The Orange Cake Problem

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The Orange Cake Problem. Answer Guide. Questions. 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? - PowerPoint PPT Presentation

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<ul><li><p>The Orange Cake Problem</p><p>Answer Guide</p></li><li><p>QuestionsAssuming 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?</p></li><li><p>Question 1Assuming 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?</p></li><li><p>Question 1The problem is to apply the recipe instructions on a timelineThis does not mean adding all the elementary times!!You have to take advantage of idle times:When the cake is baking, start preparing the curdWhen the orange slices are being poached, start preparing the mixBut you have to respect sequential dependenciesYou cannot pour the mix before the orange slices are positioned</p></li><li><p>SolutionYou should find 153 minutesminor variations (1 to 3 mn) are not much to worry aboutMajor variations (+ 5mn) should be analysed</p><p>Warm UpOven</p><p>1 mn</p><p>SliceOranges</p><p>Mix</p><p>Cook Orange Slices</p><p>Leave to Cool</p><p>TinPrep.</p><p>ArrangeSlices</p><p>Strain</p><p>Puree</p><p>DryMix</p><p>Whisk</p><p>Mix</p><p>Mix</p><p>Pour</p><p>Bake</p><p>Bake</p><p>45 mn</p><p>R</p><p>Leave to Cool</p><p>T</p><p>Mix</p><p>S</p><p>Grate</p><p>Mix</p><p>P</p><p>Leave to Cool</p><p>Bake</p><p>30 mn</p><p>19 mn</p><p>Cut in 3</p><p>Brush</p><p>Sandwich</p><p>Top</p><p>153 mn</p><p>63 mn</p><p>45 mn</p></li><li><p>The First 63 MinutesGetting the cake ready to bake</p><p>Warm UpOven</p><p>1 mn</p><p>SliceOranges</p><p>Mix</p><p>Cook Orange Slices</p><p>Leave to Cool</p><p>TinPrep.</p><p>ArrangeSlices</p><p>Strain</p><p>Puree</p><p>DryMix</p><p>Whisk</p><p>Mix</p><p>Mix</p><p>Pour</p><p>63 mn</p></li><li><p>The Middle 45 MinutesCake is BakingStart preparing the curd</p><p>Bake</p><p>Bake</p><p>45 mn</p><p>Mix</p><p>S</p><p>Grate</p><p>Mix</p><p>P</p><p>19 mn</p></li><li><p>The Last 45 Minutes</p><p>R</p><p>Leave to Cool</p><p>T</p><p>Leave to Cool</p><p>Bake</p><p>Cut in 3</p><p>Brush</p><p>Sandwich</p><p>Top</p><p>45 mn</p></li><li><p>Question 2Assume that two people are available, how fast can the cake now be prepared?</p></li><li><p>Horizontal Division of LabourBy dividing similar tasks (whisk/strain/mix) between several persons, it is possible to compress processing timesOverall time gets down to 147 minutes only a 6 minutes gain in time!</p><p>SliceOranges</p><p>Mix</p><p>Cook Orange Slices</p><p>Leave to Cool</p><p>TinPrep.</p><p>ArrangeSlices</p><p>Strain</p><p>Puree</p><p>DryMix</p><p>Whisk</p><p>Mix</p><p>Mix</p><p>Pour</p><p>Bake</p><p>Bake</p><p>45 mn</p><p>Warm UpOven</p><p>R</p><p>Leave to Cool</p><p>T</p><p>Cut in 3</p><p>Brush</p><p>Sandwich</p><p>Top</p><p>Mix</p><p>S</p><p>Grate</p><p>Mix</p><p>P</p><p>Leave to Cool</p><p>Bake</p><p>1 mn</p><p>30 mn</p><p>23 mn</p><p>147 mn</p><p>57 mn</p><p>45 mn</p></li><li><p>Question 3Categorise activity as follows: process, cook, cool. How much time is spent on each category?</p></li><li><p>Time DistributionWhy this question?To better understand where time is spentTo identify where time reduction efforts should be focused</p></li><li><p>Question 4What 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.