Gauge Blocks

Manufactured according to DIN EN ISO 3650

Kolb & Baumann has been manufacturing gauge blocks for more than 70 years. Today we are one of the few remaining manufacturers in Germany and Europe. Contrary to the general trend, we do not market Asian products. We are proud of producing our gauge blocks exclusively at our factory work floor in Aschaffenburg. This is the only way to monitor and guarantee the outstanding quality of our products. As a calibration laboratory accredited by the Deutsche Akkreditierungsstelle GmbH (DAkkS), we have the necessary measuring equipment to ensure the high quality standard. Gauge blocks are a quality product: more than 70 years of experience and research are background. The composition and purity of the material, the aging and stabilization methods, the processing, the dimensional control, the surface quality, the wear resistance, the sensible design of the storage boxes: all these aspects are subject to ongoing critical examination at KOBA

Gauge blocks

KOBA Gauge Blocks are manufactured and verified to the specifications of DIN EN ISO 3650. As tolerances are kept to a minimum by internal standards, it is guaranteed that every KOBA Gauge Block is within the limits stipulated. The high level of accuracy and the reliability of the measuring results are guaranteed by two separate feed-backs attributed to the internationally fixed unit of length by means of a wave length:

permanent comparison with master gauges interferometrically verified by the Physikalisch-Technische Bundesanstalt PTB
parallel to this calibration in our fully airconditioned laboratories

Tolerance ranges of the individual grades within the limits of which the actual size is guranteed, can be taken from the table above. The durability of gauge blocks is achieved by a special process developed by us, combining natural and artifical ageing. The grade of accuracy should be selected according to the intended purpose.

K: Gauge blocks of grade K with a DAkkS calibration certificate are excellently suited as the most accurate measuring standard of the geometric dimension length. Their field of application is checking gauge blocks of lower grades. The purchase of gauge blocks of grade K always includes a DAkkS calibration certificate. This shows the deviation from the nominal dimension for each gauge block.

0: Used as master gauges for all accurate measurements of length, for checking all gauge blocks in use, for final inspection, for setting accurate measuring instruments.

I: For checking of gauges, for setting measuring instruments.

II: Used as standard for setting or workshop gauges for jig-, gauge- as well as machine construction

A PTB calibration is available on request. In most factories the use of only one grade is not sufficient, as the accuracy varies in the individual departments and manufacturing stages. But just this very fact implies the efficient use of gague blocks. An example: Once gauge blocks of grade 0 are no longer accurate enough for inspection (as a result of frequent use) they can be passed on to a department or workshop place were the demands on the accuracy are accordingly lower. We recommend, though, to have them inspected at our laboratory before passing on.

Gauge Blocks in Steel

KOBA Steel Gauge Blocks: The carefully hardened stress relieved steel is a special steel type. The special melting results in the highest possible degree of purity. The homogeneous molecular distribution gives excellent properties against abrasion and wear due to the homogeneous dispersal of steel elements and thus uniform fine structure of carbide compoments. A clever method of ageing prevents the remainder of residual austenite and therefore guarantees smallest possible changes in size even below the ISO-standard.

up to 1000 mm according to DIN EN ISO 3650
grades K, 0, 1 und 2
single sizes available
standardised set compositions as well as customised set compositions
high wear-resistance
hardness > 800 HV
good stability in dimension due to extensive stabilisation process
thermal expansion coefficient
for Gauge Blocks in steel ≤ 100 mm α= 11,9 * 10^-6 K^-1
for Gauge Blocks in steel > 100 mm α= 11,2 * 10^-6 K^-1
traceable calibration certificate (laboratory accredited to DIN EN ISO/IEC 17025) included in delivery

Gauge Blocks in Ceramic

KOBA Ceramic Gauge Blocks: The wear characteristics of KOBA ceramic gauge blocks is similar to that of carbide. The coefficient of thermal expansion is closer to steel and is α= 9,3 * 10^–6 K^–1. Ceramic gauge blocks are not subject to corrosion and therefore excellently suitalbe for the use in a work shop. The bending strength of 800 N/mm^2 is so high that there is no danger of breakage during ordinary use.
- up to 100 mm
  grades K, 0, 1 and 2
- single sizes available
  standardised set compositions as well as customised set compositions
- in minimum quantitiy customised lengths
- corrosion resistant
- approx. quadruble wear resistance of steel
- high dimension stability due to Yttrium-stabilisation
- coefficient of thermal expansion α= 9,3 * 10^ -6 K ^-1
- traceable calibration certificate (laboratory accredited to DIN EN ISO/IEC 17025) included in delivery

Gauge Blocks in Carbide

KOBA Carbide Gauge Blocks: The wear ratio in comparison to that of steel is approx. 1:50 bis 1:100. Gauge blocks in carbide are mainly used as wear protectors as the outer measuring faces of gauge block combinations are specially prone to abrasion. Therefore, all KOBA gauge block sets are provided with 2 empty slots for storing carbide wear protectors in 1 mm and 2 mm. The material used is solid tungsten carbide and has a coefficient of thermal expansion of α = 4,5 * 10^ -6 K^ -1. The use of carbide gauge blocks is particularly rational where wear occurs most commonly: in the work shop. We wish to stress that steel gauge blocks should be used where work pieces of steel have to be checked and a standard reference temperature of exactly 20°C can not be maintained. Considering the difference of the coefficient of thermal expansion between steel and carbide, this would lead to a larger uncertainty of measurement.

Carbide Gauge Blocks (Tungsten Carbide) according to DIN EN ISO 3650
up to 100 mm
grades K, 0, 1 und 2
single sizes available
standardised set compositions as well as customised set compositions
special designs upon enquiry
customised lengths – wear resistance approx. 1,5 times better in comparison to steel
hardness > 1.350 HV
best long-term stability of all materials
coefficient of thermal expansion α = 4,5 * 10 ^-6 K ^-1
traceable calibration certificate (laboratory accredited to DIN EN ISO/IEC 17025) included in delivery

Get in contact with us.

Jutta Remmel
Tel.: +49 6021/3463-13
Fax: +49 6021/3463-813
jutta.remmel@koba.de

Accessories for Gauge Blocks

Matching our gauge blocks you will find here the corresponding accessories for the correct handling of the products