Linear slider systems are self-lubricating (therefore requiring no grease). Linear plain bearing slider systems have an advantage here as the adjustment length only depends on the length of the outer rail, that’s because the outer rail is fixed to the inner rail. The adjustment length of linear roller systems depends on both the length of the inner and outer rail. To ensure everything runs smoothly, the system needs to be greased. The ball bearing design is a three-way assembly which includes the ball carriers, the inner rail and the outer rail. In applications without high loads, linear slide bushings may be a better option. Although there is still potential for stick slip grease will be required to manage this, yet grease viscosity varies depending on temperature and dirt ingression. It’s important when designing a linear motion system to get this balance of load, friction and adjustment effort right.Īs an example, if the system must handle heavy loads and the adjustment should be as low as possible, linear roller systems are the perfect choice (100kg load will result in adjustment force of roughly 10N). The viscosity of the grease changes with temperature and can affect the sliding force of any such application.
When it comes to grease, the amount and type of grease that is applied can alter the adjustment force. The actual values you can achieve vary a lot depending on the materials you use, the grease and operating temperature.
Roller bearings typically have 10 times less friction than sliding plain bearings and therefore have minimum adjustment force. The adjustment force is all about physics! The friction that the roller bearing or linear slides generate and the load applied, give the resulting adjustment force. This is a result of getting the adjustment force wrong. Have you ever tried to adjust the seat in your car and the seat either moves too quickly, without control, sending you flying backwards, or it’s very difficult to move, causing stick slip issues. Getting the right adjustment force for the end user is important.