WELDTECH SC40C User manual

OPERATING INSTRUCTIONS
SC40C
40A INVERTER
PLASMA CUTTER
www.weldtech.net.nz

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Congratulations on your new Weldtech product. We are proud to
have you as our customer and will strive to provide you with the
best service and reliability in the industry. This product is backed
by our extensive warranty and worldwide service network. To lo-
cate your nearest distributor or service agency call 0800 387 678,
or email us at [e-mail].
This operating manual has been designed to instruct you on the
correct use and operation of your Weldtech product. Your satisfac-
tion with this product and it’s safe operation is our ultimate con-
cern. Therefore, please take time to read the entire manual, espe-
cially the Safety Precautions. They will help you to avoid potential
hazards that may exist when working with this product.
We Appreciate Your Business!
Your Are In Good Company!
Weldtech is a strong Global Brand of Welding Products. We manu-
facture and supply to major welding industry sectors world-wide
including: Manufacturing, Construction, Mining, Automotive, Aer-
ospace, Engineering, Rural and DIY/Hobbyist.
We distinguish ourselves from our competition through market-
leading, dependable products that have stood the test of time. We
pride ourselves on technical innovation, competitive prices, excel-
lent delivery, superior customer service and technical support, to-
gether with excellence in sales and marketing expertise.
Above all, we are committed to develop technologically advanced
products to achieve a safer working environment within the weld-
ing industry.

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Contents
General Safety ........................................................................................ 4
Plasma Safety .......................................................................................... 6
Overview .................................................................................................. 7
Get to Know Your Machine .............................................................. 8
Machine Specications ...................................................................... 9
Installation & Setup ............................................................................ 10
Cutting Guide ....................................................................................... 11
OperatingTechniques ....................................................................... 12
Replacing Plasma Torch Consumables ........................................ 14
Troubleshooting ..................................................................................15
Warranty..................................................................................................17

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General Safety
General Safety Information
SAVE THIS MANUAL
Keep this manual for the safety warnings and
precautions, assembly, operating, inspection,
maintenance and cleaning procedures. Write the
product’s serial number in the back of the manual
near the assembly diagram (or month and year
of purchase if product has no number). Keep this
manual and the receipt in a safe and dry place for
future reference.
IMPORTANT SAFETY INFORMATION
In this manual, on the labelling, and all other
information provided with this product:
This is the safety alert symbol. It is used to alert
you to potential personal injury hazards. Obey all
safety messages that follow this symbol to avoid
possible injury or death.
DANGER! - DANGER indicates a hazardous
situation which, if not avoided, will result in
death or serious injury.
WARNING! - WARNING indicates a hazardous
situation which, if not avoided, could result in
death or serious injury.
CAUTION! - CAUTION, used with the safety
alert symbol, indicates a hazardous situation
which, if not avoided, could result in minor or
moderate injury or damage to the equipment.
NOTE! - NOTE is used to address practices not
related to personal injury.
CAUTION!- CAUTION, without the safety alert
symbol, is used to address practices not related to
personal injury.
Work Area Safety
WARNING! Read all safety warnings and
instructions. Failure to follow the warnings and
instructions may result in electric shock, re
and/or serious injury. Save all warnings and in-
structions for future reference. The term ‘’power
tool” in the warnings refers to your mains oper-
ated (corded) power tool.
• Keepworkareacleanandwelllit.Clutteredor
dark areas invite accidents.
• Donotoperatepowertoolsinexplosive
atmospheres, such as in the presence of am-
mable liquids, gases or dust. Power tools create
sparks which may ignite the dust or fumes.
• Keepchildrenandbystandersawaywhile
operating a power tool. Distractions can cause
you to lose control.
Electrical Safety
• Powertoolplugsmustmatchtheoutlet.Never
modify the plug in any way. Do not use any
adapter plugs with grounded power tools.
Unmodied plugs and matching outlets will
reduce risk of electric shock.
• Avoidbodycontactwithgroundedsurfaces
such as pipes, radiators, ranges and refrig-
erators. There is an increased risk of electric
shock if your body is grounded.
• Donotexposepowertoolstorainorwet
conditions. Water entering a power tool will
increase the risk of electric shock.
• Donotabusethecord.Neverusethecordfor
carrying, pulling or unplugging the power tool.
Keep cord away from heat, oil, sharp edges or
moving parts. Damaged or entangled cords
increase the risk of electric shock.
• Whenoperatingapowertooloutdoors,usean
extension cord suitable for outdoor use. Use of
a cord suitable for outdoor use reduces the risk
of electric shock.
• Ifoperatingapowertoolinadamplocationis
unavoidable, use a Ground Fault Circuit
• Interrupter(GFCI)protectedsupply.Useofa
GFCI reduces the risk of electric shock.

