Question turns per year. Question pallet positions. Question turns per year

Transcription

1 turns per year pallet positions turns per year

2 5.7 Storing in carton flow rack would increase sku-density and therefore pick-density, which means that travel time would be reduced. And if the sku s are in less-than-pallet quantities they are likely handled as cases anyway so there would be no appreciable increase in labor to load them into flow rack. 5.9 By storing pallets with shorter side on the pick face, there can be more pallets facing along the aisle, which means opportunity for more skus along the aisle, i.e. an opportunity to pick more product within this aisle. This concentration of activity tends to reduce labor requirements. By storing pallets with the longer side facing the aisle, case-pickers do not have to lean over so far to retrieve the last cases from a pallet. Accordingly, store with short side on the pick face if space is tight, especially if this is a pallet-out warehouse. Store with long side on the pick face if there are many cases on the pallet and they will be picked individually.

3 Read pages and learn the proof of optimal lane depth! 6.6 The layout on the left is preferablee in several ways: _ The most convenient locations are more convenient than in the layout on the right, and the most inconvenient locations are no worse. _ The layout on the left will support more dock doors at both shipping and receiving and so may be expected to support greater product flow. 6.7 Suggestion to include in your analysis: Consider for example natural direction of product flow, travel distancess and utilization of storage capacity. 6.9 A: 4 pallet positions B: 4 pallet positions C: 5 pallet positions D: 1 or 2 pallet positions Common lane depth: 4 pallet positions 6.10 Let qi be the number of pallets of sku i in the warehouse and zithe height to which these pallets may be stacked. Then the skus that will provide the best space utilization are those for which the optimum lane depth is close to 1; that is: or those skus with no more than two columns skus with between 17 and 33 pallets 6.16 reduced in size by a factor of 1/sqrt(2)

4 6.17 Suggestion: consider change in number of pallet positions % 6.22 Suggestion: Compare options with regard to most and least convenient locations 6.25 Suggestion: Under FIFO: The sku which causes the most frequent returns to respective storage location should have priority. For example, for skua each pallet position is required to be visited once every 5 weeks. No FIFO: Move additional inventory to the back and just circle the weekly required stock directly from receiving via storage to shipping. Which sku will be most frequently handled? 6.26 A)Skux incurs work at a rate of 1 visit every 3 days. Each pallet of skuy incurs work at a rate of 1 visit every 4 days. Storing skux in position A and skuy inpositions B, C results in the following work. Every twelve days there will be 4 visitsof 1 minute each to position A for total time 4 minutes; there will be 3 visits to position B at 2 minutes each for total time 6 minutes; and there will be 3 visits to position C at 2 minutes each for total time 6 minutes. Therefore the total time spent moving product over each 12-day period will be = 16 minutes, or 16/12 = 1,33minutes/day. This is the best solution under these conditions, as may be confirmed by doing the computations for the other two possibilities. Alternatively, one may observe that the total work may be expressed as the sum of products of frequency of visits fi times the distance di. C)One pallet of skuy is requested every two weeks and so this skuleaves sooner on average than does skux. Consequently the best storage policy is to put one pallet of skuy in position A, the pallet of skux in position B and the remaining pallet of skuy in position C (from which it does not move). Every two days we would visit skuy in position A; every three days we would visit skux in position B. Consequently the total work over six days would be (6/2)(1) +(6/3)(2) = 7 minutes and the average work per day would be 7/6 =1,17 minutes. Again, the pattern of storage is static. The savings, in minutes/day, is 4/3 7/6 = 1/6 =0,16

5 Chapter Suggestion: Consider the net-benefit mentioned on page Sku B has the strongest claim to storage in the fast-pick area, followed by sku A then sku C. Suggestion: Again (since min or max are unknown) apply the net benefit, line 2, below 7.4 sku A has the strongest claim to storage in the fast-pick area, followed by sku B then sku C. Suggestion: consider Example 7.1 on page 77. Pay attention to the fact that it is not MIN that is mentioned, it is actually the re-order point of each sku. Therefore, you should calculate the MIN for each sku to be put into the fast-pick area as ropi+ 1. Note thatt Labor Efficiency is given in the unit minutes, i.e. it denotes how many minutes are saved per pallet by including a sku in the fast-pick area ( FPA). 7.5 A Sku A C C D A B Bid Slots Cumulative Value Cumulative B

6 Suggestion: Instead of calculating based on pallets it is required to allocate slots. As result, for example, sku A must consume a minimum of 2 slots and B a minimum of 1 slot. C. Suggestion: Similar to B, this time a slot includes 4 pallets. D A B Suggestion: Start with calculating all three bids (bid for min, bid for rest, bid for all) and set up a table to compare them. The final result of the auction is displayed below.

