Needle selection to maintain the accuracy of the good habit

Choose a good habit to maintain accuracy.

Which needle should I choose?

Overview of needle selection:

• Try to choose a short measuring needle, the shorter the measuring needle, the higher the hardness

• Choose as much as possible to avoid the interference of the rod and the influence of the surface finish of the workpiece under test

• Minimize connection points as it may reduce the accuracy of bending and offsetting

• The star needle allows for the simultaneous use of up to five needles and is very convenient for measuring some features of the cavity, such as the annular groove in the hole.

In addition to the above conventional methods, there are three scenarios that should be considered:

1. Test the accuracy level of the ball

In order to achieve high accuracy, most measuring machines are provided with a 5 stage measuring ball. When buying replacement parts, never choose a lower grade (grade 10) gauge needle, as this usually results in a 15% loss in overall accuracy of the machine. Saving money by measuring needles is a mistake that can greatly undermine the accuracy of your quality assurance system. Renishaw can provide high precision three-stage test balls on special orders.

2. Measure the material of the needle and ball head

• Ruby

It is a standard material in the industry with high hardness and wear resistance and can be used in the vast majority of applications.

Renishaw three coordinate needle measurement

• Silicon nitride

This is the preferred material for scanning aluminum because it avoids the phenomenon of "adhesion wear".

Select the three coordinate measuring needle

• Zirconia

The choice when scanning cast iron can avoid "adhesion wear."

3. Measure the needle material

• steel

Most of them use measuring ball with diameter greater than 2mm and length less than 30mm. All measuring needles are made of non-magnetic stainless steel measuring rod. The steel measuring rod has a good fit. That's why. * Common measuring rod material.

• Tungsten carbide

This material provides good hardness when measuring ball diameter is less than 1 mm or measuring needle length is more than 50mm.

• Ceramics

When the ball diameter is greater than 3 mm or the needle length is greater than 30mm This material provides the option of hardness equal to stainless steel but weight less than tungsten carbide.

• Carbon fiber (RenishawGF)

It is a specially developed carbon fibre that is not only light in weight but still has good rigidity for a long time (up to 800mm in length on the SP80 scanning probe).