Kristen’s Cookie Company 1. How long does it take to fill a rush order (from mix and spoon, Load oven, bake, cool pack, and receive payment)? (For orders of one dozen, and for orders of two dozens-same ingredients. ) Answer: (a) for orders of one dozen __ minutes According to the specified work arrangements, a Gant Chart (Basic case 1) is developed as follow: As obviously indicated from the above chart, it takes 26 minutes to fill a one dozen rush order. Page 3 of 10

DSME2030A ASSIGNMENT 1 (b) for orders of two dozens ___ minutes Assuming the work arrangement has not been adjusted, a Gant Chart (Basic case 2) for two dozens orders is developed as follow. Therefore, it takes 36 minutes to finish a two dozens rush order. 2. For orders of one dozen, how many orders can you fill in a night? Assuming 4 hours per night Answer: We can find from basic case 1 that we will spend 10 more minutes with one more dozen ordered because the oven has already been fully utilized and become bottleneck under this circumstance.

We know that the roommate can prepare oven for baking the second dozen just after finishing baking the first dozen, during the 10 minutes when the oven is prepared and the second dozen is baking, the first dozen can be cooled and packed in 7 minutes, and the remaining 3 minutes are enough for collecting money, moreover washing, mixing and spoon for the second dozen can be finished during the time of first baking. So we have proved that we need 10 more minutes when one more order are required.

We can construct a formula to express relationship between time (T, in minutes) and number of dozen(X) T=16+10X Assuming 4 hours(240 minutes) per night, here is the formula 240 ? 16 ? 10 x x ? 22 So we can make 22 dozen of cookies and also 22 orders per night. Page 4 of 10 DSME2030A ASSIGNMENT 1 3. 1 Given Kristen’s Cookie wants to maximize the profit, do you need to employ your roommate if all orders are one-dozen orders(assuming orders do not have the same ingredient)?

Answer: If Kristen does not employ his roommate, he needs to spend 13 more minutes for each extra one-dozen order, that is, it will take him 13+13n minutes to finish n orders. (As the following Gant Chart illustrates). Assuming 4 hours per night, Kristen can get 17 orders` profit. If Kristen employs his roommate, they need to spend 10more minutes for each extra one-dozen order (shown in basic case 1), that is, it will take them 16+10n minutes to finish n orders. (as discussed in question 2). Assuming 4 hours per night, they can get 22 orders` profit.

We assume Kristen and his roommate share the profits based on their work time (excluding idle time), for each one-dozen order, Kristen spends 8 minutes and his roommate spends 4 minutes. So Kristen will share 1/3 profits with his roommate and keep 2/3 profits for himself. Thus, Kristen can get 44/3(about 14. 67) orders` profit, which is less than 17 orders’ profit. From the comparison above, we can conclude: To maximize Kristen`s personal profit, Kristen does not need to employ his roommate if orders are one-dozen orders.

To maximize Kristen Cookies` total profit, Kristen needs to employ his roommate if orders are one dozen orders. Page 5 of 10 DSME2030A ASSIGNMENT 1 3. 2 What if orders are two-dozen orders (assuming each two-dozen order has the same ingredients)? You may reassign the job for you and your roommate. Answer: Firstly, we can compare the following two situations With Roommate (the same as basic case 2 without work rearrangement) Without Roommate (with rearrangement of work and 3 trays) As the oven is fully utilized and become the bottleneck, we can see that

Kristen doesn’t need to employ roommate if one more tray is used. Usually the cost of a tray would be cheaper than labor cost, so there is no need to employ roommate if the orders are two dozens. Page 6 of 10 DSME2030A ASSIGNMENT 1 3. 3 If orders are one-dozens orders, how many electric mixers and baking trays will you need? Answer: Assumptions: one oven, two persons, one-dozen orders. We can see from the basic case 1 that 2 trays are needed, because while the previous dozen is cooling (possessing tray 1), we can start the spooning of the second dozen. Then we can calculate the hourly capacity of the resources.

