1. What is the transfer-line manufacturing system? What are its
advantages? What are its disadvantages? (10 pts)
2. What is the flexible manufacturing? What are its advantages? What
are its disadvantages? (15 pts)
3. What is the just-in-time (JIT) manufacturing? How to achieve it?
How does it impact facilities design? (15 pts)
4. What is the U-shaped flow-line manufacturing system? Why does it become
so popular? (10 pts)
5. What are the similarities and differences between the
just-in-time (JIT) manufacturing and lean manufacturing? (This is an open-end
question. The textbook does not give full coverage. You need to do some
researches and use other books. Your answer needs to be very detailed because
this question is worth 20 pts.) (20 pts)
Name______________________________________________________________________ 1. What is the transfer-line manufacturing system? What are its advantages? What are its disadvantages? (10 pts) 2. What is the flexible manufacturing? What are its advantages? What are its disadvantages? (15 pts) 3. What is the just-in-time (JIT) manufacturing? How to achieve it? How does it impact facilities design? (15 pts) 4. What is the U-shaped flow-line manufacturing system? Why does it become so popular? (10 pts) 5. What are the similarities and differences between the just-in-time (JIT) manufacturing and lean manufacturing? (This is an open-end question. The textbook does not give full coverage. You need to do some researches and use other books. Your answer needs to be very detailed because this question is worth 20 pts.) (20 pts) PAGE 1 MSU, Qingzhou Xu Chapter 5 ETM 430: Operations & Facilities Management Chapter 8: Manufacturing Systems Qingzhou Xu 105E LC Building 8.1 Introduction Since manufacturing, as a whole, is a value-adding function, the efficiency of the manufacturing activities makes a major contribution to the firm’s short- and long-term economic profitability. This chapter talks about the different types of manufacturing systems, their characteristics and the issues to achieve their efficient operations. 8.2 Fixed Automation Systems 8.2.1 Transfer Line A transfer line is a manufacturing system where materials flow from one workstation to the next in a sequential manner. Its efficiency is determined by the slowest step. A transfer line is often used for high-volume production and is highly automated. The processing rates of individual machines are matched so that there is usually no need for buffer storage between machines. If there is buffer storage, it would be for reasons of machine breakdowns. 8.2 Fixed Automation Systems 8.2.1 Transfer Line The transfer line offers production rates unmatched by other types of manufacturing systems. But it has disadvantages: Very high equipment cost Inflexibility in the number of products manufactured Inflexibility in layout Large deviation in production rates in case of equipment failure in the line 8.2 Fixed Automation Systems 8.2.1 Transfer Line The design of a transfer line includes both the specification of the individual processing stages and the linkage of the stages. Facility planning for a transfer line is relatively straightforward. The processing equipment is arranged according to the processing sequence. Buffer storage areas between machines must be determined and accommodated by several types of material handling devices, such as vertical storage systems or spiral-type conveyors. 8.2 Flexible Manufacturing Systems A flexible manufacturing system means a system that can manufacture a large number of different types of products. A flexible manufacturing system includes the processing equipment, the material handling equipment, and the computer control equipment. The computer control equipment is used to track parts and manage the system’s overall operation. 8.2 Flexible Manufacturing Systems A flexible manufacturing system is appropriate to the following manufacturing situations: Production of a family of parts Random launching of products onto the system Reduced manufacturing lead time Increased machine utilization Reduced direct and indirect labor Better management control 8.2 Flexible Manufacturing Systems In designing the material handling system for a flexible manufacturing system, the following design practices are recommended: Random, independent movement of palletized parts between workstations Temporary storage or banking of parts Convenient access for loading and unloading Compatibility with computer control Provision for future expansion Adherence to all applicable industrial codes Access to machine tools Operation in shop environment 8.2 Flexible Manufacturing Systems A flexible manufacturing system is used to cope with changes. Specifically, the following changes are accommodated: Processing technology Processing sequence Production volumes Product sizes Product mixes 8.2 Flexible Manufacturing Systems A flexible manufacturing system is designed for small-batch (low-volume) and high-variety conditions. Flexibility can be accomplished through: Standardized handling and storage components Independent production units (manufacturing, assembly, inspection, etc.) Flexible material-delivery system Centralized work-in-process storage High-degree control 8.2 Flexible Manufacturing Systems Because of the variety of alternatives for storing, handling, and controlling material flow, the specification of the material handling system and the design of the layout can be quite different. Figure (a) illustrates an external centralized work-in-process storage while Figure (b) shows an internal centralized work-in-process storage. Work-in-process is needed because a part has to go through several machines before it eventually leaves the system. 8.2 Flexible Manufacturing Systems Another configuration of a flexible manufacturing system is based on cellular manufacturing principles, as illustrated in Figure c: In this configuration, the handling distances are reduced significantly since the machines are placed within the work envelope of the transfer device, a robot handler in this illustration. This configuration has some built-in scalability. Only one cell can be used in case there is a reduction in the demand for the products that are machined in this system. 