【正文】 t are designed to improve quality and efficiency? 487 21–11 1. Basic Standard Deluxe Price ............................................................ $ $ $ Less: Variable cost.................................. .......................... Contribution margin $ $ $ 247。 (c) to avoid shutting down manufacturing facilities。 480 CHAPTER 21 INVENTORY MANAGEMENT: ECONOMIC ORDER QUANTITY, JIT, AND THE THEORY OF CONSTRAINTS QUESTIONS FOR WRITING AND DISCUSSION 1. Ordering costs are the costs of placing and receiving an order. Examples include clerical costs, documents, and unloading. Setup costs are the costs of preparing equipment and facilities so that they can be used for producing a product or ponent. Examples include wages of idled production workers, lost ine, and the costs of test runs. Carrying costs are the costs of carrying inventory. Examples include insurance, taxes, handling costs, and the opportunity cost of capital tied up in inventory 2. As ordering costs decrease, fewer and larger orders must be placed. This, in turn, increases the units in inventory and, thus, increases carrying costs. 3. Reasons for carrying inventory: (a) to balance setup and carrying costs。 (b) to satisfy customer demand。 (d) to take advantage of discounts。 Machine hours....................................... 247。 247。 hours are used to measure resource usage and availability): Fabrication: (1/3)X + (1/3)Y ? 800 (1) Assembly: (1/2)X + (2/3)Y ? 800 (2) The constraints are graphed below. (Units are in hundreds.) 05101520250 2 4 6 8 10 12 14 16 18 20 22 24ABC 496 21–18 Continued The graph reveals that only one binding constraint is possible (assembly labor). Thus, the contribution margin per unit of scarce resource will dictate the oute. For Part A, the CM per unit of assembly labor is $40 ($20 ? 2), and for Part B it is $36 ($24 ? ). Thus, only Part A should be produced. The optimal mix is 1,600 units per day of Part A and none of Part B. The daily contribution margin is $32,000 ($20 ? 1,600). 2. The drummer constraint is the assembly constraint. The mix dictates a production rate of 1,600 units of Part A per day. At this rate, all 800 hours available of the drummer constraint are used. The fabrication constraint would use hours at this rate, leaving hours of excess capacity. The drummer constraint sets the production rate for the entire factory, 1,600 units of A per day. The rope concept simply means that the production rate of the fabrication process is controlled by tying the release of materials to assembly’s rate of production. The daily release of materials to the fabrication process should be enough to produce only 1,600 ponents. The buffer means that there should be a supply of ponents in front of the drummer process (assembly) so that production can continue should the supply of parts to assembly be interrupted. Thus, a 2,400ponent inventory is required. This protects throughput in case production or supply is interrupted. The length reflects the time thought necessary to restore most production interruptions. 3. The use of local labor efficiency measures would encourage the fabrication process to produce at a higher rate than the drummer rate (it has excess capacity) and so would run counter to the TOC objectives. In fact, efficient use of labor in fabrication would cause a buildup of about 266 units per day of workinprocess inventory—a very expensive oute. 497 21–18 Concluded 4. Adding a second shift of 50 workers for the assembly process creates an additional 400 hours of assembly resource. There would now be 1,200 hours of assembly resource available. The assembly constraint now appears as follows: (1/2)X + (2/3)Y ? 1,200 The new constraint graph appears below. (Units are in hundreds.) 05101520250 2 4 6 8 10 12 14 16 18 20 22 24 26A CB Point C is now optimal: X = 2,400, Y = 0. The contribution margin before the increase in the labor cost of the second shift is $48,000 ($20 ? 2,400). Thus, the daily contribution margin increases by $16,000 ($48,000 – $32,000). Since the cost of adding the extra shift of 50 workers is $4,800, the improvement in profit performance is $11,200 ($16,000 – $4,800). 498 21–19 1. Dept. 1 Dept. 2 Dept. 3 Total Product 401 (500 units): ........................Labor hoursa 1,000 1,500 1,500 4,000 ................... Machine hoursb 500 500 1,000 2,000 Product 402 (400 units): ........................Labor hoursc 400 800 — 1,200 ................... Machine hoursd 400 400 — 800 Product 403 (1,000 units): ........................Labor hourse 2,000 2,000 2,000 6,000 ....................Machine hoursf 2,000 2,000 1,000 5,000 Total labor hours....................... 3,400 4,300 3,500 11,200 Total machine hours ................ 2,900 2,900 2,000 7,800 a2 ? 500。 3 ? 500. d1 ? 400。 1 ? 500。 2 ? 1,000。 2 ? 400. f2 ? 1,000。 1 ? 1,000. The demand can be met in all departments except for department 3. Production requires 3,500 labor hours in department 3, but only 2,750 hours are available. 2. Product 401: CM/Unit = $196 – $103 = $93 CM/DLH = $93/3 = $31 Direct labor hours needed (Dept. 3): 3 ? 500 = 1,500 Product 402: CM/Unit = $123 – $73 = $50 Requires no hours in Department 3 Product 403: CM/Unit = $167 – $97 = $70 CM/DLH = $70/2 = $35 Direct labor hours needed (Dept. 3): 2 ? 1,000 = 2,000 Production should be equal to demand for Product 403 as it has the highest contribution margin per unit of scarce resource. After meeting demand, any additional labor hours in Department 3 should be used to produce Product 401 (2,750 – 2,000 = 750