</p></li><li><p>Time ImprovementsThree categories:Technology inputUse tools and devices which increase outputCooling TimeQuestion whether or not they are necessary?Human SpecialisationWhen you prepare the cake several times, tasks which are originally difficult (e.g. slicing the cake in 3) become easyConcept of a learning curve</p></li><li><p>Technology InputOvenA fan oven cooks slower but more evenlyWith a conventional oven, cooking time could be brought down to 35 mnThis may have a negative impact on quality?Puree PreparationThe hand mortar process is tediousA hand blender does the job better and quicker ( 1 mn instead of 10)</p></li><li><p>Cooling TimesPoached Orange SlicesIt is difficult to manipulate the slices when they are hotBut it is feasible with a skilled used of a spatula!The puree can be blended hotSo, cooling time can be brought down to 2 mn</p></li><li><p>Cooling TimesCakeIt is difficult to cut the cake when it is straight hot out of the ovenAgain, 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</p></li><li><p>Cooling TimesCurdA bit too runny when hot, and tends to spread out too fast at the sandwiching timeCooling time can be reduced to 10 mn, but not much more!</p></li><li><p>Learning CurvesOnce the operator is skilled, elementary times are reducedNote: this works well only when tasks are repeated a large number of time (division)Slicing the oranges: 2mnMix for poaching: 1 mnWhisk eggs+sugar: 3 mnMix dry mix + puree: 2 mnGrate: 3 mnStraining poached oranges: skipped altogether as by selecting the right slices and letting the drip a bit save adding liquid later onCut the cake in 3: 2 mnBrush: 3 mnSandwich: 3 mnTop: 1 mn</p></li><li><p>New Process TimesThe cake can now be prepared in 86 mnBetter use of parallel processing!</p><p>S.O</p><p>M</p><p>Cook Orange Slices</p><p>C</p><p>TinPrep.</p><p>ArrangeSlices</p><p>P</p><p>DryMix</p><p>Whisk</p><p>Mix</p><p>Mix</p><p>Pour</p><p>Bake</p><p>35 mn</p><p>Warm UpOven</p><p>R</p><p>Leave to Cool</p><p>T</p><p>Cut in 3</p><p>Brush</p><p>Sandwich</p><p>T</p><p>Mix</p><p>S</p><p>Grate</p><p>Mix</p><p>P</p><p>Leave to Cool</p><p>Bake</p><p>86 mn</p><p>1 mn</p></li><li><p>Question 5If you were commercialise this cake at a large scale, how would you design the facilities and work to achieve maximum efficiency and volume?</p></li><li><p>Suggested Layout</p><p>Poached Orange Station</p><p>SlicingandMixing</p><p>TinPrep</p><p>Cook</p><p>Mix Preparation(Dry+Puree+Pour)</p><p>Oven Conveyor Belt</p><p>Cooling Conveyor Belt</p><p>FinishingStation</p><p>Cutting&amp; Sandwiching</p><p>Cook</p><p>Prep.</p><p>Curd Preparation Station</p><p>Cool</p><p>ToPackaging</p></li><li><p>Why this layout?Use existing process centres between cooking and cooling operationsNote that each of these process centres demand about 10 minutes of workThe curd preparation station takes 10 minutes with 1 worker (per cake)The finishing station also demands 10 mn / cakeThe mix preparation demands 11 mn at two people shift the tin preparation, layout slices to the poached orange stationMake sense: do not carry the slicesThe poached orange station is under-loaded</p></li><li><p>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 dayFor a belt speed of 1 m/mn for the oven conveyor:Cooking time is 35 mn so length is 3.5 mA 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 productionHow could you improve this output?</p></li><li><p>Increasing OutputBy applying further the principle of horizontal division of labour:More operators for more elementary tasksSee assembly line design AutomationMore technology inputsSpecial tools, cooking and cooling technology</p></li></ul>