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IE 101-Industrial Engineering Orientation Fall 200 9 Motion and Time Study Engin Topan. Methodology. Methods Design. Outline of MTS Develop System Design work methods (sequence of operations and procedures) that make up the preferred solution Find better methods for work Standardize
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IE 101-Industrial Engineering Orientation Fall 2009 Motion and Time Study Engin Topan
Methodology Methods Design Outline of MTS • Develop System • Design work methods (sequence of operations and procedures) that make up the preferred solution • Find better methods for work • Standardize • Form written standards for operations • Time Standards • Determine a standard time for each operation • Training • Train the operators Develop System Standardize Work Meas.mnt Time Standards Training
Defining Work Systems Work • Is our primary means of livelihood • Serves an important economic function in the global world of commerce • Creates opportunities for social interactions and friendships • Provides the products and services that sustain and improve our standard of living
Defining Work Systems • Work consists of tasks • Tasks consist of work elements • Work elements consist of basic motion elements
Defining Work Systems Task • An amount of work that is assigned to a worker or for which a worker is responsible • Repetitive task – as in mass production • Non-repetitive task – performed periodically, infrequently, or only once Work Element • A series of work activities that are logically grouped together because they have a unified function in the task • Example: assembling a component to a base part using several nuts and bolts
Defining Work Systems Basic Motion Elements • Actuations of the limbs and other body parts • Examples: • Reaching for an object • Grasping the object • Moving the object • Walking • Eye movement • A work element consists of multiple basic motion elements
1.3 Defining Work Systems • “Time=Money”? How? • New product introduction • Product cost • Delivery time • Overnight delivery • Competitive bidding • Production scheduling • Increase profit using less time!
Defining Work Systems • Importance of Time in Work • Time is the most frequently used measure of work • How many minutes or hours are required to perform a given task? • Most workers are paid by the time they work • Hourly wage rate • Salary • Workers must arrive at work on time • Labor and staffing requirements computed in units of time
Defining Work Systems • A work system is a system consisting of humans, information, and equipment designed to perform useful work • Contributes to the production of a product or delivery of a service • Examples: • Worker operating a machine tool in a factory • Robotic welding line in an automobile plant • A receptionist answering incoming phone calls
Productivity Production as a function in Economics Q=f(K,L) • Q: Output, K: Capital, L: Labor • Is there a way to change function f with a better function g? • Better Function=Higher Productivity
Productivity Productivity • The level of output of a given process relative to the level of input • Process can refer to • Individual production or service operations • A national economy • Productivity is an important metric in work systems because • Improving productivity is the means by which worker compensation can be increased without increasing the costs of products and services they produce
Productivity Labor Productivity • The most common productivity measure is labor productivity, defined by the following ratio: LPR = • LPR = labor productivity ratio • WU = work units of output • LH = labor hours of input
Productivity Labor Productivity Index • Measure that compares input/output ratio from one year to the next LPI = • LPI = labor productivity index • LPRt = labor productivity ratio for period t • LPRb = labor productivity ratio for base period
Productivity Example • During the base year in a small steel mill, 326,000 tons of steel were produced using 203,000 labor hours. In the next year, the output was 341,000 tons using 246,000 labor hours. Determine: (a) the labor productivity ratio for the base year, (b) the labor productivity ratio for the second year, and (c) the productivity index for the second year.
Productivity Solution (a) In the base year, LPR = 326,000 / 203,000 = 1.606 tons per labor hour (b) In the second year, LPR = 341,000 / 246,000 = 1.386 tons per labor hour (c) Productivity index for the second year LPI = 1.386 / 1.606 = 0.863 • Comment: No matter how it’s measured, productivity went down in the second year.
Productivity Labor Factor in Productivity • Labor itself does not contribute much to improving productivity • More important factors: • Capital - substitution of machines for human labor • Technology - fundamental change in the way some activity or function is accomplished
Horse-drawn carts Steam locomotive Telephone operator Manually operated milling machine Railroad trains Diesel locomotive Dial phone Numerically controlled (NC) milling machine Productivity
Productivity Measuring Productivity • Not as easy as it seems because of the following problems: • Nonhomogeneous output units • Multiple input factors • Labor, capital, technology, materials, energy • Price and cost changes due to economic forces • Product mix changes • Relative proportions of products that a company sells change over time
Productivity Productive Work Content • A given task performed by a worker can be considered to consist of • Basic productive work content • Theoretical minimum amount of work required to accomplish the task • Excess nonproductive activities • Extra physical and mental actions of worker • Do not add value to the task • Do not facilitate the productive work content • Take time
Productivity • Excess Nonproductive Activities can be classified into three categories: • Excess activities due to poor design of product or service • Excess activities caused by inefficient methods, poor workplace layout, and interruptions • Excessive activities cause by the human factor
Allocation of Total Task Time Productivity
Work Systems • Manual work system • Worker performing one or more tasks without the aid of powered tools • Worker-machine system • Human worker operates powered equipment • Automated work system • Process performed without the direct participation of a human worker
Work Systems Manual Work Systems • Human body accomplishing some physical task without an external source of power • With or without hand tools • When hand tools are used, the power to operate them is derived from the strength and stamina of a human worker • Other human faculties are required, such as hand-eye coordination and mental effort
