【正文】 ($30,000 + $30,000) 21–6 1. EOQ = = = = 10,000 (batch size for large casings) 2. Setup cost = $6,000 ? 50,000/10,000 = $30,000 Carrying cost = $6 ? 10,000/2 = $30,000 Total cost = $60,000 ($30,000 + $30,000) 21–7 1. Small casings: ROP = Lead time ? Average daily sales Lead time = 3 + 20 = 23 days ROP = 23 ? 590 = 13,570 small casings Large casings: Lead time = 3 + 22 = 25 days ROP = 25 ? 200 = 5,000 large casings 2. Small casings require five batches per year (150,000/30,000). Large casings also require five batches per year (50,000/10,000). The lead time for the small casings is 23 days and that of the large casings is 25 days. Thus, the total workdays needed to produce the annual demand is 240 [(5 ? 23) + (5 ? 25)]. Since there are 250 workdays available each year, it appears possible to meet the annual demand. Given the initial inventory levels of each product, the daily and annual demand, and the lead times, the pany must build a schedule that coordinates production, inventory usage, and sales. This is a push system, as the scheduling of production and inventory is based on anticipated demand rather than current demand. $ 6 ,0 0 0 /$ 6 5 0 ,0 0 0 2 ??2DP/C000,000,100 485 21–8 Maximum daily usage....... 375 Average daily usage ......... 320 Difference ...................... 55 Lead time ............................. ? 2 Safety stock .................. 110 Reorder point = (Average rate of usage ? Lead time) + Safety stock = (320 ? 2) + 110 = 750 units 21–9 1. The entire Kanban cycle begins with the need to produce a final product—a product demanded by a customer. The demand for a product to be assembled is known from the production schedule. Assume that a final product is needed. The withdrawal Kanban controls movement of work between the assembly process and the manufacturing processes. It specifies the quantity that a subsequent process should withdraw from the preceding process. The assembly process uses withdrawal Kanbans to notify the first process that more subassemblies are needed. This is done by having an assembly worker remove the withdrawal Kanban from the container in the withdrawal store and place it on the withdrawal post. This WKanban signals that the assembly process is using one unit of subassembly A and that a replacement for it is needed. The replacement activity is initiated by a carrier who removes the production Kanban from the container of subassemblies in the SB stores area and places this PKanban on the production post. The container in the SB stores area is then moved to the withdrawal stores area with the WKanban attached (taken from the withdrawal post). The production Kanban tells the workers in the subassembly A cell to begin producing another unit. The production Kanban is removed and goes with the unit produced (which goes to the SB stores area). This Kanban system ensures that the second process withdraws subassemblies from the first process in the necessary quantity at the necessary time. The Kanban system also controls the first process by allowing it to produce only the quantities withdrawn by the second process. In this way, inventories are kept at a minimum, and the ponents arrive just in time to be used. 486 21–9 Concluded 2. The second process uses a vendor Kanban to signal the supplier that another order is needed. The process is similar to the internal flow described in Requirement 1. However, for the process to work with suppliers, the suppliers must be willing to make frequent and small deliveries. It also means that the supply activity works best if the supplier is located in close proximity to the buyer. The subassemblies must be delivered just in time for use. This calls for a close working relationship with the supplier. The inventory function on the materials side is largely assumed by the supplier. To bear this cost, there must be some pensating benefits for the supplier. Longterm contracts and the reduction of demand uncertainty are significant benefits for the supplier. EDI can facilitate the entire arrangement. If the supplier has access to the buyer’s online database, then the supplier can use the buyer’s production schedule to determine its own production and delivery schedule, making it easier to deliver parts just in time. In effect, the supplier and buyer almost operate as one pany. 21–10 The phrase ―implementing JIT‖ conveys to many the notion that one day a pany is conventional and the next day it is JIT with all of the benefits that are typically assigned to JIT. In reality, changing to a JIT environment takes time and patience. It is more of an evolutionary process than a revolutionary process. It takes time to build a ―partnersinprofits‖ relationship with suppliers. Many firms attempt to force the JIT practice with suppliers by dictating terms—but this approach really runs counter to the notion of developing close relationships—something that is vital for the JIT purchasing side to work. There must be trust and mutual benefits—not unilateral benefits—for JIT purchasing to bee a success. Also, management should be aware of the disequilibrium that workers may experience with JIT. Many workers may view JIT methodology as simply a way of extracting more and more work out of them with no pensating benefits. Others may see JIT as a threat to their job security as the nonvalueadded activities they perform are eliminated or reduced. Furthermore, management should be ready and willing to place some current sales at risk with the hope of assuring stronger future sales or with the hope of reducing inventory and operating costs to improve overall profitability. How else can you justify lost sales due to production stoppages tha