Drilling of high quality features in green powder metallurgy components

Machinability of Green Powder Metallurgy Components: Part II. Sintered Properties of Components Machined in Green State

“…The optimum cutting conditions for machining green PM components, as characterized in Part I of this study, [17] were used to fabricate fully-green-machined rings on a large scale. Both the quality of the outcome and the sintered properties have been characterized as a function of tool wear.…”

“…Nonetheless, tool wear exists in green machining and it has a strong effect on the machinability of green PM components when it is uncontrolled. In Part I of this study, [17] it has been shown that a feed rate of 0.0635 mm/r would minimize the effect of the tool wear when facing green PM components. Also, the surface speed suggested for preventing tool wear is 366 m/min.…”

“…The cutting tool and the tool holder used for the machining of the green PM specimens were chosen following the conclusions presented in Part I. [17] Table I presents the tools used for the machining of both series of samples. [19] Different tools were used for the machining of green and sintered components, to take into account the different machining behavior of the two series of samples.…”

“…The image analysis technique developed for the characterization of the width of the breakouts was detailed in Part I. [17] The surface finish was measured using a stylus profilometer. [22] Two different measures were analyzed: R a , which is the arithmetic mean of the absolute values of the profile deviation from the mean line, and R z , which is the sum of the mean height of the five highest profile peaks and the mean depth of the five deepest profile valleys, as measured from a line parallel to the mean line.…”

Tensile properties of sinter hardened powder metallurgy components machined in their green state

“…Such components have been successfully machined in their green state, in terms of surface finish and average width of breakouts, either for drilling or turning operations. 6,8,9 However, even if PM components with satisfactory geometrical quality have been produced by green machining, to our knowledge, no study concerning the sintered properties of such components has been published. Thus, in order to make green machining a viable manufacturing process, there is a need for the PM industry to characterise the mechanical properties of sintered components produced using a green machining operation.…”