05- Fundamentals OF Industrial Engineering PDF

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Source: MAYNARD’S INDUSTRIAL ENGINEERING HANDBOOK

CHAPTER 1.5

FUNDAMENTALS OF INDUSTRIAL ENGINEERING Philip E. Hicks Hicks & Associates Orlando, Florida

This chapter covers the basic industrial engineering tools, methods, and procedures and specifies their appropriate application areas for improvements and problem solving. The topics will be explained from a layman’s perspective with reference to other chapters in this handbook.

BACKGROUND The theoretical basis of industrial engineering is a science of operations. To successfully use this science in most applications one must simultaneously consider at least three criteria: (1) quality, (2) timeliness, and (3) cost—whether it be a blood bank in Missouri, the U.S. Naval Shipyard in Hawaii, or a knitted socks factory in North Carolina. The principles of industrial engineering are not only universally applicable across industries, but across all operations in government, commerce, services, or industry. Almost always, the goal of industrial engineering is to ensure that goods and services are being produced or provided at the right quality at the right time at the right cost. From a business perspective the practice of industrial engineering must culminate in successful application. This requirement typically dictates that a practicing industrial engineer effectively use “soft” as well as “hard” science. In the final analysis, the industrial engineer’s job is to make both new and existing operations perform well. The preponderance of traditional industrial engineering techniques deal with physical entities (e.g., equipment, buildings, tools) as well as informational entities (e.g., time, space) for an operation, employing what can be thought of as hard science. However, managementrelated factors in the workplace that determine the motivation level of an employee to perform his or her assigned duties well, or actively participate in operational improvement over time, represent the soft science of industrial engineering. In recent years, there has been a growing awareness of the importance of this soft science component of industrial engineering. Not only must the motivation of individual workers be attained through effective management efforts, but the motivation of work groups as well. Individual workers rarely work alone; they typically respond to a social need to fit in as a member of a work group.

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In most organizations, as a matter of modern management practice, management will create a vision, perform strategic planning and goal setting, and establish performance measurement system development roles (see Chaps. 2.1 and 2.4); the products of these efforts will be available throughout the organization. These documents guide all operational activities. In those instances when industrial engineering is attempting to perform its role and has determined that there is no clearly articulated or available vision, plan, goals, or performance measurement system in place, it is important that these prerequisite efforts be encouraged to take place before, or at least parallel with, anticipated industrial engineering activities. Nominal group technique [1, 283–284] improvement opportunity sessions of personnel throughout most components and levels of an organization can help build a consensus-driven and guiding improvement plan for everyone in the organization to embrace as their own, or at least accept as one in which they participated in its development. Such an effort is critical because there seems to be an important fundamental psychological truth that involvement leads to commitment, which leads to performance.

OPERATIONS ANALYSIS AND DESIGN Methods Engineering A production system is essentially the sum of its individual operations. Therefore, it follows that if one wants a production system to be efficient then its individual operations must be efficient. Working from a bottom-up micro perspective, one approach is to simply review all individual operations to make them the best they can be (see Chap. 4.1). One reason such an approach offers considerable opportunity for improvement today is that it has been often overlooked while the search for the single “silver bullet” macro solution occurs in the front office or the boardroom. In many firms today individual workstation cycle times can be reduced by one-third to one-half of their present average cycle times by implementing a short list of modest improvements in these workstations. Charting techniques have proven to be useful for analyzing operations. (Refer to Chap. 17.1 for a thorough discussion of the charts mentioned in the following paragraphs.) The operation process chart allows the analyst to visualize the sequence of operations for a product whether it be a bicycle or an insurance form.The circles on such a form typically represent operations that are considered to be value-added activities in the process flow. From the customers’ perspective, what they want is the completed (i.e., assembled) item; therefore, only operations that add directly to the physical completion of the product are considered value-added. Inspection does not add to the completion of the product and is considered a non-value-added activity. Many production organizations now practice simultaneous inspection by letting the next operator in a process inspect the previous operator’s work to minimize the need for inspectors. When the analyst understands this sequence of operations, his or her attention often turns next to analyzing a segment of the overall process in more detail, employing a flow process chart. The interest is more focused now on such process activities as storage, transportation (i.e., material handling), and delay. These activities do not add directly to product completion and, therefore, are typically considered non-value-added activities on the flow process chart. A multiple activity chart is any chart that displays more than one resource using a timescale to determine the best combination and timing of multiple resource activities in identifying a shortest cycle time for the operation. Such commonly used charts as a human-machine chart, “left-hand, right-hand” chart, crew chart, and gang chart involve multiple resources.An obvious example of a multiple activity chart would be a chart displaying the time-scaled activities of various resources attempting to get on a fire truck (e.g., driver, dalmatian dog, firefighter, the call taker, etc.) to permit the fire truck to leave the fire station in minimum time. Multiple activity charts are one of the simplest and yet one of the most useful techniques in industrial engineering for improving operations involving multiple resources.

