How FLT Design, Analyse & Optimise Bearings with RomaxDESIGNER


Since the 1950s, FLT Group have provided many industries with specific solutions: for automotive, bearings for passenger car wheels, driving shaft supports, differential gear boxes, axle shaft supports, and main wheels of tractors and trailers; for agricultural, self-aligning and Y-bearings, tapered roller bearings and deep groove ball bearings (wheel hubs and planetary gearbox bearings); for electric motors, ball bearings with low noise; for rail , spherical roller bearings for locomotive axles.

Alongside tools such as SolidWorks and AutoCAD LT (for preparing 3D bearing models and 2D bearing drawings), FLT Polska’s engineering team have used Romax software since 2008.

Saving time and improving quality

Integral to accurate prediction of system behaviour, bearing technology has always been at the core of RomaxDESIGNER, and Romax continue to invest in developing new bearing simulation technology. New solutions have included flexible bearing ring analysis, and, most recently, enhanced roller contact and rib loading analysis.

Zalubski says: “The main challenge we face is providing the customer with bearings that meet the required life, and have an internal design appropriate for a particular application and working condition. A particular issue is the design and development of detailed rollers and raceway pro files, and understanding the influence that modifications have on the bearing life. Before we started using RomaxDESIGNER, many calculations (including bearing life and how it varies with preload) were done manually or were completely impossible. RomaxDESIGNER enables us to save significant time in bearing analysis and design, and to achieve a higher quality product: with Romax software, we can design better bearings more quickly, and provide high quality customer service.” see Figure. 1 FLT Polska use RomaxDESIGNER’s advanced bearing analysis,housing influence, flexible bearing and efficiency analysis.

                                Fig 1: Example of calculation model with applied housing

Zalubski comments: “Romax software allows us to improve the quality of our bearing analysis, especially by calculating bearing life, operating radial clearance considering shaft and housing fits, rolling element load distribution, stress distribution along the roller, ball bearing truncation , rotating torque, power loss, and load ratings.” see Figure 2 Zalubski adds: “Romax allows us to very quickly and easily replace a bearing with another type, for rapid comparison and development. Not only does RomaxDESIGNER allow us to use the latest bearing life calculation methods, but we can also consider the effect of the housing and different types of lubricant.” see Figure 3

We use RomaxDESIGNER far complex analysis of FLT bearings in a particular application and working condition, to provide our clients with bearings of the highest quality possible. Marek Zalubski , Technical Advisor at FLT Polska

A typical FLT project

Typically, a project starts when a customer requests a bearing of a certain type, capacity or dimensions. Additional design elements may be specified, such as load ratings, lubrication and information about the operating conditions. Whole system design may also be considered for bearing sizing, through housing and shaft models from CAD or Romax software. Most customers request calculations including life against preload diagrams, load distribution and maximum contact stress.

            Fig 2: Example of calculation model of final drive unit

FLT prepare a Romax model, optimise the bearing to specified targets (adjusting in RomaxDESIGNER if required), and then quote the customer for that bearing.

Project: Bearing Life Calculations for Agricultural Wheel Hubs

FLT have completed a number of agricultural wheel hub projects. One example was to specify a bearing which met a required life and to evaluate the optimum preload . The customer provided application drawings as well as the required bearing type, expected bearing life, duty cycle and lubrication data. FLT used RomaxDESIGNER to provide the customer with a bearing which would meet their demands, and to recommend the optimum preload (see Figure 4).

                          Fig 3: Example af defiection magnitude diagram

Project: Flexible Bearing Analysis and Subsequent Roller Profile Redesign

FLT use RomaxDESIGNER’s flexible bearing functionality when a customer has supplied detailed housing information , and to create taper roller bearing axial displacement against axial force diagrams (to estimate the necessary axial displace- ment to achieve the optimum preload force).

                                           Fig 4: Predicted life against preload far two FLT bearings

A global automotive and aerospace engineering customer provided FLT with a Romax and housing FE model and asked fora bearing to be specified, along with the optimum bearing preload, the bearing preload against force, the bearing preload against temperature, the bearing contact stress and stress distribution, the drag torque, and the torque to turn. At this point, FLT Polska did not have access to the flexible bearing, efficiency, or FE solve capabilities in RomaxDESIGNER, and they tight cooperation between FLT engineering team and customer resulting implementation of low friction taper roller bearing for one of leader of automotive industry.

                     Fig 5: fvlodel before meshing {rigid rings)
                       Fig 6: fvlodel after meshing (flexible rings)

Zalubski comments : “Our experience of working with Romax people is always very positive. Their powerful software is backed up by extremely helpful and professional technical support.”

For us, what’s most important is that we can support our customers with correct bearing life calculations in order to prevent future bearing failures and claims. Our investment in the software is well worth the huge costs at risk with such issues. RomaxDES/GNER gives us the confidence to design bearings which we know will perform to our high standards of quality . We envisage we will use it far many years to come. Marek Zalubski , Technical Advisor at FLT Polska

Romax’s calculations to the selected ISO standard showed that one bearing failed the required life. The bearing design thus needed to be improved with recommendations provided by Romax experts. The roller profile of the FLT bearing was changed, and the calculation was repeat ed. The bearing subsequently passed the life test s, and the customer ordered the bearing.

Fig 7. Bearing displacement against axial load – correlation between Romax model with flexible rings. Romax model with rigid rings, and rig test

Zalubski comments: “The flexible bearing module makes FLT’s bearing analysis more complex and more advanced. We find it gives excellent correlation with test rig results” (see Figure 5, 6, 7).

This article is published in BearingNews December 2021 issue