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Objective
The objective of this chapter is to introduce the reader to programmable automation, define automation in general, and to introduce the ideas of when and where automation is applied.
1.1 Introduction to Programmable Automation
Programmable automation technology is a remarkably useful tool for manufacturing engineers/technologists who seek to improve manufacturing systems of their respective industries. It combines mechanical, electrical, and computer technologies that have been developed for very specific automation capabilities. The term “programmable automation technology” actually refers to three individually distinct technologies that have a common thread: programmability. These technologies are computer numerical control (CNC) technology, robotics technology, and programmable logic control (PLC). Each, in some form, either directly or indirectly, is used in almost all modern automation systems—one is unlikely to walk into a modern manufacturing facility without observing one of these technologies in action. This, however, has not always been the case.
Initial migration to programmable automation was gradual, hampered by the complexity, expense, and, in some cases, poor reliability of early systems. Additionally, utilization of the technology required that companies retain technical experts specifically devoted to the implementation, programming, and maintenance of the systems. However, over the last 25 years programmable automation technology has greatly matured: Modern systems are standardized, substantially less complicated and expensive, and extremely reliable. Whereas use of this technology was initially the domain of specialists—particularly engineers—now virtually every member of an engineering or maintenance staff is expected to use the technology at some level. In fact, it is now imperative that mechanical engineers and technologists—who used to avoid “electrical stuff”—have a solid foundation in it. Hence, the goal of this text: to instruct any member of an engineering team so he or she may comfortably delve into the automation arena.
Before we properly define “programmable automation” and develop a full description of its capabilities, we first must present an understandable picture of manufacturing in general. In the following section we explore manufacturing and define some of its key terms. Subsequent sections define automation in general and programmable automation in particular. The concept of productivity will be introduced, and the last few sections will address reasons for automation, corresponding benefits of it, and ways automation can be implemented.
1.2.1 Manufacturing overview
Manufacturing, regardless of the industry under consideration, is a conversion process. Some form of raw material is brought into a manufacturing facility and converted into a more useful finished product. The conversion is accomplished by applying a series of manufacturing steps, or manufacturing processes, to the raw material. Manufacturing processes alter the raw material’s shape, appearance, physical and mechanical properties, and/or assemble it with other components into a desired finished product. This is achieved through the use of equipment, tools, and supplies combined with the application of labor, time, and energy.
The way that manufacturing operations are organized within the facility defines plant layout. The term “manufacturing system” of the facility refers to the plant layout and worker execution of the operations. The manufacturing system used is determined by the product(s) characteristics. Figure 1-0 shows the plant layout of an imaginary facility, the XYZ Company. XYZ Company manufactures widgets. As the layout indicates, bar stock is processed into a widget through a series of manufacturing processes, which include sawing, turning, milling, and painting. Each manufacturing process executes a systematic sequence of operations called a program of instructions. When a program of instructions is complete for one manufacturing process, the product is routed to the next process.
Figure 1-0 XYZ Company plant layout
Note that the factory must perform operations in addition to manufacturing processes to create the product. The product must be moved between the manufacturing processes. It must also be inspected at some point to ensure that it satisfies the customer’s requirement. Additionally, someone must optimize the processes, schedule the operations, monitor labor usage, schedule maintenance, coordinate material handling, control inventory, and make sure the product is shipped on time. These activities do not contribute to the conversion process of the product per se. However, they are critically important to the manufacture of the product. The manufacturing processes and other activities combined are called manufacturing operations. Typical manufacturing operations found in factories include:
• Manufacturing processes
• Material handling
• Quality control
• Manufacturing support.
Each manufacturing process is designed to accomplish a very specific raw material conversion step. Thus, the number of manufacturing processes and the way they are organized within the facility are determined by the product(s) made. Manufacturing processes might include shaping processes such as molding or machining, property-enhancing processes such as the heat treating of steel, surface processes such as cleaning, coating, or painting, and various types of assembly processes. Assembly processes can be permanent, as in the case of welding, soldering, brazing, or adhesive bonding. However, some assembly processes are considered semi-permanent. Semi-permanent assembly processes typically include various types of mechanical joining, such as what is accomplished with the use of threaded fasteners, rivets, and expansion fits. All manufacturing processes are said to add value to the product; but, the other three operations—material handling, quality control, and manufacturing support—do not add value and are often the first targets for automation.
The way manufacturing operations are organized within a facility defines its plant layout. The term “manufacturing system” refers to both plant layout and worker execution of operations.
1.2.2 Defining the product
A given manufacturing facility may turn out only one product, a variety of models of one product, or many different products. Products may be as simple as a paper clip or as complex as a photocopier. Additionally, the facility might make only one product per year, or it might turn out millions of products. A product is either continuous, such as a liquid like gasoline, or it is discrete, like an automobile. (This text focuses on programmable automation of manufacturing processes and systems for discrete products only; continuous product manufacturing processes and systems will not be addressed.) Taken together, these distinctions make up the product definition and are naturally related to the manufacturing system(s) used within the facility.
The choice of manufacturing system employed for a discrete product is a function of the manufacturing
