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QUALITY CONTROL

Quality Control

Quality control of all products, incorporating :

> hardness measurement
> crushing strength measurement
> material analysis
> roundness & surface inspection

E & R is extremely proud of its quality control laboratory, containing some of the most sophisticated inspection equipment available. All quality control members undergo extensive training to ensure that the required skill levels are achieved and maintained.


 
 



Ball Class and Tolerances to DIN 5401
DIN class Nominal diameter mm Nominal diameter tolerance µ Dia tolerance per
unit container
µ 		Spherical deviation
µm 		Description
I Up to 10 ± 10,25 0,5 0,25 Super Precision
II Up to 25 ± 10,5 1 0,5  
III Up to 25
over 25 to 50
over 50 to 75
over 75 to 100
over 100 to 125
over 125 to 150 		± 11
± 13,5
± 14
± 17,5
± 21
± 24,5 		2
3
4
5
6
7 		1
1,5
2
2,5
3
3,5



Bearing Grade
IV Up to 10 ± 14 4 2 Cycle Grade
V Up to 25
over 25 to 50
over 50 to 75
over 75 to 100
over 100 to 125
over 125 to 150 		± 75
± 113
± 150
± 188
± 225
± 263 		50
75
100
125
150
175 		25
38
50
63
75
88


Castor Grade
VI   ± 200 400   Burnishing Grade



Definitions of DIN 5401

Nominal diameter
the diameter value that is used for the identification of all ball size (eg 1/8”, 4mm, etc)

Nominal diameter tolerance
The maximum allowable deviation of any ball lot diameter from the Nominal Diameter

Diameter tolerance per unit container
The permissible difference between the average diameter of the largest and smallest ball within any unit container

Diameter Tolerance Per Ball
The permissible difference between the largest and the smallest diameter measurable on a ball

Surface roughness
Surface roughness consists of all those irregularities which form surface relief and which are conventionally defined within the area where deviations of form and waviness are eliminated

Spherical Deviation
The difference between the largest and the smallest indication of the V-block out of round in 60° angle