Motion Study and Work Design Chapter 10 Sections

Motion Study and Work Design Chapter 10 Sections: 1. Basic Motion Elements and Work Analysis 2. Principles of Motion Economy and Work Design Work Systems and the Methods, Measurement, and Management of Work by Mikell P. Groover, ISBN 0 -13 -140650 -7. © 2007 Pearson Education, Inc. , Upper Saddle River, NJ. All rights reserved.

Definitions § 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 § Design of the work system § Includes: § Workplace layout and environment § Tooling and equipment used in the task such as workholders, fixtures, power tools, etc. Work Systems and the Methods, Measurement, and Management of Work by Mikell P. Groover, ISBN 0 -13 -140650 -7. © 2007 Pearson Education, Inc. , Upper Saddle River, NJ. All rights reserved.

Basic Motion Elements § Frank Gilbreth – first to analyze and classify the basic motion elements § “Therblig”s – 17 basic motion elements § Spelled backward except for “th” § Basic building blocks of virtually all manual work performed at a single location (so the primary interest is the hand motions) § With modification, used today in several work measurement systems, e. g. , MTM (Methods-Time Measurement) Work Systems and the Methods, Measurement, and Management of Work by Mikell P. Groover, ISBN 0 -13 -140650 -7. © 2007 Pearson Education, Inc. , Upper Saddle River, NJ. All rights reserved.

Basic Motion Elements (continued) § “Therblig”s – 17 basic motion elements § Some of the motion element names and definitions have been revised § Involves both physical and mental elements § Although it is first used in production and logistics, the principles are also applicable to service industry. Work Systems and the Methods, Measurement, and Management of Work by Mikell P. Groover, ISBN 0 -13 -140650 -7. © 2007 Pearson Education, Inc. , Upper Saddle River, NJ. All rights reserved.

17 Therbligs 1. 2. 3. 4. 5. 6. Transport empty (TE) – reach for an object with empty hand – today we call it “reach” Grasp (G) – grasp an object by contacting and closing the fingers until control has been achived Transport loaded (TL) – move an object with hand arm – today we call it “move” Hold (H) – hold an object with one hand Release load (RL) – release control of an object Use (U) – manipulate/use a tool Work Systems and the Methods, Measurement, and Management of Work by Mikell P. Groover, ISBN 0 -13 -140650 -7. © 2007 Pearson Education, Inc. , Upper Saddle River, NJ. All rights reserved.

17 Therbligs (continued) 7. Pre-position (PP) – position object for next operation 8. Position (P) – position object in defined location 9. Assemble (A) – join two parts 10. Disassemble (DA) – seperate multiple parts that were previously joined 11. Search (Sh) – attempt to find an object using eyes or hand Work Systems and the Methods, Measurement, and Management of Work by Mikell P. Groover, ISBN 0 -13 -140650 -7. © 2007 Pearson Education, Inc. , Upper Saddle River, NJ. All rights reserved.

17 Therbligs (continued) 12. Select (St) – choose among several objects in a group (hand-eye coordination is involved) 13. Plan (Pn) – decide on an action (a short pause or hesitation in the motions) 14. Inspect (I) – determine quality of object using the eyes 15. Unavoidable delay (UD) – waiting due to factors beyond worker control 16. Avoidable delay (AD) – worker waiting 17. Rest (R) – resting to overcome fatigue Work Systems and the Methods, Measurement, and Management of Work by Mikell P. Groover, ISBN 0 -13 -140650 -7. © 2007 Pearson Education, Inc. , Upper Saddle River, NJ. All rights reserved.

Therbligs Work Systems and the Methods, Measurement, and Management of Work by Mikell P. Groover, ISBN 0 -13 -140650 -7. © 2007 Pearson Education, Inc. , Upper Saddle River, NJ. All rights reserved.

Therbligs Work Systems and the Methods, Measurement, and Management of Work by Mikell P. Groover, ISBN 0 -13 -140650 -7. © 2007 Pearson Education, Inc. , Upper Saddle River, NJ. All rights reserved.