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Most products have traditionally been designed employing a sequence of organizational entities—for example, marketing, research and development, product design, process design, tool design, methods engineering, plant layout, and material handling. Such a sequential approach to product design requires each organization to operate without the benefit of inputs from organizational segments that traditionally follow their activity.When these various entities are engaged in product design as a design team, however, the overall product development time is often reduced considerably and the design is typically much improved from the perspective of the final user as well as in the manufacture of the product (see Chap. 13.1). By providing early-stage inputs, a producibility engineer, a manufacturing engineer, a materials engineer, a tool engineer, a methods engineer, a quality engineer, or an industrial engineer can request design adjustments that permit more timely and more cost-effective operations at higher quality levels (Chap. 14.2). As a member of a design team, producibility and manufacturing engineers today often employ design for manufacture (DFM), design for assembly (DFA), or manufacturability [2] concepts (Chap. 13.2) to provide more cost-effective approaches to the manufacturing process. Such upfront design adjustments typically produce tremendous cost savings and product quality improvements over the life cycle of the product. The culmination of a methods engineering effort is the determination of a documented best method for an operation that is then used as the standard method. Workers are required to employ the standard method in performing the operation. For example, when a patient arrives for an x-ray, the process of entering that person into and completing the x-ray process should be predetermined to best serve all patients, required procedures, equipment and facilities, and the x-ray department staff.

Work Measurement Fundamental to the traditional practice of industrial engineering has been the use of “labor reporting” rather than“direct supervision” as the preferred approach for attaining cost-effective labor operations (Chap. 5.7). Rather than watching an employee and telling them whether they are working hard enough (direct supervision), a supervisor employing labor reporting uses the standard time for the operation to produce an estimate of the number of items that should be produced by an employee in a given time period, such as a week or a month. This estimate assumes that the worker had the opportunity to be productive during the time period (e.g., there was no major power outage during the period in question).At the conclusion of a time period, the supervisor compares the estimate of production with the actual production accomplished as a basis for evaluating the relative productive accomplishment of the employee. Use of the labor reporting approach to worker productivity evaluation required the development of a standardized procedure for determining the standard time for an operation. The most direct method developed to date—time study—uses a stopwatch to measure the elapsed time for an employee performing an operation (Chap. 17.2). While the worker is being timed, the time study analyst must also evaluate the relative pace of the employee performing the task by estimating a performance rating factor.When completing the time study form the analyst multiplies the average observed time for each element of the operation by the performance rating factor for each element and sums these products to arrive at the expected rate of performance at a normal pace. This time value is called the normal time for the operation, and is the expected time for making one unit of production.Workers are not expected to work every minute of their shift, however, so nonwork time is added to the normal time to arrive at the standard time for the operation, which includes both the expected productive time as well as the allowed nonproductive time for producing one unit of production. The expected nonproductive time included in a time standard is referred to as an allowance (Chap. 5.5). There are typically three components of the total allowance provided, commonly referred to as P F & D, which stand for personal, fatigue, and unavoidable delay. The personal allowance is time provided to the employee to rest and to attend to personal needs, such as going to the bathroom. Morning and afternoon breaks, for example, make up a part of the per-

