Immense gain in flexibility Easy automation of a highly precise production

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Anyone who, like Frank Verzahnungstechnik, repeatedly opts for a robot cell from Halter CNC Automation as a highly specialized contract manufacturer within a few years must have good reasons for doing so. A report on a well-considered strategy.

Frank Verzahnungstechnik, based in Wehr (Germany), is an expert in the manufacture of high-precision gears for complex drive technology. "With 20 employees, we produce transmission parts for general mechanical engineering, such as gears, pinion shafts, or worms," explains owner Martin Frank. Accordingly, the range of industries for which the company manufactures is diverse: for example, the packaging industry, hydraulics industry, robotics and handling technology, cleanroom and vacuum technology, medical technology, or the food industry, to name just a few.

Extremely high manufacturing depth

The products are exclusively manufactured according to customer specifications. The manufacturing depth is therefore extremely high, says Martin Frank: "Our services range from raw material procurement through all work processes, including the most complex grinding processes, to the finished product, whereby we produce both individual parts and batches of, for example, 5 pieces up to larger series of up to 5000 pieces. Since we basically always manufacture customer—or product—specific custom products, we are anything but a classical mass production facility. That's why we have a very complex production environment, where, among other things, you see only a few identical machines."

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In view of the batch sizes to be produced, the high degree of automation is a particular strength of Frank Verzahnungstechnik. "From a quantity of 50, production is indeed already automated. This allows us to react very flexibly and quickly even with comparatively small batches and to manufacture extremely economically. Compared to other contract manufacturers, this is undoubtedly a significant competitive advantage," says Martin Frank.

Automated production of larger workpieces

And a decisive reason why the company first invested in a Turnstacker Premium robot cell from Halter CNC Automation for automated loading and unloading of a lathe in 2017.

Although Frank Verzahnungstechnik already had solutions for partial automation, such as with bar loaders on lathes, the dimensions of the workpieces to be machined go far beyond classical bar automation, which typically only reaches a diameter of about 60 mm to 65 mm (approx. 2,3 to 2,6 inches). Therefore, series with larger quantities and part diameters of up to 210 mm (approx. 8,2 inches) were manufactured on vertical lathes, for example, using rotary tables with limited workpiece capacity.

Convincing robotics concept

"This only allows for one-sided machining. However, we especially wanted to promote automated two-sided machining in the turning shop. For larger components, this can be realized either with a turning station and two machines or with a robot loading a horizontal lathe. In our case, it was a CTX beta 800 from DMG Mori, which has a main and counter spindle with identical performance data. Therefore, we can perform relatively strong turning operations on both sides of the workpiece, which is absolutely necessary for machining our larger components," explains Martin Frank, who first saw the Turnstacker Premium at a trade show. The concept of the robot cell was convincing. "In particular, the stacking stations for rotationally symmetrical parts seemed most flexible and sensible for our components, which later proved to be absolutely correct."

High workpiece capacity in a small area

The Turnstacker Premium, as an extremely compact robot cell, offers particularly high workpiece capacity on a small area and is designed for parts up to a diameter of 230 mm (approx. 9,1 inches). The automation concept is very simple, especially with the operators of the cell in mind, and is essentially immediately understandable. The rotatable workpiece buffer has a total of 12 adjustable stacking stations. At the start of production, 11 stations are equipped with raw parts, while the last station is reserved for depositing the first finished parts.

Lifting devices facilitate parts handling

A special feature of the robot cell is two lifting devices monitored by laser sensors at a specific pick-up and deposit position of the workpiece buffer. At the pick-up position, the lifting device positions the raw parts so that the robot can take the first top workpiece with its gripper. For depositing the machined parts in the respectively designated stacking station, the lifting device at the deposit position lowers the finished parts accordingly until the station is completely filled with components. The robot uses a dual gripper for workpiece handling, allowing it to remove a finished part from the machine and immediately supply the machine with a raw part. While the robot continuously loads and unloads the machine, an operator can simultaneously remove finished parts from the secured backside of the cell and restock the workpiece buffer with new raw parts.

Process reliability is the top priority

Frank Verzahnungstechnik uses automation to process workpieces up to a diameter of 200 mm (approx. 7,8 inches) and a height of up to 40 mm (approx. 1,6 inches). For smaller diameters, the workpiece height can also be 80 to 90 mm (approx. 3,1 to 3,5 inches). According to Martin Frank, the dimensions of the workpieces change every two to three days, requiring the cell to be retrofitted, which typically takes only a short time. Work is done in two shifts. The day shifts are mainly reserved for the production of more complex components, with the robot, depending on the workpiece and batch size, which ranges from hundreds to several thousand pieces, sometimes able to autonomously load and unload the lathe for up to two hours. "The materials of our gear parts are mostly very abrasive. Therefore, the manufacturing process must be cyclically monitored by an employee to, for example, timely change a cutting plate or adjust a dimension. Certainly, every machine manufacturer has its own monitoring concepts, such as for tool life or tool breakage, etc. These are standard processes that we also run, of course. However, we are specifically operating in a quality environment with very high demands, where monitoring wear limits alone is not sufficient, and this is exactly where our employees come into play for process control."

Frank Verzahnungstechnik deliberately shifts the production of simpler components to a third unmanned shift. To this end, before the end of the second shift, the machine and the Turnstacker Premium are prepared for fully automated production throughout the night. About a year ago, Frank Verzahnungstechnik further expanded the production capacities in the turning shop, including modernization with a turning center CLX 450 V6 from DMG Mori, also equipped with a main and counter spindle.

Repeated decision for a proven solution

Due to the highly positive experiences with the first robot cell from Halter CNC Automation, it was already determined in advance to automate this machine as well with a Turnstacker Premium. "The new machine, together with the robot cell, gives us the same capabilities as the system we have had since 2017. This allows us to achieve a certain redundancy on various levels because we can pursue the same manufacturing concept with both solutions and produce the same components. This has once again significantly increased our flexibility in turning part production, enabling us to make the best possible use of production resources in the interests of our customers and thus respond even faster," concludes Martin Frank.

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