Mechanical engineering seminar report

1. Ergonomics,
A seminar presentation
Made by :
Subhi sanchali Gupta
080909460 (192)

2. What is Ergonomics?
 Ergonomics, also known as human factors, is the scientific
discipline that seeks to understand and improve human
interactions with products, equipment, environments and
systems.
 Drawing upon human biology, psychology, engineering and
design, ergonomics aims to develop and apply knowledge and
techniques to optimise system performance, whilst protecting
the health, safety and well-being of individuals involved. The
attention of ergonomics extends across work, leisure and
other aspects of our daily lives.
 Basically, Ergonomics is a science concerned with the fit between
people and their work. It puts people first, taking account of their
capabilities and limitations. Ergonomics aims to make sure that
tasks, equipment, information and the environment suit each
worker.

3. Factors taken into account:
■ body size and shape
■ fitness and strength
■ posture
■ the senses, especially vision, hearing and touch
■ the stresses and strains on muscles, joints, nerves.
■ mental abilities
■ personality
■ knowledge
■ experience.
■ the job being done and the demands on the worker
■ the equipment used (its size, shape, and how appropriate it is for the task)
■ the information used (how it is presented, accessed, and changed)
■ the physical environment (temperature, humidity, lighting, noise, vibration)
■ the social environment (such as teamwork and supportive management).

4. 1. Applied Anthropometry
Introduction
 The workplace should be designed to accommodate
the body size of the user. Anthropometry is the
measure of physical human traits that is applied to
determine allowable space and equipment size and
shape used for the work environment. Factors that are
considered include agility and mobility, age, sex, body
size, strength, and disabilities.
 Engineering anthropometry applies these data to
tools, equipment, workplaces, chairs and other
consumer products, including clothing design.

5. Example
 In the design of controls, the size of the operator‘s hand
must be considered. Important hand dimensions include
the circumference of the hand, breadth of the hand,
circumference of the wrist, and the maximum grip. Knobs,
for example, must consider these dimensions so they fit the
hand comfortably and turn easily.
1. Important Hand Dimensions:
1—Circumference of hand
2—Breadth of hand
3—Circumference of wrist
4—Maximum grip (circumference of thumb and forefinger)

7. 2. Biomechanics
Introduction
 Biomechanics is the study of the structural elements of
the human body in relation to how the body functions
and how much stress, acceleration and impact it can
stand.
 Simply defined, it is the application of the
principles of mechanics to living biological
material. Today, the total energy demanded from a
person in the performance of an industrial task has
often been drastically reduced through better
engineering and technology.

8. Equipment
 Improperly designed chairs or other poorly designed
equipment may obstruct the blood flow to body tissues. It
is essential that designers as well as the evaluators of tools
and equipment be familiar with the location of blood
vessels vulnerable to compression.
 Of special importance is the knowledge of the location of
blood vessels and other pressure sensitive anatomical
structures in the hand.
 For example, poorly designed or improperly held hand
tools may squeeze the hand’s ulnar nerve, which can lead
to numbness and tingling of the fingers. The simplest of
hand tools, if designed without due consideration to
biomechanical principles, can adversely affect the health of
people as well as their performance and productivity.

9. 3. Illumination
 Lighting of a sufficient intensity is essential to
adequately perform visual tasks and to reduce worker
fatigue. How a space is used and what it is used for
influence how lighting should be applied.
 Other factors that influence lighting design for a
task include appearance, economics, building costs,
energy consumption and the quality of lighting
desired.
 Factors affecting the visual environment include
lighting fixtures, visual tasks, lighting maintenance,
lighting system design and the individuals’ eyesight.

10.  The quantity of illumination relates to the amount of
light that exists or is required at a workplace. The
amount of light necessary for effective work depends
on the nature of the work, the sharpness of a worker’s
vision and the environment in which the work is done.
 In the design of good lighting, safety and welfare
should be taken into account as well as visual
efficiency.
 In some jobs where visual demands are not great, it is
normal for recommended levels of illumination to be
based on safety, welfare and amenity (creation of a
pleasant environment).
 Too much light can be as damaging as too little.

