Develop the material requirements plan for the next 6 weeks for items D, E, and F by filling the app

 

6. Resource Planning (16 Points):The following information is available for three MPS items:
   Product A An 75-unit order is to be started in week 3 and a 55-unit order started in week 6.
   Product B   A 120-unit order is to be started in week 5.
   Product C   A 60-unit order is to be started in week 4.Develop the material requirements plan for the next 6 weeks for items D, E, and F by filling the appropriate MRP tables (the planned order releases POR row is the main row of interest, followed by the projected ending-inventory POHEI row). The BOMs are shown in the Figure below, and data from the inventory records are shown in the Table below. Notes: A safety stock requirement applies to item F. Be sure to plan a receipt for any week in which the projected on-hand inventory becomes less than the safety stock. Remember to enter any action or exception notices at the end of the MRP tables and answer the SAP question at the end.

BOM Figure (numbers in brackets are item usage quantities to make each immediate parent item):

 

Inventory Records Table:

Item	Lot Size Technique	Lead Time	Scheduled Receipts	On-Hand	Safety Stock
D	FOQ = 150	4 weeks	150 (week 3)	150	0
E	L4L	1 week	120 (week 2)	10	5
F	FOP, P = 2	2 weeks	None	100	30

L4L = Lot-for-Lot; FOQ = Fixed Order Quantity; FOP = Fixed Order Period

Acronym Key: GR = Gross Requirements; SR = Scheduled Receipts, POHEI = Projected On Hand End-of-period Inventory, NR = Net Requirements, PR = Planned Receipts, POR = Planned Order Releases

 

MRP Explosion Tables for answering MRP question (feel free to edit Word doc or use Excel)

Lot-sizing: _____F0Q=150______; Lead-Time: ____4 Week_________; Safety Stock: ______0______

Item ___D_____	Week 1	Week 2	Week 3	Week 4	Week 5	Week 6
GR
SR
POHEI
NR
PR
POR

 

Lot-sizing: _______L4L________; Lead-Time: _______1 week__________; Safety Stock: _______5_________

Item ___E______	Week 1	Week 2	Week 3	Week 4	Week 5	Week 6
GR
SR
POHEI
NR
PR
POR

Lot-sizing: ____FOP, P=2_______; Lead-Time: ______2 weeks___________; Safety Stock: ______30__________

Item ____F_____	Week 1	Week 2	Week 3	Week 4	Week 5	Week 6
GR
SR
POHEI
NR
PR
POR

 

Action / Exception / SR Adjustment Notices:(These are notices that require / suggest actions in week 1 to be implemented before the next time MRP explosion calculations are run again for Weeks 2 thru’ 7.) _________________________________________________________________________________________________________________

1. JIT/ Lean (19 Points): The Farm-4-Less tractor company produces a grain combine (GC) in addition to both a large (LT) and small size tractor (SM). Its production manager desires to produce to customer demand using a mixed-model production line. The current sequence of production, which is repeated 30 times during a shift, is SM-GC-SM-LT-SM-GC-LT-SM. A new machine (GC, LT, or SM) is produced every two minutes. Based on this information, answer the following questions:
2. (4 points) How long does it take for the repeating production cycle to be completed? How long is the working duration of a shift at Farm-4-Less?
3. (3 points) How many of each type of machine does Farm-4-Less produce in a shift?
4. (6 points) How might the production sequence be improved? [Provide a new improved sequence and mention why your sequence is better.]
5. (6 points) Consider a common component X that is used in GC, LT, and SM, with usage quantities given by: 1X to make each GC, 2X for each LT, 3X for each SM. Suppose each container with 10 units of X waits in queue, on average, 1 hour before it starts being processed. Each unit of X takes 0.5 minutes to process (make) at a station, so the container process time is (0.5)x10 = 5 minutes. The safety stock factor for X is 20%. How many kanban cards should there be for X at the station?

 

• Factory Dynamics (30 points): Consider a balanced serial line with four single-machine stations and exponentially distributed process times. Let t and r_b denote, respectively, the average process time per job at each station and the bottleneck production rate. [Use specific values of t and r_b, if useful. For example, if each of the stations was like those in Penny Fab One, t = 2 hours and r_b = 0.5 jobs per hour. You should get the same answers no matter what t and r_b you choose, as long as r_b = 1/t (as required in single-machine stations).] Suppose the line utilization is 75 percent (i.e., TH = 0.75 r_b) and the line runs under the CONWIP protocol, i.e., a new job enters when an old completed job leaves.
  1. (13 points) What is the value of W₀ for this line? Calculate the WIP level, w, for the line assuming its current throughput corresponds to the Practical Worst Case.
  2. (9 points) Calculate the practical worst case cycle time as a percentage or multiple of T₀, the raw process time (If CT = 2 T₀, cycle time is two times or 200% of T₀)
  3. (8 points) How would you expect the line’s performance to change if a machine was added to the middle station # 3, ceteris paribus (all else remaining unchanged)?Why? Outline an approach to estimate the line’s average cycle time when the line becomes imbalanced by the added machine at station 3. [No need for any calculations.]

 

1. Variability (35 Points):This question is intended to build and test your intuition on the design of waiting lines with variability and two identical streams of customer arrivals (e.g., men and women). The three systems being considered are shown below, where the arrow denotes flow with arrival rate r_ak, for stream k = 1, 2, the triangle represents the waiting line or queue and the rectangles represent processing by a server with specified average unit processing time – the two rectangles inside a larger rectangle in System B corresponds to a two-server station; System C is a single-server station with average unit process time cut by 50%; assume values for r_ak and t_e, for instance, take r_a1 = r_a2 = 0.9 customers per hour, t_e = 1 hour. Unless otherwise stated, assume all coefficients of variation are 1.0.

 

 

1. Utilization: (5 points)Calculate the utilization of the three systems, A, B, and C. Show your work.
2. Time in Queue: (15 points)Calculate the average time in queue in the three systems. Show your data values / approach.
3. CT_q and CT comparison: (10 points) Which system has the lowest average time in queue, CT_q?Which system has the lowest time in system, CT?Explain qualitatively (in layman’s terms) why the pooled system B has lower CT_q than the independent system A.Will the choice of which system has the lowest CT continue to hold if the variability factor, V, is not 1 but could be large (e.g., V = (c_a² + c_e² )/2 = 2.5, corresponding to c_a² = 1, and c_e² = 5)? Explain your Yes / No choice.
4. Practical / non-quantitative aspect: (5 points) Some have argued that, in queuing systems with human customers, it is not only the time in queue that matters but the psychological perception of the time in queue. One such discussion is presented in https://www.youtube.com/watch?v=_CBD2z51u5c (this 8-minute INFORMS Society video showcases Dr. Dick Larsen from MIT discussing “queueing” theory); another is discussed in the blog at http://davidmaister.com/articles/the-psychology-of-waiting-lines/.Answer ANY ONE of the following:
5. Present your own examples of waiting lines where the psychology of queuing is more important and where is it less important.
6. Discuss possible new “Human Element” type laws (not the ones in the text) that relate to the psychology of queuing.