Management Engineering - Operations Management

Full exam

Operations Management Exam – 11/01/2023 O PERATIONS M ANAGEMENT E XAM P r o f . A l b e r t o P o r t i o l i S t a u d a c h e r , M a r c o T a i s c h , M a t t e o R o s s i n i LEAN (13 points) LEGNUM s.r.l. produces wooden toys, both standard and customised based on customers preferences. The range of the standard family is composed of 50 variants: 5 different sizes, 2 shapes and 5 different surface paintings. The customized toys have peculiar colours chosen by the clients and each request differs from the others. The product customization starts from the painting phase. If the customer demands a standard toy, she requires to have it immediately, if she asks for a customised one, she is willing to wait up to 10 days. The demand for standard toys is stable with an average of 500 standard toys per day. The demand for the customised toys is equal to 20 customized toys per day: daily demand is very variable (+/- 30%) but observing a week it is stable. On average, a special order is composed of 10 items of the same variant. Production process: The production system is composed of 5 stages: Wood leaching, Wood cutting, Assembly, Painting, and Packaging. Wood leaching: there is one operator that uses semi-automatic machines; a setup is necessary when product shape changes; Wood cutting: there are two operators using semi-automatic machines; a setup is necessary when product shape changes; Assembly: there are two operators working in parallel on manual machines; a setup is necessary when product size changes. Painting: 3 operators work in parallel at three tables. Each operator works on a painting working station and he does all the activities necessary to complete a toy: first, he attaches chemical additives to the toy, then he paints it, and then he dries the paints. The three activities take more or less the same time. A setup is necessary when the surface painting changes; Packaging: there is one operator that uses a semi-automatic machine. A setup is necessary when the variant changes. Each shift lasts 8 hours and there is one break of 30 minutes per shift. Wood Leaching, Wood Cutting, and Painting are fully dedicated to this product family. Instead, Assembly is 50% dedicated to this product family, and the packaging is only 70%. Upstream the production system there is a stock of raw materials of 10000 pieces. There is no scrap in any process. Stations Cycle Time (sec.) (single operator) Changeover (min.) Availability (%) Shift per day Inventory (downstream) Wood Leaching 50 0 95 2 3000 Wood Cutting 80 25 (shape) 100 2 2000 Assembly 70 50 (size) 100 3 3000 Painting 180 20 (surface painting ) 98 2 5500 Packaging 40 5 (variant) 95 3 4500 The company receives everyday customer orders. The production control function issues a weekly production plan for each production stage. Twice per week, the Wood Leaching stage informs the production control function about the raw material inventory level. The production control function places a raw materials order to the supplier once per week. Twice per month it makes a forecast about the consumption of raw materials and sends it to the supplier. The supplier delivers the day after the order. Q1) Draw the current-state map of the operations system. Q2) Create a future-state map of the system (answer the first six questions of the future state): Define the minimum changes to have an EPE value for a standard product of a maximum of 1 day and to produce every day 20 special items (assuming that it is not possible to modify Availability, CT, and shifts in future state improvement targets). If a FIFO is introduced assume the demand per single shift. Operations Management Exam –January 11th, 2022 page 1/1 O PERATIONS M ANAGEMENT E XAM Prof. Alberto Portioli Staudacher, Marco Taisch, Matteo Rossini January 11th, 2023 Yield-Queue Exercise (9 points) The Love4Planet foundation is organizing a fundraising event with a social dinner that can hold up to 1000 guests. The event consists of a short documentary about the education in Tanzania at primary and secondary schools, a showroom with a shop where people can purchase some products as gifts for their friends and families and the social dinner. Considering that all the revenues will be donated to the Tanzanian population to create a new school, Love4Planet wants to maximize the revenues from this event so they decided to offer two types of tickets: a discounted one that people can buy from 90 days to 30 days before the event at 200 € and a full price one that people can buy from 29 days to the day before the event at 350 €. They can certainly fill the venue selling only discounted tickets. The demand for full-price tickets follows a normal distribution with a mean of 500 and a standard deviation of 100. The company will pay the social dinner to a catering company, a week after the event, 50 € for each meal consumed by discounted and 70 € for each meal consumed by full-price tickets. Based on the historical data they know that 80% of the participants (both discounted and full) will take the meal. Only to full- price participants, the company will give a framed poster of a Tanzanian landscape that costs 35 € each. The poster will be bought before the event. Moreover, thanks to the support of National Geographic, Love4Planet decided to donate to each participant a souvenir. Respectively, the small bag souvenir for Discounted costs 45 € each, while the big bag for Full customers costs 60 € each. National Geographic will participate to the expenses donating to Love4Planet 20 € for each souvenir bought. The souvenirs will be purchased before the event. The rental service of the place costs 10000 €. Regarding the shop, 3 assitants welcome customers entering the shop based on a FIFO logic. Once the customers are in the shop, if they are interested in purchasing something, they can ask support from the 4 shop assistants, each characterized by a single queue. If customers are not interested in purchasing something, on average 30% of those people that entered the shop, they can exit the shop. Instead, for those customers willing to purchase a gadget, 5 cash counters manage the purchasing process in a FIFO line. On average the number of customers entering the store is 800 per day. The store is open 8 hours per day. Process Service rate (1 resource) Stage 1: Welcome stage 500 people/day Stage 2: Walking around the store 450 people/day Stage 3: Chash counter 420 people/day Data interpolation is not requested. You can take the value that is closest to the one you desire. Question 1) (2 points) Define how many tickets to allocate for each customer segment (Protection Level). Question 2) (2,5 points) Define if and how the protection level changes if there is the possibility to sell the seats that are remained empty (both because they are not sold and because they are linked to a 10 % no-show phenomenon for the Discounted segment) with a last-minute ticket price of 100 € the same day of the event, knowing that in this way it would be possible to sell without any problem all the ones offered. The buyers of the last-minute tickets will be offered the same services of discounted rate tickets. It is assumed that the last-minute buyers have the same behavior as discounted ticket buyers. Question 3) (1 point) Considering the shop, please select the proper system among the 4 options available. Question 4) (2 points) Considering the shop, please fill in the table with all the relevant parameters for each stage (Arrival rate (pieces/day), Service rate, Type of queue, Ws (in minutes), and ρ). Approximate values are acceptable, no need for interpolation Question 5) (1.5 points) Calculate the expected throughput time for each path as well as the expected throughput time of the system considering the clients passing through all stages including the purchase.