DWF is utilized for operation which need
Accurate time standards.
The Work-Factor system is based on the
principle that the Four Major Variables
which affect the time to perform manual
1. Body Member used
2. Distance Moved
3. Manual Control required
4. weight or Resistance involved
1. Body Member
7 definite body members…
1) Finger or Hand
3) Forearm Swivel
Time values for these body members are illustrated in
All distances are measurements in straight lines
between the starting and stopping points of the
motion as described by body members.
Measured in inches.
Tables specify the point at which various body
members motion has to be measured.
3. Manual control
Definite Stop Work-Factor
Direction Change Work-Factor
• Its evaluation is made more difficult as
there is no physical measuring device
with which its effects can be checked
4. Weight or Resistance
Effect of weight on time varies with
Body Members used
Sex of operator
Measured in pounds for all Body
Members except Forearm Swivel.
Forearm Swivel Motions are rotary,
measured in pound-inches of torque.
ARM MOVES 18 inches to TOSS A
SMALL COIN IN A TRAY….
Body member involve is Arm (A)
Distance 18 inch
No manual controls requirements
As per table, value is 55, corresponds to
Body members Symbol
• Finger F
• Hand H
• Arm A
• Forearm Swivel FS
• Trunk T
• Foot Ft
• Leg L
• Head Turn HT
• Weight W
• Steer S
• Precaution P
• Direction Change U
• Definite Stop D
RECORDING THE ANALYSIS
Toss small part aside 10 in. (Basic Motion)
Reach 30 inches to bolt in bin (Definite
Move 4 pound brick 30 in. from pile to
place on work table (Weight, Definite Stop
ELEMENTS OF WORK
8 Work-Factor Standard Elements of
1. Transport (Reach & Move) (R, M)
2. Grasp (Gr)
3. Pre-position (PP)
4. Assemble (Asy)
5. Use (Manual, Process or Machine Time) (Use)
6. Disassemble (Dsy)
7. Mental Process (MP)
8. Release (Rl)
The Standard Element Transport
involves a single motion by a given
Act of obtaining Manual Control of an
object for the purpose of
transporting, using, or holding.
Act of turning or orienting an object to a
correct position for a subsequent Standard
Element of Work.
A bolt 2 inches long weighing 3 pound can be
pre-positioned for assembly into a tapped hole
by turning it end-for-end with one hand. An
average of 3 Finger Motion is required to
complete the Pre-position.
Analysis for this Pre-position is V3F1-50%.
Act of joining objects together or placing them
in useful locations.
Assemble begins immediately after the Move
bringing the objects to a position where
Assemble can start.
All Work-Factor Assembles utilize the concept
of Plug and Target, where a Plug is inserted
into or placed on a Target.
The Unwrap Release
Concurrent Mental Process
Sequential Mental Process
General higher level system
Suitable for medium quantity
Developed from Detailed Work-Factor
Quite effective in preparing estimates
before actual production starts.
Developed from Detailed Work-Factor
Suitable for small quantity job shops.
Abbreviated time unit is 0.005
(recorded as 5) minutes rather than
0.0001 minutes used in the DWF.
Accuracy of AWF is expected to
average +12 percent of the DWF.
Based on Detailed Work-Factor
Normally utilized in evaluating
manual work in industry.
One Ready Units equals 10 Detailed
Work-Factor Time Units (0.0010
15 inch Arm factor with two Work-
Factor required 9 Ready Units, or
BWF system is relatively new and like
the AWF uses the time unit of 0.005
It was developed to make the format
conform with the Detailed, and with
the Ready systems.
DETAILED MENTO FACTOR
It is a basic level system which is
used for measuring mental processes
such as …
Any repetitive predominantly mental
Quick J. H., Duncan J. H., Malcolm J. A., Jr.,
Work-Factor Time Standards, McGraw-Hill
Book Company, New York, 1962.
Barnes R. M., Motion and Time Study- Design
and Measurement of Work, Seventh Edition,
John Wiley and Sons.
Sharma S. K., Work Study and Ergonomics,
Katson Books, Delhi, 2003-04.
ILO, Introduction to Work Study, vol-3, 1986.