In October 2020, I was offered the opportunity to assist a graduate research team at WPI in manufacturing materials testing samples for their winter conference. I completed an Independent Study Project (ISP) for mechanical engineering credit over the course of the term with the Integrative Materials Design Center.

The most difficult machining challenge I faced was determining and executing a process for extracting samples from a cylinder head similar to the one pictured (the actual block cannot be shown for confidentiality purposes) with a CNC mill. Due to the unpredictable geometry of the cast engine, some of the locations we planned to extract from produced unusable samples. After several weeks of trial and error, we determined which locations would provide consistently good samples.

Because the outside surface of the cylinder head was not machined, we first clamped it down and faced off enough material to tram and probe the workpiece. To extract each sample, we contoured the profile with a small endmill and sliced off the part with a slitting saw. After removing the samples from the block, we ran another operation on a separate mill to add threads to the end in order to attach it to the testing machine. The samples were then cleaned and polished before testing.

The sample to the right shows visible plastic deformation after performing a preliminary tensile test to make sure it would fail at the desired location.

In addition to the engine block, I assisted one of the postdoctoral team members in machining cylindrical test samples from a titanium alloy. Because titanium is so unforgiving, I had to adjust the toolpaths quite a bit to produce threads that fit into the testing machine. We used a endmill in a radial live tooling spindle to machine the flats.