Effects of milling condition on the surface integrity of hot forged steel
AUTOR(ES)
Rodrigues, Alessandro R., Matsumoto, Hidekasu, Yamakami, Wyser J., Paulo, Rafael Gustavo da R., Assis, Cleiton Lazaro F. de
FONTE
Journal of the Brazilian Society of Mechanical Sciences and Engineering
DATA DE PUBLICAÇÃO
2010-03
RESUMO
This paper presents a study on the influence of milling condition on workpiece surface integrity focusing on hardness and roughness. The experimental work was carried out on a CNC machining center considering roughing and finishing operations. A 25 mm diameter endmill with two cemented carbide inserts coated with TiN layer were used for end milling operation. Low carbon alloyed steel Cr-Mo forged at 1200 ºC was used as workpiece on the tests. Two kinds of workpiece conditions were considered, i.e. air cooled after hot forging and normalized at 950 ºC for 2 h. The results showed that finishing operation was able to significantly decrease the roughness by at least 46% without changing the hardness. On the other hand, roughing operation caused an increase in hardness statistically significant by about 6%. The machined surface presented deformed regions within feed marks, which directly affected the roughness. Surface finish behavior seems to correlate to the chip ratio given the decrease of 25% for roughing condition, which damaged the chip formation. The material removal rate for finishing operation 41% greater than roughing condition demonstrated to be favorable to the heat dissipation and minimized the effect on material hardness.
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