Therbligs Work Systems and the Methods, Measurement, and Management of Work by Mikell P. Groover, ISBN 0 -13 -140650 -7. © 2007 Pearson Education, Inc. , Upper Saddle River, NJ. All rights reserved.

Therbligs Work Systems and the Methods, Measurement, and Management of Work by Mikell P. Groover, ISBN 0 -13 -140650 -7. © 2007 Pearson Education, Inc. , Upper Saddle River, NJ. All rights reserved.

Therbligs Work Systems and the Methods, Measurement, and Management of Work by Mikell P. Groover, ISBN 0 -13 -140650 -7. © 2007 Pearson Education, Inc. , Upper Saddle River, NJ. All rights reserved.

Example Work Systems and the Methods, Measurement, and Management of Work by Mikell P. Groover, ISBN 0 -13 -140650 -7. © 2007 Pearson Education, Inc. , Upper Saddle River, NJ. All rights reserved.

Classification of Therbligs Effective therbligs: Physical Basic Motion Elements: § Transport empty § Grasp § Transport loaded § Release load § Use § Assemble § Disassemble Mental Basic Elements: § Inspect Delay Elements: § Rest Ineffective therbligs: Physical Basic Motion Elements: § Hold § Pre-position Physical and Mental Basic Motion Elements: § Position § Search § Select Mental Basic Elements: § Plan Delay elements: § Unavoidable delay § Avoidable delay § Method study at therblig level seeks to eliminate or reduce ineffective therbligs. Work Systems and the Methods, Measurement, and Management of Work by Mikell P. Groover, ISBN 0 -13 -140650 -7. © 2007 Pearson Education, Inc. , Upper Saddle River, NJ. All rights reserved.

Micromotion Analysis § The main idea of method study at therblig level: seeks to eliminate or reduce ineffective therbligs. § Each therblig represents time and energy expended by a worker. § If task is repetitive, this will be performed many times. Then, it becomes meaningul to analyze therbligs. § Known as micromotion analysis Work Systems and the Methods, Measurement, and Management of Work by Mikell P. Groover, ISBN 0 -13 -140650 -7. © 2007 Pearson Education, Inc. , Upper Saddle River, NJ. All rights reserved.

Micromotion Analysis § Analysis of therbligs that make up a repetitive task § Objectives: § Eliminate ineffective therbligs if possible § Avoid holding objects with hand – Use workholder § Combine therbligs – Perform right-hand left-hand motions simultaneously § Simplify overall method § Reduce time for a motion, e. g. , shorten distance § Checklists: § Checklist 1 (discussed in the in class) § Checklist 2 (given in the book – Table 10. 3) Work Systems and the Methods, Measurement, and Management of Work by Mikell P. Groover, ISBN 0 -13 -140650 -7. © 2007 Pearson Education, Inc. , Upper Saddle River, NJ. All rights reserved.

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 § Many people don’t understand why these principles are necessary, but you know that these principles are violated in work systems (think about your summer training). Work Systems and the Methods, Measurement, and Management of Work by Mikell P. Groover, ISBN 0 -13 -140650 -7. © 2007 Pearson Education, Inc. , Upper Saddle River, NJ. All rights reserved.

Three Categories of Principles 1. Principles that apply to the use of the human body 2. Principles that apply to the workplace arrangement 3. Principles that apply to the design of tooling and equipment Work Systems and the Methods, Measurement, and Management of Work by Mikell P. Groover, ISBN 0 -13 -140650 -7. © 2007 Pearson Education, Inc. , Upper Saddle River, NJ. All rights reserved.

