Streamlined automation of high-precision production 

Anyone who, like Frank Verzahnungstechnik e.K., decides to invest in a HALTER CNC Automation robot cell multiple times within just a few years — as a highly specialized contract manufacturer — must have good reasons for doing so. A case study on a well-thought-out strategy.

Frank Verzahnungstechnik e.K., based in Wehr (Baden-Württemberg), about 30 kilometers east of Basel, is a specialist in the production of high-precision gears for complex drive technology. “With 20 employees, we manufacture transmission components such as gears, pinion shafts, and worm drives for general mechanical engineering,” explains owner Martin Frank.
Accordingly, the company serves a wide range of industries — including packaging, hydraulics, robotics and handling systems, cleanroom and vacuum technology, medical technology, and the food industry, to name just a few.

Extremely high level of vertical integration
All products are manufactured exclusively according to customer specifications. As Martin Frank explains, the company’s level of vertical integration is exceptionally high: “Our services cover everything — from purchasing raw materials to all machining processes, including the most complex grinding operations, all the way to the finished product. We produce both individual parts and batches, ranging from quantities of 5 to larger series of up to 5,000 pieces. Since we essentially manufacture custom parts tailored to the customer and the product, we are anything but a typical mass production operation. That’s why our production setup is very diverse — for example, you’ll hardly find any identical machines on the shop floor.”

Given the batch sizes we produce, a high level of automation is one of
Frank Verzahnungstechnik’s key strengths.
“We start using automation from batch sizes as low as 50,” says Martin Frank. “This allows us to respond very quickly and flexibly, even with relatively small quantities — and to manufacture in a highly cost-effective way. Compared to other contract manufacturers, that’s undoubtedly a clear competitive advantage.”

Automated production of larger workpieces
And this was a key reason why, in 2017, the company invested for the first time in a TurnStacker Premium robot cell from HALTER CNC Automation — to automate the loading and unloading of a lathe.

Although Frank Verzahnungstechnik had already implemented some partial automation solutions — for example, bar feeders on lathes — the dimensions of the workpieces to be machined far exceeded the typical limits of bar automation, which generally handles diameters of only around 60 to 65 mm. As a result, larger batch sizes and parts with diameters of up to 210 mm were machined on vertical lathes, using solutions such as rotary indexing tables with limited workpiece capacity.

A convincing robotics concept
“With those earlier setups, only one-sided machining was possible. But what we really wanted was to enable automated two-sided machining in our turning department,” explains Martin Frank.
“For larger components, this can be done either with a flipping station and two machines — or with a robot that loads a horizontal lathe. In our case, we used a CTX beta 800 from DMG Mori, equipped with a main and counter spindle that offer identical performance. This allows us to carry out relatively heavy turning operations on both sides of the workpiece — which is absolutely essential for machining our larger components.”

Martin Frank first saw the TurnStacker Premium at a trade fair, and the robot cell’s concept won him over.
“The stack stations for rotationally symmetrical parts seemed, at the time, to be the most flexible and suitable solution for our components — and in hindsight, that turned out to be absolutely right.”

High Workpiece Capacity in a compact footprint
The TurnStacker Premium is an extremely compact robot cell that offers particularly high workpiece capacity within a small footprint. It is designed for parts with diameters of up to 230 mm. The automation concept is remarkably user-friendly — especially from the operator’s perspective — and is intuitive to understand right from the start.

The rotating workpiece buffer features a total of 12 adjustable stacking stations. At the start of production, 11 stations are loaded with raw parts, while the final station is reserved for placing the first finished components.

Lifting devices simplify part handling
A distinctive feature of the robot cell is the presence of two lifting devices, monitored by laser sensors, located at specific pick-up and drop-off positions on the workpiece buffer. At the pick-up position, the lifting device raises the raw parts so that the robot can grab the topmost workpiece with its gripper. For placing the machined parts into the designated stacking station, the lifting device at the drop-off position gradually lowers the finished components until the station is fully loaded.

The robot uses a double gripper for handling the parts, allowing it to remove a finished part from the machine and immediately load a new raw part. While the robot continuously loads and unloads the machine, an operator can — in parallel with the main processing time — retrieve finished parts and replenish the buffer with new raw materials from the secured rear side of the cell.

Process reliability is the top priority
With the help of automation, Frank Verzahnungstechnik machines workpieces with diameters of up to 200 mm and heights up to 40 mm. For smaller diameters, workpiece heights can reach 80 to 90 mm.
According to Martin Frank, the dimensions of the parts change every two to three days, which means the cell must be reconfigured accordingly — though this usually requires only a short amount of time.

Two-Shift Operation with high demands on quality
The company runs a two-shift operation. Day shifts are primarily reserved for the production of more complex components, during which the robot can autonomously load and unload the lathe for up to two hours — depending on the workpiece and batch size, which typically ranges from a few hundred to several thousand units.

“The materials used in our gear components are usually very abrasive,” explains Martin Frank. “That means the machining process must be regularly monitored by an operator — for example, to replace an insert in time or to make fine dimensional adjustments. Of course, every machine manufacturer offers monitoring solutions, such as for tool life or tool breakage. These standard systems are in use here as well.
But we operate in a high-precision environment with exceptionally strict quality requirements — where monitoring tool wear limits alone is simply not enough. That’s where our employees come in to ensure active process control.” Frank Verzahnungstechnik deliberately shifts the production of simpler components to a third, unmanned shift. To enable this, the machine and the TurnStacker Premium are set up before the end of the second shift to run fully automated throughout the night.

Renewed decision for a proven solution
Around a year ago, Frank Verzahnungstechnik further expanded its turning department’s production capacity — including the modernization of its operations with a CLX 450 V6 turning center from DMG Mori, also equipped with a main and counter spindle.

Based on the extremely positive experience with the first robot cell from HALTER CNC Automation, it was clear from the outset that this machine would also be automated using a TurnStacker Premium..

“The new machine, together with the robot cell, gives us the same capabilities as the system we've been using since 2017,” says Martin Frank in conclusion. “This creates a level of redundancy across multiple areas, as both setups follow the same production concept and can manufacture the same components. As a result, our flexibility in turned parts production has increased significantly. We’re now able to make optimal use of our production resources — and respond to customer needs even more quickly.”.

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