Presentation on theme: "Predetermined Time Systems INSY 3021 Auburn University Spring 2007."— Presentation transcript:
Predetermined Time Systems INSY 3021 Auburn University Spring 2007
History Fredrick Taylor Time Study Frank and Lillian Gilbreth Motion Studies Predetermined Time Systems (PDTS) Combination of time and motion studies
Therbligs! Work can be described by these 17. Effective/Productive: Reach, Move, Grasp, Release, Pre-Position, Use, Assemble & Disassemble. Ineffective/Non-Productive: Search, Select, Position, Inspect, Plan, Unavoidable Delay, Avoidable Delay, Hold, Rest to overcome fatigue.
Uses To predict standard times for new or modified jobs Used to improve method analysis Can identify ergonomic risk factors and risk of repetitive strain indices (RSI)
Composition Sets of motion-time tables with rules and instructions Specialized training is essential to the practical application of these techniques Times are at 100% - which eliminates performance rating May be slight variability among different people using the same tool
Types of Systems Acceleration-deceleration Systems Different body motions move at different velocities 40% of total time is used during acceleration, 20% for constant velocity, and 40% for deceleration Not widely used today Very important in fields of Biomechanics and Kinematics Average-motion Systems Represents average motion difficulties for industrial operations Additive Systems Basic time values are used with a correction factor for difficult motions
Methods-Time Measurement (MTM) A procedure that analyses manual operations or methods into basic motions needed to perform it, and assigns each a pre-determined time based on the motion and environmental conditions
MTM-1 Fundamental Motions Reach, turn, position, release, move, grasp, disengage Procedure Summarize all right-hand and left-hand motions Determine time measurement unit (TMU) Remove non-limiting motion values
Time Measurement Units (TMU) 1 TMU = hour 1 TMU = min 1 TMU = sec 1 hour = 100,000 TMU 1 min = 1667 TMU 1 sec = 27.8 TMU
Maynard Operation Sequence Technique (MOST) Developed in 1980 by Zjell Zandin Establishes standards at least 5 times faster than MTM-1, w/little if any sacrifice in accuracy Concentrates on the movements of objects
MOST Procedure Watch job/task Determine sequence(s) to use Determine index values Add index values to determine TMU Multiply TMU by 10 Convert TMU to seconds, minutes, hours
Concept of MOST f = 10 lbs. d = 4 in. f = 10 lbs. d = 0 in. Definition of work Work is the displacement of a mass or object Work = Force X Distance
In Work, an object is moved GET and PUT For example, you can lift a box and place it down three feet away. Basic body motions used to perform work occur in repeating patterns or sequences. This is the foundation of BasicMOST and the sequence models that make up MOST. Concept of MOST
MOST Analysis Index Values (1, 3, 6…) Sequence ModelMethod Description Parameters (A, B, G…) Phases
Concept of MOST Method Description Documents the action performed Clear, concise and easily understood Comprised of recommended words Example: Grasp marker located three steps away on the floor and put in holder.
Sequence Models Sequence models represent the sequence of events that occurs when an object is moved or a tool is used. Predefined sequence models represent different types of activities. Three sequence models can be used to analyze all types of manual work: General Move (moved freely through space) Controlled Move (movement restricted; attached or in contact) Tool Use (using common hand tools)
Phases Sequence models are structured into phases used to describe the action performed. Each of the predefined sequence models has a different set of phases. From Method Description Example: Grasp marker located three steps away on the floor and put in holder. Phase: Get Put Return How did I GET the marker? How did I PUT the marker? Did I RETURN?
Index Values A B G A B P A Each parameter is assigned an index value based on the motion needed to perform the activity. Index values are then used to generate the total time required to perform a task. Get Put Return
How is Work Measurement Done? Method Description from video: Grasp heavy box located within reach, walk eight steps, position on pallet and return to initial location. A B G A B P A Get Put Return 300 TMU x.036 sec/TMU = 10.8 seconds
How is Work Measurement Done? A B G A B P A Get Put Return A B G A B P A Get Put Return A B G A B P A Get Put Return Top Row Middle Row Bottom Row TMU
Sources of error & variance Hard to classify some motions Difference in opinion between team members Variation in distance measurements Repeatability and variation of worker Very time-consuming to break up job Repetitive to enter in data May not match actual times
Pros & Cons Disadvantages: Requires exact job description and layout Chance of omitting elements when estimating new jobs Not always applicable to non-repetitive operations Advantages: Efficiently estimates the time to perform a task Accurate results Methods are easily understood Sequence models result in minimal paperwork Encourages method development and continuous improvement
Basic Sequence Models General Move The spatial movement of an object freely through the air Controlled Move The movement of an object when it either remains in contact with a surface or remains attached to another object during movement Tool Use
Basic Sequence Models ActivitySequence ModelParameter General Move ABG ABP AA – action distance B – body motion G – gain control P – placement Controlled Move ABG MXI AM – move controlled X – process time I – alignment Tool UseABG ABP * ABP AF/L – fasten/loosen C – cut S – surface treat M – measure R – record T – think
General Move Parameters Action Distance (A) – horizontal distance Body Motion (B) – vertical distance Gain Control (G) Placement (P) ABG | ABP | A Get | Put | Return Assign an index value based on complexity Accounts for 50-60% of most industrial work
MOST (PTS) When determining the normal time that it takes to obtain an object, Action Distance is accounted for in the calculation
MOST (PTS) As you can see, Body Movement is taken into account for the calculation
Controlled Move Parameters: Action Distance (A) – horizontal distance Body Motion (B) – vertical distance Gain Control (G) Move Controlled (M) Process Time (X) – machine time Alignment (I) ABG | MXI | A Get | Move or Actuate | Return
Tool Use Parameters: Fasten (F) Loosen (L) Cut (C) Surface Treat (S) Measure (M) Record (R) Think (T) ABG | ABP | * | ABP | A Get | Put | Tool Action | Put | Return
Examples Example: Get a handful of washers and put them onto 3 bolts located 5 inches apart. A1 B0 G3 (A1 B0 P1) A0 (3) = 100 TMU Example: A worker slides a ruler within reach and pushes it 6 inches (15 cm) to measure two points that are 8 inches apart. A1 B0 G1 M1 X0 I6 A0 = 90 TMU Example: Grasp wrench and fasten bolt with 3 wrist strokes and aside. A1 B0 G1 A1 B0 P3 F10 A1 B0 P1 A0 = 180 TMU
Other MOST Systems MiniMOST MaxiMOST AdminMOST MOST ® Work Measurement Systems: Third Edition, Revised and Expanded, Kjell B. Zandin
Special Issues Work Factors For instance, allows the incorporation of stairs & gates into PDTS models.