11. Measures taken:
 The best ergonomic solution for these varying needs is
to provide general workplace lighting and supplement
it with specific task lighting.
 Lighting systems should be designed to provide a
uniform distribution of light over the entire work area.
 To ensure that a given illumination level will be
maintained, give more light initially than is minimally
required. The reason for this is that such factors as
dirt, use and time deteriorate lighting.
 Lighting should be directed to the work, or special
local lighting should be provided to match the needs
of the work and the general lighting levels.

12. Cumulative Trauma Disorders
 Introduction
 Musculoskeletal injuries caused by working are
common. The majority of these injuries are not
accident-related broken bones or strained ligaments.
 They usually develop over a period of time as a result
of repeated stress on a particular body part. The
condition is often ignored until the symptoms become
chronic and permanent injury occurs.
 Cumulative trauma disorders (CTDs) and repetitive
motion injuries are terms used to refer to certain
musculoskeletal injuries.

13.  A key reason for the increase in CTDs is the increase in
production due to automation. The assembly line,
computerized office machines and electronic checkout
stations in grocery stores are examples of workstations
that require a high volume of output.
 One simple, strain-producing task may be repeated
several thousand times a day. High production
demands do not allow much time for rest and recovery.
 The aging workforce relates to the incidence of CTDs
because the ability to withstand shock, chronic strain
and stress decreases as an individual ages.

14. A. Carpal Tunnel Syndrome
 Carpal Tunnel Syndrome (CTS) is a common nerve CTD.
 It is a progressively disabling and painful condition of the
hand.
 CTS results from injury to the median nerve, which is
located in the wrist. It is a nerve entrapment that develops
from the build-up of pressure on the median nerve as it
passes through the carpal tunnel.
 This is a dime size passage between the carpal (wrist)
bones and the anterior transverse carpal ligament.
Since musculoskeletal strain from repeatedly flexing the
wrist or applying arm-wrist-finger force does not cause
observable injuries, it often takes months or years for
workers to detect damage.

15.  Symptoms of CTS include
weakness, clumsiness, numbness, pain, tingling
and a lack of sweating in parts of the hand
innervated by the median nerve.
 The condition is progressive and can lead to
compensable hand disabilities.
 CTS is considered an occupational disease, as it is
often associated with the performance of
particular repetitive tasks.

16.  Tenosynovitis.
Tenosynovitis is the inflammation of the tendons and
sheaths. It is often associated with tasks demanding
extreme wrist deviation. For example, wrist deviation is
required to hold an in-line nut-runner in a horizontal
position.
 Trigger finger.
Trigger finger is a form of tenosynovitis that results when
any finger must be frequently flexed against resistance. It
may be avoided by designing tool handles for operation
by the thumb, by more than one finger, with lower force
requirements, or by not requiring constant pressure.
 De Quervain’s Disease.
In De Quervain’s disease, the tendon sheath of both the
long and the short abductor muscles of the thumb
narrows. The disease is common among women,
particularly those who perform repetitive manual tasks
involving radial or inward hand motion and firm grips.

17.  Tennis Elbow.
Also called epicondylitis, this form of tendinitis is an
inflammatory reaction of tissues in the elbow region. In an
industrial environment, tennis elbow may follow effort
requiring palm-upward hand motion against resistance,
such as using a screwdriver, the violent upward extension
of the wrist with the palm down. The condition may be
avoided by ensuring that the rotation axis of the tool or
machine coincides with the rotation axis of the forearm.
 Raynaud’s Syndrome
Raynaud’s syndrome occurs when blood vessels and nerves
in the hands constrict from conditions such as cold
temperature, vibration or emotion. The hands, fingers or
finger tips may become cold, blue, numb, and lose fine
manipulative ability. Upon recovery, the hands become red,
accompanied by a burning sensation. It can be confused
with the one-sided numbness of carpal tunnel syndrome.

18. CORRECTIVE ACTIONS:
 Corrective actions to prevent CTDs include adjusting the
height of work tables, conveyors and seats; automating
tasks to eliminate manual handling;
 reducing the frequency of tasks or increasing the frequency
to a point where automation is necessary;
 reducing the size or weight of loads; providing arm rests;
redesigning hand tools so that the axis of rotation or
application of force coincides with the axis of rotation of
the arm; providing operator training;
 using careful pre-placement screening to identify high risk
employees; changing load positions in relation to the body
or hands; minimizing the time that a load is held in the
hands; and eliminating gloves if they cause a problem or
trying different gloves.