5
Personal Safety
• Stayalert,watchwhatyouaredoinganduse
common sense when operating a power tool.
Do not use a power tool while you are tired or
under the inuence of drugs, alcohol or medi-
cation. A moment of inattention while operat-
ing power tools may result in serious personal
injury.
• Usesafetyequipment.AlwayswearANSI- 
approved safety glasses and arc shaded, im
pact safety full face shield. Safety equipment
suchasNIOSH-approvedrespirator,heavy-du-
ty work gloves, non-skid safety shoes, or hear-
ing protection used for appropriate conditions
will reduce personal injuries.
• Preventunintentionalstarting.Ensurethe
switch is in the o position before connecting
to power source or moving the tool. Carrying
power tools with your nger on the switch or
energizing power tools that have the switch on
invites accidents.
• Removeanyadjustingkeyorwrenchbefore
turning the power tool on. A wrench or a key
left attached to a rotating part of the power
tool may result in personal injury.
• Donotoverreach.Keepproperfootingand
balance at all times. This enables better control
of the power tool in unexpected situations.
• Dressproperly.Donotwearlooseclothing
or jewellery. Keep your hair, clothing and
gloves away from moving parts. Loose clothes,
jewellery or long hair can be caught in moving
parts.
• Ifdevicesareprovidedfortheconnectionof
dust extraction and collection facilities, ensure
these are connected and properly used. Use of
these devices can reduce dust related hazards.
• Onlyusesafetyequipmentthathasbeenap-
proved by an appropriate standards agency.
Unapproved safety equipment may not pro-
vide adequate protection. Eye protection must
beANSI-approvedandbreathingprotection
must be OSH-approved for the specic hazards
in the work area.
Power Tool Use and Care
• Donotforcethepowertool.Usethecorrect
power tool for your application. The correct
power tool will do the job better and safer at
the rate for which it was designed.
• Donotusethepowertooliftheswitchdoes
not turn it on and o. Any power tool that can-
not be controlled with the switch is dangerous
and must be repaired.
• Disconnecttheplugfromthepowersource
from the power tool before making any adjust-
ments, changing accessories, or storing power
tools. Such preventive safety measures reduce
the risk of starting the power tool accidentally.
• Storeidlepowertoolsoutofthereachofchil-
dren and do not allow persons unfamiliar with
the power tool or these instructions to operate
the power tool. Power tools are dangerous in
the hands of untrained users.
• Maintainpowertools.Checkformisalignment
or binding of moving parts, breakage of parts
and any other condition that may aect the
power tool’s operation. If damaged, have the
power tool repaired before use. Many acci-
dents are caused by poorly maintained power
tools.
• Keepcuttingtoolssharpandclean.Properly
maintained cutting tools with sharp cutting
edges are less likely to bind and are easier to
control
• Usethepowertool,accessoriesandtoolbits
etc. in accordance with these instructions, tak-
ing into account the working conditions and
the work to be performed. Use of the power
tool for operations dierent from those intend-
ed could result in a hazardous situation.
Service
• Haveyourpowertoolservicedbyaqualied
repair person using only identical replacement
parts. This will ensure that the safety of the
power tool is maintained.

