ISO 230-3:2020 defines four tests:

— an environmental temperature variation error (ETVE) test;

— a test for thermal distortion caused by rotating spindles;

— a test for thermal distortion caused by moving linear axes;

— a test for thermal distortion caused by rotary motion of components.

The tests for thermal distortion caused by moving linear axes (see Clause 7) are applicable to numerically controlled (NC) machines only and are designed to quantify the effects of thermal expansion and contraction as well as the angular deformation of structures. For practical reasons, the test methods described in Clause 7 apply to machines with linear axes up to 2 000 mm in length. If they are used for machines with axes longer than 2 000 mm, a representative length of 2 000 mm in the normal range of each axis is chosen for the tests.

The tests correspond to the drift test procedure as described in ISO/TR 16015:2003, A.4.2, applied for machine tools with special consideration of thermal distortion of moving linear components and thermal distortion of moving rotary components. On machine tools equipped with compensation for thermal effects these tests demonstrate any uncertainty in nominal thermal expansion due to uncertainty of coefficient of thermal expansion and any uncertainty of length due to temperature measurement.