Predetermined Time Systems

INSY 3021

Auburn UniversitySpring 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 = 0.00001 hour 1 TMU = 0.0006 min 1 TMU = 0.036 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 movedGET 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

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 ReturnHow did I GET the marker?

How did I PUT the marker?

Did I RETURN?

Index Values

A B G A B P A 6 6 1 6 0 1 0

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 1 0 3 10 0 6 10 Get Put Return

300 TMU x .036 sec/TMU = 10.8 seconds

How is Work Measurement Done?

A B G A B P A 1 0 3 10 6 3 10 Get Put Return

A B G A B P A 1 0 3 10 0 6 10 Get Put Return

A B G A B P A 1 0 3 10 0 1 10 Get Put Return

Top Row

Middle Row

Bottom Row

TMU

300

250

330

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

Pro’s & Con’sDisadvantages: 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 ModelsActivity Sequence Model Parameter

General Move

ABG ABP A A – action distanceB – body motionG – gain controlP – placement

Controlled Move

ABG MXI A M – move controlledX – process timeI – alignment

Tool Use ABG ABP * ABP A F/L – fasten/loosenC – cutS – surface treatM – measureR – recordT – 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

General Move

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.

Questions & Comments