Wherever you find a production line, you will find the need to move items through your manufacturing process with great precision and as little friction as possible. This is where Linear Rails come in, and you will find these devices across the full range of industrial sectors.
A Linear Rail System allows the movement of an item in a linear way, either vertically or horizontally. It’s a relatively simple piece of mechanical equipment created to do a very simple job well, letting you move things smoothly and safely through a manufacturing or packaging process.
Lots of Different Terms are used
It does not help when these simple devices have so many different names, as they are also known as linear guide rails, linear guides, linear guideways, linear slides, and linear guidance systems.
But whatever name you use, a Linear Rail efficiently moves items (sometimes quite heavy loads) along a horizontal or vertical path, all with the minimum possible level of friction or resistance.
Constructed using high-strength, hardened, and galvanised steel, they are very strong and resist corrosion (this being important in some environments).
What is known as a cold drawing process is used when they are being manufactured, the metal is shaped and profiled before adding the all-important roller runner? Profiled rail guides are best where high loads are anticipated, an added benefit being that they deliver an exact linear motion.
These guides come in every size, ranging from miniature rails designed for moving tiny components in limited spaces right up to huge examples that allow the movement of components that could weigh more than a tonne.
What are the common applications for a Linear Rail?
Linear Rails are suitable for virtually any situation where things have to be moved. There’s such a wide variety of sizes, accuracy classes, and preloads available that one is bound to be a good fit.
Linear rails tend to perform better than other guide devices as they have greater load capacity, displacement accuracy and are more rigid. For this reason, Linear Rails are found in many industrial applications.
Whenever there is a need for a low-friction guide system with high rigidity, one capable of coping with loads weighing anything from a few grams to a few tons, there will be a suitable linear rail.
The Best Solution
Their superior load capacity, travel accuracy, and rigidity make them a far better solution in most applications. For example, round shaft guides only withstand downward or lift-off loads, where, Linear Rail guides can withstand downward loads, lift-off loads, and moment loads.
They are also far better than crossed roller guides, which can only travel a limited distance. Linear rales offer impressively ‘travel ranges’ whilst at the same time providing increased stiffness, rigidity. These factors and their long life span have resulted in them being very popular indeed.
If you need a suitable system for applications that require high precision, high rigidity, and long life, a Linear Rail is the very best solution.
What are the challenges of using Linear Rails?
There are some issues that need to be considered, but all are easily overcome if you take account of the following:
• When specifying the materials and plating to be used in a Linear Rail, do bear in mind the effect on the cost and lead time. Plating, for example, may have to take place overseas.
• Your mounting surfaces must be made to the specified tolerance. Any misalignment of the mounting surfaces directly adds preload to the whole system and will affect performance.
• Always ensure that the preload is accurately calculated. You have to include negative factors like vibration, noise, heat generation, and deflection, otherwise, you can significantly increase friction and degrade performance.
• Always test over the full run of any installation, otherwise, if there’s a problem, you won’t know about it until you start using the line.
• Ensure you include any mounting features that will improve alignment. If you don’t, the system won’t perform to specification.
How do you go about specifying a Linear Rail?
This process follows a very logical path. First, clearly define the most important parameters of the application. Once you know these, you can narrow down the available choice and can apply your critical variables to make the right final choice.
There are many things to consider here; the profile of the rails (commonly square or round), the kind of bearings (either cantilever or saddle slides), plus the stroke, load, speed, duty cycle, mounting area, and of course, the mounting orientation. All these are important issues as the ‘saddle’ could potentially move horizontally, vertically, along a wall mount, or even be inverted.
How do you maintain a Linear Rail for optimum performance?
All systems with moving parts eventually wear out, but attention to basic maintenance can extend the life of Linear rails quite substantially.
Under-lubricated guides wear excessively, which also affects performance and leads to premature failure. You have to carefully choose the lubrication product, as the lubrication product’s characteristics make all the difference. Successful lubrication depending on the quality of the lubricant applied.
You can get guides with inbuilt automated lubrication systems, but they do increase the complexity and cost and are in most instances, not the best choice.
Maintenance-free bearings are a more straightforward, integrated mechanical feature that is added to the bearing slider to store and deliver the lubricant.
Listen to your lines
The best way to locate problems before they become serious is to look and listen to the rails. Any change in the sound the system makes can indicate that something is amiss. Usually, this will be either that the line isn’t lubricated enough, the guide rails are misaligned, or there’s an uneven loading on the bearing blocks.
One of the main things you will need to do is replace the seals, which keep dirt out and lubricate. These are usually easy enough to inspect and replace, though.