One of the important features of the LM Guideway is its capacity to carry heavy loads. The optimum design of geometric mechanics makes the linear guideway to bear the load in all four directions, radial, reversed radial, and two lateral directions.
There are 2 major considerations to be accounted for while selecting the suitable LM Guide, those are as below:
Static Load Rating
A localized permanent deformation will develop between raceways and rolling elements when a linear guideway receives an excessive load or a large impact. If the magnitude of the deformation exceeds a certain limit, it could obstruct the smooth motion of the linear guideway. The basic static load rating (C0) refers to a static load in a given direction with a specific magnitude applied at the contact area under the most stress where the sum of permanent deformation develops between the raceway and rolling elements is 0.0001 times of the diameter of the rolling ball. Therefore, the basic static load rating sets a limit on the static permissible load.
Static Permissible Moment
When a moment is applied to a linear guideway, the rolling balls on both ends will receive the most stress among the stress distribution over the rolling elements in the system. The static permissible moment (M0) refers to a static moment in a given direction with specific magnitude applied at the contact area under the most stress where the sum of permanent deformation develops between the raceway and rolling elements is 0.0001 times the diameter of rolling elements. Therefore, the static permissible moment sets a limit on the static moment. In the linear guideway system, the static permissible moment is defined as MP, MY, MR three directions.
These 3 moments are called as follows: MP – Pitching Moment, MY – Yawing Moment and MR – Rolling Moment
To understand these moments please see the below image of an airplane, consider the airplane as a linear guideway, and the wings of the plane as the flange of our LM Block. Now, the Rolling moment occurs when the block topples from the side (flange portion) while in motion, the Pitching moment occurs when the block topples from the front and the back end like a car moving on a speed breaker, and Yawing moment occurs when the block skews while moving.
Selecting a suitable LM Guide accounting such moments is crucial for providing a smooth motion. In addition to this, there are different classes based on which LM Guides are distingusied i.e. Normal class, High Class, Precision Class, Super Precision Class and Ultra Precision. The later one to have the most lowest tolerances for the product.
For any more information on the selection and analysis of LM Guideways, feel free to contact us through email (firstname.lastname@example.org) or phone (+91-22-49355555).