine tool companies. But he soon knew better.

2010 saw him standing in front of a world first from GROB – the first fully hydrau-lics-free, fully CNC controlled machining center. Back then, he wasn’t interested in all the arguments for and against hydrau-lics-free machine tools. He was much more interested in the horizontal spindle position on the G550 and that you could mill and drill with it at the same time without having to re-clamp the workpiece or take it to a deep- hole drilling machine. An important factor for tool and die construction, but for many mechanical engineers, too, when they have to drill deep holes. The highly experienced Friedhelm Herhaus had never seen milling and drilling on a single machine of this kind before. So it initially got his interest, at any event. He found the travel and GROB kine-matics – the whole machine concept in fact – very appealing.

Thorough preliminary research and intensive technical analysis

Nevertheless, the disinclination to opt for a GROB 5-axis universal machining center was strong. Basic issues needed to be clarified first as to whether HETEC actu-ally wanted to implement the axis sys tem (with rotated Y axis). An axis system that was totally new territory to HETEC at the time. But as he traveled back from the trade fair, Friedhelm Herhaus called Hans Rink to discuss the machine’s axis symmetry and the machining technology for workpieces with long tools. He was increasingly persuaded, recognizing that workpieces can be machined with long tools with the GROB machine and that the horizontal spindle position enables opti-mum chip removal for both drilling and deep cavities. The question of the extent to which the GROB machine would suit existing HETEC machine tools also needed to be clarified, and whether this type of GROB machine with its specific axis con-cept could be integrated in the HETEC en-vironment successfully.

Friedhelm Herhaus could instinctively see the potential of the GROB machine. Fur ther discussions took place in Mindelheim and Breidenbach – with long phone calls – and they finally hatched the idea of deve-loping a “fantasy component”, for which the GROB machine concept minus re-clam-ping and multiple clamping would deliver rapid results. There was also a requirement to create various contours on the GROB machine. Chip removal with deep pockets was another major issue on the check list. “We were really impressed by the assistan-ce we received from the GROB technicians. Even at an early stage of our collaboration, when we hadn’t even bought a machine yet, we quickly realized that GROB loo-ked after new customers really well, the aim being to find the best user solutions”, Friedhelm Herhaus looks back to the time with fondness.

HETEC team impressed by GROB technology

The more Friedhelm Herhaus and his tech-nicians got to grips with the technology of the GROB machining centers, the more they could see the strength of these machi-nes. First the benefit that – thanks to the special axis concept – the entire length of the tool can be used in each axis setting – even at maximum workpiece size. And the special tunnel concept means that the whole work area can be used, as the motor spindle plus tool withdraws into the spind-le shaft, meaning that the machine table can rotate and swivel with the workpiece and clamping mechanism without colliding a definite plus point. Something comple-tely new to the die HETEC technicians. In Mindelheim for training during the initial and test periods, the machine operators soon appreciated another benefit provided by GROB machines: The spindle is positio-ned almost at eye level, giving a good view of the machining tool.

From the first G550 to the G550 with rotary pallet storage system (PSS-R)

After successful testing at GROB in Mindel-heim, the HETEC management team finally took the decision to buy a G550. Particularly because the axis concept allows for machi-ning deeper cavities with good chip remo-val and drilling operations with deep hole drilling tools (Ø 8 x 650 mm) went without a hitch. The first GROB G550 was then in-stalled as planned for machining modelling components with complex contours, high surface requirements and parallel introduc-tion of cooling bores in a single clamp. La-ter on, HETEC soon saw the machine’s ac-tual potential at HETEC for machining used in die and mold construction. The G550 was ideal for machining the high-strength, hardened steels typically used in this area. HETEC technicians were amazed by the option of full introduction of cooling and ejector bore with tool lengths of up to 650 mm in the same clamp.

Continuing close collaboration between HETEC and GROB, allied with a desire to introduce automation for die- and tool-ma-king processes with typically long running times, led to the purchase in 2014 of a G350 with a zero point clamp system and a pallet system that made it possible to set up workpieces outside of the machine. Completed pallets were replaced by newly fitted ones manually. But it was also clear that simultaneously setting up the workpie-ces while the machine was running would result in greater flexibility and improved spindle running times. And then came the GROB in-house trade show in 2015. The HETEC management team were impressed by the benefits of a G550 with a rotary pal-let storage system (PSS-R), purchasing one soon afterwards with a master computer. A major plus point in their eyes was the fact that, even with the GROB automation ap-plication, the machine operator still had a good view and access to the work area.

A solid partnership is formed
At an early stage of discussions and the process of getting to know each other, HETEC dismissed fears of a David and Goliath situation. Both sides soon learned to value each other as they looked for the best solution. The GROB philosophy of “nothing’s impossible” ultimately won the day. GROB acceded to nearly all of the customer’s wishes, developing special solutions. The purchase of a G550 seven years ago marked the beginning of a solid collaboration based on trust – something that HETEC had never before experienced in over twenty years of existence. HETEC are also really impressed by the GROB Ser-vice hotline and expert technical support. So it’s no surprise that Friedhelm Herhaus is really pleased with his Swabian Bava-rian partners, buying more machines in Mindelheim.