The surface precision of the tray

                                                  The surface precision of the tray

     The selection of the surface precision of the tray is depended on the operational condition requirements

of the bearings. To fully develop the load capacity of the bearing, the roughness of the tray surface should

be Rz1(Ra0.2). For lower requirements, the surface  roughness can be lowered down to Rz4(Ra0.8).But for those

operation which needs higher stability and low noise , the tray should be ground or super ground so that the

minimum ripple surface can be reached.

     The dimensional tolerances between the needle and retainer assembly and  the punched outer ring tray are

shown in the technical remarks before the dimension table of this brochure . the dimensional tolerances of the

trays of the needle bearings without inner ring are shown in Table 16. The round tolerances will be no greater

than 25% of the associated dimensional tolerances while the parallel tolerances are 50%.

     When needle and retainer assembly is used, the width of the tray , after the subtraction of the chamfered

sized ( or the radium of the circular angle) , should be enough to ensure that the full width of the retainer

will have enough guiding surface .