This presentation will give insights in importance of ergonomics, and time and motion study in designing workplace and how an ergonomically designed workstation/workplace impacts on productivity of operators/workers.
This presentation gives suggestions with examples on how to evaluate workplace for lighter assembly works and how cycle time can be reduced for specific jobs
1. Workstation Redesign
Of
Vane Pump and Valve
Assembly
By: Parth Shukla
(Operations Management Consultant)
ME Industrial Engineer / BE Automobile Engineer
2. Presentation Map
Topic Introduction
Literature Review and Learning
Goal and Objectives of study
Methodology
Proposed designs and evaluation
Cost-Benefit Analysis
Concluding Remarks
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3. Topic Introduction
• The term “ergonomics” is derived from two Greek words: ergon,
meaning work, and nomos, meaning law.
• Matching the work and working environment with the physical and
mental abilities and skills of human beings.
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4. “Ergonomics is the scientific discipline concerned with the understanding
of interactions among humans and other elements of a system, and the
profession that applies theory, principles, data and methods to design in
order to optimize human well-being and overall system performance.”
(International Ergonomics Association)
“Ergonomics deal with the arrangement/designing of the working
conditions (Workplaces, equipment, working environment, work
sequences) with the goal to provide a workplace to the working personnel,
which corresponds to human properties and capabilities, neither
overloading nor under-loading, and to achieve as far as possible a high
utilization of work system.”
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Ergonomics
4
5. 21-04-2019
Details of Papers Reviewed
Total Papers Reviewed
(32)
International Journal
papers (18)
National Journal papers
(1)
International & National
Conferences (13)
Literature Review
Elsevie
r8
Taylor
&
Francis
7
Emerald
7
Others
10
5
6. Key Learning from Literature
• Ergonomics indicates the synchronization among labor, machines and the
environment.
• Training related to ergonomics and principles of motion economy to the operator
can help him use the workplace in better way and utilize capabilities of workstation
and his own to maximum extent in most desirable way.
• As much as it addresses the comfort of the operator, it equally contributes to
productivity and safety parameters for the operator and the organization on the
whole.
• The methodologies adopted by the researchers gives an overview of how traditional
way of data collection through questionnaire is one of the best practices of doing
this task, be it in general sense or work specific sense.
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7. • Proactive ergonomics by using software like RULA (Rapid Upper Limb
Assessment), is a fine way of comparing and evaluating different
workstation designs and providing best suited design for a specific job.
• Emphasis given to workplace ergonomics by the management can serve a
great deal in improving productivity and avoiding MSD (Musculo Skeletal
Disorders) occurrence to the operator.
• Workstation should be designed keeping in view principles of motion
economy so as to improve productivity and reduce fatigue in manual work.
• Considering industrial scenario where one workstation may be operated in
multiple shifts by multiple operators, it should be designed in accordance
with anthropometric data most suited for the industry or area it is designed
for.
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8. The primary goal of this dissertation work is to provide new design of the
assembly workstations so as to improve the productivity of the operators along
with reducing muscular strain.
Workstations: (1) Vane Pump assembly & (2) Industrial Valve assembly.
Goal and Objectives of study
Based on the goal the following specific objectives are chosen for study
1. To find out the common ergonomics problems that is experienced by the operator while
working.
2. To observe the current condition of the workplace and working method of the operator.
3. To get involvement of operators in improving workplace.
5. To provide suggestions for improving the workplace condition.
6. To provide design of fixtures that can reduce the assembly time.
7. To identify the financial implications.
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9. 1. Project selection:
Ergonomics is one of the fields that the company undertaking this project keeps working on.
Assembly time reduction along with improvement of workplace of the Assembly
workstations with Ergonomics at the core is suggested by the company itself.
2. Knowing the workplace:
By casual walk through, observation of the workplace and workstation.
3. Interaction with Operator:
Knowing the working technique, muscular strains experienced by them, asking problems
faced by them and extracting suggestions from the operators.
