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Slide 1
MGT3303 Operations Management The Orange Cake Problem Answer
Guide
Slide 2
MGT3303 Operations Management QuestionsQuestions Assuming you
work alone and follow the instructions above, how long will it take
you to bake the cake? Is there any obvious way to shorten the
preparation time? Assume that two people are available, how fast
can the cake now be prepared? Categorise activity as follows:
process, cook, cool. How much time is spent on each category? What
type of technology could be used to shorten the preparation time?
Distinguish these improvements which do not impact quality of the
cake from those that do. If you were commercialise this cake at a
large scale, how would you design the facilities and work to
achieve maximum efficiency and volume?
Slide 3
MGT3303 Operations Management Question 1 Assuming you work
alone and follow the instructions above, how long will it take you
to bake the cake? Is there any obvious way to shorten the
preparation time?
Slide 4
MGT3303 Operations Management Question 1 The problem is to
apply the recipe instructions on a timeline This does not mean
adding all the elementary times!! You have to take advantage of
idle times: When the cake is baking, start preparing the curd When
the orange slices are being poached, start preparing the mix But
you have to respect sequential dependencies You cannot pour the mix
before the orange slices are positioned
Slide 5
MGT3303 Operations Management SolutionSolution You should find
153 minutes minor variations (1 to 3 mn) are not much to worry
about Major variations (+ 5mn) should be analysed
Slide 6
MGT3303 Operations Management The First 63 Minutes Getting the
cake ready to bake
Slide 7
MGT3303 Operations Management The Middle 45 Minutes Cake is
Baking Start preparing the curd
Slide 8
MGT3303 Operations Management The Last 45 Minutes
Slide 9
MGT3303 Operations Management Question 2 Assume that two people
are available, how fast can the cake now be prepared?
Slide 10
MGT3303 Operations Management Horizontal Division of Labour By
dividing similar tasks (whisk/strain/mix) between several persons,
it is possible to compress processing times Overall time gets down
to 147 minutes only a 6 minutes gain in time!
Slide 11
MGT3303 Operations Management Question 3 Categorise activity as
follows: process, cook, cool. How much time is spent on each
category?
Slide 12
MGT3303 Operations Management Time Distribution Why this
question? To better understand where time is spent To identify
where time reduction efforts should be focused Timeline TimeMasks
Process43process 2414process 11cook 2314cool Cook20 4510cook
15process 18cool Cool102process 2019cook 1cool 14797244 Total
Process86 Cook95 Cool63 244
Slide 13
MGT3303 Operations Management Question 4 What type of
technology could be used to shorten the preparation time?
Distinguish these improvements which do not impact quality of the
cake from those that do.
Slide 14
MGT3303 Operations Management Time Improvements Three
categories: Technology input Use tools and devices which increase
output Cooling Time Question whether or not they are necessary?
Human Specialisation When you prepare the cake several times, tasks
which are originally difficult (e.g. slicing the cake in 3) become
easy Concept of a learning curve
Slide 15
MGT3303 Operations Management Technology Input Oven A fan oven
cooks slower but more evenly With a conventional oven, cooking time
could be brought down to 35 mn This may have a negative impact on
quality? Puree Preparation The hand mortar process is tedious A
hand blender does the job better and quicker ( 1 mn instead of
10)
Slide 16
MGT3303 Operations Management Cooling Times Poached Orange
Slices It is difficult to manipulate the slices when they are hot
But it is feasible with a skilled used of a spatula! The puree can
be blended hot So, cooling time can be brought down to 2 mn
Slide 17
MGT3303 Operations Management Cooling Times Cake It is
difficult to cut the cake when it is straight hot out of the oven
Again, experiencing with knifes and how to hold the cake means it
is possible to slice the cake when it is still warm. Reduce the
cooling time from 20 mn to 10 mn
Slide 18
MGT3303 Operations Management Cooling Times Curd A bit too
runny when hot, and tends to spread out too fast at the sandwiching
time Cooling time can be reduced to 10 mn, but not much more!
Slide 19
MGT3303 Operations Management Learning Curves Once the operator
is skilled, elementary times are reduced Note: this works well only
when tasks are repeated a large number of time (division) Slicing
the oranges: 2mn Mix for poaching: 1 mn Whisk eggs+sugar: 3 mn Mix
dry mix + puree: 2 mn Grate: 3 mn Straining poached oranges:
skipped altogether as by selecting the right slices and letting the
drip a bit save adding liquid later on Cut the cake in 3: 2 mn
Brush: 3 mn Sandwich: 3 mn Top: 1 mn
Slide 20
MGT3303 Operations Management New Process Times The cake can
now be prepared in 86 mn Better use of parallel processing!
Slide 21
MGT3303 Operations Management Question 5 If you were
commercialise this cake at a large scale, how would you design the
facilities and work to achieve maximum efficiency and volume?
Slide 22
MGT3303 Operations Management Suggested Layout
Slide 23
MGT3303 Operations Management Why this layout? Use existing
process centres between cooking and cooling operations Note that
each of these process centres demand about 10 minutes of work The
curd preparation station takes 10 minutes with 1 worker (per cake)
The finishing station also demands 10 mn / cake The mix preparation
demands 11 mn at two people shift the tin preparation, layout
slices to the poached orange station Make sense: do not carry the
slices The poached orange station is under-loaded
Slide 24
MGT3303 Operations Management Output?Output? With this staffing
level: Output is one cake every 10 minutes, or 6 cakes per hour, or
48 cakes a day for an 8 hour working day For a belt speed of 1 m/mn
for the oven conveyor: Cooking time is 35 mn so length is 3.5 m A
cake is loaded/emptied every 10 mn Plenty of space! (only 3.5 cakes
in the oven) 48 cakes per day is not much! We are a very, very long
way from mass production How could you improve this output?
Slide 25
MGT3303 Operations Management Increasing Output By applying
further the principle of horizontal division of labour: More
operators for more elementary tasks See assembly line design
Automation More technology inputs Special tools, cooking and
cooling technology