"Shop-floor CMM." The term is one of the hottest buzz phrases is dimensional metrology. But for a coordinate measuring machine to be truly shop-floor it must be able to withstand the heat and temperature changes found on the floor.
Thermal expansion, the effect that temperature has on material at the microscopic level, can cause structural changes to a CMM at temperatures greater than 20 C. Depending on the factory's climate-control capability, temperatures from season-to-season can vary by 30 to 50 degrees. In addition to seasonal changes, day-to-day problems can affect measurement. Sunlight filtering through skylights or ambient-lighting windows can cause a machine to bend and can throw off measurements. Machine exhaust and heat generated by a machining center or boring machine can affect results. Temperature variations can creep in from nearby heating and cooling ducts, human body heat and even thermal memory from previous climatic environments.