Programmable Automation Technologies. Daniel Kandray
typically be turned out by a relatively simple manufacturing system. Thus, once a manufacturing system is established within the facility it will dictate the type of future products that can be produced, unless, of course, capital is allocated to add other manufacturing systems to the facility.
1.2.3 Manufacturing system
As mentioned already, the manufacturing system is the combination of manufacturing processes and the organization of workers, designed so as to efficiently and effectively create the desired product. There are essentially four standard systems, with numerous variations, that have evolved over time. Each system is geared to produce a fairly specific product definition. The four standard manufacturing systems are:
1. Fixed-position
2. Process
3. Quantity manufacturing system
4. Flow-line.
(Refer to Figure 1-3.) Because of the narrowness of product definition relating to each system, an individual facility may employ one or more of these systems.
Fixed-position manufacturing systems (Figure 1-3(a)) are used for making large, complex products. Because such products are not easily moved, the manufacturing processes are taken to the product; the product remains in a fixed position throughout manufacture. This system produces items that are highly complex, relatively large and immobile, with low volume production requirements, and of soft product variety. Submarines, ships, and large aircraft are examples of products that use this system.
The process manufacturing system is used when product complexity is relatively low and there is hard product variety. Accordingly, production quantities range from low to moderate. This system is also called a job shop system because it can accommodate a wide variety of products or jobs. The manufacturing processes are grouped together according to function or process. Products are routed though the facility to the required manufacturing processes in groups called lots or batches. The size of the lot, or lot size, is the number of products in the group. The use of lots is necessary because of the variety of products the system must accommodate. In a process manufacturing system each manufacturing process to which a product is routed will have to be set up, or prepared, to process that particular product. Consequently, it is economically desirable to run a specific number of products through the process each time it is set up. Some factors that influence lot size include variety of the products made in the facility, setup times, order sizes, and manufacturing lead-time. This system is shown in Figures 1-0 and 1-3(b).
Figure 1-3 Standard manufacturing systems
The quantity and the flow-line manufacturing systems are often combined into one category, called the product manufacturing system. These systems produce mass quantities of products and are thus mass production systems. However, both product complexity and product variety of mass-produced items dictate the division of the product manufacturing system into the quantity and flow-line manufacturing systems.
The quantity manufacturing system is used with low product complexity and hard product variety. These products are produced on a single standard machine, like a plastic injection molding machine with exchangeable tooling. (Refer to Figure 1-3(c).) Other examples of products manufactured with this system include metal stampings and blow molded plastic products, like water bottles.
Flow-line manufacturing is for products with high product complexity and soft product variety. For assembled products, flow-line is more commonly called assembly line manufacturing system. Raw material flows down a line of manufacturing processes, in the end to be converted into a finished product. Henry Ford is often credited with perfecting this system. He produced the Model T using the flow-line manufacturing system to reduce cost so that the average American could afford his automobile. Because of the nature of the flow-line manufacturing system, product variety was essentially nonexistent. All Model T cars had the same body shape and were made in one color. The early flow-line system evolved to a modern form that accommodates soft product variety. Figure 1-3(d) illustrates the flow-line manufacturing system.
The manufacturing systems discussed above are summarized in the table of Figure 1-4 as shown on page 9 according to product complexity, variety, and volume. Also, it cannot be emphasized enough that many manufacturing facilities will have more than one of these systems and/or a variation of some system as dictated by the product definition. Consider Figure 1-6. This figure demonstrates how some manufacturing systems feed into other manufacturing systems to produce the finished product. In this example a flow-line manufacturing system in the form of an assembly line produces the finished product. The components of the finished products are produced on various other manufacturing systems as shown. This is typical of most, if not all, assembled products.
Figure 1-4 Manufacturing systems versus product complexity, variety, and volume
Figure 1-5 Manufacturing support systems
Figure 1-6 Multiple manufacturing processes used to make a product
1.2.4 Manufacturing Support Systems
Another key ingredient to the conversion process is the manufacturing support system. Manufacturing support systems provide the management of the business operations of the facility and the manufacturing system. Thus, the success of a facility, in terms of productivity and thus profitability, is dictated by how well its manufacturing support systems manage its manufacturing system.
A manufacturing support system utilizes people and procedures to manage the manufacturing system and the overall facility. Whereas the manufacturing system processes the raw material, the manufacturing support system processes information necessary to accomplish the conversion of the raw material into the finished product. Accounting, customer service, marketing, human resources, product design, manufacturing engineering, materials engineering, quality control, production planning, and shop floor control are all good examples of manufacturing support systems. Figure 1-5 as shown on page 9 demonstrates how manufacturing support systems interact with the manufacturing system.
Through understanding the different manufacturing systems and manufacturing support systems, as well as how the systems interact, the seeds for automation are sown. The next section will define automation in more precise terms and identify specific types of automation.
Webster’s Online Dictionary (http://www.websters-online-dictionary.org/definition/ automation) defines automation as “a highly technical implementation; usually involving electronic hardware; automation replaces human workers by machines.” In his first book Automation, Production Systems and Computer-Integrated Manufacturing, 2nd ed. (2001), M.P. Groover defined automation,