BMFI 2112 WORK SYSTEM DESIGN
PAR T 3 : T I M E S T U D Y AN D W O R K M E AS U R E M E N T
1 . 0 : I N T R O D U C T I O N TO T I M E S T U D Y AN D W O R K M E AS U R E M E N T
References:
1. Mikell P. Groover (2014) Work Systems and the Methods, Measurement, and Management of
Work.1st Edition, Pearson.
2. Benjamin W. Niebel (1993) Motion and Time Study. 9th Edition, Irwin
3. Stevenson, W.J., and Chong, S.C. (2014),Operation Management, 2nd Edition. Mc Graw Hill.
4. Jay Heizer, and Barry Render (2014), Operations Management: Sustainability and Supply Chain
Management. Pearson
Nor Akramin Mohamad
Faculty of Manufacturing Engineering
Universiti Teknikal Malaysia Melaka
Learning Objectives
When you complete this chapter you should be able to:
1. Describe ways of establishing labor standards / work
measurement
2. Analyse the normal and standard times in a time
study using Direct Time Study
3. Analyse the proper sample size for a time study
4. Analyse task using Predetermined Time Standards.
5. Analyse task using Work Sampling Method.
Time Study and Work Measurement
Chapter:
1. Introduction to Work Measurement
2. Direct Time Study
3. Predetermined Motion Time Systems
4. Standard Data Systems
5. Work Sampling
Introduction to Work Measurement
Sections:
1. Time Standards and How They Are
Chapter 1 Determined
2. Prerequisites for Valid Time Standards
3. Allowances in Time Standards
4. Accuracy, Precision, and Speed of
Application in Work Measurement
Nor Akramin Mohamad
Faculty of Manufacturing Engineering
Universiti Teknikal Malaysia Melaka
Rusty Wallace’s NASCAR
Racing Team
NASCAR racing became very popular in the 1990s
with huge sponsorship and prize money
High performance pit crews are a key element of a
successful race team
Pit crew members can earn $100,000 per year – for
changing tires!
Each position has very specific work standards
Pit crews are highly organized and go though
rigorous physical training
Pit stops are videotaped to look for improvements
Rusty Wallace’s NASCAR
Racing Team
Introduction
Time Is Important
Most workers are paid for their time on the job
The labor content (cost of labor time) is often a major factor in the total
cost of a product or service
For any organization, it is important to know how much time will be
required to accomplish a given amount of work
Some Definitions
Work measurement – evaluation of a task in terms of the time that
should be allowed by an average worker to perform the task
Standard time – amount of time that should be allowed for an average
worker to process one work unit using the standard method and
working at normal pace
Time study – all the ways in which time is analyzed in work situations
When Are Time Standards Beneficial?
Characteristics of industrial situations in which time standards would be
beneficial
Low productivity
Repeat orders
Long production runs
Repetitive work cycles
Short cycle times
Functions of Time Standards
They define a “fair day’s work”
They provide a means to convert workload into staffing and equipment
needs
They allow alternative methods to be compared objectively
They provide a basis for wage incentives and evaluation of worker
performance
They provide time data for:
Production planning and scheduling
Cost estimating
Material requirements planning
Methods to Determine Time Standards
Work Measurement Techniques
1. Direct time study (DTS)
2. Predetermined motion time system (PMTS)
Performance rating is not required
Can be applied to determine the time standard for a task before
production
3. Standard data systems (SDS)
4. Work sampling
Task Hierarchy & Work Measurement 4 Work
Measurement
Techniques
Prerequisites for Valid Time Standards
4 Factors that must be standardized before a time standard can be set
A pace of working that can be maintained by 4
an average worker throughout an entire
work shift without harmful effects on the
worker’s health or physical well-being 2
3
A worker who is Must include all of the details
representative of the on how the task is performed
persons who usually
perform tasks similar
to the task being
measured
1
The time needed to process
the work unit depends on its
starting and final condition
1
Standard Work Units
The time needed to process the work unit depends on its
starting condition
Therefore this condition must be specified
If the actual condition deviates from the specification,
then extra time may be required to accomplish the task
Exactly what changes are made in the work unit by the
task?
What is the final state of the completed work unit?