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Notes, Cautions and Warnings
Throughout his manual, notes are used to high-
light important information.
NOTE - NOTE indicates an operation, procedure or
background information which requires additional
emphasis or is helpful in ecient operation of the
system.
Important Safety Precautions
WARNING! - Operation and maintenance of
plasma arc equipment can be dangerous and
hazardous to your health.
Plasma arc cutting produces intense electric and
magnetic emissions that may interfere with the
proper function of cardiac pacemakers, hear-
ing aids, or other electronic health equipment.
Persons who work near plasma arc cutting ap-
plications should consult their medical health
professional and the manufacturer of the health
equipment to determine whether a hazard exists.
Gases and Fumes
Gases and fumes produced during the plasma
cutting process can be dangerous and hazardous
to your health.
• Keepallfumesandgasesfromthebreathing
area. Keep your head out of the welding fume
plume.
• Useanair-suppliedrespiratorifventilationis
not adequate to remove all fumes and gases.
• Thekindsoffumesandgasesfromtheplasma
arc depend on the kind of metal being used,
coatings on the metal, and the dierent pro-
cesses. You must be very careful when cutting
or welding any metals which may contain one
or more of the following:
Antimony Chromium Mercury
Beryllium Lead Silver
Arsenic Cobalt Nickel
Barium Copper Selenium
Cadmium Manganese Vanadium
Plasma Safety
• AlwaysreadtheMaterialSafetyDataSheets
(MSDS) that should be supplied with the mate-
rial you are using. These MSDSs will give you the
information regarding the kind and amount of
fumes and gases that may be dangerous to your
health.
• Usespecialequipment,suchaswaterordown
draft cutting tables, to capture fumes and gases.
• Donotusetheplasmatorchinanareawhere
combustible or explosive gases or materials are
located.
• Phosgene,atoxicgas,isgeneratedfromthe
vapours of chlorinated solvents and cleansers.
Remove all sources of these vapours.
• Thisproduct,whenusedforweldingorcutting
the metals mentioned above can produce fumes
or gases which contain chemicals known to
cause birth defects and, in some cases, cancer.
Electric Shock
Electric Shock can injure or kill. The plasma arc
process uses and produces high voltage electri-
cal energy. This electric energy can cause severe
or fatal shock to the operator or others in the
workplace.
• Nevertouchanypartsthatareelectrically“live”
or“hot.”
• Weardryglovesandclothing.Insulateyourself
from the work piece or other parts of the weld-
ing circuit.
• Repairorreplaceallwornordamagedparts.
• Extracaremustbetakenwhentheworkplace
is moist or damp.
• Disconnectpowersourcebeforeperforming
any service or repairs.
• Readandfollowalltheinstructionsinthe
Operating Manual.
Fire and Explosion
Fire and explosion can be caused by hot slag,
sparks, or the plasma arc.
• Besurethereisnocombustibleorammable
material in the workplace. Any material that
cannot be removed must be protected.

