Digital & real: Wheel-hub production 4.0

FRÖHLICH CNC Produktion GmbH, based in Kürnbach in Baden- Württemberg, has been machining 1,400 wheel hubs per day for the com­mercial vehicles industry almost com­pletely automatically in three-shift operation for no less than 16 months now. The turning, drilling and milling work is performed by 4-axis lathes from PITTLER T&S GmbH. Expansion of the highly efficient production facility for wheel hubs and discs is part of the DVS company strategy and is to be carried out in close cooperation with further OEMs and suppliers to the ve­hicle industry.

 

At FRÖHLICH CNC Produktion, digitalisation primarily me­ans intelligent communication between all objects within the logistics chain, via which the correct and efficient production workflow is ensured. Components must get to the suitable machine, raw parts be machined according to parts specifications and correctly transported and stored. The intelligent communication takes place via RFID chips which can be used to save, read out or modify the relevant component in­formation. The advantage of RFID techno­logy is that the chips are written and read out magnetically and are scarcely affected by soiling. Dot matrix markings directly on the workpiece are not possible yet on account of the rough surface of the blank cast parts.

 

From the raw part to the finished product

The raw parts run through production on specially developed and water-resistant aluminium pallets which they only leave during machining and for the measuring process. Each pallet has an RFID chip which is used to identify the components on the pallet. Control and logistics are taken over by the central computer, which receives material requests from the production islands. Two PITTLER PV 400 machining centres make up one production island. The main com­puter transmits the requests to the dri­verless transport system, forklifts without drivers, also known as AGV (automated guided vehicles), which carry out the ne­cessary transport jobs independently and supply material to the production islands from the rear. The safety scanner of the AGVs ensures that the transport system initiates an emergency stop immediately if there are any obstacles or people in the vi­cinity. When the person moves away or the obstacle is removed, the fully automated lift truck continues its work, always in close cooperation with the master computer. At the beginning of the logistics chain there is a flow rack which is filled automa­tically with pallets of raw parts from one side by an AGV. There is a reading but­ton integrated in the fork of the AGV via which it can read the information about the pallet stored on the RFID chip and can thus store them in the prescribed rack slots. The rack slots have been designed in such a way that a complete night shift can be supplied via a raw parts buffer and suf­ficient finished parts can be stored to the same extent. The manufacturing cells request the raw parts pallets via the central computer. The plausibility of the order is checked during removal from the rack on the basis of the information stored on the RFID chip. Only one order each is taken over per AVG, whereby one is responsible for picking up the finished parts and another for supply­ing the raw parts.

 

The raw parts of the wheel hubs are ma­chined highly efficiently at FRÖHLICH CNC Produktion using 16 specially developed PITTLER four-axis la­thes. Pairs of machines are connected to a machining centre via a robot and carry out the first and second operating step (OP 10, OP 20). “Our leading quality standard in the ma­chining of complex components is main­ly due to our fine tuned combination of high-capacity tool systems, modern clam­ping systems and the efficient 4-axis ma­chining on PITTLER machines,” says Sven Fröhlich, managing director at FRÖHLICH CNC Produktion GmbH.

 

Different work pieces are not an obstacle

More than 20 different types of wheel hub can be produced on all the systems thanks to very short retooling times. The resulting conversion work does not affect the automation, because the robot grip­pers in the machining centres only have to be adapted to the different heights of the wheel hub types. When the machining in the manufacturing cell has been finished, the machine sends a request to the central computer for the finished parts pallet to be removed. As soon as an AGV has collected the finished parts pallet, a new raw parts pallet is requested.

 

While the next order is being processed in the machine, the finished parts pallet is transported to the measuring, washing and laser marking system. Following brief pre-washing, the pallets enter the PLC check, where every machined component undergoes a 100% visual inspection. Axial run-out, diameter and the mean depth of roughness are measured and then lasered directly onto the workpiece together with the production data from the RFID chip in the form of a dot matrix code. This means the customer can track every wheel hub and read out all the relevant manufactu­ring data for years to come.

 

Reliable and Just-in-Sequence

In the final step, the components are rou­ted through a specially developed three-chamber wash plant on the aluminium pallet and cleaned according to customer specifications. Once again, collection by the AGV system is fully automatic and con­trolled by the central computer. Following the cool-down process, the individual components are subjected to a final visual inspection and then packed on the custo­mer pallets. FRÖHLICH CNC Produktion delivers the parts just-in-sequence, in other words directly to the assembly line at the truck manufactur­ers. “Thanks to the corresponding produc­tion lead time and sufficient stocks of raw parts, we can meet these requirements reliably and safely,” Sven Fröhlich adds. “In addition, we have a reliable supplier of cast parts who can meet the high de­mands made on material and processing,” he continues.

 

The great potential of the digitalised pro­duction of vehicle components is demons­trated by FRÖHLICH CNC Produktion. The high degree of automation and the networked world of production have not only made the com­pany more competitive, they have turned it into one of the leading manufacturing companies for truck wheel hubs and discs in Germany. As part of the DVS company strategy, FRÖHLICH CNC Produktion is set to expand further and is on the lookout for further partners who wish to benefit from short transport paths, low unit prices and top manufactu­ring quality.