Precision and commercial weights of the classes M1 | M2 | M3
General: Test weights are divided into different accuracy classes. From E0 (most accurate) via E1, E2, F1, F2, M1, M1-2, M2, M2-3 to M3 (most inaccurate). It can be said that the further ahead the letter is in the alphabet and the smaller the following number is, the more accurate the respective weight is. These weights, which are classified according to error margins (OIML), are used for various purposes, depending on production accuracy or permissible variations in mass.
Weights of classes M1, M2 and M3 are called precision or commercial weights. They are used as test weights for commercial scales of class III (M1 and M2) or for rough scales of class IV (M3). More ...
Class M1 (precision weights)
Class II scales with a number of steps <30 000 can be adjusted, tested and calibrated with these weights according to ISO 9001ff for quality assurance. For calibration and official verification of weights of the lower classes M2 and M3.
Class M2 (precision weights)
Class III scales (commercial scales) with a number of steps <10 000 can be adjusted, tested and calibrated with these weights according to ISO 9001ff for quality assurance. For calibration and official verification of weights of the lower class M3. Use in general commerce and together with commercial scales (class III).
Class M3 (commercial weights)
Class III scales (rough scales) with a number of steps <3 000 can be adjusted, tested and calibrated with these weights according to ISO 9001ff for quality assurance. The weights are used together with commercial scales (class III) and rough scales (class IIII) as learning aids in schools and training or for load tests in lift, crane and vehicle construction.
Weights of all three classes are suitable – depending on accuracy requirements – as load cells for tension, compression and torsion determinations.
Marking according to OIML R111:2004
Weights from 1 g to 500 g are marked with their nominal value and the unit symbol “g” (e.g. “10 g”).
Weights of 1 kg and more are marked with their nominal value and the unit symbol “kg” (e.g. “1 kg”).
Additional marking of the class:
Class M1 → “M” or “M1”
Class M2 → “M2”
Class M3 → “M3” or “X”
are applied to the top side.
Weights according to DIN 1924 do not have markings regarding class.
The manufacturer’s mark may be applied to rectangular block weights of class M1 and to all weights of classes M2 and M3.
To differentiate between weights of the same nominal value that are present more than once in sets, they are identified by dots or stars.