SKF, the knowledge engineering company, has developed a performance bearing arrangement that forms the heart of a new generation of machine tool spindles. These have been designed by Vigel S.p.A., the leading Italian manufacturer of advanced CNC (Computer Numerically Controlled) machining centers, and are a key step in the company’s program of improving still further the performance, accuracy and functionality of its machine tools.
Founded in 1947, Vigel is a leading international company in designing and manufacturing technologies. It has a worldwide presence, in order to provide close proximity to its customers, with production plants in Torino, Italy, and Pune, India, and sales and service subsidiaries in the United States (U.S.), Mexico and China. Vigel multi-spindle machining centers are sold to customers in a number of industrial sectors around the world, in particular automotive, where they are used either as stand-alone or integrated in-line systems, for the production of parts such as powertrain, chassis, transmission and brake components.
Daniele Francesia Villa, Standard Products Development Manager at Vigel, explains that, “Over the years, we have built a strong reputation for the quality, performance and reliability of our machining centers. We work closely with each customer, engineering machining systems that meet their exact requirements and developing solutions that help them adapt to changing market conditions”.
Over the last few decades, Vigel products have evolved from special purpose machines to high speed horizontal and vertical multi-spindle machining centers. Compact and dynamic, these machines are designed to meet medium-high production volumes and deliver world class manufacturing standards. As part of its ongoing research and development program, Vigel works closely with its strategic suppliers on both the design and engineering of manufacturing technologies in order to further improve the performance and reliability of its equipment.
“Our new, quick-change, multi-purpose spindle designs are an important step in this process, enabling customers to reduce manufacturing times while improving still further the quality and complexity of components.”
One of the challenges for Vigel was to develop spindles that were quick and easy to change yet still retained the standards of quality and reliability traditionally associated with the company’s products. In addition, each spindle had to be suitable for use in both horizontal and vertical machining centers, and be capable of handling the wide variety of stresses imposed by the different speeds and axial loads from each machining operation; for example, milling and turning operations for different parts can range in speed from 1 rpm to over 12,000 rpm.
Vigel has worked with SKF for over 30 years and it was therefore a logical step for the company to call in SKF’s specialists to help with the development of the new spindle system. Together, the two companies investigated a number of options before arriving at a solution that utilizes SKF’s super-precision angular contact ball bearings.
These compact and lightweight bearings have been designed to run at extremely high speeds, with excellent stiffness, load carrying capability and operating life. For the new Vigel spindles, SKF supplied sealed high-speed super-precision angular contact ball bearings with ceramic balls.
Each spindle incorporates a dedicated and customized matched bearing set that creates a unique combination of characteristics, especially the ability to operate at high speeds with high levels of stiffness.
These super-precision bearings are protected by integral seals, mounted on both sides of the bearing and manufactured from oil and wear resistant NBR, reinforced with steel inserts. This solution eliminates the risk of contamination from cutting fluids or minute particles of metal swarf. The seal also has a specially designed profile that, in conjunction with high quality, low viscosity bearing grease, minimizes frictional losses and rolling resistance.
Giovanni Nava, Machine Tool Account Manager at SKF, explains, “This bearing arrangement has been developed to give Vigel a solution that is tough, compact and lightweight. This helps them to minimize the size, weight and complexity of their new spindles. Just as importantly, the use of ceramic balls with sealed, lubricated for life, super precision bearings means that operating life is significantly extended, even under the most demanding conditions.”
The new Vigel spindles have a modular design, which makes tool changeover quick and simple. As Daniele Francesia Villa says, “This helps our customers to reduce downtime and improve productivity.” He concludes, “The new spindles are the smallest and lightest that we have ever produced yet, thanks to the close cooperation with the SKF application engineers, are among the stiffest, most accurate and reliable that we are able to offer. This exciting new generation of CNC machine tool spindles clearly differentiate Vigel from competitors, will allow our customers to cut costs while improving component quality, and give us the opportunity to penetrate new markets around the world.”