The main conclusion that we can draw from this experiment is that different Ferrous materials of different composition of variable hardness give different types of spark. The pattern of spark and the length of spark of different metals are different.
Generally in most of the cases ferrous metals and alloys such as Stainless Steel, H.S.S (High Speed Steel), Carbide Tool, Mild steel, C.R Sheet (Cold rod Sheet), give out spark. Where as the Non Metals such as Copper, Brass, and Aluminum do no give out any spark.
The MMR(material removal rate) of the metals if we take into account the particle deposition of the Non metals are higher than the Ferrous metals .One special that we can see in the Ferrous Metals is that the harder the metals the lower the MMR rate. The small length of spark greater is the hardness.
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