6 steps to linear guide selection

Linear guide selection
Linear Rail
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Profiled linear guideways are a key component of many linear motion systems. When deciding to incorporate a profiled rail system into your design, there is critical criteria that should be considered to ensure you choose the optimal linear guide system for your application. Here we look at the 6 key steps to correct linear guide selection.

Estimated reading time: 6 minutes

Our top linear guide selection tips:

1. Check static, dynamic and moment load capacity

The load that will be applied to your linear guide rail system should be the first consideration. Will the guides see just a static load, or will they also need to carry a load while in motion, a dynamic load? Manufacturers will list the maximum static and dynamic load capacities for that particular linear guide to make selection easier. A static load refers to a stationary load when the linear component is fixed or stationary. The static load rating will always be higher than the dynamic load rating.

Manufacturers will also list moment load ratings, and these must also be carefully considered. If the linear rail and guide is likely to encounter a moment load, then a dual guide rail setup could minimise roll moment load by distributing the forces onto one or two linear guides per rail. By using a dual rail configuration and thus eliminating any moment loads will greatly increase the lifetime of the linear system.  

Static vs dynamic load capacity axis

2. Layout and mounting considerations

Once static and dynamic load capacities have been considered, the layout of the linear system should be next on the list. A single rail with one linear guide may suffice, however as mentioned previously if there are over-hung moment loads, using a double rail setup with one or more linear guides per rail might eliminate these moment loads by spreading the load over two rails.

Making sure that your prepared surfaces are suitable to mount linear rails is critical and should be thought of carefully. Surfaces should be flat, clean and when using a dual rail setup, rails should be checked after mounting for alignment. Installation instructions for all CPC linear guides can be found via Kiwi Motion data sheets.

Linear guide selection -Installation
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3. Consider speed & acceleration requirements

Critical speed should be the next consideration for linear guide selection. How fast you need the linear system to operate will narrow your selection. Generally, profiled linear guides have a maximum permissible speed of between 3-5m/s and 300m/s2 acceleration. However, CPC – available in the UK through Kiwi Motion – have pushed the boundaries of linear rail technology and now 10m/s max speed and 500m/s2 acceleration is obtainable, so you can push the boundaries of machine design.

Linear guide selection

4. What accuracy grade does the application require?

Once load, speed and layout have been specified, making sure that your linear system is going to be repeatable to achieve the desired end result is key. Linear rail manufacturers show accuracy grades as running parallelism over a defined length of rail with deviation over the set length shown in microns. Accuracy grades are then defined as N, H, P, SP and UP. By using these tables and matching the grade to the requirement of the machine a correct linear guide selection can be made. CPC offer accuracy grades to suit all applications, from Normal Grade for general automation to Ultra Precision Grade for precision machine tool applications.

Linear guide selection

5. Travel length (stroke)

A simple but crucial step of linear guide selection. Calculating the total travel length required, remembering to account for the ‘lost’ travel from the length of the linear guide(s). If the overall travel is required to be longer than 4000mm a butt join will be required for a smooth joint where two linear rails connect. Kiwi Motion can supply perfectly finished ends for butt joins, resulting in smooth, quiet linear motion along the whole travel. 

Linear rail length

6. Linear guide selection for environmental conditions

Nearly there. Considering the conditions in which the linear rail system is going to operate is critical. If the environmental conditions are likely to be harsh it is important to make sure that the correct seals and scrapers are chosen to ensure long lifetime. CPC have a market leading range of seals and scrapers to protect against contaminants like dust and swarf.

Linear guides are used in a wide variety of industries from robotics to laboratory equipment to machine tool to 3D printing.

If you require some advice and reassurance, then Kiwi Motion are always on hand to provide guidance and support. As linear experts we can advise on linear systems including linear rails and guides, linear actuators, ballscrews and more.

Kiwi Motion are UK distributors for CPC, who manufacture innovative, market leading linear solutions with patented performance characteristics such as high-speed linear guides, in built lubrication storage pads and inverse hook recirculating ball design.

Linear guide selection conclusion

In conclusion, selecting the right linear guide system involves careful consideration of several key factors. By following the six steps outlined – evaluating load capacities, considering layout and mounting, addressing speed and acceleration requirements, determining accuracy grades, accounting for travel length, and assessing environmental conditions – you can ensure the optimal performance and longevity of your linear motion system. With the support and expertise of Kiwi Motion, distributors for CPC’s innovative linear solutions, navigating these steps becomes more manageable, ensuring your design meets its performance goals across various industries and applications.

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