Thomson has developed a high load ball screw by implementing a unique thread form that increases load bearing capacity four to eight times over traditional ball screws. This gives the application engineer the option of deploying a ball screw in most any application that previously required a roller screw. Or, because the life of the assembly is a direct function of the load capacity (see L10 Life Expectancy Calculation) using a high load ball screw in a low load application would extend the life of the product.
Standard L10 Life Expectancy Calculation of a Ball Screw Assembly
Bearings are often specified to give a "L10" life. This is the life at which ten percent of the ball screw assemblies in that application can be expected to have failed due to classical fatigue failure or, alternatively, the life at which ninety percent will still be operating. The L10 life of the ball screw assembly is a theoretical life and may not represent service life of the assembly. It can be calculated according to the following formula:
L10 = (Cam/Load)3
Where: L10 = Life expectancy (expressed in millions of revolutions)
Cam = Dynamic capacity of the ball screw
Thomson provides a standard range of high load ball screws up to 160 mm diameter with max. 1400 kN dynamic load capacity, and customised ball screw assemblies according to specific application demands are available upon request. Specifying high load ball screws in applications previously relegated to roller screws can save money, extend product life or both. Any new application will require careful analysis of load capacity, product life and cost, and in doing so, there may still be some applications well-suited to roller screws. But given new ball screw technology advances that increase ball screw load bearing capacity, it is now wise to consider Thomson high load ball screws in any application for which you might now be considering a roller screw. It could pay off significantly.