Use of Human Body Most applicable to manual work 1. Design work to fully utilize both hands 2. The two hands should begin and end their motions at the same time to distribute the work equally to hands 3. Hand arm motions should be symmetrical and simultaneous to minimize hand/arm-eye coordination n Avoid different independent motions of hands/arms 4. Design work to favor preferred hand n Work units should enter the workplace on the side of the worker’s preferred hand 5. Worker’s two hands should not be idle at the same time n except for the rest breaks Don’t forget that not all tasks can be organized according to these principles. Work Systems and the Methods, Measurement, and Management of Work n by Mikell P. Groover, ISBN 0 -13 -140650 -7. © 2007 Pearson Education, Inc. , Upper Saddle River, NJ. All rights reserved.

An experiment § A relatively simple task § Reaching, selecting, grasping, transporting, releasing small parts. § Two types of containers § A rectangular bin § A bin with a tray § The worker performed the work cycle with each container using § Only the right hand § Only the left hand § Both hands performing symmetrical and simultaneous motions. Work Systems and the Methods, Measurement, and Management of Work by Mikell P. Groover, ISBN 0 -13 -140650 -7. © 2007 Pearson Education, Inc. , Upper Saddle River, NJ. All rights reserved.

0. 72 sec / work unit Work Systems and the Methods, Measurement, and Management of Work by Mikell P. Groover, ISBN 0 -13 -140650 -7. © 2007 Pearson Education, Inc. , Upper Saddle River, NJ. All rights reserved. 0. 54 sec / work unit

Use of Human Body Utilize laws of physics 6. Method should consist of smooth continuous curved motions rather than straight motions with abrupt changes in direction n n 7. Although shortest distance between two points is a straight line Because straight-line path sequence includes start and stop actions (accelerations and decelerations) consume worker’s time and energy Use momentum (mass * velocity) to facilitate task n Carpenter using a hammer to strike a nail 8. Take advantage of gravity – Don’t oppose it 9. Method should achieve a natural rhythm of the motions involved Work Systems and the Methods, Measurement, and Management of Work by Mikell P. Groover, ISBN 0 -13 -140650 -7. © 2007 Pearson Education, Inc. , Upper Saddle River, NJ. All rights reserved.

Use of Human Body 10. Use lowest classification of hand arm motion (five classifications) 1) Finger 2) Finger and wrist 3) Finger, wrist, and forearm 4) Finger, wrist, forearm, and upper arm 5) Finger, wrist, forearm, upper arm, and shoulder Work Systems and the Methods, Measurement, and Management of Work by Mikell P. Groover, ISBN 0 -13 -140650 -7. © 2007 Pearson Education, Inc. , Upper Saddle River, NJ. All rights reserved.

I Movement of the fingers only as when picking up a cotton roll. II Fingers and wrist motion as used when transferring an instrument to the operator, or manipulating a hand instrument. Work Systems and the Methods, Measurement, and Management of Work by Mikell P. Groover, ISBN 0 -13 -140650 -7. © 2007 Pearson Education, Inc. , Upper Saddle River, NJ. All rights reserved.

III Fingers, wrist, and forearm as when reaching for a handpiece. IV The entire arm when reaching for supplies away from the work area, or to adjust the operating light. Work Systems and the Methods, Measurement, and Management of Work by Mikell P. Groover, ISBN 0 -13 -140650 -7. © 2007 Pearson Education, Inc. , Upper Saddle River, NJ. All rights reserved.

V The entire arm and shoulder as when turning around to reach for equipment from adjacent fixed cabinetry. Work Systems and the Methods, Measurement, and Management of Work by Mikell P. Groover, ISBN 0 -13 -140650 -7. © 2007 Pearson Education, Inc. , Upper Saddle River, NJ. All rights reserved.

Use of Human Body For using body members other than the hands, and arms 11. Minimize eye focus and travel n Minimize the distance between the object 12. Design method to utilize feet and legs where appropriate n Since they are stronger than arms Work Systems and the Methods, Measurement, and Management of Work by Mikell P. Groover, ISBN 0 -13 -140650 -7. © 2007 Pearson Education, Inc. , Upper Saddle River, NJ. All rights reserved.

