8) CMM Calibration

Question 1

What Is the golden rule of metrology? Do CMM’s follow this?

Answer 1

Traceability - only measure using one degree of freedom at a time

No, CMM’s take multiple measurements at a time.

Question 2

What Is the purpose of calibration?

Answer 2

Calibration:

• provide confidence about a measurement instruments accuracy and repeatability
• To ensure a measurement is traceable

Question 3

Each country has specific standards, however what is the most dominant international standard in CMM calibration?

Answer 3

ISO10360

Question 4

What does Part 2 of iso10360 cover?

Answer 4

Guide to verification of CMM accuracy within measuring volume.

Question 5

How many measurement test lengths are recommend, for how many configurations, within iso10360?

Answer 5

For each 7 configurations, take and record 5 test lengths (within each of the 7 orientations.

Question 6

How is a machine verified using 10360?

Answer 6

Total length measurements = 105

Machine verified if none of the 105 values are greater than manufacturers stated error value.

Question 7

What apparatus is used for calibration within iso10360?

Answer 7

• Measurements taken with gauge blocks or length bars. These are clamped during measurement process
• Smallest gauge no smaller than 30mm
• Longest gauge greater than 66% of the diagonal of the CMM measurement volume.

Question 8

What is a cheaper and less time consuming solution to a full iso10360 verification?

Answer 8

Interim checking using a machine checking gauge is carried out more regularly. Less accurate than iso10360.