necessarily replaced. Their level of participation may be greatly reduced, typically displacing them to other activities. This point is important because often great fear exists in the workforce when system automation is considered. Workers inevitably assume that such automation will eliminate jobs, which, as discussed, does not always occur, particularly in a company that values its workforce. Thus, the distinction between “displacing” workers and “replacing” them needs to be emphasized. The other notable aspect of the definition is that it emphasizes that automation can be implemented with various forms and combinations of technology.
Now that a clear definition of automation has been established, the different automation types that have evolved in manufacturing are discussed.
1.3.1 Types of Automation
Automation in a manufacturing facility can occur in the manufacturing support systems and/or in manufacturing systems. Automation in manufacturing support systems is primarily accomplished through the use of computer technology to automate the business operations of the facility. Computer-aided design (CAD) software and computer-aided manufacturing (CAM) software have dramatically impacted the way products are designed and engineered. Shop floor control systems combined with material resource planning systems provide management with a very fast and accurate picture of a facility’s current status. Computer-integrated manufacturing (CIM) takes the automation of the manufacturing support systems a step further. CIM is intended to integrate and thereby automate the entire manufacturing enterprise. In other words, CIM links the automation in the manufacturing support systems directly with automation in the manufacturing systems, resulting in a completely integrated manufacturing facility. However, the focus of this text is not on the automation of manufacturing support systems. Rather, it is on a specific type of automation of manufacturing systems.
Automation in manufacturing systems is centered on reducing the level of human participation in manufacturing processes. Three standard types of automation can be defined. Each type has very specific capabilities relating to the sequence of the processing steps and the definition of the product being processed. The three types are:
• Fixed automation
• Programmable automation
• Flexible automation.
Fixed automation equipment typically consists of processing stations linked together with some form of material handling, which progressively moves the workpiece through the processing steps. Fixed automation can be considered special purpose automation because it is designed to automate a specific process or series of processes. Therefore, the processing sequence is fixed by the organization of the processing stations. In general, it is relatively inflexible in accommodating any type of product variety. However, if it is capable of handling soft product variety, conversion of the machine allowing it to run the variation may be time-consuming. The time to make this change is often termed “changeover time” or “setup time.” Fixed automation can handle a wide variety of product complexity from simple to very complex products; but, the cost of creating such a specialized machine is often quite high. Consequently, fixed automation is typically only used with extremely high volume products. To accommodate the volume, these systems operate at very high rates. Hence, fixed automation equipment is most often associated with flow-line manufacturing systems, often as assembly lines. Early fixed automation was created using mostly mechanical technology combined with electrical technology to drive its mechanical components. Current systems make extensive use of computer technology and often integrate programmable automation into the machine, as well.
Whereas fixed automation is “fixed” to a specific operation progression, programmable automation has the capability to alter both the type of operation to be performed and the order in which it is to be executed. Thus, it can adjust the process to accommodate the product, which makes it capable of handling hard product variety. Programmable automation equipment is multipurpose equipment that can be programmed, and repeatedly reprogrammed, to perform a wide variety of processing operations. However, each programmable automation machine is limited to a specific type of manufacturing process such as machining material removal, metal forming, or material handling. Reprogramming and changing tooling is necessary to accommodate the different products, creating long setup times between products. This combination of versatility, hard product variety, and long setup times would appear to limit programmable automation to use in the process manufacturing system. It is interesting to note that this is in fact the manufacturing system for which programmable automation was developed and where it is still primarily used. However, programmable automation equipment has proven to be so very capable and reliable that it is also used in the quantity and flow line manufacturing systems, either outside of or integrated into fixed and flexible automated equipment.
Flexible automation possesses some of the features of both fixed and programmable automation, with an added characteristic of no time lost for changeover between products. It utilizes, essentially, a fixed automation machine that can process soft product variety with no setup. The elimination of the setup is achieved with the versatility of programmable automation integrated directly into the machine. The machine recognizes or identifies different product configurations and automatically adjusts the operation sequence. The exorbitant cost of such a system limits its use to high volume applications typical of the flow-line manufacturing system. However, this added versatility means reduced production rates when compared with what is possible by a fixed automation machine.
Figure 1-7 summarizes the capabilities of each of the automation types.
Figure 1-7 Automation types
It should be noted that the lines of distinction between these three types of automation and the manufacturing systems in which they appear are often blurred. What should become clear is that programmable automation is at the core of both fixed and flexible automation. In fact, it has become a primary building block of almost all automated machines. Additionally, it is unlikely that a person would walk into any modern manufacturing facility and not encounter programmable automation, as it is found in practically every manufacturing system.
1.3.2 Programmable Automation
Improved productivity is the primary focus of global competition in the world economy. As will be shown in subsequent sections and chapters, automation is a key ingredient to improving productivity. Programmable automation, in some form, is found in almost all automation systems. It is used individually in process manufacturing systems, or it can be fully integrated into fixed automation machines in flow-line manufacturing systems. Flexible automation machines were not even possible prior to the development and maturation of programmable automation. Hence, it is imperative that manufacturing engineers and technologists understand the capabilities of this technology and how it may be used effectively.
Programmable automation, as is shown in Figure 1-8, has evolved into three distinct technologies:
• Computer numerical control (CNC) technology
• Robotic technology
• Programmable logic control (PLC) technology.
Computer numerical control (CNC) technology utilizes a combination of mechanical, electrical, and computer technology to move a tool relative to a workpiece to perform some type of processing. It is most often related to the machining processes, such as milling, turning, and grinding. However, it can be used in any process that requires precise control of a tool relative to a workpiece. Non-material removal examples include wire-bending machines and pen plotters. Some CNC technology examples are shown in
