#Datum engineers iso#

The guiding system can automatically survey TBM position and the deviation of the tunnel axis. Only the professional surveyor with strict training can operate the guidance system.

Shengjun Jiao, in Shield Construction Techniques in Tunneling, 2021 10.2.3.4 Guide system operation Furthermore, with A Ⓛ, the datum cylinder A of least material (virtual) size must be contained in the material (and is not allowed to lie outside of the material, as applicable to the maximum material virtual condition of A Ⓜ or A without a modifier ).

#Datum engineers iso#

It should be noted that the indication of the least material requirement Ⓛ at the datum has a meaning different from ISO 5459. Around this boundary, the datum feature may take, if possible, the position where the requirements of the toleranced features are fulfilled. A prerequisite is that the surface of the datum feature does not violate the least material virtual condition (which is geometrically ideally positioned in relation to the geometrical ideal position of the toleranced features). The least material requirement for the datum permits floating of the datum axis or datum median plane relative to the toleranced feature(s) when the datum feature deviates from its least material condition (in the direction of the maximum material condition). Georg Henzold, in Geometrical Dimensioning and Tolerancing for Design, Manufacturing and Inspection (Third Edition), 2021 4.6.3.3 Least material requirement for the datum