4.Observing the working sequence and technique of the operator:
For knowing which elements to record and which to ignore.
Methodology
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10. 5. Recording through photographs and videos for time study :
Photographs of the workplace and workstation are clicked for proof keeping
Videos recorded for time study and comparisons with the proposed alternatives developed and analysed
by PTS technique of MTM.
6.Developing fixtures and tools/equipments to reduce assembling time:
• Workplace recommendation
• New workstation design
• Fixture design and equipment recommendation for reducing time of assembling.
7. Fatigue analysis:
Current activities and way of doing work are analysed to gain idea of how much fatigue an operator
undergoes.
8. Time reduction analysis and financial implication analysis:
• Stopwatch time study
• MTM calculations
• Financial benefits calculation.
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11. 21-04-2019 11
Good points:
•Bins are arranged as per sequence of assembling.
•More no. of units are assembled together which saves time by reducing few elements per unit.
Limitations:
•Space constraints.
•2 kinds of pumps are assembled different in design. So only general improvements can be proposed and not
specific. Product specific redesigning of workstation is difficult.
•6-7 units are assembled together. A fixture can be designed to assist work, but the weight of the fixture would be
more than the combined wt. of all units. This is not preferable as operator would have change the whole fixture for
assembling other kind of pump.
Vane Pump Assembly Workstation
Observations:
•Space availability is less.
•2 types of pumps are assembled which are
very different in terms of design and
assembling.
•Tools like hammer, file, bush, etc are on the
table most of the time.
•6-7 units are assembled together in one cycle.
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Sr. No. Current Status As per Ergonomics Principles Recommended
Solutions
1 Tools like hammer, file,
bush, etc are on the table
most of the time.
There should be a definite and
fixed place for all tools and
materials.
HTT- hand tools tray for
keeping tools.
2 operator has to lift from
workstation and put on
dispatch trolley.
Heavy lifting must be as
minimum as possible
Roller conveyor or slide
for shifting units from
workstation to dispatch
trolley.
3 Each Vane slot is to be
checked by the operator
which is time consuming.
Repeated movements should be
minimum.
Gauge for checking
vane slots.
Vane Pump Assembly Workstation
13. Worktable
Features:
•Space for hand tools tray within max
working area and outside normal working
area.
•Space for loose items.
•Extreme dimensions equal to current
dimensions of workstation
•Rotatable platform for bins.
•Bins can be loaded from behind so that
whoever has to refill the bins does not have to
enter into the operator’s workspace.
•Platforms are set at an angle which permits
the material to be fed by gravity and so
relieves the operator of having to dip down
into the container to grasp the parts.
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14. Worktable
Place objects within zone
of convenient reach
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14
Top most platform (which is at max
distance from operator) can be rotated
towards operator so that the bin at
greatest distance can be taken within
maximum working area of operator.
Point is taken at the shoulder height of
operator. (standard dimension: 142 cm)
Max working range considered: radius of
70 cm. (ideally 67 cm.)
Standards considered in designing:
• Shoulder height: 141.9 cm (for
max working area)
• Elbow height: 112.3 cm (for
normal working area)
Designed in a way that nothing hinders
the normal working area and max
things are covered within max
working zone.
16. Vane Gauge
Suggested modification:
Repetitive actions are time consuming and it should be reduced.
This can be reduced by using these gauges.
Operator will have to slide the vane shaft only once into the gauge
to inspect every slot at once.
11 slots 13 slots
Current status:
The operator inspects each slots in the vane shaft individually i.e. with one vane in hand and inspecting slots by sliding
it through each slot.
