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Ball screw

Ball screws are feed screws that convert rotary motion from a motor into linear motion by rolling multiple steel balls between the screw shaft and the nut. Compared with sliding screws, they have lower friction and higher transmission efficiency, enabling precise positioning with less drive torque. The steel balls recirculate repeatedly through return components inside the nut. There are precision ball screws with ground thread grooves and rolled ball screws formed by rolling, distinguished by accuracy grade (C0 to C10, etc.). Some types have the nut preloaded to eliminate axial play. They are used in positioning mechanisms such as feed axes of machine tools, semiconductor and electronic component manufacturing equipment, conveyors, and XY tables.

How to choose Ball screw

  1. 1. Determine lead from required speed and resolution

    Lead is the linear travel per shaft revolution. Listed products range from 1 to 40 mm. A larger lead allows faster feed at the same rotational speed but increases required torque and makes the travel per pulse coarser. Calculate it backward from maximum speed, maximum motor rotational speed, and positioning resolution.

  2. 2. Select shaft outer diameter from load and rigidity

    Shaft outer diameter affects load capacity, rigidity, buckling load, and critical speed. Listed products range from 8 to 32 mm. For long overall lengths or high-speed rotation, a thicker shaft is required to avoid deflection and resonance. Check the permissible rotational speed including the support method.

  3. 3. Verify life using basic dynamic load rating

    The basic dynamic load rating Ca is the axial load used as the reference for life calculation. Listed products range from 1950 to 16100 N. Calculate the rated life from the average operating load and travel distance, and confirm it meets the required service years. Life is approximately inversely proportional to the cube of the load ratio.

  4. 4. Check shock loads against static load rating

    The basic static load rating C0a is the axial load permissible at standstill or under impact. Listed products range from 2600 to 33400 N. Confirm that a sufficient static safety factor is secured against maximum loads such as inertial forces during sudden stops and machining reaction forces.

  5. 5. Select accuracy grade matching positioning accuracy

    The accuracy grade indicates the permissible lead error range; a smaller number means higher accuracy. Listed examples are mainly C5 with ground finish. Choosing a grade beyond what is required raises cost, so determine it by comparing with the required positioning accuracy.

  6. 6. Balance backlash and preload torque

    Axial clearance for listed products is 0 to 0.03 mm. For applications where backlash (play on reversal) is undesirable in reciprocating motion, select preloaded types. However, a higher preload torque (2 to 25 N·cm for listed products) increases drive torque and heat generation, so verify it against motor capacity.

  7. 7. Match overall length and shaft end machining to the equipment

    Overall length for listed products ranges from 85 to 2500 mm. Determine it by adding nut length and clearance to the stroke, including the mounting section for the support bearings. Long shafts face stricter constraints from critical speed and buckling, so consider them together with shaft outer diameter.

This guide was written by AI based on the listed products' documents and specification items. Check each manufacturer's documents before adopting.