Workplace Arrangement Design of the workplace 1. Locate tools and materials in fixed positions within the work area 2. Locate tools and materials close to where they are used n To minimize the distances to be covered 3. Locate tools and materials to be consistent with sequence of work elements n Decrease the time required for searching Work Systems and the Methods, Measurement, and Management of Work by Mikell P. Groover, ISBN 0 -13 -140650 -7. © 2007 Pearson Education, Inc. , Upper Saddle River, NJ. All rights reserved.

Workplace Arrangement § Normal and maximum working areas in the workplace Design for average user Work Systems and the Methods, Measurement, and Management of Work by Mikell P. Groover, ISBN 0 -13 -140650 -7. © 2007 Pearson Education, Inc. , Upper Saddle River, NJ. All rights reserved.

Work Systems and the Methods, Measurement, and Management of Work by Mikell P. Groover, ISBN 0 -13 -140650 -7. © 2007 Pearson Education, Inc. , Upper Saddle River, NJ. All rights reserved.

Illustration of First Three Principles Poor arrangement of parts and tools in workplace Numbers indicate the sequence of operations Work Systems and the Methods, Measurement, and Management of Work by Mikell P. Groover, ISBN 0 -13 -140650 -7. © 2007 Pearson Education, Inc. , Upper Saddle River, NJ. All rights reserved.

Illustration of First Three Principles Good arrangement of parts and tools in workplace Numbers indicate the sequence of operations Work Systems and the Methods, Measurement, and Management of Work by Mikell P. Groover, ISBN 0 -13 -140650 -7. © 2007 Pearson Education, Inc. , Upper Saddle River, NJ. All rights reserved.

Workplace Arrangement 4. Use gravity feed bins to deliver small parts and fasteners Two types of bins used for small parts and fasteners in the workplace: (a) gravity feed bin (b) conventional rectangular bin Work Systems and the Methods, Measurement, and Management of Work by Mikell P. Groover, ISBN 0 -13 -140650 -7. © 2007 Pearson Education, Inc. , Upper Saddle River, NJ. All rights reserved.

Workplace Arrangement 5. Use gravity drop chutes for completed work units where appropriate 6. Provide adequate illumination n Also color, constrast among items, location of the light source are important 7. A proper chair should be provided for the worker § Adjustable to the size of the worker § Seat height and back adjustments § Padded seat and back Work Systems and the Methods, Measurement, and Management of Work by Mikell P. Groover, ISBN 0 -13 -140650 -7. © 2007 Pearson Education, Inc. , Upper Saddle River, NJ. All rights reserved.

Adjustable Chair for Workplace Work Systems and the Methods, Measurement, and Management of Work by Mikell P. Groover, ISBN 0 -13 -140650 -7. © 2007 Pearson Education, Inc. , Upper Saddle River, NJ. All rights reserved.

Design of Tooling and Equipment 1. Workholding devices should be designed for the task 2. Hands should be relieved of work elements that can be performed by the feet using foot pedals § sewing machine 3. Combine multiple functions into one tool where possible n Pencils designed for writing and erasing 4. Perform multiple operations simultaneously rather than sequentially n Multiple-spindle drill presses to drill holes in PCBs Work Systems and the Methods, Measurement, and Management of Work by Mikell P. Groover, ISBN 0 -13 -140650 -7. © 2007 Pearson Education, Inc. , Upper Saddle River, NJ. All rights reserved.

Design of Tooling and Equipment 5. Where feasible, perform operation on multiple parts simultaneously n 6. Design equipment controls for operator convenience and error avoidance n 7. Controls should be located within easy reach to minimize the body motions required to access them Hand tools and portable power tools should be designed for operator comfort and convenience n 8. Machines in a cake factory e. g. tools that can accomodate both right-handed and left -handed workers Mechanize or automate manual economically and technically feasible Work Systems and the Methods, Measurement, and Management of Work by Mikell P. Groover, ISBN 0 -13 -140650 -7. © 2007 Pearson Education, Inc. , Upper Saddle River, NJ. All rights reserved. operations if