These are for comparison purposes to determine degree of operator accuracy in manual microscope measurement.
These are steel blocks containing 5 Reference Indentations made with a 10mm ball in the range 2.40-6mm and 5 Reference Indentions made with a 5mm ball in the range 1.30-3mm. These measuring ranges cover all Brinell scales using 10mm and 5mm Brinell balls.
The weakness of the Brinell test is in the measurement of Brinell indentations. With the exception of the very few acceptable automatic systems this applies to all machines and microscopes to varying degrees. The problem lies in the fact that the start and finish of the measurement depends on a subjective judgement of where the edge of the indentation is. If one person measures the diameter of an indentation as being “A” and another measures it as being “B” who is to say who is right?
Because they are made in a traceable Brinell Calibration machine, the measurements of the indentations on Foundrax Reference Indentation Reading Blocks are correct by definition and represent the standard of measurement to which operators should aspire. Each Reference Indentation has been measured in accordance with BS EN ISO 6506 in a master Brinell Calibration Microscope which is traceable to National Standards and its mean diameter is given on the accompanying certificate.
Foundrax Reference Indentation Reading blocks are supplied in protective boxes with certificates of calibration from our UKAS-accredited laboratory. By measuring each indentation it is possible to determine the uncertainty of measurement for each operator and, if necessary, to train them to measure correctly or to tighter limits than they have been used to.
The mean diameters of the Reference Indentations are given on the certificate and not on the block. To avoid being influenced by the true measurements the person measuring the indentations should be asked to write down the measurements and should not be told what the actual measurements are.
It can then be seen whether the operator’s measurements are large or small (and by how much) consistent, inconsistent etc. When disputes over Brinell hardness arise it is possible to find which party is making the truer measurements. Foundrax Brinell Reference Indentation Reading Blocks may be used for the Indirect Verification of Brinell microscopes to BS EN ISO 6506.
