Construction of CMM:
The co-ordinate measuring machines has movements in X-Y-Z which can be easily controlled and measured. Each slide in three in three directions has transducer which gives digital display and senses +ve/-ve direction. The measuring head has a probe tip, which can be different kinds like taper tip, ball tip etc.
- Length bar measuring machine.
- Newall measuring machine.
- Universal measuring machine.
- Co-ordinate measuring machine.
- Computer controlled co-ordinate measuring machine.
Length bar measuring machine
When the length of any bar is to be measured, a length bar of appropriate grade whose dimensions are exactly known is placed over the vee supports which are then adjusted in height so that axis of the bar and axis of measurement are coincident.
Newall measuring machine
The work has been placed between the anvils, the micrometer screw is adjusted until the bubble in the sprit level is brought to a fixed position. Again for other settings, the conditions are kept same and settings can also be done accurately by the adjustment upto the set accuracy.
Universal measuring machine
It can be utilized to measure length and diameters of both plain and threaded work, tapers and the pitch of the screw threads to a high degree of accuracy. Some machines employ two and three co-ordinate measuring systems. The accuracy of measurement for these machines is an accurately divided scale viewed through a microscope.
Co-ordinate measuring machine
Three dimensional measurements are essential for various components. CMM is useful for this purpose. Some co-ordinate measuring machines utilize electronic indicator probe which can reach over and under the work piece to check squareness in a single setup.
Computer controlled co-ordinate measuring machine
The measurement as well as the inspection of parts is done at the same time in a fully coordinated manner for dimension, form, surface characteristics and position of geometrical elements.