Sen et al, International Journal of Advanced Engineering Research and Studies E-ISSN2249–8974
Research Paper
MAKING TABLE MOUNTED CIRCULAR SAW OPERATIONS
SAFER IN CONSTRUCTION INDUSTRY: A PRACTICAL
APPROACH
Krishna Nirmalya Sen1, Dr R.K Elangovan2 Dr Shrihari3,
Dr Nihal Anwar Siddiqui3
Address for Correspondence
1
Hydrocarbon Construction & Pipelines, L&T Hydrocarbon Engineering Limited, Chennai, India.
2
Regional Labour Institute, Chennai
3
University of Petroleum & Energy Studies, Dehradun, India
deficiencies. Total thirty table mounted circular-saw
INTRODUCTION:
Unguarded moving parts in a machine can cause
machines were covered under this study at various
severe workplace injuries, such as crushed fingers or
construction site locations. Those machines were
hands, amputations etc. Naturally, safeguards are
classified in three types according to the type of
essential for protecting workers from these injuries
guard provided on the same.
which are mostly preventable. When operating a
It was found that existing guards poses various
circular saw, accidental contact with rotating circular
operational challenges including visibility. All of
saw blade must be safeguarded. Consequently,
these guards had restricted visibility of the cutting
providing a suitable enclosure/guard to such
point as existing design of guards restricted vision of
machines is also part of legal requirements globally1.
the operator – where operator may not be able to see
In this paper hazards associated with operation of
the cutting points clearly in most situations.
table mounted circular saw for construction activities
On detailed survey, the following reasons emerged
are studied. In construction work, for RCC
for not using conventional circular saw guards:
(Reinforced Cement Concrete) structures, solid wood
 Overall arrangement of the guard is not user
and plywood are extensively used for holding the
friendly
concrete it its shape, while it is being cast in a pre Restricted visibility during operation
determined shape. Circular saw is extensively used
 Operational access to saw blade is hindered
for making various types of formwork. It is generally
 Frequent damage of hinges and fittings
mounted on a bench/table.
 Difficulties in assessing the cutting operation
Studies2 also point that table mounted circular saw
Restriction to versatile operations when using
machines are responsible for most wood working
conventional saw guards:
accidents. Many of these result in severe injuries.
Construction work is associated with various shapes
Analysis of accidents investigated by HSE - UK has
of structures and to achieve the required form,
found that most were caused by inadequate or
various types and shapes of wooden material are
missing guards. Many of these accidents could have
required. This requires handling of a wide range of
been avoided by having a correctly adjusted saw
wood material including full length ply wood to long
guard and using a push-stick3.
logs. The guards provided to a circular saw should be
Circular saw is one of the most commonly used
able to accommodate all sorts of varying shapes and
power tool in civil construction work. Circular saw is
sizes without creating hindrance. Otherwise the
mainly used for cutting wood materials, including
operator might tend to remove the guard for
plywood for shuttering work. Various types of wood
operational convenience which is rarely re-fitted.
cutting operations some of which involves high level
International studies also highlights that more than
of precision such as crosscut, rip, and bevel cut etc.
80% of accidents concerning circular saws related to
are done by circular saw4.
injuries results in serious harm, are due to missing or
The most dangerous part of the Circular Saw is its
poorly adjusted guards, or push sticks not being used6
blade. Severe cuts and even amputations of upper
Most significant hazards associated with the circular
extremities could occur, when the operator
saw operations are as given below:
accidentally come in contact with the blade moving
 Entanglement from contact with blade
at a high speed. Chances of injuries occurring
 Contact or impact from poor tooling
increases when the blade is kept fully exposed during
 Noise
5
cutting operation . Existing circular saw blade guards
 Dust
are not really effective due to technical limitations
 Slips, trips & falls
and not operator friendly; hence these are frequently
 Contact or impact from unexpected
removed from the equipment.
movement (during maintenance, cleaning &
METHODS:
repairs)
Study of various types of existing guards on table
mounted circular saw machines and related
Table I given below highlights the potential harm associated with these hazards and its control measures:
Table I
Sl
No
Hazards
1
Entanglement
from
contact with blade
Harm
Controls


Serious injuries – amputation
of fingers; bone fractures and
deep cuts to hands and fingers
Int. J. Adv. Engg. Res. Studies/IV/III/April-June,2015/22-28

Fixing adjustable hood guards to all benches, large
enough to cover the blades, to prevent contact with blade
and access underneath the machine table.
Push sticks for each machine (at least 300 mm long and
pointed to grip the work piece).
Sen et al, International Journal of Advanced Engineering Research and Studies E-ISSN2249–8974
Table I
Sl
No
Hazards
Harm
Controls






2
Contact or impact
from poor tooling


Bruises
Fractures



3
4
Noise


Hearing damage or
loss







Eye irritation or damage
Breathing problems, lung
damage or cancer
Worsening of existing
health problems
Trapping
Cuts
Bruising