7 7.7 Note: labor efficiency is the marginal net benefit per pallet position in the forward pick area (assuming that the sku gets all the positions it requestswith the corresponding bid). The column labeled Value gives the total benefit of thisaward. To allocate the 50 pallet positions, simply search down the field Cumulative Positions and stop immediately before increasing beyond 50. In this case 45 pallet positions are allocated and theree is no additional value to be derived from the remaining 50-5 = 5 pallet positions (unless you want to skip down to skus F and J, which leavesone pallet position remaining, and the same issue presents itself. When auctioning 50 pallet positions, the results are as follows: Skus that are stored only in the forward area: All of the pallets of A, B, and E entered the forward area on the strength of their only bid. Skus C and H won the minimum allocation on their first bid and additional space on a later bid. Skus that are stored only in the reserve area: D, F, I, J. (Thesee are the skuss that won no space in the auction.) Skus that are stored in both the forward and reserve areas: G. (This is the only sku thatt won space with its Bid #1 but was not successful with its Bid #2.) 7.13 Suggestion: Consider how bid # 2 and # 3 would change. (Is it possible to say anything how bid #1 changes??).

8 times Suggestion: Pay attention to the fact that only the less-than-pallet picks will be taken from the FPA. Full pallets will be taken directly from the reserve and thus do not add to number of restocks Suggestion: compare labor efficiency between sku A and B for the three situations Suggestion: The net benefit of picking this sku from the ground floor would be no more than (2-1)pi-(3)di. This is positive when the average picks per restock exceeds 3, or, equivalently, an average order requests less than 1/3 pallet. This is not the case here and so this would not be beneficial. Follow the same approach for the other two options and compare Suggestion: The sku which accounts for most restocks can generate the highest savings by being kept in a more convenient location.

9 8.2 Space for sku A is 2/3. Suggestion: See question 8.3 below how to take into consideration cost for restocking A: 12.0 B: 22.5 C: 45.5 Suggestion: First consider that 40 units of volume is reserved for safety storage. Put these aside for a moment and focus on the remaining space. According to the formula (OPT), calculate what fraction each sku should be allocated. As you will notice, one of the skuss will be allocated too little space in comparison with the established lead time demand. I propose that you increase that sku (the answer above gives you a hint which one it is) to cover its minimumm lead time demand then redo the allocation exercise for the other two skus based on the remaining space. 8.9 Sku A should be allocated 0.71 times (71% of) the space given to B. Suggestion: Note that allocation of space in the FPA does not take into account number of picks / how often a sku is requested. As the formula indicates, only the flow matters for dividing the space in the FPA. Develop an expression for v(a) and v(b) and calculate the ratio between them, ie v( (A)/v(B) 8.13 Suggestion: consider formula for labor efficiency 8.14 Green pen is more labor efficient Becausee the product is now sold in concentrated form, customers will request it half as often and its flow through the warehouse will be reduced by half. Furthermore, the number of picks remains the same: Because each store had ordered at least several bottles each week, we may assume that they now order at least one bottle each week. Thereforee the labor efficiency will become

10 which is greater than its previous labor efficiency. Therefore it has become more suitable for inclusion in the fast-pick area Suggestion: it is given that flow will increase. However, you can assume that picks remain the same (see question 8.17). Note: It may seem paradoxical that a very popular sku may not be suitable for the FPA; but this makes sense when we realize that restocking may consume any pick-savings. Such sku s (very popular but with large flows) could instead be stored in pallets near the shipping dock and never put in any storage rack. This way they can be picked quickly but never need restocking Suggestion: Think about and compare which costs would not be incurred unless the sku was picked from the FPA Solution for A and B: Suggestion: calculate flow as volume per month (can be done per year as well, but since everything is already presented per month this will be an easier approach just make sure that all skus are calculated for the same period of time). Note thatt the following formula only gives the fraction of available space in the FPA (i.e. 0 < v* < 1). Thus, you need to multiply with the given size. Solution for C:

11 8.26 Suggestion: Reduce the allocated space for sku B to 5 cubic feet and then reallocate the remaining space to 8.27 A: The total cost/month is smallest ($239.50/month) if only sku A is stored in the 10 cubic feet of flow rack and skuss B and C are picked from the alternative pick area. Suggestion: First calculate labor efficiency to determine which sku should be first to consider for the FPA. Thereafter, search among the ways of dividing the ranked sku s between flow rack and reserve and compute the total cost for each. The approach should be the following: 1) Put all skus ( A,B,C) in the reserve and calculate total cost 2) Include only the highest ranking (labor efficiency) sku in the FPA, and calculate total cost include costss for picking in FPA, restocking, picking from reserve 3) Include also the second highest ranking sku and recalculate total cost. Continue this process until costs increase instead of decrease. (and as you will notice, the total cost will decrease when including sku A but thereafter increasee if you add the second highest ranking sku to the FPA) For each calculation, consider setting up a table such as the below Suggestion: consider chapter ; sku i will be restocked as follows (reorder point going up is the same as increasing safety stock).