Time consumed at present-
70sec for 8 units (i.e. 8.75 sec per unit)
Estimated time consumption by using gauges- 21
sec for 8 units (i.e. 2.625sec per unit)
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17. (For 1 unit)
(For 8 units)
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MTM Calculation for use of Vane Gauge
19. Sea
t
Proposed Workplace Setup
1
2
34
5
6 8 9
10
1213
7
11
14
Trolley
Trolley
Workstation
Time consumed in movement:
67 sec for 8 units (8.37 sec per unit).
Estimated time to be taken with new
arrangement:
8.55 sec for 8 units (1.092 sec per unit)
20. Adjustment for spring ring
Current status:
The spring ring is positioned before the key way by using this kind
of adjustment for sliding by hammering.
The lower part of this adjustment is threaded to match with the
threads of the rotor shaft.
The operator tightens this piece onto the shaft before hammering the
spring ring near the key way. Then he removes this piece and goes
on to other unit doing the same.
Suggested modification:
Instead of the threaded lower part, simple unthreaded piece can be
used for aligning with the hole of the shaft. This consumes less time
in placing it in as well as in removing out. This activity can be made
less time consuming.
Time consumed in current situation: 40 sec for 8 units (5s per unit)
Estimated time consumption: 6.824 sec for 8 units (0.853s per unit)
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21. Multi Spindle Power Wrench
Current status:
Pump cover is fastened by using a torque gun / power wrench with single spindle which can fasten one bolt
at a time. This has to be done 5 times to fit one cover. (1 time for positioning and 4 for fastening).
Also if the power of the tool is high, it can cause vibrations in the hands of operator.(carpal tunnel
syndrome- CTS can be the likely occurrence)
Suggested modification:
Multiple spindle air operated bolt runners are used in automotive workshops
where 5 bolts are fastened at once.
4 bolts can be fastened in single go by using this concept of multiple spindle.
For fastening pump cover on to the assembly, shape specific housing designed
for multi spindle power wrench can save time.(as much as ¾th of the time can
be saved)
Less powered (lesser rpm) tool can also serve good here. So vibrations
transmitted to operator’s arm will be less.
Time consumed in fastening bolts- 11sec per unit
Estimated time required for fastening- 2.75sec per unit
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22. Time consumed in fastening bolts- 11sec per unit
Estimated time required for fastening- 2.75sec per unit
For both kind of pumps, adjustment can be made in the same housing so that:
Cost for making this multiple spindle head becomes less.
Housing/head need not be changed when the product changes from one kind to another.
23. Hand tools tray
Current Status:
Tools like hammer, file, bush, etc are on the table most of the time and placed randomly once used on
the table itself.
Operator has to look for a certain tool when needed.
This adds to the total time consumed in the assembly
Suggested modification:
HTT- hand tools tray for keeping tools.
It serves principle of 5S as well and saves time of finding the
required tool.
Operator would have to take out tray from the drawer and put
into slot for HTT on the table and only at the end of the day he
has to put it back into the drawer.
According to principles of motion economy as related to workplace, there should be definite and fixed
place for all tools and materials.
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24. 21-04-2019 24
Industrial Valve Assembly Workstation
Observations:
•1 piece is assembled at a time.
•Assembly holding fixture is available which is used while fastening pilot and covers
to the housing.
Good points:
•Assembly holding fixture.
•Bins location.
•Equipments for fastening the
assembly are good.
Limitations:
•Space constraints.
26. 21-04-2019 26
Industrial Valve Assembly Workstation
Sr.
No.
Current Status As per Ergonomics
Principles
Suggestions
1 Loading Area location Movement of the workers
must be as minimum as
possible.
Loading of components should be
as close to the workstation as
possible.
2 Hand tools are kept on the
table even when not in use.
There should be a definite and
fixed place for all tools and
materials.
HTT- hand tools tray for keeping
tools.
3 Operator has to lift from
workstation and put on
dispatch trolley.
Heavy lifting must be as
minimum as possible
Roller conveyor or slide for
shifting units from workstation to
dispatch trolley
4 Housing and cover are to be
lifted from pallets kept on
ground.
