Question C5 [7.5 marks]: The Hastelloy-X plate stock cost from the supplier is $61 /kg and has a material density of 8,220
kg/m3 . The recoverable cost of scrap Hastelloy-X machining chips is $7.8 /kg. If you sell the scrap chips to recover some cost,
what is the net material cost of each plate? assume the following to simplify the calculation:
• Tool 1 is used for 15% of the face milling process duration with an average depth of cut of 11mm. Tool 2 is used 50% of the
face milling process with an average depth of cut of 7mm. The remaining time is taken up by repositioning of the tool.
• The full width of the tools is used for all cutting operations.
 

Question C6 [10 Marks]:
(a) Estimate the manufacturing time and cost for a single injector plate if a Selective Laser Melting (SLM) manufacturing process
is used with the following assumptions:
• The plate is vertically orientated during the build such that the base of the part is its 300mm x 26mm face.
• Layer thickness is 50
μm
• Average layer laser scan time 24 seconds,
• Average layer recoating time 10 sec
• Every 4th layer is scanned twice by the laser for in-situ heat treatment
• A single laser is used
• The SLM machine costs $70 per hour to run
• The Hastelloy-X powder feedstock for the SLM machine costs $120/kg
• The volume of feedstock powder consumed to build one plate corresponds to the volume of the plate after peripheral
milling but prior to face milling.
• Ignore any additional time or costs associated with handling or processing of the parts
(b) Compare the cost SLM manufacture to machining assuming that CNC machining costs $275 per hour
(c) Discuss the outcome of your analysis and suggest ways in which the cost of SLM manufacture could be reduced and comment
on whether it is an appropriate manufacturing process for the injector plate.