MANUAL LABOR IN PRODUCTION SYSTEMS
Is there a place for manual labor in the modern production system? The answer is certainly yes. Even in a highly automated production system, humans are still a necessary component of the manufacturing enterprise. For the foreseeable future, people will be required to manage and maintain the plant, even in those cases where they do not participate directly in its manufacturing operations. Let us separate our discussion of the labor issue into two parts, corresponding to our previous distinction between facilities and manufacturing support: (1) manual labor in factory operations and (2) labor in the manufacturing support systems.
1. Manual Labor in Factory Operations
There is no denying that the longterm trend in manufacturing is toward greater use of automated machines to substitute for manual labor. This has been true throughout human history, and there is every reason to believe the trend will continue. It has been made possible by applying advances in technology to factory operations. In parallel, and sometimes in conflict, with this technologically driven trend are issues of economics that continue to find reasons for employing manual labor in manufacturing operations.
Certainly one of the current economic realities in the world is that there are countries whose average hourly wage rates are sufficiently low that most automation projects are im possible to justify strictly on the basis of cost reduction. At time of writing, these countries include Mexico, China, and most of the countries of Southeast Asia. With the recent passage of the North American Free Trade Agreement (NAFTA), the North American continent has become one large labor pool. Within this pool, Mexico’s labor rate is an order of magnitude less than that in the United States. For U.S. corporate executives making decisions on a factory location or the outsourcing of work, this is an economic reality that must be reckoned with.
In addition to the labor rate issue, there are other reasons, ultimately based on economics, that make the use of manual labor a feasible alternative to automation. Humans possess certain attributes that give them an advantage over machines in certain situations and certain kinds of tasks. Table 1.1 lists the relative strengths and attributes of humans and machines. A number of situations can be listed in which manual labor is usually preferred over automation:
• Task is too technological difficulty to automated. Certain tasks are very difficult (either technologically or economically) to automate. Reasons for the difficulty include:
(1) problems with physical access to the work location, (2) adjustments required in the task, (3) manual dexterity requirements, and (3) demands on handeye coordination. Manual labor is used to perform the tasks in these cases. Examples include automobile final assembly lines where many final trim operations are accomplished by human workers.
• Short product life cycle. If the product must be designed and introduced in a short period of time to meet a nearterm window of opportunity in the marketplace, or if the product is anticipated to be on the market for a relatively short period, then a manufacturing method designed around manual labor allows for a much faster product launch than does an automated method.Tooling for manual production can be fabricated in much less time and at much lower cost than comparable automation tooling.
• Customized product. If the customer requires a oneofakind item with unique features, manual labor may have the advantage as the appropriate production resource because of its versatility and adaptability. Humans are more flexible than any automated machine.
• To cope with ups and downs in demand. Changes in demand for a product necessitate changes in production output levels. Such changes are more easily made when manual labor is used as the means of production. An automated manufacturing system has a fixed cost associated with its investment. If output is reduced, that fixed cost must be spread over fewer units, driving up the unit cost of the product. On the other hand,
an automated system has an ultimate upper limit on its output capacity. It cannot produce more than its rated capacity. By contrast, manual labor can be added or reduced as needed to meet demand, and the associated cost of the resource is in direct proportion to its usage. Manual labor can be used to augment the output of an existing automated system during those periods when demand exceeds the capacity of the automated system.
• To reduce risk of product failure. A company introducing a new product to the market never knows for sure what the ultimate success of that product will be. Some products will have long life cycles, while others will be on the market for relatively short lives. The use of manual labor as the productive resource at the beginning of the product’s life reduces the company’s risk of losing a significant investment in automation if the product fails to achieve a long market life. In Section 1.5.3, we discuss an automation migration strategy that is suitable for introducing a new product.
2. Labor in Manufacturing Support Systems
In manufacturing support functions, many of the routine manual and clerical tasks can be automated using computer systems. Certain production planning activities are better accomplished by computer than by clerks. Material requirements planning (MRP, Section 26.2) is an example: In material requirements planning, order releases are generated for component parts and raw materials based on the master production schedule for final products. This requires a massive amount of data processing that is best suited to computer automation. Many commercial software packages are available to perform MRP. With few exceptions, companies that need to accomplish MRP rely on the computer. Humans are still required to interpret and implement the output of these MRP computations and to otherwise manage the production planning function.
In modern production systems, the computer is used as an aid in performing virtually all manufacturing support activities. Computeraided design systems are used in product design. The human designer is still required to do the creative work. The CAD system is a tool that assists and amplifies the designer’s creative talents. Computeraided process planning systems are used by manufacturing engineers to plan the production methods and routings. In these examples, humans are integral components in the operation of the manufacturing support functions, and the computeraided systems are tools to increase productivity and improve quality. CAD and CAM systems rarely operate completely in automatic mode.
It is very unlikely that humans will never be needed in manufacturing support systems, no matter how automated the systems are. People will be needed to do the decision making, learning, engineering, evaluating, managing, and other functions for which humans are much better suited than are machines, according to Table 1.1.
Even if all of the manufacturing systems in the factory are automated, there will still be a need for the following kinds of work to be performed:
• Equipment maintenance. Skilled technicians will be required to maintain and repair the automated systems in the factory when these systems break down.To improve the reliability of the automated systems, preventive maintenance will have to be carried out.
Programming and computer operation. There will be a continual demand to upgrade software, install new versions of software packages, and execute the programs. It is anticipated that much of the routine process planning, numerical control part pro gramming, and robot programming may be highly automated using artificial intelligence in the future.
• Engineering project work. The computerautomated and integrated factory is likely never to be finished. There will be a continual need to upgrade production machines, design tooling, and undertake continuous improvement projects. These activities require the skills of engineers working in the factory.
• Plant management. Someone must be responsible for running the factory. There will be a limited staff of professional managers and engineers who are responsible for plant operations. There is likely to be an increased emphasis on managers’ technical skills rather than in traditional factory management positions, where the emphasis is on personnel skills.
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