MECHENG352 - Industrial Environment and Ergonomics Flashcards
What is ergonomics?
Definition:-
Ergonomics is a technology that seeks to improve mental and physical wellbeing by optimising the function of “human-machine-environment” systems or “Fitting the task to the person”
From ‘ergo’ = work and ‘nomos’ = laws
What is the scope of ergonomics?
- Anthropometry - workplace design to suit the human operator.
- Biomechanics - knowledge of human physical limitations and acceptable exertions to be expected in a job.
- Work physiology - ensuring that adequate provisions are made for recovery from physically and mentally demanding work.
- Environmental engineering - the design and control of the physical environment within which the work must be undertaken.
- Skill psychology - understanding and optimising the exchange of information between the person and the equipment he or she uses.
- Occupational psychology - namely the selection, training and motivation of personnel.
Causes of musculoskeletal disorders (MSDs)
Over time, exposure to risk factors leads to MSD
risk factors: ergonomic, individual, equipment (vibration), repetition
Factors contributing to repetitive task risk factor
- Stress on muscles and tendons
- Contributing factors
o Duration and speed of repetitious movement
o Number of muscles involved o Required force
o Raising and lowering the arm over and over again
Factors contributing to forceful exertion risk factor
- Inflammation of tendons, nerves, joints
- Contributing factors
o Type of grip
o Weight of object
o Body posture
o Type and duration of the task
Factors contributing to awkward posture risk factor
- Stress on muscles and tendons
- Contributing factors
o Reaching overhead
o Force the body must maintain to hold the position
o Holding fixing positions (static loading) - Lifting while twisting, reaching, or turning
Factors contributing to contact stress risk factor
- Pressing against or grabbing a hard object puts pressure on nerves, tendons and blood vessels
- Contributing factors
o Repetition
o Duration of contact
o Grip strength required
Factors contributing to vibration risk factor
- Affects tendons, muscles, joints, nerves
- Contributing factors
o Prolonged grip
o Restricts blood supply to hands and fingers
o Tools without vibration dampening device
o Poor power tool maintenance
10 Principles of Ergonomics
Work in neutral postures
Work at proper heights
Keep everything in easy reach
Reduce excessive force
Reduce excessive motions
Minimize fatigue and static load
Minimize pressure points
Provide clearance
Maintain a comfortable environment
Move, exercise, and stretch
Environment factors in work system design
Temperature, ventilation, noise, and lighting are all factors in work system design
Importance of proper illumination
Rotating parts can look as if they are standing still. This can lead to dangerous actions such as touching.
Poor illumination can increase the chance of mistakes
Poor illumination can increase effects of colour blindness
Definition of illuminance
Definition: The amount of light falling on a surface. Measured in Lux.
1 Lux = 1 lumen/m2
Human range is approximatively from 10 lux at night,
to 100,000 lux in mid-day sun.
Definition of luminance
Definition: The amount of light emitted by objects or from surfaces. Measured in Candela/m2
10 lux is roughly 1 FC.
A measure of the brightness of a surface. Dependant on reflectivity.
Definition of luminous flux
Definition: The total amount of visible light present. Measured in lumens.
Human eye luminance range
The human eye can detect a luminance range of 1014, or one hundred trillion.
One millionth of a candela per square metre to one hundred million candelas
per square metre.
Importance of visual acuity consideration
Visual acuity Definition: The measure of a person’s ability to distinguish fine details
Changes with age as the ability to focus changes and range of accommodation reduces.
Allowance must be made by the engineer for these effects.
Importance of noise level
Noise induced hearing loss (NIHL)
The damage caused by noise is insidious.
It is:
* Painless
* Often very gradual
* Irreparable
* Permanent
Noise level catergories
- Up to 80 dB (green): there is no risk for the ear, regardless of the duration of the sound exposure
- From 80 to 90 dB (yellow): we are getting closer to the danger zone, but the risks are limited to very long exposures.
- From 90 to 115 dB (red): the danger zone: the louder the sound the less time is needed for damage to occur.
- Above 115 dB (brown), very brief sounds immediately cause irreversible damage.
Noise level limit in NZ
Accepted exposure times for noise before damage occurs.
The limit for 8h exposure will be reduced probably to 80 dB also in NZ. (from 85)
What is included in the legislation for noise level exposure?
Average level - 85 dB
Peak level - 140 dB
Regulation 11(1) states clearly that “all practicable steps” must be taken to reduce an employee’s exposure to noise so that it does not exceed the exposure standards.
The regulation states that using hearing protectors does not remove the requirement for the reduction in noise exposure.
Regulation 11(3) states that use of hearing protectors can only be used as a permanent solution to protect people’s hearing if all the practicable steps taken in Regulation 11(1) have failed to reduce workers exposure to below the exposure limits.
How to avoid noise induced hearing loss
- Control the source of noise (e.g. large noise reductions were made in one factory simply by lining metal chutes and bins with scrap conveyor belting).
- Stopping the noise from reaching people. This may be done by moving a noisy machine away from staff, by building a soundproof enclosure around it or by putting up a barrier between the machine and staff.
- Reducing the time staff are exposed.
- Use individual protection such as earmuffs or earplugs.