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• Ventilateallammableorexplosivevapours
from the work place.
• Donotcutorweldoncontainersthatmay 
have held combustibles.
• Providearewatchwhenworkinginan 
area where re hazards may exist.
• Hydrogengasmaybeformedandtrapped
under aluminium work pieces when they
are cut underwater or while using a water
table.DONOTcutaluminiumalloysunderwa-
ter or on a water table unless the hydrogen
gas can be eliminated or dissipated. Trapped
hydrogen gas that is ignited will cause an
explosion.
Noise
Noisecancausepermanenthearingloss.Plasma
arc processes can cause noise levels to exceed
safe limits. You must protect your ears from loud
noise to prevent permanent loss of hearing.
• Toprotectyourhearingfromloudnoise,wear
protective ear plugs and/or ear mus. Protect
others in the workplace.
• Noiselevelsshouldbemeasuredtobesurethe
decibels (sound) do not exceed safe levels.
* These values apply where the actual arc is clearly
seen. Experience has shown that lighter lters may
be used when the arc is hidden by the workpiece.
Less Than 300* 6 9
300- 400* 9 12
400- 800* 10 14
Arc Current
Minimum
Protective
Shade No
Suggested
Shade No
Plasma Arc Rays
Plasma Arc Rays can injure your eyes and burn
your skin. The plasma arc process produces very
bright ultra violet and infra-red light. These arc
rays will damage your eyes and burn your skin if
you are not properly protected.
• Toprotectyoureyes,alwayswearaweld-
ing helmet or shield. Also always wear safety
glasses with side shields, goggles or other
protective eye wear.
• Wearweldingglovesandsuitableclothingto
protect your skin from the arc rays and sparks.
• Keephelmetandsafetyglassesingoodcondi-
tion. Replace lenses when cracked, chipped or
dirty.
• Protectothersintheworkareafromthearc
rays. Use protective booths, screens or shields.
Overview
The SC40C is a compact, single phase, plasma
cutting system. As shipped the SC40C is ready
to plug in and cut once coupled to the appropri-
ate compressed air supply (see Compressed Air
Requirements page 10).
The SC40C is capable of cutting from thin panel
steel up to a severance cut of 8mm and will save
you hours of time with your metal cutting require-
ments.
The high frequency arc starting system ensures
easy starts to your cuts and the inbuilt inverter
cutting control ensures smooth and ecient cut-
ting. The built in air regulator and gauge keep the
machine compact and protected from transporta-
tion damages. The electric fan ensures eective
cooling and good duty cycles.
What is Plasma Cutting?
PLASMA DEFINED
Plasma cutters work by sending a pressurized gas,
such as air, through a small channel or orice. In
the centre of this channel, you’ll nd a negatively
charged electrode. The electrode is at the centre,
and the nozzle is just below it. The swirl ring caus-
es the air ow to turn rapidly as it passes. When
you apply power to the negative electrode, and
you touch the tip of the nozzle to the metal, the
connection creates a circuit. A powerful spark is
generated between the electrode and the metal.
As the inert gas passes through the channel, the
spark heats the gas until it reaches the fourth
state of matter. This reaction creates a stream of
directed plasma, approximately 30,000 F (16,649
C) or more and moving at 20,000 feet per second

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(6,096 m/sec) that reduces metal to vapour and
molten slag. The plasma itself conducts electrical
current.
The cycle of creating the arc is continuous as long
as power is supplied to the electrode and the
plasma stays in contact with the metal that is be-
ing cut.
The cutter nozzle has a second set of channels.
These channels release a constant ow of shield-
ing gas around the cutting area. The pressure of
this gas ow eectively controls the radius of the
plasma beam.
NOTE! This machine is designed to use only com-
pressed air as the “gas”.
Parts
1. Mains Power Switch
2. Mains Power Indicator Light
3. Thermal Protection Indicator
4. Cutting Current Adjustment Knob
5. Air Pressure Gauge
6. Air Pressure Regulator Knob
7. Plasma Torch Male Connection
8. Torch Switch Connection
9. Earth Lead Connection
10. Cooling Fan Intake
11. Compressed Air Inlet Nitto Fitting
12. Mains Power Cable
13. Specication Plate
14. Internal Air Filter Water Drain
(underneath machine)
15. Torch Switch Button
16. Plasma Torch Head
17. Workpiece Earth Clamp
Get to Know Your Machine
10
11 12
13
14
1
234
5
6
789
15
16
17
Unpacking your Machine
When unpacking, inspect carefully for any damage
that may have occurred during transit. Check care-
fully to ensure all the contents on the list below have
been received in good condition:
1 x SC40C Plasma Cutter Power Source
1 x PT-31 Plasma Torch
1 x Earth Clamp & Lead
1 x Plasma Goggles
If you have any questions, please
contact your nearest
Weldtech Dealer.

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Machine Specifications
Cutting Depth: 0.5mm to 10mm (severance cut) in Mild Steel
Cutting Current: 14 to 40 Amps
Rated Load Voltage:  96VDC
No-load Voltage:  272VDC
Input Power:  230VAC+/-15%,50/60Hz,SinglePhase
Input Cable: 2m, 15A, 25mm2
Plasma Torch: PT-31, 5m
Earth Lead: 2.5m x 16mm²
Air Requirement: 60 – 75PSI, Dry Compressed Air, 3.5 CFM @ 65PSI
Arc Striking System: High Frequency
Power Switch: Rocker Type Power Indicator
Overall Dimensions: 485 x 195 x 320mm
Weight: 9kg
Accessories: BuiltinAirRegulator(1/4”–18NPT),Electrode,Tip,CeramicSwirlRing
Rated Duty Cycle: 40%at40Amps
Duty Cycle is a welding or cutting equipment
specication, which denes the number of min-
utes, within a 10 minute period, that a given piece
of equipment can safely weld or cut at its rated
load without overheating.
For example, if a welder or cutting type piece
ofequipmentisratedata40%dutycycleat30
amps, that particular piece of equipment must be
‘rested’for at least 6 minutes after 4 minutes of
continuous welding or cutting.
NOTE! Failure to carefully observe duty cycle limita-
tions can easily overstress the power generation
systems of a piece of equipment contributing to the
premature failure of that piece of equipment and the
voiding of the warranty.
Thermal Protection
The thermal protection circuits will engage if unit
exceeds duty cycle. This will cause the machine to
stop working. The indicator will be lit on the front
of the machine. The fan will continue to run while
the unit cools down. When it reaches an accept-
able temperature the machine will operate again
as normal.

