Select a dedicated measuring needle for workpiece inspection

Some simple and correct rules can be used to ensure the highest accuracy for most measurement applications

Select appropriate measuring needles to achieve the highest accuracy

Selecting measuring needles from Renishaw's full range of original measuring needles ensures optimal performance in needle design and materials.

However, the configuration of the measuring needle you choose will also have a significant impact on the measurement accuracy.

term

A=Diameter of the measuring ball

B=Total length

C=Measuring Rod Diameter Measuring Needle Terminology

D=effective working length

Total length

Renishaw's standard definition of the total length of a measuring needle is the length from the end face of the needle after installation to the center of the measuring ball.

Effective Working Length (EWL)

The effective working length is the distance between the center of the measuring ball and the interference point between the measuring rod and the measured target when measured in the normal direction of the part.

Selection rules for measuring needles

Some simple needle selection rules can be used to achieve the highest accuracy for most probe measurement applications.

Try to use short measuring needles as much as possible

The greater the bending or deformation of the measuring needle, the lower the accuracy. Using the shortest possible measuring needle is your best choice.

Try to minimize joints as much as possible

For every additional connection between a measuring needle and an extension rod, a potential bending and deformation point is added. Minimize the number of probe components as much as possible in the application.

The diameter of the selected measuring ball should be as large as possible

The reasons are as follows.

This can increase the distance between the measuring ball/measuring rod, thereby reducing false triggering caused by collisions with the measuring rod and increasing the effective working length;

The larger the measuring ball, the larger the diameter of the available measuring rodIncreased the rigidity of the measuring needle;

The larger the diameter of the ruby measuring ball, the less affected it is by the surface smoothness of the tested workpiece.

The effective working length is also affected by assembly tolerances. For this reason, Renishaw probes are assembled according to strict standards under controlled conditions.