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Innovative products through innovative production

Milling/turning centre enables complete machining of complex pump parts

Herborner Pumpentechnik, a company with a long tradition now spanning more than 140 years, is achieving great success with innovative pumps. The basis for this is provided by equally innovative production equipment, including a fully automated manufacturing system with two machining centres. In particular, the newly installed Heckert HEC 800 HV MT milling/turning centre ensures economical manufacturing costs through reliable complete machining of large and small cast components.

Anyone wishing to succeed as a medium-sized pump manufacturer surrounded by large competitors needs to show they have something special. Innovations are the key to success – in terms of a company’s own products, but also the equipment that is available for development and production. Sascha Korupp, Authorised Representative and Technical Manager of Herborner Pumpentechnik is convinced of this. However, he first points out another success factor: “The employees are particularly important. For example, the willingness of our development department to experiment leads again and again to results that are reflected in the longevity, cost effectiveness and high utility value of our products. Then when the ideas are implemented in production, we are again reliant on employees who know how technically challenging components can be produced economically on modern machines.”

The fact that Herborner Pumpentechnik is well positioned on all of these points is demonstrated by its growing market share and the success of its new products, such as the 100 percent coated pumps, which have been on the market since 2012. What is referred to as the HPC (Herborner Pump Coating) is 500 to 1000 µm thick, extremely smooth and can even level out slight bumps and cavities. “It allowed us to improve the hydraulic efficiency by up to 10 percent”, emphasises Sascha Korupp. “It also offers high corrosion protection and therefore enables the use of grey cast iron components where considerably more expensive stainless steel or bronze elements would otherwise be needed.”

Herborner Pumpentechnik worked its way consistently towards this new development, which required a changeover in production among other things, as the Technical Manager explains: “Our pumps are based on a modular design and consist primarily of the four cast parts pump housing, back panel, impeller and cover. These parts had to have a slightly more complex structure for the coating, meaning that we are reliant on the most advanced equipment when it comes to machining. In addition to this, the pumps requested are getting bigger and bigger, which is another important reason for the investment in a new, larger machining centre.”

Sascha Korupp, Technical Manager with full signing powers at Herborner Pumpentechnik.

Profitability: “As a result of complete machining, machining times can be reduced by up to a third.”

Complete machining of all cast parts

Production Manager Klaus Tollerian explains the requirements in detail: “Because we now produce pumps in sizes up to nominal diameter 400, we need a large enough working area. These parts – whether it be impellers or housings – require turning as well as drilling and milling operations. So everyone feared we would have to invest in a vertical turning lathe and a machining centre.” However, with the Heckert HEC 800 Athletic HV MT milling/turning centre, the team in Herborn found a suitable alternative that combined both capabilities. With its horizontal/vertical milling head and the powerful, directly driven NC rotary table, the horizontal machining centre offers ideal conditions for the complete machining of all cast parts.

Regarding the preliminary benchmark with other machines, Heckert had a prior advantage. Ultimately, Klaus Tollerian and his colleagues already have more than 15 years’ experience with the Chemnitz-based company and its machines. Back then, a Heckert CWK 630 replaced a Japanese milling centre and, over the years, it has impressed with its performance and enormous reliability. Sascha Korupp adds: “Even the cooperation with the Heckert employees was always conducted at a particularly high level. It’s a crucial factor for us that we receive competent and reliable support right from sales to service, and that the response times are fast. At the moment, none of our other machine suppliers can keep up with Heckert on these points, so we feel we are in very good hands with this partner.”

Process reliability and availability — pillars of successful automation

Part of the success strategy of Herborner Pumpentechnik is to continuously optimise the production processes. From an early stage, linking machines and pallet storage units appeared inevitable to the team in order to achieve unmanned night shifts and therefore remain competitive in Germany. So in 2008, the pump manufacturer put a fully automatic Liebherr manufacturing system into operation, which incorporated the two Heckert centres.

“The system has proven its worth in the last eight years”, explains Production Manager Klaus Tollerian. This is largely attributable to the high level of process reliability and availability of the Heckert machining centres, without which reliable automated operation is not possible. “Our new HEC 800 Athletic HV MT, which replaces one of the two integrated CWK 630 machines, will also not disappoint in this regard”, says the machining expert with conviction.

