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MGT3303 Operations Management The Orange Cake Problem Answer Guide

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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?

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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?

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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

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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

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MGT3303 Operations Management The First 63 Minutes Getting the cake ready to bake

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MGT3303 Operations Management The Middle 45 Minutes Cake is Baking Start preparing the curd

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MGT3303 Operations Management The Last 45 Minutes

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MGT3303 Operations Management Question 2 Assume that two people are available, how fast can the cake now be prepared?

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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!

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MGT3303 Operations Management Question 3 Categorise activity as follows: process, cook, cool. How much time is spent on each category?

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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

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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.

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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

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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)

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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

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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

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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!

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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

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MGT3303 Operations Management New Process Times The cake can now be prepared in 86 mn Better use of parallel processing!

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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?

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MGT3303 Operations Management Suggested Layout

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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

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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?

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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