Master gears are used for single and double flank gear rolling inspections of gears and for other rolling inspections (e.g. noise testing, runout inspection etc). They are manufactured with absolute high-precision and mainly in very small quantities. Up until now, DIN 3970:1974-11 part 1 (Master Gears) and part 2 (Receiving Arbours) was used as reference standard for the manufacture and use of master gears. This standard dates from 1974 and has not been changed since. The design of master gears for double flank gear rolling inspections was only partly and incompletely described in it. DIN 3962 and DIN 3963 were used for the classification of master gears. However, the tolerances given in these standards are suitable to a limited extent only for master gears.
In April 2010, the new master gear standard DIN 3970:2010-04 was published.
Apart from a few changes with regard to terminology and contents, essential amendments were introduced, which we would like to point out to our customers:
The area of application has been extended to include module 0.2; this finally redundantizes DIN 58420:1981-08 - which was rarely used.
Accuracy classes A, B, C were introduced, which means that the tolerances for individual deviations for master gears are no longer taken from DIN 3962 and DIN 3963. Instead they are now included in the new DIN 3970 and adapted to the requirements of master gears.
To ensure that these classes can be distinguished from the gear quality classes Q2, Q3 and Q4, they have been named accuracy classes A, B and C.
The tolerances used to monitor inspection equipment were defined (1.5 x new condition).
FRENCO GmbH will be working in accordance with this standard as of August 2010.
This means: Quotations, drawings and of course master gears and their markings will conform to this new standard. If a customer asks for master gears with e.g. Q3, the quotation will state accuracy class B, which essentially corresponds to Q3. The relations are shown in the following table for information:
Master gears of accuracy class A are used for the inspection of gears of mainly gear qualities 4 and 5 as per DIN 3962 and DIN 3963. Manufacturing master gears of accuracy class A is only possible with certain materials that are particularly well suited for grinding.
Master gears of accuracy class B are used for the inspection of gears of mainly gear qualities 6 and 7 as per DIN 3962 and DIN 3963. This is the “standard” for uncoated master gears.
Master gears of accuracy class C are used for the inspection of gears of mainly gear qualities 8 and less as per DIN 3962 and DIN 3963. This accuracy class C is “standard” for coated master gears.
Should you have any further questions, please do not hesitate to contact:
Vladimir Gresche
Tel +49 (0) 9187 9522 23
e-mail
