ASME B89.4.21.1-2020 pdf free

ASME B89.4.21.1-2020 pdf free.Environmental Effects on Coordinate Measuring Machine Measurements.
PCM 200 (ret. [1]) defines rated operating conditions (4.9) and limiting owrating conditions (410). Machine speci— fications, typically stated is maximum permissible errors (Ml’Es). are intended to be applicable to a CMM that is used within its rated operating conditions. These rated operating conditions are the conditions that must be fulfilled for the nuchine to wiiormn as designed (i.e., meet the MPKs). These conditionS include. but are not limited to, eiiviroiiinental conditions. Limiting operating conditions are the extreme at which a machine can he operated without sustainingdamage and without degradation of specifications when subsequently operated within its rated operating conditiomis.
2.2 Definition of Environment
For the l)UP0SC of this Technical Report. the CM M environment includes those elements in the machine surroundings that affect CMM system fwrtornlance; effects of operators are not addressed in this Report. The environmental ellects included are temperature and humidity. illumination, vibration, electrical effects, and contamination. These effects are caused or transmitted by surrounding air, building structure, other equipment, supply air, and the electrical system.
For the purpose of this Technical Report. environnwnts are classified as “laboratory” or “shop.” A laboratory environment is controlled in order to perform measurements at an acceptable accuracy level. A shop environment is controlled only to the level required to produce acceptable workpieces. A shop elivironmfleilt may not he acceptable for performing measurement tasks,
2.3 EnvironmentaL Effects
The influence o environ,nental variables on the measurement results obtained using the CMM are classified as environmental effects. The variables are identified in para. 2.2,and their influence can vamygreatlyamongdilferent facilities, or even within one facility. Whereas temperature and humidity may vary depending on the time ot day or season olthe year, influences such as illumination, electrical noise, and vibration may be fairly constant for a given CMM installation. (:onumiiiration, either airborne or on the CMM and workpieces. may be either a steady-state or varying condition. The ability to manage contmniination will depend on the nature of the installation and the perceived impact of the contamination on measurement results.
Three main methods are employed to mitigate the influence of the environmental effects, as follows:
(a) ,1ttenpt to Remove the Source v1he Iimfluence. This may be done by shutting down or moving equipment causing vibration or removing heat sources from the immediate vicinity of the measuring equipment.
(h) AUenum#e the Ef/’a.c of (he Injhn’nce. Vibration isolators may he used between the tctory or laboratory floor and the CM M, or baffles may be installed to block radiation from a heat source that cannot be moved.
(cJ coni pen.sate fr the Influence. Ily using knowledge about how a particulmr influence effects the measurement and sensors to quantify the environmental state, (1w mneasimremiwnt results can beadiusted to comfwnsate for the eI)ViroflmL’nt.
After mitigation, simply evaluate the influence; the uncertainty of uleasureinent can be increased to accommodate the effect of environmental influences where these methods are not employed.ASME B89.4.21.1 pdf download.