Bending must be avoided as
much as possible
Pallets carrying covers and
housing should be at the height of
worktable.
5 Difficulty in reading
assembly manual. Also time
consumed for interpretation
of Production Order is more.
Frequent change in the focus
creates problem for the
operator and should be
avoided
Colour coding can be done for all
variants and accordingly bins
should be arranged.
27. Trolley
Reduces bending and reaching .
Change of job from lifting to pulling.
Total spinal compression due to bending and lifting
the housing= 1361.347714 N
Current status:
Pallets carrying the housing are kept below the worktable
height. Operator has to lift the housing from pallet by
bending.
Proposed modification:
Pallet Trolley has to be adjusted at the work table height.
Gate on one side of trolley (can be used as base for sliding
also).
Can be constructed or set at an angle so that housings placed
in the inner part can slide down as one in the front and taken
on to the table.
Operator can pull the housings out of the trolley directly onto
the worktable at the same height.
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28. Workplace
Conveyor (simple or roller conveyor) , hinged with the dispatch trolley, can be used to dispatch the completed assembly
from worktable to dispatch trolley by sliding it.
Heavy lifting can be avoided and subsequently the probable musculoskeletal disorders like lower back pain and shoulder
pain.
Pallet trolley can be positioned as shown in picture instead of at the back of the table so as to reduce movement of
operator. Also height of this trolley is equal to working height in standing position. So bending is avoided.
Fixture surface to be levelled with
worktable surface.
(Fixture for holding valve housing
fastening spool cover)
Time consumed in travelling: 9 sec
Estimated time for activity: 3.8 sec
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29. Suggested Modification:
Colour coding. For each type of valve one colour should be
allocated for bins and accordingly the PO and assembly manual
should be provided (components can be highlighted with specific
colour).
Time to interpret the manual/PO will be less and finding a particular
component becomes less time consuming.
Strain on eyes (because of frequent focus change) can be avoided.
Bins modification
Current status:
4 variants of valves are assembled here based on PO given, and
operator has to look for which spool, compression spring, o rings, R
rings, Allen bolts etc are to be placed.
Each type has components of particular specification to be
assembled in the housing and operator consumes more time in
reading specification and looking for particular bin carrying that
component.
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31. Total time savings
Vane pump assembly
Total time savings with suggested
improvements for 1 cycle: 143.298 sec
(i.e. 2.388 minutes).
Assembly cycle time can be reduced as
much as by 3-4 minutes approx.
Industrial valve assembly
Total estimated time savings with
suggested improvements: 2-3 minutes
Suggested modifications in workplace
and colour coding can be very helpful
in revising new assembly cycle time
and workplace becomes easy to
operate by new worker also.
32. 21-04-2019 32
Fatigue analysis
Since such facilities are not available in the industry for
fatigue evaluation of the operator, only theoretical
calculation has been done based on literature available
from books.
Work done can be measured by various methods like from energy consumption, increase in
heart rate, volume of oxygen consumed, calculating force exerted on various muscles
involved into the work by attaching probes over the operator’s body, etc.
But all these methods require high-tech laboratories which is not possible for an industry to
have.
Fatigue calculation is done theoretically and spinal
loading and spinal compression of L5-S1 is calculated.
33. Fatigue Calculation
Human spine experiences compression due to the upper body weight itself even if no other weighing
component is handled in standing position.
The position of the COG (center of gravity) of the upper body is to be considered in calculating the
moment on L5/S1.
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34. Load moment and spinal compression experienced during bending at different degrees of
flexion:
Total spinal loading can be then shown as
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36. Sample calculation for total compression that the L5/S1 vertebrae undergoes is:
Considering the following assumptions,
By using conveyors for dispatch of finished assembly onto the trolley and pallet trolley for
housing, this much force exerted on the spine can be avoided.
