What is Industrial Engineering?
Concerned with the
DESIGN, IMPROVEMENT and INSTALLATION of SYSTEMS of MEN, MATERIALS and EQUIPMENT.
It draws upon specialised knowledge and skills in the mathematical, physical and social sciences together with the principles and methods of engineering analysis and design to
SPECIFY, PREDICT and EVALUATE the results obtained from such systems.
Name the primary activities in IE
Selection of processes
Design of tools and equipment
Design of facilities: layout of equipment, buildings, machines
Design of control systems
Development of cost control systems
Development of wage incentive systems
Development of job evaluation systems
Development of data processing systems
What is work made up of?
Work - An activity in which a person exerts physical or mental effort to complete a task.
Made up of
- Work elements
- Basic motion elements
What is a method study?
Method study is the
systematic recording and examination
of existing and proposed ways of doing work,
as a means of
applying and developing easier and more effective methods and reducing costs.
What are the typical objectives of a method study?
Increase productivity and efficiency
- Reduce cycle time
- Reduce product cost
- Reduce labour content
Improve customer satisfaction
- Improve product quality
- Reduce lead times
Increase flexibility of the work system
Improve worker safety
More ergonomic work methods
What is the basic steps for completing a work study?
SELECT - work to be studied
RECORD - the relevant facts by observations
EXAMINE - the facts critically and in ordered sequence
DEVELOP - the most practical, economic and effective method
DEFINE - the new method so it can always be identified
INSTALL - it as standard practice
MAINTAIN - standard practice by regular checks
What are the main areas for selection?
Labour intensive operations
Operations with high material handling
Operations with high scrap
Movement over long distances
Prior to automation
What are diagrams and charts widely used for? Name them.
Diagrams and charts are widely used to: improve understanding; facilitate communication.
SEQUENCE: operational charts, process charts
TIMES: multiple activity charts
POSITION and MOVEMENT: layouts and string diagrams
What are operational charts and what are the two types of operations?
Graphical representation of operations to produce a product
Two types of operation
1. Process and assembly
What are process maps used for and what do they look like?
Process mapping techniques have been widely used to provide a detailed picture of the process or system of interest.
CYLINDER - beginning or ending point of a process
RECTANGLE - task or activity step
DIAMOND - decision point
What are process charts used for and what are the principal types?
Graphical representation of processing activities performed on or by someone.
Material process chart - analysis of material
Worker process chart - analysis of worker
Describe the 5 symbols used to detail the work performed by a material or workpiece as it is processed through a series of operations
What is a two handed process chart?
Used for detailed analysis of operator at a work station
Each hand charted individually and to a greater detail than normal process chart
Meaning for conventional symbols is modified. ‘Inspection’ is omitted for ‘operation’
Operation – used for grasp, use, release etc. of tool, component or material
Transport – used for the movement of the hand to/from the work, tool etc.
Delay – used when hand is idle
Storage – designated ‘hold.’ Used when the hand is used as a holding fixture
What is an activity chart and what are the various types?
Activity chart is a list of activities of one or more subjects plotted against a time scale to indicate how much time is spent on ecah task.
Left/right hand activity chart
Worker machine activity chart
Gang (multi worker) activity chart
What is a multiple activity chart and why are they useful?
Activities of more than one subject are each recorded on a common time scale to show their inter-relationship.
Useful for analysing and improving operations especially where there are a number of interrelated activities involving several operators/pieces of equipment.
What is a string diagram and why is it useful?
Used when looking at the layout of the plant by plotting movements on a scale drawing.
Useful to understand complex layouts.
What are the three categories of process/assembly operations?
Make ready - preparation
Do - operation/transformation
Put away - work is moved (includes inspection)
Aim is to maximise DO as these add value
What is the systematic questions asked when examining an activity?
the PURPOSE of the activity (elimination)
the PLACE where the activity is undertaken
the SEQUENCE of the activity
the PERSON who does the activity
the MEANS by which the activity is undertaken (simplify)
Examine with a view to
or SIMPLIFY the activity
What are the three parts of motion economy?
Use of human body
(both hands utilised, symmetric actions, curved actions, momentum, gravity)
Design of workplace
(stations for tools, gravity feed bins, located in max working area, arranged for best sequence of motion, lighting)
Design of tools
(use fixtures/jigs not hands, combine tools, operations simulataneously, mechanised and automated where possible)
What is included in standard operating procedures?
