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Task:
At KTS Technologiepark Stahl, sheet metal parts of different thicknesses are cut. As the workpieces are very heavy and there is also a shortage of staff, KTS needed an automated solution.

Solution:
Together with the system integrator Essert Robotics, the automated solution was implemented with a FANUC R-2000 robot. The milling machine is now designed in such a way that the robot takes over the series, but manual loading for a single piece is still possible.

Result:
The employees are now relieved thanks to this solution. The FANUC R-2000iC/210F robot not only has the required load capacity, but also a reach of 2655 mm. The robot already has the hardware of the vision system integrated, making it easy to integrate image processing with a camera into the robot cell.

FANUC products used

KTS Technologiepark Stahl 

When Mario Koch and his father Josef were making plans to launch KTS Technologiepark Stahl back in 2010, they had to make a decision: thick plate or thin sheet. The reorganisation of a company in the Bruchsal area provided for the disposal of one of two sheet metal divisions. Since Josef Koch had previously produced HGV trailers and parts for this company, his decision favoured thick plate. With five employees, the Kochs threw themselves into plasma cutting and oxy-fuel machining. After deliberately choosing the company name ‘Technologiepark Stahl’ (Steel Technology Park), the concept from the outset was to offer the entire steel processing chain in-house at its 90,000 m² premises. 

"The idea of locating other companies here that either work for us - or that we can work for - is not yet off the table," says Mario Koch, the managing partner. KTS concentrates on structural steels and fine-grained steels. The company can process unit weights up to 20 tonne in its recently built production hall, offering a complete process chain through to the finished painted part. A special feature highlights the customer-oriented ethos of KTS: an online shop allows customers to place direct orders for both laser and flame-cut parts measuring between 1 and 200 mm thick.

Since its investment last year in a laser-cutting system, KTS has also been taking on the processing of thinner sheet. 

"We usually only cut steel thicker than 6 mm," says Mario Koch. And in huge dimensions: it is possible to cut panels measuring 2,500 x 9,000 mm on the company’s laser system. "This puts us far ahead of our competitors,” he adds. “I don't know of many plants with bigger capacity."

Milling complements cutting

So how is it possible to expand the range of products offered by a steel plate/sheet processor? Well, by extending the process chain. Consequently, in 2011, the first milling machine arrived at KTS: "We wanted to see whether our customers would let us undertake this additional machining and thus add value," says the company boss.  “A growing number of customers were beginning to appreciate the principle of everything from a single source.”

The original plan was to use the machine in single-shift operation for simple parts. However, it ran for nine years in multi-shift operation before its ultimate replacement with a new machine.
Conversations began on how best to feed the new milling machine. Heavy workpieces and staff shortages solidified the idea of an automated solution during planning discussions with system integrator ESSERT Robotics of Ubstadt-Weiher. Analysis of the existing component portfolio did the rest. Koch summarises the considerations: "In total, we have about 15 components that utilise the machine non-stop across two shifts." Of two possible solutions, the preferred choice was feeding the machine with a FANUC robot. The team rejected a solution involving a pallet changer and one clamping device per component for cost reasons and due to a lack of flexibility. At KTS, the new milling machine sees the robot take control of series production, although manual feeding for 1-off parts is still possible. For this purpose, the robot moves to a parking position (the same position used during maintenance work), ensuring no interruption to manufacturing.

Workers load the cell by positioning pre-prepared pallets on marked parking spaces with a pallet truck. A 3D camera scans the parts on the pallet and thus provides information for the gripping process. Although the height of the stacks for flat workpieces is irrelevant, the parts must not protrude from the pallet nor be so close together that they prevent the camera from capturing a clear image. The respective main points of the parts are stored in the machining program.
Two special features are crucial for precise insertion into the milling machine: a mechanical chute and the ‘Soft Float’ software option from FANUC. Initially, the aim was to load components directly from the pallet into the machine's clamping devices. Under certain circumstances, however, component tolerances result in angular errors when gripping the parts, "which can be fatal for precise insertion", states Robin Häfner, project manager at ESSERT Robotics. For fine adjustment, the robot places the respective part on a simple slide before it descends into an exactly traceable position due to the slope.
An alternative proposal was the use of insert prisms within the machine, although the need for a mechanical aid for every component meant they would be too expensive in the long run. Originally, no slide was planned either. However, since it is not always possible to ensure the insertion accuracy of the clamping elements via the camera alone, a mechanical chute was the only possible solution. In this way, the robot grips individual components in a defined manner before inserting them into the work-holding equipment without any risk of damaging the clamping elements. This is where ‘Soft Float’ comes in.

KTS knows how to deal with tolerances. Flame-cut parts or components pre-fabricated on a bending press have a tolerance of ±1 to ±2 mm. The robot benefits from the gentle software assistance when it inserts the workpiece into the milling machine’s clamping device. Once the R-2000iC has accurately gripped the part on the chute, it travels the final millimetres in the machine at reduced speed. Either it reaches its deposit position or ‘Soft Float’ corrects it, whereby the robot’s motor current is the controlled variable.

Perfect timing for the robot

Cycle times are in the range of minutes; sufficient for the robot to safely prepare for inserting the next component. "The seconds that the robot needs for insertion are negligible and we save ourselves a lot of mechanical effort," confirms Koch. And do not forget the set-up time saved when changing a component. On this subject, two electro-permanent magnetic grippers are available for different-sized components that operatives can change manually if required. A gripper station for an automatic changeover is a further consideration under review.

The milling cell has two storage spaces for pallets with un-machined parts and two pallet storage spaces with finished components. "Depending on the machining time, we can work almost three shifts autonomously," says Koch. Even for workpieces with relatively short cycle times, the supply is enough for eight hours.
KTS creates milling programs for new components at a dedicated programming station before loading into the machine via the network. Whether the associated robot program is also created at a programming station and loaded into the robot controller via a data carrier, or created directly at the cell via a teach pendant, depends on the preference of the setter. Says Häfner: "Some prefer to create the program on a notebook; others choose to observe the robot while programming."

Häfner is used to working with FANUC solutions: "We collaborate with FANUC frequently as they appreciate the smooth co-operation in project planning and service. For the task at KTS, the selected R-2000iC/210F robot not only has the required carrying capacity, but a reach of 2,655 mm. In addition - and this is of particular interest to Häfner - the vision system hardware is already integrated in the robot controller as standard, while image processing with a camera can integrate easily into the robot cell via ‘Vision Connection’."

In everyday operation, KTS uses a tablet with a 10" screen to observe and manage the cell. All information is bundled into a PLC and processed for visualisation. "For us, this is a proven standard structure,” says Häfner. The tablet’s monitor displays the cell in 3D, and always with a customer-specific user interface. It is possible to call up current information about job progress and - very importantly - the cause of a possible stoppage. 
Customer cases

However, Koch appreciates far more than the bundling of operational data: "We had no experience with robots, so it was very important to make the cell easy to operate. We have achieved this because the design of the customised interfaces is such that even employees without programming knowledge can ‘drive’ the cell.” His conclusion: "The whole project has been visualised very well."