Who is this article for?

• You’re designing a new machine that uses linear motion driven by a ball screw
• You’re troubleshooting an existing machine
• You’re learning about different bearing arrangements

Can I Use a Ball Bearing to Support my Ball Screw?

You can, but let’s make sure the correct ball bearing is specified and sourced.

Ball screw ends are either fixed, supported, or free.

1. Fixed: axially located, designed to handle axial loads in both directions
2. Supported: axially non-located, design to support radial loads and radial stiffness
3. Free: non-located, unsupported, cantilevered screw - generally not recommended. Drastic reduction in stability, strength, and stiffness.

Ball bearings are used in the majority of ball screw supports, but you should specifically specify the type based on the position and function. Ball bearings, using balls as the rolling elements, are available as deep groove ball bearings and angular contact ball bearings, among other configurations. Fixed ends use angular contact ball bearings, thrust bearings, or combined axial/radial bearings. Supported ends can use non-locating needle roller bearings or cylindrical roller bearings, or slip fit in housing deep groove ball bearings.

Fixed end

Now that you’ve identified angular contact ball bearings, you should specify the contact angle. Angular contact ball bearings are available in a range of contact angles (off radial direction):

* 7000 P4 Super precision angular contact ball bearings 15, 17, 25 degrees
* 3200/3300 Series Double row angular contact ball bearings 25, 30, 45 degrees
* 7000 Series Single row angular contact ball bearings 40 degrees
* Axial angular contact ball bearings 60 degrees

Ball screw supports are classified as axial angular contact ball bearings. These bearings, with a 60 degree contact angle, are designed to accommodate more axial, or thrust, loads than radial loads (60 degrees > 45 degrees). These bearings are available as single bearings used in pairs, double row bearings, or multi row bearings, and even with or without mounting flanges. Additionally, premium ball screw support bearings are spindle bearing quality tolerances for axial runout and precision ground, which allows for preloading of the support assembly. Preload creates stiffness and rigidity. 2 single row bearings or a double row bearing is the minimum requirement because the position has to support axial loads in both directions, during forward and reverse ball nut movement. Schaeffler is the world leader in these ball screw supports, with their INA brand ZKLN, ZKLF, ZKLFA, DKLFA, and ZKLR designs - all available on borecode.com.

Supported end

This position will allow stretching and expansion of the screw while supporting radial (side to side, up and down) loads and stability. Standard precision deep groove ball bearings, in the 6000, 6200, 6300, 61800, or 61900 series with minimal radial internal clearance such as CN (standard clearance, usually unmarked), are an easy choice based on their widespread availability and similar dimensions (bore and OD) to the angular contact ball bearings. These supports should be fixed to the shaft, but not located axially in the housing. The allows the bearings to move axially and prevent binding and overloading. We stock SKF and FAG deep groove ball bearings, available at www.borecode.com.

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Would you consider this ball screw support bearing 1) fixed, 2) supported, or 3) unsupported? borecode.com features a BEARING TECH blog to answer questions about common problems, introduce new products, and deliver cost saving solutions related to electromechanical power transmission. Our latest post introduces these 3 definitions for screw supports and dives deep into how simple ball screws function. Next, we’ll explore pretensioned screws and what’s required of the screw supports. ———————— #ballscrew #ballscrews #ballscrewrepair #ballscrewrebuild #ballscrewsupport #electromechanical #screwdrives #manufacturing #powertransmission #bearings #precisionmachinery #skf #nsk #ntn #boschrexroth #thomson

A post shared by BoreCode - Bearing Supplier (@borecode) on Jul 26, 2020 at 2:13pm PDT