Oven Cycle time Hourly capacity 10 min/each 6 dz Mixer 6 min/each 10 dz. Kristen 8 min 7. 5 dz Tray 19 min 6. 32 dz for 2 Roommate 4 min 15 dz Now the oven is the bottleneck. Neither increasing the number of mixer nor tray can improve the efficiency. So our conclusion is that we need 1 mixer and 2 trays. A Gantt Chart (the same as basic case 1) for illustration is as follow. If we can rearrange the work distribution, Oven Cycle time Hourly capacity 10 min/each 6dz Mixer 6 min/each 10 dz. Kristen 6 min 10 dz Tray 19 min 6. 32 dz for 2 Roommate 6 min 10 dz

Still, the oven is the bottleneck of the work flow, so only 1 mixer and 2 trays are needed. If we want to further improve the performance, we need more ovens. Page 7 of 10 DSME2030A ASSIGNMENT 1 3. 4 What if we have 2 ovens? Answer: 1 mixer, 3 trays. Suppose batch size= 1 dozen, then we can calculate each facility or person’s cycle time and hourly capacity. Bake 1min (roommate) Oven1 10min Cool Mix(Kristen) 6 min per order Spoon(K) 2min Bake 1 min (roommate) Oven 2 10min 5min Pack and Payment (roommate) 3min According to the figure above, we can get: Oven Cycle time Hourly capacity 10 in/each 12dz Mixer 6 min/each 10 dz. Kristen 8 min 7. 5 dz Tray 17 min 3 dz for 1 7. 05 dz for 2 10dz for3 Because the trays are cheap,so it’s not sensible if we cannot maximize the hourly capacity because of the lack of trays. Therefore, we need 3 trays. Then we can see from the figure that Kristen is the bottleneck given that we have 2 ovens,1 mixer and 3 trays. The detailed process is shown in the Gantt Chart . Roommate 4 min 15 dz Page 8 of 10 DSME2030A ASSIGNMENT 1 If we can rearrange the working process, so it is good to give the spooning to roommate.

Under this circumstance,we can get: Oven Cycle time Hourly capacity 10 min/each 12dz Mixer 6 min/each 10 dz. Kristen 6 min 10 dz Tray 17 min 3 dz for 1 7. 05 dz for 2 10. 6 dz for3 Roommate 6 min 10 dz Then the hourly capacity increase from 7. 5 dz to 10 dz. Gantt Chart is below. Put all in the nutshell,we need 1 mixer and 3 trays provided that we have 2 ovens. Page 9 of 10 DSME2030A ASSIGNMENT 1 4. Are there any changes you can make in your production plans that will allow you to make better cookies in less time and less cost? – Establish online payment platform.

Currently the payment is processed manually. If an online payment platform is established, and we could further integrate the payment into the order entry stage so as to be performed automatically. In this way, one minute of labor time per cycle could be saved. Given that when we have two ovens and jobs reassigned, the labor will become bottleneck. Hence one minute labor time saved per cycle would be significant in terms of long run. – Use fan or air conditioner. Kristen can buy a fan or use air conditioner in the room to shorten the time of cooling.

Because cooling cost about 5 minutes in the whole process, which can be shorten when using external tools, so they can make use of air conditioner and fan. It is very common to use air conditioner in the halls, and the cost can be calculated within everyday expenditure. When it comes to winter or cold season, they can open windows and make room colder, so it also a useful method to shorten cooling time. – Use bigger and inexpensive packages. Currently, the package bag can only hold one dozen cookies, yet it takes 2 minutes to pack each dozen.

If we can use bigger packages, which, say, can hold 2 dozens each, then we can save half of the cost of the box. Also, it’s very likely that the time of packaging can also be saved by using bigger packages. So this improvement can allow us to make cookies in less time and less cost. Since the mixer can hold three dozens each time, to make the mixer more efficient, we can offer customers who order two-dozen or three-dozen orders containing same ingredient some small gifts or a little discount to encourage them. Page 10 of 10