SKF Group Rolls Out New Roller Bearing

Efficiently designing a revolutionary new bearing type


The SKF Group, headquartered in Göteborg, Sweden, is the leading global supplier of products, customer solutions and services in the business of rolling bearings and seals. For the last century SKF, now a $6 billion company with 40,000 employees, has been the source of every new bearing type in the evolution of one of the most pervasive technologies in the industrial world — the rolling bearing.

The latest new bearing type is the CARB® Toroidal Roller Bearing, which was introduced in 1995. It has been designed entirely by the use of PTC Mathcad, a visual design environment that allows engineers from all industries to draw from a variety of data sources during the design phase of a product and document all mathematical formulas and calculations.

The Challenge: To Efficiently Design a Revolutionary New Bearing Type

Magnus Kellstrom is the manager of design and development for SKF Industrial Division's Toroidal Roller Bearings. He sought to create a bearing that could take angular misalignment as well as axial displacement and higher load — properties that no previous bearing has possessed. The result was the CARB Toroidal Roller Bearing.

CARB combines the self-aligning capability of a spherical roller bearing, the axial alignment ability of a cylindrical roller bearing, the possibility of low section height and great carrying capacity of a needle roller bearing. It is used exclusively as a non-locating bearing. This completely new kind of bearing opens up new opportunities to save space, weight and arrangement costs. Applications for CARB now include paper machines, continuous casters, gear boxes, wind mills, electric motors, sugar cane shredders, mobile cranes/wheels on rails, compressors and wind energy plants. It is also used as a maintenance-free bearing for oscillating movement, such as in steering mechanisms.

Good Reasons to Design CARB Using PTC Mathcad

Kellstrom and his team selected PTC Mathcad, which is currently used by more than 1.5 million engineers worldwide, as the design tool for this innovation. PTC Mathcad performs every calculation from basic dimensions to complete finished product with all its tolerances. It also makes the necessary choices of materials and dimensions, based on given rules.

"PTC Mathcad was the ideal design tool because the software makes it so easy to read and follow the design process," said Kellstrom. "The program allows us to try out various design variants very quickly. When we are satisfied, the latest calculation is saved as an Adobe Acrobat PDF file. For every bearing designed, there is then a complete documentation of how and why every dimension and tolerance was chosen. This is an easy way to meet SKF's strict requirements for quality assurance."

Managing Design Calculations Globally

SKF has harnessed the power of PTC Mathcad for managing its critical design calculations. To make the results available to their manufacturing units around the world, SKF uses PTC Mathcad in combination with a database and a Web interface. Starting from basic dimensions, PTC Mathcad programs extract data from the base and feed back results after calculating and optimizing the components of the bearing. Once this process has been completed, which can be within minutes, SKF manufacturing units in any country can have access to the data they need through a Web interface. Using PTC Mathcad this way, SKF has been able to efficiently create hundreds of designs of toroidal roller bearings in sizes ranging from 50 millimeters to 2 meters.

Streamlining the Design Process

PTC Mathcad streamlines the design work for these cutting-edge bearings by allowing SKF's engineers to easily perform complex computations through a simple interface that displays calculations as they would appear on a written page. Kellstrom and his team can specify critical design parameters, such as load-carrying capacity, size and material compositions, then perform what-if analyses for different bearing sizes and applications. Because of its unique, self-documenting interface, as PTC Mathcad performs the calculation processes, it creates a record of the work and the thinking behind it at the same time. This is the key to Kellstrom's well-documented designs and the future products that will be based on them.