Procedure: description of work elements to perform task
Tools: list of tools
Layout: plan or photo of workplace arrangement
Checks: checks or inspections required
Benefits of SOP?
Reduce variations in operation time, quality
Basis for training
Allow variations to be easily identified
Fixed basis for further improvement
What is ergonomics?
Applied scientific discipline concerned with how humans interact with tools and equipment while performing tasks
Ergonomics seeks to provide a fit between people and the jobs they do
Physical ergonomics - why do we need to take breaks?
Metabolism - provide energy for vital processes, assimilate new organic material in body
Basal metabolism - sustain circulatory and respiratory functions (average 1 kcal/hr/kg of body weight)
Activity metabolism - energy concerned with physcial activity
Recommended max. for mean energy expenditure of 8 hr shift
5kcal/min for male, 4kcal/min for female
This plus oxygen debt demonstrates need for breaks!
What is muscle endurance?
Muscle endurance defined as capacity to maintain an applied force over time
Ability to maintain maximum static force only lasts a short time
After about 8-10 mins a person can only apply about 25% of max static force at the start
Shows the importance of use of mechanical work holders, fixtures
What is Anthropometry and what are the design principles associated?
Anthropometry - empirical science concerned with the physical measurement of the human body
design for extreme individuals
design for adjustability
design for average user: last resort
design for different sizes
What is cognitive ergonomics and what are the guidelines for sensory reception?
Study of the capabilities and limitations of the human brain and sensory system while performing activities that have significant information processing content
Guidelines for sensory reception and perception
Redundancy – info using more than one sense
Stimulus variation: use of variable stimuli
What is attention and what are te different types of it
Attention means keeping one’s mind on something. Involves mental concentration and readiness for such concentration
Selective attention: person needs to monitor multiple sources of information to perceive irregularities
Focused attention: person must cope with multiple input channels but focus on one
Divided attention: there are multiple stimuli and multiple tasks to be performed together
Sustained attention: must watch signal of interest over a long period of time
Name factors leading to boredom
Factors leading to boredom
Short cycle times
Low requirements for body movements
Lack of contact with other works
What are the guidelines for memory?
Guidelines for memory
Minimise demands on working memory
Exploit chunking (limit chunk size)
Increase frequency and recency of using info stored in long-term memory
Use memory aids
What are the factors affecting the difficulty and speed of response selection and execution
Factors affecting the difficulty and speed of response selection and execution
Decision complexity: more choices longer to make selection
Response expectancy: can process info you are expecting quickly
Compatibility: positive response should be consistent with one’s expectations
Trade-off between speed and accuracy: negative correlation
Feedback: learn from the effects of their actions
What are the factors affecting the physical work environment?
Visual environment and lighting
Auditory environment and noise
What is the difference between luminous flux, luminous intensity and Illuminance?
Luminous flux – rate at which light energy is emitted in all directions from a light source (lumen)
Luminous intensity – luminous flux emitted in a given direction (candela)
1 cd isotropic point source of light radiates 4 pi lumens
Illuminance: luminous flux shining per unit area on a surface
Units: lux = 1 lumen per sq meter = 1 cd.sr.m^-2
E (illuminance) = l (luminous intensity) /d^2 (distance)
What are the permissible noise levels?
Sound intensity measured from listener’s perspective.
It is not a power measurement of the sound source
Could be measured as pressure. Intensity is measured relative to a reference pressure and converted to log scale called sound pressure level with the units decibel
Noise regulations specify actions at certain levels of noise, when averaged over an 8hr working day and also specify exposure to maximum noise (peak sound pressure)
For daily exposure averaging over 80 dBA employers must provide hearing protection if requested
For daily exposure over 85 dBA must provide and ensure it is used
What are the Physiological effects of noise
Startle response – due to sudden loud noise
Causes spontaneous muscle contractions, blinking eyes, head jerk movement
Temporary threshold shift: hearing impairment of short duration
Noise induced permanent threshold shift: long term exposure to high noise level
Acoustic trauma: single exposure to high intensity noise can cause temporary or permanent hearing loss
What are the three noise abatement techniques?
Noise abatement at three locations
Source: quieter machinery, insulation
Receiver: use of ear plugs
Path between source and receiver
What are the four variables that affect climate of the workplace?
Radiation from surrounding objects
Ways to reduce heat stress
Reducing heat stress
- Water for workers
- Frequent rest breaks
- Limit time in hot environment
- Work in shade not sun
- Provide air conditioning
- Shield radiant heat sources
- Wear protective clothing