Dispatching finished assembly
Lifting valve housing by bending
This ease of work would result in decrease in fatigue experienced by the worker and
subsequently, increase in productivity
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37. Cost Benefit Analysis
Estimated costs associated with each proposed suggestions is:
sr. no.
item
suggested
quantity
approx.
cost/
unit
PV7-vane
pump
WEH16/2
2valve
total
1 woktable 2 10000 100000 100000 200000
2 gauge 2 2000 4000 4000
3 trolley 1 4000 - 4000 4000
4 tray 2 1000 1000 1000 2000
5
sliding
conveyor
2 1000 1000 1000 2000
6
multi spindle
power wrench
1 100000 100000 - 100000
7
spring ring
adjustment
1 1500 1500 - 1500
8 bins 22 1200 - 26400 26400
total 207500 132400 339900
38. Benefits are evaluated in terms of money saved on yearly basis for same quantity of units produced.
Considering operation of both workstations as one shift model for 300 working days in a year, cost of
operating for current and new proposed cycle time is:
units in
1 year
scenario
cycle
time (s)
total time
taken (s)
no. of
shifts
min. utilized
in 1 day
operating
rate(rs/min)
cost of
making (rs)
vane pump 4436
current 25.1 111343.6 300 371.145333 28 10392.069
reduced 22.712 100750.43 300 335.834773 28 9403.3737
valve 4724
current 12 56688 300 188.96 28 5290.88
reduced 10 47240 300 157.466667 28 4409.0667
As a result of the reduced cycle time for the same amount units to be produced, total savings on
operating cost for both workstations is:
vane pump
daily saving 988.696 Rs.
yearly saving 296609 Rs.
valve
daily saving 881.813 Rs.
yearly saving 264544 Rs.
39. Benefit to Cost Ratio
Since for both the products B-C ratio is greater than 1, the project is financially beneficial
and can be carried out.
In term of financial benefits as well as time savings, both workstations can become more
productive as much as by..
product beneift cost ratio
vane pump 296608.7 207500 1.42944
valve 264544 132400 1.998066
total 561152.7 339900 1.650935
Possible Increase in Productivity
Vane Pump
Workstation
Valve
Workstation
9.51 % 16.67 %
40. Concluding Remarks
Conclusion:
• The work provides some guidance about how to implement knowledge of
Ergonomics, Principles of Motion Economy and Anthropometric considerations in
redesigning a workplace to provide better or best working conditions to the
workers.
• The modifications and designs suggested are in accordance with the topic of the
study.
• The use of PTS method like MTM-Basic, describes how the new proposed
modifications can be evaluated in terms of time.
• This dissertation work signifies that Ergonomically designed workplace are
beneficial to both, the operator (in terms of lesser fatigue occurrence) and the
industry (in terms of financial savings).
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41. Limitations:
• Fatigue calculation is done theoretically and based on few assumptions. The results obtained
may be near to the actual values but are not absolute.
• MTM evaluation is done only for the activities for which improvements are suggested. The
whole assembly work is not evaluated.
• Time study is done from the video recorded only once for both workstations. Depending on
time of the day, the time consumed in different activities might differ slightly for each cycle.
As a result, the time consumption comparison of present and proposed situations is not 100%
reliable.
• The proposals given are not yet developed and implemented. The outcome of the project is
just an estimation which may vary when implemented in real life.
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Future Scope:
• When these proposals are implemented in real situation, they might pose some other issues.
These issues can be rectified for further simplification and better results.
• There are many assumptions made for getting the results. The actual scenario may change the
results to some extent and can be reviewed in details to get values closer to the actual ones.
• Also, this dissertation work is carried out for two specific workstations for light assembly
work. The methodology and thinking process may vary for different types of jobs.
1. Animation in fig shows sequence in which components are brought on worktable for assembly.
2. Table shows arrangements of bins on platform in a way that as end of cycle approaches, the components to be assembled are in range of eye vision with least movement of eyes and can be reached in sitting position.
