NMR 7WL SU Assembly

Accuracy

NMR Miniature Linear Guide Series have three accuracy classes: P, H, and N.

Preload Classes

The NMR Miniature Linear Guide series have three degrees of preload: V0, Vs and V1 (as described in the Table of Preload below). Preload can enhance stiffness, precision, and torsion resistance, but will negatively affect life and friction.

Speed

Static Load Rating C

For the static load traveling along the acting direction, the maximum calculated stress at the rolling elements and the raceway, by a curvature radius ? 0.52, is 4200MPa and, by a curvature radius ? 0.6, is 4600MPa.

To convert 100kl of life to 50kl of live, use the following formula:

Note: Under such stress, a permanent total deformation is generated at this contact point corresponding to about 0.0001 times the rolling element diameter (ISO 14728-2).

Static Moment Ratings M

For C, Co, M of each model refer to dimensional table. Nook Precision Profile Rails have the same dynamic load capacity in four directions: radial, reverse-radial and bi-lateral.

Static Safety Factor

Generally, the maximum permitted static load on the runner block is equivalent to static load ratings C0. However, in repeated linear motion applications, unexpected load is caused by the inertia when the system starts or stops. Therefore, the safety factor fs should be calculated in order to determine the allowable load.

Dynamic Load Rating C

When the dynamic loads are applied to normal load zones with constant magnitude and direction, theoretically, the rate life of a linear guide can reach 100 km of travel distance (ISO 14728-1).

Rating Life L

The dynamic rating is based on 100km of life. When the standard of 50km travel distance is used, the dynamic load rating will exceed the value based on the standard ISO 14728-1 by 20% or more.

Where the stroke (m) and the number of cycles per minute n1 (cpm) are constant, the rated fatigue life Lh (hr) is calculated by the following formula.

Equivalent Dynamic Load And Speed

If the load and speed are not constant, each actual load and speed must be taken into account and both will influence the life.

Equivalent Dynamic Load

If there is a change in load only, the equivalent dynamic load can be calculated according to the following formula:

Combined Dynamic Load

If the linear guide takes on load from an arbitrary angle, it’s equivalent dynamic load rating is calculated using the following formula:

Equivalent Speed

If there is a change in speed only, the equivalent speed can be calculated using the following formula:

If there are changes in both load and speed, the equivalent dynamic load can be calculated using the following formula:

Combining Linear Forces With Moment Loads

If both load and moment act on the linear guide, the equivalent dynamic load can be calculated by the formula.

Friction

The NMR miniature linear guide series is characterized with light starting friction and low, stable and consistent friction during operation.

Source Of Friction

• Resistance of the sealing system
• Resistance of the collision between the balls during operation
• Resistance from the collision between the balls and the returnpath
• Rolling resistance of the balls in the gothic arch load zone
• Resistance from the churning of the lubricant in the runner block
• Resistance from the penetrated contaminant

Proper lubrication and contamination protection are an essential requirement for NOOK Precision Profile Rails.

Seal

A standard feature of NOOK runner blocks is a special composite rubber seal on both ends of the block that effectively retains grease (lithium soap base) within the runner block. This seal also acts to keep out many contaminants. (See Image 1.1 in Figure 1 Below)

Scrapers

Stainless scraper plate option for enhanced protection of the seal as well as removal of contaminant build up such as light weld spatter and overspray. (See Image 1.2 in Figure 1 Below)

Mounting Hole Caps

For sealing quality and protection use the cap plugs supplied by NOOK to cover the mounting holes in the rail flush with the top surface. (See Image 2.1 in Figure 1 Below)

Grease Gun

Refillable and reusable push style grease gun for lubricating size 15 block. Ships empty to allow for application specific grease. (See Image 2.2 in Figure 1 Below)

Grease Fittings

Lubrication is recommended every six months or after every 100km (about 330,000 ft.) of travel. If lubrication every six months or 100km is not practical, forced oil lubrication is necessary. Refer to the catalog pages for the runner block types to determine the style of grease fitting supplied. (See Image 3 in Figure 1 Below)

Figure 1

Image 1

Image 2

Image 3