Question 2
A flat, stainless steel plate, of area 8 cm by 8 cm, needs to be ground to a high surface finish.
It is required to remove a depth of 0.4 mm across the surface of the plate.
a) Suggest a suitable type of grinding wheel for this job, in terms of abrasive and
bonding materials used, grit size, wheel grade and wheel structure. Give reasons for
your suggestions.
(6 marks)
b) Describe the preparatory and safety procedures that need to be carried out on the
grinding wheel prior to mounting onto the surface grinder, and prior to the
commencement of machining.
(7 marks)
c) It is planned to carry out the grinding operation using a grinding wheel of diameter
15 cm and width 2 cm, and using successive depths of cut of 0.02 mm, with two final
cuts of 0.01 mm each. Wheel speed is 1450 m/min, work speed is 0.25 m/s and the
cross feed is 0.4 mm. The number of active grits per area of the wheel surface is 0.75
grits/mm² with a grain aspect ratio of 20.
i) Determine the Material Removal Rates for both depths of cut.
(5 marks)
ii) If the cycle time for one forward/return stroke of the work during grinding is 5
sec., estimate the total time taken to complete the job.
(5 marks)
iii) Considering a constant of proportionality $K_2$ of 40,000, determine the maximum
surface temperature of the work.
(5 marks)
iv) What recommendations would you give to reduce any surface damage owing to
high work temperatures?
(5 marks)