Analysis of Metrology Methods for Micro-endmills   
Undergraduate Thesis, MIT, Spring 2009

Micromilling is a machining method used in the medical, optical, and electronics industries to create high quality, detailed 3D microcomponents. However, micromilling causes increased amounts of tool wear and breakage, which are not easily visible on micro-scaled tools because of their small size. Size differences on the order of tens or hundreds of microns may be critical in microscale milling; thus, appropriate tool measurement is crucial.

My thesis studied and compared four micro tool metrology methods - laser-occlusion and optical, digital, and scanning electron microscopy - by measuring the diameters of ten endmills of five different sizes using all four measurement techniques. Qualitative measures including ease of use, image quality, and rate were reported as well as the numerical validity of tool measurements.

I found that while certain metrology methods may produce superior qualitative information, they lack suitable methods to process that data; other methods produce higher quantitative accuracy and repeatability yet require greater training or setup time to use them. Based on this research, depending on the constraints of a particular project, one method may be far more suitable than others options.

This thesis can be accessed in full here.

A 0.005’’ diameter endmill, imaged under (from left to right) optical microscope, scanning electron microscope, and digital microscope.