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PMI Linear Bearing Units – Part 1


The PMI (formerly AMT) linear guideways are designed to have a rolling motion that produces low friction while maintaining high precision. The company has produced a number of other models that we will feature on this blog in the future, but here we focus on the linear bearing units that are named after variations of the product code MSA00ESSFCN, with the zeroes replaced by the differentiating numbers that reference the size of the guideway.


This linear ball bearing guideway unit features an E-type flange, with the mounting position optional at either the top or the bottom. The end seal is bi-directional with there being both a bottom and inner seal.

A popular feature of these PMI-AMT linear bearing units is the low frictional resistance they produce which enables the guideways to maintain their high precision standards. Other slide guide models not manufactured by PMI will often have up to 20 or even 40 times the amount of frictional resistance affecting their operational precision. Lubrication for this MSA15ESSFCN linear bearing unit and other PMI-AMT linear guideways is easily supplied via a ‘grease nipple’ on the carriage, which further reduces the frictional resistance.

Technical Specification:

  • Model No. MSA15ESSFCN
  • Outer Diameter: 47mm
  • Width: 24mm
  • Weight: 180g (0.40lbs)


Also using an E-type flange is the MSA20ESSFCN linear bearing unit, which provides two options for its mounting position at either the top or the bottom of the guideway. The bottom and inner seals are again present in this model with the bi-directional seal at the end.

These PMI-Amt linear guideways are all suitable for high speed operations thanks to the previously mentioned low frictional resistance. In addition, the requisite driving force for these linear bearing units is significantly lower than slide guide systems produced by other linear guideway manufacturers. This means the power consumption is greatly reduced, saving on energy costs, especially as the operational temperatures do not rise too high even under the highest speed.

Technical Specifications:

  • Model No. MSA20ESSFCN
  • Outer Diameter: 63mm
  • Width: 30mm
  • Weight: 400g (0.88lbs)


As with the other models in this category, the MSA25ESSFCN linear bearing unit features the bi-directional seal at the end, with the bottom and inner seal keeping the guideway in good condition. The E-flange type continues to provide mounting options either above or below the guideway.

The PMI-AMT linear guideways described here are all designed to have high rigidity via their four-way load design. The manufacturers have optimised the geometric mechanics to ensure these high quality linear guideways can bear loads in a radial and reversed radial direction, as well as in both lateral directions.

Technical Specifications:

  • Model No. MSA25ESSFCN
  • Outer Diameter: 70mm
  • Width: 36mm
  • Weight: 620g (1.37lbs)


The largest model in this category is the MSA30ESSFCN linear bearing unit, which features the same seals as the previous models as well as the E-type flange which provides the multiple mounting options.

All of these PMI-AMT linear guideways are easy to install with plenty of customisable options thanks to the interchange-ability of the parts. These superbly designed linear guideways always provide a high level of precision even when operating from a mounting surface that has been machined via milling or grinding.

Technical Specifications:

  • Model No. MSA30ESSFCN 
  • Outer Diameter: 90mm
  • Width: 42mm
  • Weight: 1090g (1.09kg or 2.4lbs)

If you require any PMI linear bearing units such as the MSA15ESSFCN, MSA20ESSFCN , MSA25ESSFCN  or the MSA30ESSFCN , then contact YB Components who are the UK’s leading linear guideway suppliers who can ship these parts all over the world.