Geometrical OR Alignment Tests

Geometrical OR Alignment Tests

Geometrical OR Alignment Tests -Geometrical tests check the manufacturing accuracy of the machine tool i.e., the accuracy with which the machine tool has been assembled. This is measured while the machine is idle and free of any load.

Geometrical tests check the dimensions of forms and positions of machine tool parts and also their displacement relative to one another. Such tests concern only sizes, forms, position and relative movements of the machine tool parts which may affect the accuracy of working of the machine tool.

The degree of working accuracy of the machine besides depending on the machine tool itself, is also influenced by such other factors as :

(i) The type of cutting tool and its condition (rake angles, hardness, eccentricity in the case of milling cutters, etc.),

(ii) The tool holder (example milling arbours),

(iii) The cutting speed, feed and chip section,

(iv) The material to be machined,

(v) The shape, size and rigidity of the workpiece,

(vi) The chucking or clamping equipment,

(vii) The skill of the operator.

Machine tool geometrical accuracy tests include: The checking of,

(1) Guideways for straightness,

(2) Work tables for flatness,

(3) Columns, uprights, and baseplates for deviation from the vertical and horizontal planes,

(4) Spindles for correct location and accuracy of rotation,

(5) Relative position of axis and surfaces, for parallelism and squareness,

(6) Lead screws and indexing devices for specific errors, etc.