10
Electrical Connection
The SC40C is designed to run on a standard 10A
230VACpowersupply.Ifanextensioncordmust
be used, it should be no longer than 10m and
must be a heavy duty industrial version, with a
minimum cable core of 2.5mm². It is also required
that the plasma machine is run o a separate
power supply point to the air compressor provid-
ing the compressed air supply.
Operating Environment
Adequate ventilation is required to provide
proper cooling for the SC40C. Ensure that the
machine is placed on a stable level surface where
clean cool air can easily ow through the unit.
The SC40C has electrical components and control
circuit boards which will be damaged by excessive
dust and dirt, so a clean operating environment is
essential.
Compressed Air Requirements
A reliable and consistent supply of clean dry com-
pressed air is essential for proper operation of the
SC40C. The compressed air supply must have
ltration in the line feeding the SC40C, both a
standard water trap (sintered bronze lter) and
also a coalescing lter (for oil in air). The SC40C
requires a minimum of 3.5cfm Free Air Delivery
(FAD) and 60 – 80 PSI pressure. This normally
means the compressor must be a belt drive model
or if a direct drive it must have a motor power of
2.5HP or greater.
The air must be dry and free of oil and moisture
(normally a symptom of older, worn out
compressors). The air hose must also be of su-
cientsize(3/8”/10mmminimum)tosupplythe
machine.
Installation & Set-Up
Setting Up Your Machine
1. Fasten the female plasma torch connection
tting (17) to the male torch tting (7). Hand-
tighten.
2. Ensure the machine is on a level, stable surface
and connect the inlet power plug to the power
supply socket. Turn on the wall power supply
switch (leave the machine power switch in the
O position).
3. Connect the machine to a suitable compressed
air supply, clipping the supply hose onto the
malequickconnectNittocouplerontheback
of the machine (11).
4. Adjust the air pressure regulator (6) until the
gauge (5) is reading between 60 and 70PSI. To
adjust the pressure, pull the knob out to
unlock, push it in to lock the position. Clock-
wise will increase pressure, anticlockwise will
decrease pressure.
5. Check that the plasma torch consumables
are assembled properly, all components are
in place correctly and that they are in good
condition. Refer to‘Replacing Plasma Torch
Consumables’page 14 for torch consumable
layout and wear guide.
6. Connect the earth clamp connection plug (20)
to the earth lead connection socket (9). Secure
plug by turning clockwise until it locks.
7. Connect the earth clamp (19) to the work-
piece. If the surface to be cut is painted, rusty
or covered, clean the surface so that good
contact with bare metal is made by the earth
clamp.
8. Connect the torch switch plug (18) to the
switch connection socket (8).
9. Ensure that you are wearing appropriate per-
sonal safety gear (at minimum welding gog-
gles and gloves)
10. You are ready to start cutting! Turn the ma-
chine switch to‘On’ position. Press torch trig-
ger and air will exhaust from the torch. Double
check the pressure remains constantly on/
above 60PSI when torch trigger is held down.
11. Set the current adjustment knob (4) to the
appropriate amperage for the work thick-
ness. Correct settings will vary with consum-
able condition, operator technique and travel
speed but use the table on the following page
asageneralguide.Notethataluminiumalloys
generallytake25%moreamperageforthe
same thickness than mild or stainless steels.