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sonal allowance. The fatigue allowance is the recovery time needed by an employee performing a fatiguing operation, such as shoveling coal into a boiler.After performing the work for a while the employee needs to rest to recover from the fatigue before performing the shoveling task again. It essentially involves estimating an appropriate duty cycle (i.e., analogous to “on” and “off” times for a heater controlled by a thermostat) for the employee, for work and rest. The unavoidable delay allowance factor is typically determined by measuring the percent of time an employee is prevented from being productive by the production system in which he or she works. Equipment downtimes, supervisor conversations, unavailability of tools or materials are all typical unavoidable delay causes. The three allowance factor percentages (i.e., P F & D) are added together and the sum (e.g., 8 percent) is used to add additional time to the normal time (work time) to determine the standard time (work and nonwork time) for the operation. The total time in minutes an employee works in a given work period can be divided by the standard time to determine how many production units he or she should have produced in that period (see Chap. 5.4). Predetermined time systems have been developed over the years, such as methods time measurement (MTM) and Maynard Operation Sequence Technique (MOST), which provide standard times for categorized human motions (see Chap. 17.4). By specifying a sequence of human motions that represent a task employing such a system, an estimate of the standard time for performance can be determined. More macro work measurement techniques, such as work sampling, are used to acquire macrolevel information about operations. Work sampling (Chap. 17.3) involves making a series of random observations of activity. The results of such a study provide estimates of the percent of time devoted to numerous categories of work and nonwork for a specific type of job function, such as mechanical maintenance of a generating unit at a power plant. By using standard times discussed earlier as a basis for evaluating productive performance, numerous work incentive systems (Chaps. 7.1 and 7.4) were developed in the past to reward employees for their work performance beyond the expected standard performance. Because these systems compensate employees relative to their performance, they have been a primary source of labor grievances (Chap. 7.5) concerning the details associated with incentive systems development and maintenance.Although useful for gaining higher levels of worker performance, such systems have tended to separate employees from their management. Ergonomics Most production and service processes involve a combination of equipment and human resources. Equipment resources can be modified to suit the needs of the process whereas the only opportunity for changing human resources in a process is through selection (e.g., perhaps no former NBA basketball player could fly a military fighter jet because he would likely exceed the height limitations). Equipment typically proves superior to humans for tasks involving controlled, and very high or very low, levels of force, activities performed in hostile environments, or rapid and complex calculation. The most cost competitive capabilities of humans are their sensory abilities (i.e., sight, hearing, smell, feel, etc.) and their ability to make judgments in complex situations. Their ability to perform well however can be severely limited by environmental factors, both physical and psychological. Therefore, over the years two primary roles for machines and humans have evolved. Machines do the work: Humans in protected environments monitor and maintain machines. There are four primary subcategories of ergonomics concerned with the ability of humans to perform work: (1) skeletal/muscular, (2) sensory, (3) environmental, and (4) mental. See Chaps. 6.2 and 6.4 for further discussion. An excellent brochure recommended to all who wish to know more about ergonomics is “Sprains and Strains: A Worker’s Guide to Job Design,” [3] which is specifically concerned with ergonomics problems in the automotive industry, and is a bargain at $2 a copy. Much of what is described, however, exists in most industries. The brochure is divided into three key areas of ergonomics concern in most industries: (1) the back, (2) the hands, and (3) the arms.

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Specific maladies affecting the hands such as carpal tunnel syndrome, tendonitis, and white finger are discussed. Facilities Planning and Design A question that must be resolved by any organization is where to locate what facilities of what size and arrangement? The location question is typically hierarchical in that one must determine 1. Where should facilities be located geographically—southern Alabama? 2. On which specific site in southern Alabama? 3. How should each facility component (plant, water tower, office, warehouse) be located on the site? 4. How should space groupings (e.g., departments) be located within buildings and in relation to one another? 5. How should equipment be arranged within a designated production space? The goal is to place properly sized and arranged facilities at locations that will result in a minimum total cost of delivered products to the organization’s customers (e.g., distribution centers) of such facilities. See Chap. 8.1 for further discussion on location. A key step in the layout of any production facility is the determination of how best to locate major spaces one to another within a building envelope—commonly referred to as a block layout (Chap. 8.2). Fortunately for all who must deal with this problem, Richard Muther [4] years ago developed a technique called the activity relationship chart, which effectively addresses this problem. The activity relationship chart [1, 93–97] requires the analyst to list a proximity-level (i.e., need for closeness) estimate for all space pairs. For example, the proximity-level relationship between receiving and raw materials warehouse would typically be “E” for especially important, because almost all raw material entering the plant through receiving will proceed to the raw material warehouse. After all space pair relationships have been estimated, a block layout is developed by taking the space with the largest number of high-level relationships and locating it first in the layout as a nucleus space (e.g., production), and then successively adding the remaining highest level relationships space, until all spaces have been located in the layout. Next, all space shapes are adjusted so that they will fit into a reasonably shaped facility envelope (e.g., a rectangle). This technique typically prevents the misplacement of spaces in a block layout. There is a relatively consistent process [1, 84] for developing a facility design.The first step in the process is to evaluate two product attributes: the product design, and the life cycle sales volume of the product (Chap. 3.5). The design of the product typically limits the selection of costeffective manufacturing processes (e.g., a part designed as an extrusion allows fabricating the part from an extruded raw material). The second attribute—life cycle volume—allows one to consider higher levels of automation, or at least mechanization, if the total number of products to be produced is sufficient to justify the higher initial cost of such equipment. Once these issues are resolved, the choice of specific equipment to be employed at various steps in the process can be determined. With assumptions of unit processing times, yield rates, and desired output rates, one can next estim...