Linear Ball Bushings

Frequently asked questions — Bushings

• Which bushing should be selected for mounting on a shaft supported along its full length?

  For applications where the shaft is held by a continuous shaft support, it is essential to use the open bushing of the LMUK type. Its characteristic longitudinal slot allows it to pass over the shaft support without interference, unlike closed bushings such as the LM, LMK or LMF models, which would require installation on an unsupported shaft. This technical choice is indispensable to ensure proper operation of the guidance system in this specific configuration.
• What are the preparation requirements for the shaft used with a linear ball bushing?

  To ensure the longevity and accuracy of the system, the shaft must imperatively have a tolerance class of h6 minimum. In addition, its surface must be ground and hardened to a minimum hardness of HRC 58. Strict compliance with these physical characteristics is necessary to avoid premature wear of the ball bushing and to maintain the reduced coefficient of friction of around 0.002 under normal service conditions.
• In which cases is it preferable to use a linear ball bushing rather than a rail-based guide?

  The linear ball bushing represents the simplest and most economical linear guidance system, ideal for movements requiring very little effort or for lightly loaded axes. However, its dynamic load capacity remains modest, typically limited to a few hundred Newtons or a few kiloNewtons depending on size. For applications requiring higher loads or greater rigidity, rail-based guidance systems offer a more suitable alternative than the linear ball bushing.
• How do you choose between the LM, LMK, LMUK and LMF formats?

  The choice of format depends on the required mode of mechanical integration. The standard LM bushing is designed for insertion into a bearing or machined housing. The LMK bushing has a base with mounting holes for direct installation on a frame, while the LMF bushing incorporates a circular mounting flange. Finally, the open LMUK bushing is the only variant suited to applications where the shaft rests on a continuous support. These distinctions ensure precise mechanical compatibility according to the architecture of your assembly.
• What maintenance is required for a linear ball bushing in harsh environments?

  Standard lubrication relies on lithium grease for typical applications. However, for contaminated environments or use at high speeds exceeding 1 metre per second, the protection must be reinforced. Reinforced seals should then be fitted on the bushing and regular lubrication ensured through an integrated grease nipple, in order to maintain the closed ball circuit and prevent premature degradation of the mechanism.