Manual Work Systems Work Systems
Work Systems Pure Manual Work • Material handler moving cartons in a warehouse • Assembly worker snap-fitting two parts together Manual Work with Hand Tools • Material handling worker using a dolly to move furniture • Assembly worker using screwdriver
Work Systems Worker-Machine Systems • Worker operating a piece of powered equipment • Examples: • Machinist operating a milling machine • Construction worker operating a backhoe • Truck driver driving an 18-wheeler • Worker crew operating a rolling mill • Clerical worker entering data into a PC
Worker-Machine Systems Work Systems
Work Systems Automated Work Systems • Automation is the technology by which a process or procedure is accomplished without human assistance • Implemented using a program of instructions combined with a control system that executes the instructions • Power is required to drive the process and operate the control system
Automated Work System Work Systems
Methods Design Develop System Standardize Time Standards Training Methods Design • Motion study - analysis of the basic hand, arm, and body movements of workers as they perform work • Work design - design of the methods and motions used to perform a task • Includes: • Workplace layout and environment • Tooling and equipment used in the task
Motion Study Basic Motion Elements • Therbligs – 17 basic motion elements • Basic building blocks of virtually all manual work performed at a single location • With modification, used today in several work measurement systems, e.g., MTM and MOST • Some of the motion element names and definitions have been revised
Motion Study 17 Therbligs • Transport empty (TE) – reach for an object • Grasp (G) – grasp an object • Transport loaded (TL) – move an object with hand and arm • Hold (H) – hold an object • Release load (RL) – release control of an object • Use (U) – manipulate a tool
Motion Study • Pre-position (PP) – position object for next operation • Position (P) – position object in defined location • Assemble (A) – join two parts • Disassemble (DA) – separate multiple parts that were previously joined • Search (Sh) – attempt to find an object using eyes or hand
Motion Study • Select (St) – choose among several objects in a group • Plan (Pn) – decide on an action • Inspect (I) – determine quality of object • Unavoidable delay (UD) – waiting due to factors beyond worker control • Avoidable delay (AD) – worker waiting • Rest (R) – resting to overcome fatigue
Effective therbligs: Transport empty Grasp Transport loaded Release load Use Assemble Disassemble Inspect Rest Ineffective therbligs: Hold Pre-position Position Search Select Plan Unavoidable delay Avoidable delay Classification of Therbligs Motion Study
Motion Study Micromotion Analysis • Objectives: • Eliminate ineffective therbligs if possible • Avoid holding objects with hand – Use workholder • Combine therbligs – Perform right-hand and left-hand motions simultaneously • Simplify overall method • Reduce time for a motion, e.g., shorten distance
Example: A repetitive Manual Task • Current method: An assembly worker performs a repetitive task consisting of inserting 8 pegs into 8 holes in a board. A sightly interference fit is involved in each insertion. The worker holds the board in one hand and picks up the pegs from a tray with other hand and inserts them into the holes, one peg at a time.
Example: A repetitive Manual Task • Current method and current layout:
Example A repetitive Manual Task • Improved method and improved layout: • Use a work-holding device to hold and position the board while the worker uses both hands simultaneously to insert pegs. • Instead of picking one peg at a time, each hand will grab four pegs to minimize the number of times the worker’s hands must reach the trays.
Motion Study Principles of Motion Economy • Developed over many years of practical experience in work design • Guidelines to help determine • Work method • Workplace layout • Tools, and equipment • Objective: to maximize efficiency and minimize worker fatigue
Work Methods Design To select preferred work method: • Eliminate all unnecessary work • Combine operations or elements • Change the sequence of operations • Simplify the necessary operations
Develop System Standardize Work Meas.mnt Time Standards Training Time Study and Work Measurement Time Is Important • Most workers are paid for their time on the job • The labor content (cost of labor time) is often a major factor in the total cost of a product or service • For any organization, it is important to know how much time will be required to accomplish a given amount of work
Time Study and Work Measurement • Work measurement – evaluation of a task in terms of the time that should be allowed by an average worker to perform the task • Time study – all the ways in which time is analyzed in work situations • Standard time – amount of time that should be allowed for an average worker to process one work unit using the standard method and working at normal pace
Time Study and Work Measurement Standard times • define a “fair day’s work” • provide a means to convert workload into staffing and equipment needs • provide a basis for wage incentives and evaluation of worker performance • provide time data for: • Production planning and scheduling • Cost estimating • Material requirements planning
Task Hierarchy & Work Measurement Time Study and Work Measurement
Time Study and Work Measurement Prerequisites for Valid Time Standards: Factors that must be standardized before a time standard can be set
Time Study and Work Measurement Normal Performance • A pace of working that can be maintained by a properly trained average worker throughout an entire work shift without deleterious short-term or long-term effects on the worker’s health or physical well-being • Normal performance = 100% performance • Common benchmark of normal performance: • Walking at 3 mi/hr
Time Study and Work Measurement Performance Rating • Analyst judges the performance or pace of the worker relative to the definition of standard performance used by the organization • Standard performance Pw = 100% • Slower pace than standard Pw < 100% • Faster pace than standard Pw > 100% • Normal time Tn = Tobs(Pw )
Time Study and Work Measurement Normal Time • The time to complete a task when working at normal performance Tn = Tobs(Pw ) where Tobs = observed time, Tn = normal time, and Pw = worker performance or pace