19.  Among recommendations to help prevent the
development of CTS5 are these:
 Low frequency vibration in hand tools should be
eliminated or reduced.
 Wrist deviation from the straight position should be
minimized especially where a great deal of force must
be exerted.
 Where possible, a closed fist (rather than a pinch)
should be used to reduce tendon tension

20. 1. Hand tool corrections
 Each year, hand tools are the source of approximately 6
percent of all compensable injuries.6 Improper use of hand
tools and defective tools can cause biomechanical stress
and injuries.
 Types of injuries frequently reported include broken bones,
contusions, loss of eyes and eyesight, and puncture
wounds. Additionally, fingers, tendons and arteries are
severed from the use of cutting tools.
 Basic safety precautions mandate that tools always be kept
in good condition and be used properly. Workers should be
careful to use the proper tool for the job performed. Figure
illustrates particular hand tools with ergonomically
designed features

21. Hand Tools with Ergonomic
Features

22. 2. Hand and Wrist Postures
 Some hand tools may force the wrist to assume
awkward postures. The wrist position affects the
effective strength of the contracting muscles.
 Therefore, as the angle of the joint increases or
decreases from the neutral position, there is more
stress on the tendons. Ulnar deviation is the bending
of the wrist toward the little finger, and radial
deviation is the bending of the wrist toward the
thumb. Extension is bending the wrist up and
back, and flexion is bending of the wrist down towards
the palm

24. 3. Finger and Hand Grips
 The grips used most frequently to hold objects are
shown in Figure. The tip grip (pinching) is a position
grasp used for precise manipulations.
 The side grip is also classified as a precision grip.
Repeated use of these grips creates stress on the two
tendons controlling the thumbs and fingers.
 The power grip requires the thumb to align with the
long axis of the forearm and the wrist assumes a slight
ulnar deviation. The posture may be stressful when
combined with high repetition and extreme force.

26. 4. Seating
 Almost 50 percent of workers in the industrial world
are thought to suffer from back problems. Many back
problems originate from improper sitting positions.
Complications that may arise from poor seating
conditions include:
 Lumbar damage from lack of support in the lumbar
region.
 Damage to the erector spinae muscles due to sitting
without back support.
 Damage to the knees, legs, and lumbar region, from
sitting without footrests of the proper height.
 Damage to various muscle groups

27. A. Proper Sitting Positions
 Proper sitting contributes to the physical well-being of
a worker. It may also add as much as 40 minutes of
production to each worker’s day if the chair is properly
selected and customized to support the lower back.
 The ideal position for sitting at work exists when there
is a slight curve in the lumbar region of the back, as is
found in the standing position. The worker’s shoulders
should be relaxed, with the upper arms hanging down
loosely. During work, the neck should not be bent too
much

28. B. Guidelines to Chair Adjustment
 The human body dimension that provides a starting
point for determining correct chair height is the
“popliteal” height.
 Figure illustrates the popliteal height. This is the
height from the floor to the point at the crease behind
the knee. The chair height is correct when the entire
sole of the foot can rest on the floor or footrest and the
back of the knee is slightly higher than the seat of the
chair. This allows the blood to circulate freely in the
legs and feet.
 The back of the chair should be adjusted so that it
catches the concave portion of the back’s lumbar
region.

31. 5. Physical Space Arrangements
 For workspace to be functional, both the user of the
space and the work to be performed must be
considered. Workspace arrangements should consider
worker comfort, physical constraints and performance
requirements.
 Four basic considerations regarding the worker that
must be taken into account are:
 What the worker needs to see.
 The amount of communication needed with co-workers
and supervisors.
 Equipment and material that the worker must be able
to work with and reach.
 Body clearances that are needed by the worker.

32. 6. Driving
 The goal of ergonomics is to fit your car so you can
drive in a way that maximizes the natural ability of
your body to move and respond to physical stress. This
minimizes exposures to risk factors that may result in
injury or illness.

