Linear Motion Control - 2011-07-22
Röders GmbH has a good reputation worldwide as a specialist in high-speed cutting (HSC). NSK supplies high-precision linear guides for the company’s RXP series, which was launched six years ago. Since the product range was introduced, the two companies have completed various joint development projects that have significantly optimised the drive technology for high-performance cutting centres. Their aim: to further improve precision during the machining process.
The utmost quality and precision is crucial for tool and mould manufacturing. It is not a question of millimetres – precision here is gauged in micrometres and nanometres. The surface quality of these components – usually produced in batches of one – also has to conform to an exacting set of requirements.
NSK: a development partner for linear technology
Röders GmbH in Soltau, Germany, has established an excellent reputation in this demanding field of metalworking. Röders develops and produces machine tools for high-speed cutting with speeds of up to 75,000 min-1 that are hallmarked by the very highest precision and technical innovations. The company is one of the pioneers in this field and has already garnered over 20 years of experience.
Extraordinarily in-depth development work on both the mechanical construction and the automatic control engineering plays a key role in the machines’ high levels of quality and precision. However, the company relies on intense and timely collaboration with expert suppliers for central drive components.
How it all began: high rigidity as the main parameter
Just such a partnership also gave rise to the RXP series, which is suitable for simultaneous multi-axis cutting operations and features linear drives that are both low-wear and energy-efficient. This drive technology enables the greatest possible precision, speeds and surface qualities. The product range – to which new models are constantly added – is used around the world for countless applications that require precise processing.
When Röders started developing the RXP series six years ago, the designers wanted a roller guiding system with the highest possible rigidity for their machining bench. They initiated a benchmarking process to compare the products offered by relevant suppliers. NSK’s roller guiding system was selected because its rigidity was highest thanks to a special manufacturing process developed by NSK.
Special seal prevents contamination
NSK and Röders recently completed another innovative project focusing on seals. A high-speed cutting centre inevitably produces shavings, so the working area is not necessarily clean. This means that the slides on the roller guiding systems have to be carefully sealed. If foreign matter enters the contact surface between the guiding element and the slides, this can impair precision. The contaminants also accelerate wear and tear.
It is easy enough to cope with these challenges when cutting standard steels if conventional roller guides are used. However, alternative materials are becoming more common and these can cause problems. For example, graphitic steels are often used to manufacture moulds, which generate ultra-fine, highly abrasive dust when they are machined. Röders is also increasingly branching out into the ceramic processing market, e.g. for dental technology. Ceramic cutting residue is also very hard and abrasive. It would cause long-term damage to the linear guides if no preventative action were taken.
Bespoke development for Röders
A combination of two measures provides the solution to this issue. Firstly, Röders developed an effective suction cleaning system. Secondly, special seals are used that NSK developed specifically for Röders using its extensive experience of designing seals.
The new seal is not only highly efficient, but also boasts low friction. This innovative computer-aided design creates a multi-functional seal with two distinct features: the ability to physically push the debris away from the sealed boundries and creating a more precisely refined barrier against foreign matter. The result is a greatly improved clean, closed system within the guiding element for proper lubricant retention which yields longer life and shorter lubrication intervals. The highly effective roller guide seal was constructed at NSK’s Japanese development centre and underwent comprehensive testing. It has now gone into series production – and NSK and Röders are already planning their next joint development projects.