High expectations from regular customers are part of everyday life for Starrag from Switzerland. This order was no different: The KSB factory in Pegnitz ordered a high-performance vertical turning lathe which allows very fast, precise and efficient machining of pump housings weighing up to 3 tonnes in one clamping operation, even when the materials are difficult to work.
"Our business is characterised by very short delivery times", explains Fritz Suttner, a member of the production technology department at KSB AG in Pegnitz (near Nuremberg). "We place value on tight production structures, through which we can carry out processing very quickly and with very low dwell times." This concerns the production of large pump housings up to 3 tonnes in weight created for the power and chemical industries among others. These are custom-made in batch sizes 1 to 2 from corrosion- and acid-proof stainless steel as well as heat-resistant special ferrous alloys. Pegnitz plays a special role within the KSB Group because the plant has its own foundry for producing special alloys. This makes it possible to produce tailor-made materials, used for example when deploying pumps for smoke desulphurisation, which are resistant to corrosion, aggressive media and abrasion.
The previous production method had been difficult for the firm from Upper Franconia. "We used to turn first the front and then the rear side in two clamping operations, then the drilling was carried out using another machine", explains Suttner. "This naturally led to long throughput times with many interruptions and dwell periods." Now everything takes place in one process on a compact Dörries CONTUMAT VCE 2800/220 MC single column vertical lathe (swing diameter: 2,800 mm) from Starrag. The vertical turning lathe performs turning, drilling and cutting in a single clamping operation.
In addition to the complete machining, being able to program on the machine was important to KSB. Until now, a programming office has been writing around 4,000 programs a year in Exapt, which can be inserted directly into the machines after post-processing with DNC. Cast raw parts are also processed with a wide variety of stock contours. "We don't need to go back to the NC programs being created by the programming office. Instead they are created on site because of the variety of contours", explains the production technician. "The operator inserts the component, aligns it, inserts the appropriate tool and enters the machining cycles directly into the 840 D sl controller." Machine operators receive the necessary training in a custom programming extension course "P2" at the Starrag location in Mönchengladbach.
One machine doing the work of three
Dörries CONTUMAT vertical turning lathe: Use in KSB pump production
The new option for workshop-oriented programming with Siemens Operate, which represented a new direction for KSB with Starrag, has also proven its worth in post processing. This isn’t the only reason why the production expert calls the Dörries CONTUMAT a multi-functional machine concept that can machine even large, hard-to-work components with low vibration through its rigid cast construction and hydrostatic guides. The low vibration has proven itself in particular with the process-secure manufacturing of very precise workpieces, made to the exacting IT6 tolerance standards.
Suttner and his team are especially satisfied with the complete processing of many typical pump components (housings), since even the machining process of these workpieces can be monitored by the machine operator thanks to investment in an integrated image processing system. "The camera was expensive, but the investment has paid off", he comments on the extra feature. "On our components, most of the machining work is done on the inner contour. There would have been little opportunity to observe the process in a completely enclosed machine otherwise."
The alignment enables another special feature: The machine can also be run in operating mode 5, which allows the workpiece to be aligned with the door open when the table is turning at a low speed, guaranteeing safety of work. To improve ergonomics and employee motivation, KSB also had power chuck cylinders installed, which make life easier for workers. Now the clamping plates can be opened and closed easily with a small torque spanner. KSB also integrated a special suction cup whose high suction power allows even heavy chips, damp with coolant, to be reliably removed.
So there are many equipment details which KSB value in a vertical turning lathe. But, all in all, does the machine reflect the Starrag claim "Engineering precisely what you value"? Has the customer, KSB, received exactly what they need and what is important to them? "Yes, as in our investment planning we have defined a marked increase in productivity", says the production technician. "It is becoming clear that this requirement has been met." The vertical turning lathe has also met another demand from the specification: It has a far smaller footprint, since it replaces two to three conventional machines. He also praises the commissioning competence in particular. Suttner: "Starrag impress with their meticulous approach."
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