Studer combines grinding and hard turning

With the Studer S242, which combines grinding and hard turning, the Kleinhenz company has reduced operating times by up to 50 per cent.

Bernd Kleinhenz, managing director, is responsible for all technical aspects of the company.

He describes his company as a classic job shop, focusing on turning operations.

It also manufactures and sells its own product, a flow rectifier for monitoring cooling circuits, but the lion's share of turnover comes from job order production.

Kleinhenz supplies the automotive industry in the fields of sample production and prototype building, and has customers in medical technology and other industries.

Its mainstay is toolmaking for plastic injection moulding.

Kleinhenz's strongest growth in the last few years has been in tools for PET bottles.

Since 1980, as founding supplier, the company has supplied the market with components that are used for the injection moulding of so-called pre-forms.

These plastic components look like test tubes with pre-formed bottle necks.

Before filling, they are blown up into their final bottle shape on special blow-moulding machines.

The Kleinhenz company has considerable production expertise and a modern equipment fleet, which is designed for efficient precision machining.

Besides the strongest area - that of lathes - milling and grinding machines are the pillars of the job shop.

Bernd Kleinhenz sees the boundaries between the various technologies increasingly merging.

'Our equipment fleet includes lathes with powered tools for executing milling and drilling operations that are able to manufacture complex components in a single work cycle,' he said.

'In addition, both milling machines and grinding machines are able to perform turning operations.' Kleinhenz has ultimately realised this chain of ideas and openness to new developments in its latest investment - a Studer S242.

Harald Ernst, grinding and hard turning foreman, was looking for a machine that would enable him to take the increasing deadline pressure off his department.

He said: 'Hard turning has replaced many grinding operations in the last few years, thus reducing operating times.

'Nevertheless, hard turning cannot be reliably used to produce certain components.

'Additional grinding is required in these cases, which made reclamping necessary in the past.

'We wanted to be able to completely machine these parts on one machine - that was our fundamental aim.' The Friedrichsdorf machining professionals were made aware of the new Studer S242 by the Studer dealer in the province of Hessen, Sudler Werkzeugmaschinen, located in Kelkheim.

With the S242, Studer has created a machine that enables high-capacity grinding and hard turning in a single clamping.

To this end, the Swiss grinding specialists developed a machine concept that offers ideal conditions for both processes.

Stable tool holding fixtures, a large workhead spindle rpm range and vibration-resistant workpiece clamping systems are available for hard turning.

To ensure the necessary free chip fall, the machine bed has an inclined construction.

A scraper-chain conveyor ensures reliable removal of the turning chips.

High-performance grinding spindles are available, as well as a device for balancing, dressing tools, in-process gauging, a device for fine cylindricity adjustment and efficient coolant systems.

The grinding sludge lands on a paper band filter, which separates the fine grinding chips from the coolant.

In the case of the S242, modularity means that it is available as a short or a long machine.

In the short version, the distance between centres is 400mm, and 1000mm in the long version.

It is available as a chucking machine, but it can also be configured as a shaft machine with tailstock.

Depending on the version, the S242 can be equipped with two or three cross slides.

These slides can be used in a variety of ways - with a wheel head for external grinding, an internal grinding attachment or a turret with 12 tool positions.

Kleinhenz decided on the long S242 with two slides, external grinding spindle and turret.

Harald Ernst said: 'The typical workpieces for this machine are chucking components with cross bores and multi-edged surfaces, which require interrupted cut machining.

'Most of the parts are made of difficult-to-machine materials and also have an inner contour that is often conical or contains tangentially converging radii.

'This would be very expensive to manufacture with grinding and must therefore be hard turned.' Production reliability is of the utmost importance for Kleinhenz.

By the time the components reach the machine, they are already pre-machined and expensive.

Precision also plays an important role since the tolerances are under 5um.

'Depending on the part, we achieve a reduction in operating time of between 30 and 50 per cent with the S242,' said Ernst.

The machine, which has now been in production at Kleinhenz for around six months, is nowhere near pushed to the limit yet.

The chief executive officer remarks that they are still in the process of discovering the full potential.

After one week of training, using the S242 was no problem for the operators at Kleinhenz.

The control system - a Fanuc CNC series 310i model A - and the Studerwin user interface in particular make it easy for the user.

Grinding operations can be programmed with the help of self-explanatory pictograms.

Fanuc cycles and ISO programming are available for turning.

Whenever questions arose about the machine, it was possible to resolve these by phone at any time.

The effort needed for setup and changeover is considered small.

'For us, mainly dealing with small-batch and mid-volume production, the Studer S242 is the best solution,' said Bernd Kleinhenz.

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