Gebr. Heller Maschinenfabrik specialises in CNC machine tools and manufacturing systems for machining. As part of an optimisation project, the company's own production is being made so efficient that the high level of vertical integration, including in-house production, continues to pay off. One component of the project was the introduction of an SAP-integrated MES system.

"HELLER machines manufacture HELLER machines"

This is the guiding principle behind the CNC machine tools and manufacturing systems produced by the medium-sized family business Heller. The company is one of the leading manufacturers in this segment and employs around 2,580 people worldwide. The product range includes 4- and 5-axis machining centres, milling-turning centres, machines for crankshaft and camshaft machining, flexible manufacturing systems and a modular range of services.

"Like any modern company, Heller wants to constantly develop and improve internal processes," says Christian Kurtenbach, Project Manager at Heller. At some point, the question arose as to whether the high level of vertical integration could be maintained in the future - or whether the guiding principle might have to be reformulated. The discussion "in-house production or external production" raised the question of which parts the manufacturer could possibly buy in externally without jeopardising the high precision that customers value so highly in Heller machines. If only development and assembly were to be carried out in-house, but the parts required for production were to be bought in, there would be a risk of compromises.

The project was therefore launched as part of the "Fokus Heller" (Continuous Improvement) programme. The aim is to make the production area so efficient that in-house production continues to pay off. One of the first decisions made by Christian Kurtenbach, who was entrusted with managing the project, was to install a manufacturing execution system (MES). The requirement for the potential supplier of the MES was that the system should be able to be linked to the SAP system already in use and be easily implemented at all of the machine tool specialists' production sites. Other components of "Fokus Heller" are systems for APS (Advanced Planning and Scheduling System), TLM (Tool Life Cycle System) and 3D CAM.

Less Paper, More Speed

"One of the aims of the MES was to replace the previous paper-based processes in production with electronically controlled workflows," explains Kurtenbach. Thanks to the MES, workers interact directly at the machine with a terminal that immediately transmits all entries to the SAP system behind it. This reduces the susceptibility to errors by eliminating the need to transfer information recorded on paper, such as working time, machine time or the number of workpieces produced, to the IT system. And, of course, the speed of production and transparency also increase: machines that are linked to an MES can immediately transmit information such as the tool currently in use or the reason for any downtime to a control centre or the tablet of the responsible worker.

The project managers at Heller decided in favour of the production control system from Infotec AG. One of the points in favour of this solution was that it is integrated into SAP. This has the advantage that the data does not have to be saved twice - once in the SAP system and once in the MES - and then synchronised via interfaces, which is time-consuming. Especially as there is always the question of which data store can supply the current or precise data when analyses are being carried out. The more data you want to link together, for example working time data from SAP HCM or material data from SAP ERP, the more complicated this exchange becomes. At Infotec, on the other hand, the data flows directly from the machines in production to the SAP system. There, productivity can be measured or a comparison can be made between planned and actual hours worked. The planned data comes from SAP ERP, while the actual data, such as machine times, rejects or material used, comes directly from the machines. If something needs to be changed in the master data, for example information on certain components, this only needs to be done in one place thanks to SAP integration. The MES automatically receives the current data from the ERP. Ultimately, the MES connects the factory level with the SAP level.

After just a short time, it became clear how successful the introduction of the production control system was: "The production result at the main site in Nürtingen increased by an average of ten to twenty per cent," summarises project manager Christian Kurtenbach. One of the reasons for this is the higher motivation of the workers: as the Infotec solution displays all important data clearly, the employees regularly take a look at the displays and see their own performance level as well as the downtimes and running times of the machines. This created a friendly competition that quickly made the improvements brought about by the MES visible. The production control system also minimises the risk of a worker, for example, wanting to install a set-up unit in the machine he is looking after that is not suitable for the job in hand.

Customisation is a Must

After completing an order, the worker reports back the details of the order - digitally, no longer on paper. This means that details such as quantity good, rework quantity or inspection characteristics flow directly into the ERP system, where they serve as the basis for analyses. The status of a machine, the booking status of workers and foremen, faults that have occurred or an order evaluation can be recorded at a glance. The commissioning of the MES, including the machine connection, was completed quickly. The reason: Heller found sufficient mechanical engineering expertise at Infotec AG to be able to provide the IGH project team with a processing machine. Thanks to this loan, the developers were able to configure and thoroughly test the necessary interfaces between the MES and the respective production machine in advance. As the machines in each production plant are virtually customised, the interfaces have to be adapted precisely each time. There are no standardised communication protocols for machine control at factory level. The MES must therefore mediate between the S7 protocol, Open Modbus or OPC UA (Open Platform Communications United Architecture) and SAP.

Do Not Overload Machines

In the meantime, the loaned machine is available to Infotec's developers on a long-term basis. In addition, an agreement was concluded with Heller to ensure that the latest control components are always available in the test processing machine. This enables the Infotec developers to connect the HELLER machines precisely. In principle, this connection is a new challenge for every project. Especially with models whose control components are older - the oldest of the 70 or so machines used at Heller date back to 1980 - and do not communicate via OPC (Open Platform Communications) or OPC UA, for example. But even in such cases, the machine can be connected to Infotec's MES. In the case of an OPC UA-capable machine, for example Sinumerik, only one or two developer days are required to connect the respective model to the MES solution. Extensive testing is essential before the actual commissioning. Thanks to the loan, it was possible to carry out these tests. For example, it is important to determine the extent to which the MES can request data from the machine. If the request rate is too high, the machine may come to its knees or slow down its processes in order to fulfil the MES requests. The machine's Linux-based control system sets the priority of the interface to the MES so high for queries at millisecond intervals that the priority of the axis control system slips down and it comes to a standstill. Only in the laboratory is it possible to find out where the respective limits are for each model.

"We at HELLER are convinced by the Infotec solution," says Christian Kurtenbach. This has resulted in the company working together with its suppliers and Infotec to design interfaces for Heller machine customers. The aim is to achieve a simpler link between the machines and MES solutions, without which no production company will be able to manage in future.