2
Standard Method
Must include all of the details on how the task is
performed, including:
Procedure - hand and body motions
Tools
Equipment
Workplace layout
Irregular work
Working conditions
Setup
3
Average Worker
A worker who is representative of the persons who usually
perform tasks similar to the task being measured
If the work is performed mostly by men, then the average
worker is male
If the work is performed mostly by women, then the
average worker is female
4
Standard Performance
A pace of working that can be maintained by an average worker throughout an
entire work shift without harmful effects on the worker’s health or physical
well-being
The work shift includes periodic rest breaks and occasional interruptions are
experienced by the worker
Benchmarks of standard performance:
Walking at 3 miles/hr on level flat ground
Dealing four hands of cards from a 52 card deck in exactly 30 sec
Distribution of Worker Performance
This figure shows how a worker
performance is expressed in terms of daily
output
More on Standard Performance
Standard performance is commonly defined to be a pace that can be
readily attained by the majority of workers
Standard performance is denoted as 100
A performance rating greater than 100 means the worker's
performance is more than standard, and less than 100 means the
worker's performance is less than standard.
How a Standard Time is Defined
This figure shows the distribution of worker
performance, indicating how standard time
is defined so that it can be readily achieved
by most workers
Allowances in Time Standards
Normal time is adjusted by an allowance factor Apfd to obtain the standard time
Purpose of allowance factor is to compensate for lost time due to work
interruptions and other reasons
Standard time:
Tstd = Tn(1 + Apfd)
where pfd = personal time, fatigue, and delays
How to Allow for Lost Time
Reasons for Lost Time at Work
Two approaches used by
Work-related interruptions Non-work-related companies:
interruptions
1. Scheduled rest breaks
Machine breakdowns during the shift
Waiting for materials or Personal needs (e.g., Typical - one 15-minute
parts restroom breaks) break in mid-morning and
Receiving instructions from Talking to co-workers about another in mid-afternoon
foreman matters unrelated to work 2. A PFD allowance is added
Talking to co-workers Lunch break to the normal time
about work-related matters Smoke break This allows the worker to
Rest breaks for fatigue Beverage break take a break on his/her
Cleaning up at end of shift Personal telephone call own time
PFD Allowance
PFD Allowance
Contingency Allowance
Additional allowance due to a problem with the task (e.g., raw
material problem ) - not greater than 5%
Temporary basis – solve the underlying problem
Policy allowance
Machine allowance (set by company policy)
Training allowance – for teaching new workers
Learning allowance – learning a new task
Other Types of Allowances
Personal time
Rest room breaks, phone calls, water fountain stops, cigarette breaks
(5% typical)
Fatigue
Rest allowance to overcome fatigue due to work-related stresses and
conditions (5% or more)
Delays
Machine breakdowns, foreman instructions (5% typical)
Contingency Allowances
Problem area Problems and examples
Materials or Starting materials or parts are out of specification, and extra time is
parts needed to correct the nonconformance (e.g., oversized casting that
requires an extra machining pass or slower feed rate).
Process Manufacturing process is not in statistical control (Section 10.2),
and additional time is required to inspect every piece rather than
inspect on a sampling basis.
Equipment Equipment is malfunctioning or breaking down more frequently
than what is provided by the unavoidable delay factor, and
additional time is needed to compensate the worker to make
adjustments, lubricate the machine more frequently, or other extra
task(s) not included in the standard time.
Measurement
A procedure in which an unknown quantity is compared to a known standard,
using an accepted and consistent system of units
Important attributes of a measurement system:
Accuracy
Precision
Speed of response
Work measurement is a measurement process
Accuracy and Precision
Accuracy
Freedom from systematic errors, which are positive or negative deviations from
the true value that are consistent from measurement to measurement
Precision
Repeatability of the measurement system
Plus or minus three standard deviations often used as a benchmark
Accuracy and Measurement Accuracy vs. Precision
Precision in Work
Measurement
Accuracy in Work Measurement
Accuracy is concerned with closeness to the true value
But what is the true value of a task time?
Measurement is a procedure in which an unknown quantity is compared with
a known standard
But the known standard in work measurement is the definition of
standard performance used by the company
The standard is not based on time
Precision in Work Measurement Relative Accuracy of Time Standards
Precision is concerned with the expected variability within a single time study
Precision of a time standard is determined at a certain reliability or confidence level
For example, the standard time for a task is 4.00 min, and we are 95% confident
that the actual time is within 5% of that time
Related term: Consistency – concerned with variations in standard time values among
different time study analysts
Application Speed Ratio
Speed of application – how much time is required to determine the time
standard for a given task
Varies for different work measurement techniques
Application speed ratio = ratio of the time required to set the standard
divided by the value of the time standard itself
Typical values = 100 to 250
Engineered Standards
Time standards that are based on measured time values
that have been adjusted for worker performance
Some effort has been made to determine best method to
accomplish the task