33. Here are 10 easy things to look for before you
start your next drive:
 Remove items from your pockets, such as a wallet or
keys, which may press on soft tissue as you sit down. This
compression can reduce circulation or press on nerves and other
soft tissues.
 2. Position items that you may need during your drive :
sunglasses, tissue, if you have allergies like the rest of us, throat
lozenges or mints, etc. Place these in a location so you do not
have to reach for them while driving. If you have to reach for an
item, take the time to pull over in a safe place instead of risking
an accident and/or injury due to awkward reaching.
 3. Buckle up! If the seat belt strap is uncomfortable, take a short
piece of large diameter soft pipe insulation or foam and place it
on the part of the strap that is not comfortable against your body.
If you like to spend money, purchase a shoulder strap cushion at
your favorite store where car accessories are sold.

34.  4. Adjust your mirrors so that you do not have to crane your neck
to see. If you have a blind spot in your car you can attach a small mirror
your dashboard to improve your view.
 5. Lumbar support – the lower part of your back sho uld feel
supported. If it is not supported by your car seat you can roll up a small
towel and place it in the curve of your lower back. A lumbar roll is a
cylindrical shaped pillow sold at back stores and physical therapy
offices. This is more expensive but some people like the support of
foam and they also like to spend money.
 6. Back tilt – The least amount of pressure on the back occurs when
your seat back is at 100-110 degrees so that you are slightly reclined. The
seat back should fully support your back. If you cannot recline your
seat back, take frequent breaks from your upright posture by shifting
your weight side to side and using small upper body motions to relax
the back (see the Wellness Center staff for more ideas on exercises and
stretches while driving).
 7. Seat cushion length – when seated in your car, scoot your tale bone
as far back to the seat back as possible. After doing this, you should be
able to place your hand comfortably between the back of your knee and
the front of the seat. If you cannot do this, add a pillow or back cushion
to your car seat to move you forward.

35.  8. Seat pan tilt – the seat of your car should allow for your
knees to be slightly lower than your hips. This opens up
your hip flexors and increases circulation to the back and
decreases pressure on the lower back.
 9. Stepping up and stepping out – If you drive one of
those large vehicles with a high step up/down add an extra
step or slowly step in and out of your vehicle versus
jumping down. Over time, the jumping down can cause
compression to your spine. Straps and other hand assist
devices for holding on to should be checked frequently for
wear and tear.
 10. Steering wheel grip – “the best posture is the next
posture.” It is advisable to keep two hands on your steering
wheel except when shifting gears. Change your hand
postures frequently to improve circulation and reduce
fatigue.

36. There are common postures that should be
avoided :
 The death grip – this grip results in decreased circulation and muscle
tension. Your grip should be light. If your knuckles are white, you are gripping
too hard!
 The one arm cool dude – You know the one: the wrist rests
at 12 o’clock on the steering wheel and the fingers flop over the top. Not only
does this cause compression of soft tissue of the wrist, but it reduces
circulation at the neck and shoulder, too.
 Arms straight out in front to reach the steering wheel –
you should be able to drive with your shoulders relaxed and your arms close to
the sides of your body. If you have to reach too far forward your steering wheel
maybe too far away. You can try tilting the steering wheel upwards and using a
light grasp lower on the steering wheel.
 One arm propped on your window – this posture decreases
circulation at the neck and shoulder and may compress soft tissue on the
arm/wrist.

37. Summary
This report:
 mentions the significance of ergonomic design of
environment
 glances upon the various negative health effects of
improper postures, arrangements and positions, and
 lists the various methods which if taken into
consideration; increases the harmony, ergonomical
stability in a system, and significantly reduces the
work, or mechanically related injuries.

38. Bibliography:
 casestudy-itgs.wikispaces.com
 Wikipedia.org/ergonomics
 http://www.ohcow.on.ca/resources/handbooks/ergon
omics_driving/Ergonomics_And_Driving.pdf
 http://www.nclabor.com/osha/etta/indguide/ig9.pdf
 http://www.knoll.com/research/downloads/healthcar
e_ergonomics.pdf

39. Thank you