Precision ball screws used in electronic microscope

The low friction within precision ball screws means that they benefit from higher mechanical efficiency than comparable lead screws. A typical ball screw may be 90 per cent efficient, which is far better than the 50 per cent that might be obtained from a lead screw of equal size. Ball screw specification is often a result of an application's requirement to have smooth, accurate and repeatable linear movement.

Abssac was recently requested to supply a precision ball screw for use within an electronic microscope that placed a precision guillotine against test pharmaceutical materials. Extremely fine slithers of test material are cut off the material in rapid succession for microscopic investigation. A small variance in the sliced material's overall thickness would have a detrimental effect on the accuracy of the test results. The application therefore demanded a high degree of repeatable accuracy and a precision ball screw could also satisfy the other design prerequisites for it to be compact, quiet and cost-effective.

By using precision ground ball nuts and pairing these with precision cold-rolled ball screw threads, Abssac could provide a ball screw with lead accuracies of less than 52 microns of error for 300mm of linear travel. By utilising both ground nuts and rolled screws, large cost savings could be made when compared against a fully ground ball screw and nut.

Abssac has over 30 years of experience in supplying precision ball screws; typically, precision ball screws have outside diameters in the range 4mm to 25mm, and a choice of leads can be supplied for each diameter. Abssac's ball screw customers often request that the journal ends of the screws are supplied pre-machined so that the parts are ready to fit. This eliminates potential scrap rates for the customer and also ensures that the assemblies are supplied and certified to the accuracy tolerances required.

Phil Jones at Abssac says: "The precision miniature ball screw ranges we supply are ideally suited to optical devices or miniaturised positioning equipment. As manufacturing designs get smaller, and demand for more accuracy increases, we can now offer a way of supplying what the designer has previously not been able to obtain."

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