8.2 Flexible Manufacturing Systems For a manufacturing system to be categorized as flexible, it must have the capability to: Process different part styles in a non-batch mode Accept changes in production schedule Respond gracefully to equipment malfunction and breakdown Accommodate the introduction of new part designs From these conditions, it is seen that an automated system is not always flexible (e.g., a transfer line), and vice versa, and that a flexible system need not be automated (a manual assembly line). 8.4 Single-Stage Multi-machine Systems Single-stage multi-machine systems (SSMS) are another alternative in automatic manufacturing. A SSMS is described in terms of the resources involved: Manufacturing configuration and machines The machining centers are very versatile. They are all identical and versatile so that all operations on any part can be performed on any machine. There is only one setup per part. There is a tool magazine on each machine but with limited capacity. The tool-handling system supplies the tools that are not resident on the machine. Each machine has a separate input and output spur with limited capacity. Once a part is loaded on a machine, it does not leave the machine until all required operations are performed. 8.4 Single-Stage Multi-machine Systems (continued from last slide) Manufacturing configuration and machines: Under this type of manufacturing system, the tool-delivery system becomes the critical resource. The figure illustrates two alternative tool-delivery systems: 8.4 Single-Stage Multi-machine Systems Parts Parts arrive according to the production schedule. As mentioned above, parts visit only one machine since all operations can be performed in a single machine. A part transport system handles the delivery of parts from the input station to the machine and from the machine to the output station. A part cannot be processed unless the required tool is available. 8.4 Single-Stage Multi-machine Systems Tools The required tools are specified by the process plan. Some tools are resident on the machine, while others are stored in a centralized tool storage system. These tools are generally expensive; dynamic sharing of tools may be an economic choice. Part transporter The part transportation activity is minimal since a part visits a machine only once. Deadheading still occurs, and there must be an efficient dispatching algorithm for the vehicles. Vehicles are dispatched based on part arrivals and job completions. 8.4 Single-Stage Multi-machine Systems Tool carriers A tool carrier handles the transport of tools to and from the centralized tool storage and the machines requiring the tools. Under dynamic tool sharing, these tools are dynamically dispatched to the machines needing them. One can also reallocate the tools when opportunities arise. The following figure illustrates a combined schedule of machines and tools. 8.4 Single-Stage Multi-machine Systems The same layout can be used for both the flexible manufacturing system (FMS) and the single-stage multi-machine system (SSMS). The difference is in the composition of the machine tools. 8.5 Reduction of Work in Process This section is about handling and storing operations. In-process handling includes the movement of materials, tools and supplies to and from production units, as well as the handling activities that occur at a machining center. In-process storage includes the storage of materials, tools, and supplies needed to support production. Several rules of thumb can be used in designing in-process handling and storage systems: Handling less is the best: The number of times that materials are picked up and put down and the distances that materials are moved should be reduced. Grab, hold, and do not turn loose: It emphasizes the importance of maintaining the physical control of materials. Eliminate, combine, and simplify: It emphasizes the principle of simplification. Handling and storage are completely eliminated by changing the processing sequence or combining tasks. 8.5 Reduction of Work in Process (continued from last slide) Moving and storing materials incur costs: It serves as a reminder that inventory levels should be kept as small as possible. Pre-position materials: It has two aspects. First, parts should be pre-positioned to facilitate automatic load/unload, insertion, inspection, and so on. Second, when materials are delivered to a machining centers, it should be placed in a pre-specified location with a desirable orientation. The rules of thumb discussed above can be used to improve operations so that non-value-adding time is reduced and, consequently, the manufacturing cycle time is shortened. Control of work-in-process has been the focus of many manufacturing firms. Demand-driven manufacturing systems (produce only what the customer needs) have gained popularity, spawned by the success of just-in-time production in Toyota , Japan. 8.6 Just-In-Time Manufacturing The just-in-time (JIT) production system was developed more than four decades ago at the Toyota Motor Company in Japan. In a broad sense, JIT applies to all the forms of manufacturing. It is stated that, no matter how difficult it may be, take it up as challenge to reduce man-hours as a means of improving efficiency by decreasing or eliminating: Waste arising from overproduction Waste arising from time on hand (waiting) Waste arising from transporting Waste arising from processing itself Waste arising from unnecessary stock on hand Waste arising from unnecessary motion Waste arising from producing defective goods 8.6 Just-In-Time Manufacturing 8.6.1 JIT impact on facilities design There are many concepts and techniques related to the JIT production system that impact building design, facility layout, and the materials handling system, such as: Reduction of inventories Delivery to the points of use Quality at the source Better communication, line balancing, and multifunctional workers Let’s talk about these individually. 8.6 Just-In-Time Manufacturing 8.6.1 JIT impact on facilities design: Reduction of inventories One of the main objectives of the JIT production system is the reduction of inventories. Inventories can be reduced if products are produced, purchased, and delivered in small lots. If inventories are reduced, then: Space requirements are reduced Smaller loads are moved and stored Storage requirements are reduced Consequently, the building could be smaller, a better plant layout could be used, and fewer handling and storage requirements might be needed. 8.6 Just-In-Time Manufacturing 8.6.1 JIT impact on facilities design: Delivery to the points of use If products are purchased and produced in smaller lots, they should be delivered to the points of use to avoid stockouts. If