12 8.32 Suggestion: Following the logic of 8.31, increasing the safety stock (or reorder point) decreasess the denominator in the expression above. Thus, number of restocks will increase. Intuitively, increased number of restocks for a sku implies higher restocking costs and thereby less benefit for the claimed space in the FPA Suggestion: Read chapter With a large FPA no sku will be restocked very often under any reasonable allocation of space. Consequently, in this case, the difference between the optimal allocations and merely decent allocations can be small Suggestion: Compare the three allocation methods in terms of a) allocated volume per sku b) number of restocks per sku c) labor required to restock the FPA For example: Equal Space technique implies uniform volume allocation for all skus but results in most variation in frequency of restocking between the skus Sku I A B H C G E D F labor efficiency 182,6 74,5 65,7 39,5 26,4 22,4 17,0 10,5 4, Suggestion: build on the ranking from question You should apply greedy heuristics: first calculate the total cost without including any sku in the FPA (Flow rack in this case). Thereafter, include the highest ranking sku (I) and calculate the total cost again this time you will have incurred some restocking costs

13 as well. Then include the second highest ranking sku, and again calculate the total cost. This time you will first have to calculate the optimal allocation of space in the FPA between the two included skus. The optimal inclusion which generates the minimum operating cost is to include the top three skus. The minimum cost is 32, The net benefit of flow rack is 46,400 32, = 13, Suggestion: use same approach as in Again, you will find that the top three skus (ranked according to labor efficiency) should be included to minimize the operating costs. Total cost: 34,139; Net benefit: 12,261 Flow rack offers higher net benefit Suggestion: Find the optimal combination of flow rack and shelving using the greedy heuristic approach. Try for example to put the top 2 highest ranking skus in the flow rack (since this generated the highest net benefit) and complement by putting the next 2 skus into shelves. The total cost for this arrangement would be 27, Suggestion: Sku C is ranked higher than sku A; and sku A is ranked higher than sku B. If all skus are stored in the FPA, then A would be allocated the most space Suggestion: When considering which one is the single best to store forward, you also need to consider the savings in picking cost and the incurred restock costs. Therefore, calculate the bang-for-buck for k=1, this will reveal that sku A generates the largest saving. For k=2: select A and C; these should then be allocated half the space in the FPA (according to the EQS strategy) Total net benefit (sku A and C in FPA) is Sku A has highest flow and consequently will be allocated the most space if EQT strategy is implemented and all three skus are included in the FPA. Suggestion: remember that total net benefit and allocations are the same for EQT and EQS Suggestion: similar approach as previous exercises. Solution is to store sku B and D with a total net benefit of 86. Adopt approach for EQS and EQT.

14 9.3 Given that the depth of the shelf is 10, the following solution holds. Note that for the orientation [2,3,1], the solution is a multiplication between space utilization on depth and height. [H,D,W] 1,2,3 1,3,2 2,1,3 2,3,1 3,1,2 3,2,1 Shelf height 1 1,00 0,90 Shelf height 2 1,00 0,90 1,00 0,90 Shelf height 3 1,00 0,90 0,67 0,60 1,00 1, Given that the depth is 9, the below table indicates the volume utilization. Note that columns indicate the utilization as the carton is turned in the different dimensions. [H,D,W] 1.25 * 2.4 * 2.75 (abc) acb bac bca cab cba Shelf height 1.5 0,67 0,76 Shelf height 2 0,50 0,57 Shelf height 2.5 0,80 0,92 0,93 0, Suggestion: to quickly understand what is the absolute (theoretical) minimum of shelves needed, just add the sku widths together and divide by the shelf width: ( ) / 10 = 33 / 10 = 3,3 => at least 4 shelves are needed! Next Fit uses six shelves First Fit uses four shelves Next Fit decreasing uses five shelves First Fit decreasing uses four shelves 9.7 Pick-density = picks divided by width of the allocation Note: this strategy for allocation will concentrate picking along the pick path. This can be good (by for example reducing travel time), however it could potentially cause congestion in the aisles. Therefore, consider carefully the situation before recommending strategy for slotting.

15 10.1 See illustration for an example: B C E A D end 10.6 Suggestion: Study the example in the text book carefully. The answer to this exercise is as follows:

16 11.4 Production rate of the line is 23 orders / hour If workers are arranged from fastest to slowest, eventually all of them will work at the rate of the slowest worker, i.e. 5 orders per hour => production rate 15 orders / hour 11.5 A. 16 orders per hour B C. f(x) = (3 / 5)(1 x) D. Yes, that point is 0.625

17 12.13 A operations per hour B. 32% increase C operations per hour D. Increase: 46% A operations per hour B operations per hour C. 37% increase D. 78% for uniform SC cycles; 70% for class-based SC cycles E. 3.4 minutes F operations per hour

18 14.3 Most picking devoted to 3-line orders

19 15.2 Efficiency score of warehouse A is 75%