With its robust, thermo-symmetrically designed main assemblies, the digital AC feed drives and complex profile rail guides and ball screws in all linear axes, the machine concept lays a solid foundation for the reliable processes required. It also incorporates various control and monitoring devices. As standard, these include a vibration sensor on the spindle, via which the machining process can be monitored and optimised. Holger Quintus, Regional Sales Manager of the Starrag Group, explains: “The sensor includes evaluation software that detects tools with a very high imbalance, just as it detects wear on the spindle bearings. This allows service work to be planned in advance and sudden failures to be avoided. As it also indicates vibrations during machining, the process can be optimised with regard to higher quality and longer service life of the spindle.”

For Klaus Tollerian, there are other important details: “The working area is designed in such a way that the swarf falls freely into the centrally positioned swarf conveyor. This prevents a build-up of swarf in the working area, which in turn would jeopardise process reliability.” He also takes a positive view of the use of fixed plates instead of telescopic covers to optimally protect the functional elements against swarf and coolant. This enables higher acceleration and rapid traverses, as the plates do not need to be carried along with the linear axes. While the machines of other suppliers could not combine all the benefits of the Heckert HEC 800 Athletic HV MT (or only by using expensive additional services), the complete package of compatibility with the existing machines, performance and cost advantage was a crucial factor in the decision, argues Klaus Tollerian. “Also, we can now manufacture a far broader range of parts on the machine, due to the fact that the machining area is around a third larger than on the CWK 630. This is sufficient right through to the large impellers – our pump sizes now range up to nominal diameter 400 – for which our cycle lathes reach their limits.”

Fast-rotating table and additional axis in the head extend the range of applications

The chosen machine configuration with horizontal/vertical milling head and NC rotary table played a significant part in the success. The HV head has two working positions, horizontal and vertical, into which it can swivel even while the spindle is running, significantly reducing unproductive times. Once the respective end position is reached, the head is locked with a Hirth coupling. The form fit created as a result contributes to high stability, which is particularly important during turning. The additional decoupling of the drive train in rotary mode absorbs any impacts on the housing in the event of interrupted cuts, thus sustainably preserving the spindle bearings. In addition, the HSK-T100 tool holder is used for turning work, enabling precise radial positioning. This means that the high level of accuracy that is expected from Heckert is also guaranteed with turning.

The high-precision NC rotary table with a load-bearing capacity of two tonnes provides another condition for internal machining of the large impellers thanks to its output of 57 kW (at 100 % duty cycle), speed of up to 500 rpm and maximum torque of 2,520 Nm. Holger Quintus points out the automatic unbalance detection that the HEC 800 Athletic features as standard: “An integrated program measures the unbalance and indicates the position and size of the balancing weights required, so that the operator can quickly rectify the unbalance.”

Due to the entire kinematic system of the Heckert HEC 800 Athletic HV MT, the machining team at Herborner Pumpentechnik can now process numerous parts in a single clamping position instead of several as previously required. “This allows us to reduce the machining time by up a third”, says Klaus Tollerian with delight. He is also happy about the fact that the programs available on both of the machines installed in the Liebherr system can be used without any adjustments, and that all the previous components can be machined on the HEC 800 Athletic HV MT without any problems.

To create the conditions for this, the team did not have the normal machine table installed on the new HEC 800 Athletic HV MT, but a modified table of size 630 × 630 mm. Another special feature is the automatic loading hatch in the roof of the machine, through which oversized workpieces can be loaded easily. The Production Manager also mentions another plus point: the tool magazine with 180 slots that can automatically accommodate tools of up to 340 mm in diameter and up to 800 mm in length. “Despite the extended range of applications, this capacity is sufficient for all tasks. There is even enough room left for sister tools.” In spite of its large capacity, the tool magazine has a small footprint compared to other solutions on the market, which is a key argument in cases where space is confined.

Conclusion

By investing in a Heckert HEC 800 HV MT milling/turning centre, Herborner Pumpentechnik extended the capabilities of its linked manufacturing system, which includes a Heckert CWK 630 as a second machining centre. Thanks to their high process reliability and availability, both machines guarantee reliable automated operation, even during unmanned night shifts. With its large working area, the horizontal/vertical milling head and the fast-rotating machine table, the HEC 800 HV MT creates the ideal conditions for drilling, milling and turning large and small cast parts. As a result of complete machining, machining times can be reduced by up to a third. 

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