Harmonized axes

Marginal Column

March 2014

 

By manufacturing its fittings entirely on rotary table systems equipped with Rexroth CNC controls, Seppelfricke has reduced production cycles by up to 84 percent.

 
 

Seppelfricke Armaturen GmbH has about 7,000 items in its program, ranging from faucets and fittings to intelligent actuators. Like every other plumbing manufacturer, the company in Gelsenkirchen, Germany, faces some tough challenges when producing these goods. Even though sales markets have become ever larger, pressure from competitors has grown enormously at the same time. To be able to manufacture high-quality products economically and quickly in the future, Seppelfricke decided to completely modernize its machine concept.

This fittings specialist now manufactures numerous components – from start to finish – on two rotary table systems supplied by Italian machine constructors BTB Transfer. The Rexroth CNC and drive technology were adopted to control the axes. These machines excel with their short cycle times, high precision, repetition accuracy, and easy operation. The highlight is a carousel with ten workstations for turning and milling. Seppelfricke uses this to process blanks that the company produces in its own press department.

One machine – 400 products

“While in the past we were forced to manufacture complicated components on up to three different machines, we can now perform all the milling, drilling and turning operations on a single machine,” is how plant manager Uwe Schölich explains the new concept. This machine permits manufacturing of more than 400 different items. A uniform production concept and short cycle times are especially important aspects, since the unit can thus machine products in parallel, at multiple workstations. This is why the rotary table system has at its disposal a large number of processing shafts, for which several CNC controls are required: a master control unit and up to three slave controls. The greatest challenge was to develop a common operating interface for the CNC controls – up to four in number – and also to safeguard communications between the controls themselves.

Left: Uwe Schölich, plant manager at Seppelfricke Armaturen GmbH, is enthusiastic about shorter cycle times and greater productivity. Right: Simple and intuitive operation with the IndraMotion MTX

 

Fast and efficient

To achieve all this, BTB Transfer used three Rexroth IndraMotion MTX controls. The performance of each individual CNC makes it possible to control up to 64 axes, irrespective of whether turning, drilling or milling operations are involved. “We can start off by tapping a thread and then perform a milling operation at the next workstation. Doing all the manufacturing on a single machine shortens cycle times by up to 84 percent in comparison to earlier machines,” says Schölich.

Rexroth’s modular IndraDrive M drive system, combined with high-performance IndraDyn servomotors, ensures that all the shafts move precisely. Inverters with energy recovery features and regulated intermediate circuits guarantee efficient energy use. This means that the energy generated when a motor is braked is converted into electricity and fed back into the grid.

Seppelfricke uses Rexroth PC simulation firstly to program its rotating table and secondly to make it much easier to prepare NC programs offline, in preparation for component production. “We no longer need to do this right at the machine; that means a substantial reduction in machine stoppages thanks to faster changing from one part to the next,” enthuses Schölich.

As a result of its favorable experiences with the rotary table system, Seppelfricke has now also performed a retrofitting operation on an existing machine. Uwe Schölich: “Again, we used Rexroth components to this. We will be installing the IndraMotion MTX drive system as a standard item on future new investments.