Bruising
Fractures
Dust
5
Slips, trips & falls
6
Contact or impact
from
unexpected
movement
(during
maintenance, cleaning
& repairs)
In view of the hazards and serious consequences as
narrated above, it is required to mitigate the risks
through effective and sustainable control measures.
While administrative control measures such as
training of the operators, safety inspection, audit etc.
could be applied for reducing risk potential,
implementation of effective engineering controls
measures could be the best option, in this case.
However, engineering interventions need to be
effective in terms of versatility accommodating
diverse functional requirements of the job. In this
paper our focus of research is on exploring most
suitable and effective guarding arrangements for
table mounted circular saw machine deployed for
wood cutting operations at construction sites.
Important step towards evaluation of risk in various
types of circular saw machine is done through Hazard
identification and risk assessments (HIRA).
According to the hazards at various stages of
operation risk are evaluated for its probability of
occurrence as well as severity of consequence. In
order to bring down the risk to acceptable level,
additional control measures are be implemented.
While doing so, hierarchy of control Is followed
through the following preferred sequence:
Elimination, Substitution, Engineering Control,



Steel riving knife to every circular saw.
Knives are securely mounted, have a smooth surface,
slanting leading edge, and curved to the shape of the saw
blade.
Extension tables and roller stands on the in-feed and outfeed sides to support larger work pieces
Tools safely maintained.
Marking tools with their maximum rotational speed.
Any woodworking machines should have a braking
device fitted.
Retro-fit older machines with a braking device where
possible.
Isolate saws to minimize the chance of a person being hit
by timber.
Reduce noise levels by isolating machines or enclosing
within noise barriers.
Monitor noise levels.
Always wear hearing protection


Dust extraction equipment to minimize dust getting in
the operator’s breathing zone.
Using respiratory protection.
Eye protection.


Regular housekeeping.
Area around saws clear of slip and trip hazards

Lock-out / Tag-out all power supplies before
maintenance, cleaning or repairs.
Ensure regular maintenance and testing, in accordance
with the original manufacturer’s specifications

Administrative control and usage of PPE. Table
given below provide the detail on risk matrix
associated with the same.
A typical HIRA for woodcutting operation using table mounted circular saw is given below in the table 5.
Int. J. Adv. Engg. Res. Studies/IV/III/April-June,2015/22-28
Sen et al, International Journal of Advanced Engineering Research and Studies E-ISSN2249–8974
Table 5 : Hazard Identification and Risk Assessment for Wood Cutting Operations
Various types of guarding arrangements &
Features:
Type I: Circular Saw without any guard
Description of guarding

Guard not provided

Guard provided but removed by the user
Features

Ease of operation, can handle various jobs
without hindrance

Chances of kickback is high

No containment of generated saw dust
resulting in poor housekeeping and

Increased exposure to wood dust particles
causing health hazards.
Hazard Identification and Risk Assessment for Wood
Cutting Operations
Table 6: Type I - Circular Saw without any guard
Type II: Fixed type saw guard made of steel plate
Description of guarding
 Fixed guard, limited adjustment
 Metallic guard made of 2 mm steel plate
 Rip fence
Features
 Obstruction caused by the guard blocking
visibility
 Chances of kickback is very high
 Ergonomic deficiencies
 Frequent removal of the guard by the operator
Hazard Identification and Risk Assessment for Wood
Cutting Operations.
Table 7: Type II- Fixed type saw guard made of steel plate
Int. J. Adv. Engg. Res. Studies/IV/III/April-June,2015/22-28
Sen et al, International Journal of Advanced Engineering Research and Studies E-ISSN2249–8974
Type III: Suspended saw guard made of steel
plate
Description of guarding

