Statistical process control (13+15 = 28 questions) – engg381-14a

Details of Questions ( 13 + 15 *2 = 43)


ENGG381-14A Engineering Statistics 


Assignment 5  (15 Questions done twice by two people, i.e. 30 answers given in separate files)


-TASK A: SPC for Rod Thickness (7 Questions done twice by two people i.e. 14 Questions)

-TASK B: SPC for Pigment Manufacture Process (4 Questions done twice by two people i.e. 8 Questions)

-TASK C: Statistical Engineering Algorithm for truckpull2014.mtw Truck Pull (4 Questions done twice by two people i.e. 8 Questions)


Description of work:

A plant manufactured approximately 12,000 connecting rods per day for use in an engine assembled

in the plant. The rod, illustrated above, connects the piston (at the small or pin end of the rod) to the

crankshaft (at the large or crank end of the rod). The plant received forged blanks and machined the

rods in a large number of process steps.


Management identified the rod line for a variation reduction project because the overall scrap cost

was greater than budget. The yearly scrap cost was excessive, and the scrap rate had been 3.2% over

the previous four months. Looking at scrap records, the team found that scrap occurred at several

stages in the process and for several reasons. The results showed that 65% of the scrap occurred at a

grinding operation. At this operation, the team discovered that about 90% of the scrap was due to

rods with their crank end thickness less than specification. The team focused their attention on

reducing variation in rod thickness. Their first step was to set up control charts to see whether the

grinding step produced rods with a stable crank end thickness.


The worksheet contains the output from the first five days of charting. Thicknesses were recorded

from subgroups of 5 consecutive rods chosen at 8 times spread through each day. As in normal

operation, each rod was measured at 4 positions (white circles in figure); the worksheet contains their

mean thickness as a deviation from 0.900 inches in thousandths of an inch (i.e. mil). In that scale the

specification range is [10, 60] mil and in practice if any of the 4 deviation measurements was less than

10 mil the rod would be scrapped. Those with any over 60 mil were reworked.


All software output files and data files given in separate .zip files.


Another 13 questions + above 15 question details are as per the attachments.







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