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Engineering activities involved in the creation and operation of the technical and economic processes that convert raw materials, energy, and purchased items into components for sale to other manufacturers or into end products for sale to the public. Defined in this way, manufacturing engineering includes product design and manufacturing system design as well as operation of the factory. More specifically, manufacturing engineering involves the analysis and modification of product designs so as to assure manufacturability; the design, selection, specification, and optimization of the required equipment, tooling, processes, and operations; and the determination of other technical matters required to make a given product according to the desired volume, timetable, cost, quality level, and other specifications. See Process engineering
The formulation of a process plan for a given part has seven aspects: (1) a thorough understanding of processing techniques, their yield and their reliability, precedences, and constraints (both economic as well as technical); (2) the material and tolerances of the part; (3) proper definition of machinability or process data; (4) proper work-holding design of the stock or piece part during the fabrication process, a key consideration in generating piece parts of consistent quality; (5) proper tool selection for the task; (6) the capability of the equipment selected; and (7) personnel skills required and available.
Process planning aids based on computer programs that incorporate a type of spread sheet can be used to reduce significantly the time required to generate individual process plans. For example, systems have been developed that calculate the cycle time for each part as well as the number of tools used per part, the number of unique tools per part set, and the total time for cutting operations per tool type. See Computer-aided design and manufacturing
In parallel with the definition of process equipment, the manufacturing system designer must determine the most appropriate materials-handling techniques for the transfer of parts from machine to machine of each family of parts. During the manufacture of pieces, the parts are organized by the type of feature desired. The parts are then grouped and manufactured as a family, a method known as group technology. This includes the selection of storage devices appropriate for raw material, work in process, and finished-goods inventory as well as fixtures, gages, and tooling. Materials-handling equipment may be very different for each family, depending on part size and weight, aggregate production volume, part quality considerations during transfer, and ease of loading and unloading candidate machines. Different materials-handling approaches may also be appropriate within individual fabrication systems. See Materials-handling equipment
A quality assurance philosophy must be developed that emphasizes process control as the means to assure part conformance rather than emphasizing the detection of part nonconformance as a means of detecting an out-of-control process. The success of any fabrication process is based on rigid work-holding devices that are accurately referenced to the machine, accurate tool sizing, and tool position control. The basic way to determine if these three factors are functioning together acceptably is to measure a feature they produce as they produce it or as soon as possible after that feature is machined. The primary objective of this measurement is to determine that the combination is working within acceptable limits (statistical process control); the fact that the part feature is in conformance to print (conformance to tolerance specified on the print/drawing) is a by-product of a process that is in control. See Quality control
In a modern manufacturing environment an organization's strategies for highly automated systems and the role for workers in these systems are generally based on one of two distinct philosophical approaches. One approach views workers within the plant as the greatest source of error. This approach uses computer-integrated manufacturing technology to reduce the workers' influence on the manufacturing process. The second approach uses computer-integrated manufacturing technology to help the workers make the best product possible. It implies that workers use the technology to control variance, detect and correct error, and adapt to a changing marketplace. See Computer-integrated manufacturing
The best approach utilizes the attributes of employees in the factory to produce products in response to customer demand. This viewpoint enables the employees to exert some control over the system, rather than simply serving it. The employees can then use the system as a tool to achieve production goals.
As technology and automation have advanced, it has become necessary for manufacturing engineers to gain a much broader perspective. They must be able to function in an integrated activity involving product design, product manufacture, and product use. They also have to consider how the product will be destroyed as well as the efficient recovery of the materials used in its manufacture.
Manufacturing engineers must also be able to use an increasing array of computerized support tools, ranging from process planning and monitoring to total factory simulation—and in some cases, including models of the total enterprise. See Simulation