Metallic guard made of 2 mm steel plate

Suspension arrangement made of 20 mm
mild steel rod to hold the saw guard

Rip fence
Features

Obstruction caused by the guard blocking
visibility

Chances of kickback reduced

Ergonomic compliance improved

Suspension arrangements using rod was
hindering the work place

Frequent removal of the guard by the
operator

Though wasn’t unsafe, the set up doesn’t
cater with requirements of workplace
Hazard Identification and Risk Assessment for Wood
Cutting Operations.
Table 8: Type III - Suspended saw guard made of steel plate
Type IV: Saw guard with integrated sensor
Description of guarding
 Metallic guard made of 2 mm steel plate
 Acrylic Sensor with inbuilt : Infra-red (IR)
rays
 Infra-red rays signal linked to PLC
 PLC cuts motor if IR signal gets interrupted.
Features
 Aspect of vicinity while cutting was improved
 Chances of Kickback reduced
 Ergonomically convenient
 Since the tip of cutting saw had an infra-red
sensor, any accidental disturbance to the
signal cuts the machine operation frequently
 Though wasn’t unsafe, the set up doesn’t cater
with requirements of workplace.
Programmable Logic Control: Emitter is provided
just above the tip of circular saw which emits infrared rays. When the same gets interrupted by any
object the logic controller sends output signal to stop
electric supply to the motor and subsequently the
entire equipment stops functioning.
Hazard Identification and Risk Assessment for Wood
Cutting Operations
Table 9: Type IV- Saw guard with integrated sensor
Considering the findings of various conventional
models (Type I to III) and improvised model (Type
Int. J. Adv. Engg. Res. Studies/IV/III/April-June,2015/22-28
IV), further improvement in the configuration of the
circular guard was felt required. Subsequently the a
Sen et al, International Journal of Advanced Engineering Research and Studies E-ISSN2249–8974
new design was developed. While developing the
new circular saw guard, the following factors were
considered7
 Arrangement
for
fixing
it
on
the
table(1910.213(a)(6) )
 Slide in grooves or tracks that are accurately
machined (1910.213(a)(7))
 Hinged saw tables with true-alignment with
saw(1910.213(a)(8))
 Covering the possibility of contact of saw either
beneath / behind the table(1910.213(a)(12) )
 Vicinity of blade
Type V: Circular saw guard with flap type acrylic material
Finally, acrylic guard is developed in-house which is
Hazard Identification and Risk Assessment for Wood
connected with the rip fence eliminating various
Cutting Operations
deficiencies experienced in previous models. Refer
figure 5
Table 10: Type V - Circular saw guard with flap type acrylic material
Int. J. Adv. Engg. Res. Studies/IV/III/April-June,2015/22-28
Sen et al, International Journal of Advanced Engineering Research and Studies E-ISSN2249–8974
Checklist is developed identifying the important
checkpoints of circular saw machine
Table 11
Sl
1
2
3
4
5
6
7
8
9
10
11
Description
Status
(Ok / Not
Ok)
12
13
14
Remarks
Is the machine stable and unlikely
to move during operation
Are the machine guards installed
and functioning correctly
Are push sticks available and used
to move the timber through the
saw
Are the operating controls easily
accessible to the operator
Do the operating controls prevent
accidental start-up?
Are the control functions clearly
marked
Hinged saw tables with truealignment with saw
Visibility of circular blade
Are the transmission drive and
other moving parts totally
enclosed or guarded
Are there systems in place for the
machine to be isolated
Is there an appropriate emergency
stop which is easily accessible and
labelled?
15
Is there a clear work space around
the machine?
Is the illumination adequate
Are sharp and well maintained
blades used to reduce noise level
Is the floor area regularly cleaned,
and all off-cuts and other debris
removed
RESULT AND DISCUSSIONS:
Study of circular saw without guard and two with
conventional type guards were initially studied. Then
two modified type of circular saw guards with better
visibility and protection for operators were evaluated
to ensure that while operating the circular saw
machine, improvement safety as well as cutting
operation is achieved. During the process,
productivity and operational were kept in mind.
During the development of guard focus was on
providing better visibility for cutting operation which
is the main aspects associated with prevention of
kickbacks.
Summary of inference derived from hazard
identification and risk assessment (HIRA) of wood
cutting operation using table mounted circular saw
machine with different types of guards is given below
in table 12.
Table 12: Summary of Hazard Identification of Risk Assessments : Wood cutting operations with various types of guards
Type of guards
Risk Matrix
Remarks
Non guarded and high potential for
Type I: Circular Saw without any guard

High
Medium
Low
cut injuries
Hinders cutting operation
Type II: Fixed type saw guard made of
Guard
being
removed
for

High
Medium
Low
steel plate
convenience and has high injury
potential
Visibility slightly improved
Type III: Suspended saw guard made of
Suspended arrangements hinders

High
Medium
Low
steel plate
cutting arrangement
Has cut injury potential
Visibility improved through acrylic
Type IV: Saw guard with integrated
guard

High
Medium
Low
sensor
Infra-red sensors to stop motor
Hinders job frequently
Flap type acrylic guard
Type V: Circular saw guard with flap
Doesn’t hinders cutting operation
High
Medium
Low

type acrylic material
Improved visibility
Safe operation
Int. J. Adv. Engg. Res. Studies/IV/III/April-June,2015/22-28
Sen et al, International Journal of Advanced Engineering Research and Studies E-ISSN2249–8974
CONCLUSION
In view of the finding of the HIRA and workplace
assessments circular saw guard of Type V is
recommended for adoption for safe operation. As an
additional control measures regular inspecting to be
carried as per table no 11 while administrative
controls such as training, and audits should also be in
place.
Perspectives of saw dust control / any exhaust
arrangements is still a great challenge in construction
industry. Hence saw duct control can be considered
for further research or study on improving health and
safety of wood cutting operations.
REFERENCE
1.
2.
3.
4.
5.
6.
7.
LO Safety and Health in Construction – Code of
Practice 1992_ Sec 7.1.1 (e)
Health and Safety Executive (2011) Circular saw
benches – Safe working practices
Health and Safety Executive (2011) Circular saw
benches – Safe working practices
Jeremy Stranks. (2010). Engineering Safety. Health &
Safety at Work (PP. 241-250). Safety in Offices,
Workshops and in Catering Operations. Health &
Safety at Work (PP. 317-332).New Delhi. Vinod
Vasishta for Kogan Page India Private Limited
http://www.healthyworkinglives.com/advice/workequipment/working-at-height#risks
Work Safe Newzealand
Occupational Safety & Health Administration (OSHA)
1910.213: Woodworking machinery requirements _
Sub Part Machinery and Machine Guarding.
Int. J. Adv. Engg. Res. Studies/IV/III/April-June,2015/22-28