To design we need to follow some rules that ensure the proper ergonomics design. Here different types of hand tools is discussed, awkward situation, Different injuries of using hand tools ,hand anthropometry also showed here. And at last the general guidence are given here.

1. Hand Tool Design
Submitted to
Dr. Engr. Mohammad Iqbal
Professor
Industrial & Production Engineering,
Shahjalal University of Science &
Technology,Sylhet
Industrial & Production Engineering,
Shahjalal University of Science & Technology
Submitted By
Group B4
Tanni Das 2013334054
Kyaw Zaw Thowai 2013334055
Aminul Islam 2013334056
K A M Shahrier 2013334057
Mahbub Alam 2013334058
Ali Akbar Tanim 2013334060

2. Industrial & Production Engineering,
Shahjalal University of Science & Technology
and tool is any tool that is powered by
. hand (manual labor) rather than by an
engine.
Hand tool aid the Human for
Cutting, smashing, scraping, and piercing.
Fit the work.
Fit the user and hand.
Not create injuries.
H

3. Industrial & Production Engineering,
Shahjalal University of Science & Technology
 Handled with power grip or with a precious
grip.
 Small or large
 Flexible or, stiff
 One can design special purpose hand tool
for specific task
 Possible to combine several hand tools into one.
Fig: A special Handtool
A tool use in multipurpose task at a time can be said as a special
Hand tool. It saves time and make work easier.
E.g. Hammer with an extension pulling nails,
pliers with Hammer parts etc.

4. Fittingthetask
Power Grip
 The hand makes a fist with the forefinger on one side and the
thumb reaching around.
 It can be differentiate by direction of force
i)Force parallel to the forearm. E.g. saw;
ii) Force at angle to forearm. E.g. Hammer
iii)Torque about the forearm. E.g. Screwdriver
Industrial & Production Engineering,
Shahjalal University of Science & Technology
Saw
Hammer
Screw driver

5. Precision Grip
Industrial & Production Engineering,
Shahjalal University of Science & Technology
Internal Precision Grip
The tool is held inside the hand.
E.g. A table knife
External Precision Grip
The tool is pinched by the thumbs
. against the index finger and the
middle finger. E.g. A pen.
Fig: Gripping a table Knife
Fig: Writing by pen

6. Industrial & Production Engineering,
Shahjalal University of Science & Technology
Hand Tools Power Tools
Hand tools are devices for performing
work on a material or a physical
system using only hands
Power tools are tools powered by an
electric motor
Hand tools are propelled only by
human power
Power tools always have a motor
Hand tools mechanism is very easy Power tools mechanism is not easy as
hand tools
It is environment friendly and
cheaper but take more time than
power tools
Power tool save a considerable
amount of time and effort in a larger
project.

7. Industrial & Production Engineering,
Shahjalal University of Science & Technology
Good
Pistol Handle
Vertical surface
Elbow height
Bad
Pistol Handle
Horizontal surface
Elbow height
Bad
Straight Handle
Vertical surface
Elbow height
Good
Straight Handle
Horizontal surface
Elbow height
Bad
Straight Handle
Horizontal surface
Below elbow height
Good
Piston Handle
Horizontal surface
Below elbow height

8. Industrial & Production Engineering,
Shahjalal University of Science & Technology
Fig: Maximum grip strength for male and
female employees in electronics manufacturing

9. Industrial & Production Engineering,
Shahjalal University of Science & Technology

10.  Right handed tools for left handed users
create awkward situation.
 Awkward postures may cause to use more
force.
 Cut-outs for the fingers are responsible
 Awkward wrist position results in a loss of
strength
 It is responsible for CTD
 It affects torque exertion capability
Awkward wrist position (Terrell and
Pursell-1976) :
 Decreases grip strength by 12%
 Flexion/extension by 25%
 Radial/ulnar deviation by 15%
Prevention:
 Hand-tool should be designed both the
left handed & right handed user.
 Design hand-tools by hand
anthropometry
Industrial & Production Engineering,
Shahjalal University of Science & Technology

11. Industrial & Production Engineering,
Shahjalal University of Science & Technology
Cumulative Trauma disorder (CTD)
Repetitive usage of hand tools
Wear & tear on tissue on the joint.
Vibration-Induced Injuries
Hand tool vibration
1)Reynaud’s disease:
Hand tool vibration in the frequency range 50-100 Hz
2)Dart’s disease:
Vibration frequencies around 100 Hz

12. Industrial & Production Engineering,
Shahjalal University of Science & Technology
2)Stiffness and numbness
 Reduction of blood flow
 Gradual loss of muscle control of the
hand
1)White finger disease
 Reduction in blood flow to the hand
and the finger
Fig: White finger disease
Fig: Stiffness and numbness

13. Industrial & Production Engineering,
Shahjalal University of Science & Technology
Aim:
To increase operator comfort, convenience and controllability of hand tools .
Guidelines:
 For precision grip
 Grip between thumb and finger
Grip thickness is 8 to 13 mm
Grip length minimum 100 mm
Toll weight maximum 1.75 kg
Trigger activated by distal phalanges of fingers with fast release
mechanism.

14. Industrial & Production Engineering,
Shahjalal University of Science & Technology
For power grip
Grip with entire hand
Grip thickness 50-60 mm
Grip length minimum 125 mm
Grip force maximum 100 m
Grip shape non-cylindrical
Tool weight maximum 2.3 kg, 1.2 kg is preferable
Trigger activated by thumb with locking mechanism

15. Industrial & Production Engineering,
Shahjalal University of Science & Technology
Grip surface smooth
Slightly compressible and non conductive
Avoid vibration, Particularly in the range of 50-100 Hz
Design Handles for use by either hands
Keep the wrist straight in the handshake orientation
Tool weight balanced about the grip axis
Eliminate pinching hazard

16. The End