In
this the last article of our TIG welding series, we turn our attention
to the design, construction and testing of Lincoln's Precision™
TIG 275 and 375 welding units. Lincoln's exacting standards ensure
a machine that is rugged, built to last and loaded with high-quality
components.
Add Lincoln's superior design process to the long list of items that
we have covered in previous articles - and the Precision TIG is a
must for every shop. These attributes include:
- Superior arc performance
- Better output with lower input current draws than the competitor
- Easy set-up
- Lower price than the Miller Electric® Syncrowave®
- Innovative features not found on any other TIG machine
Many attributes of the Precision TIGs are readily apparent just by looking
at or welding with the machines. Today, we examine some of the less
'obvious' items on the unit - things that may not be seen at a glance,
but make a difference in the overall reliability and service life of
the product. This attention to detail is just another example of how
Lincoln Electric carefully addressed each aspect for these new TIG welders.
Not only did Lincoln pay attention to details; the company also paid
attention to the customer! Interviews with TIG operators, distributors
and sales personnel revealed that having a rugged machine that could
stand the test of time was an important factor in purchasing decisions.
By utilizing outstanding design and construction techniques in adherence
to ISO 9001 certification procedures and conducting a variety of tests
to ascertain the quality of the design…Lincoln delivers a machine
that fits in with the company's mission statement of providing products
that exceed customer expectations.
Reliable and Innovative Features
Built into the new Precision TIG 275 and 375 are features that consumers
will not find anywhere else:
Fan As Needed
When the user strikes an arc with these Lincoln TIG units, the fan
automatically turns on, runs during the entire welding period and
then shuts off after a specified time delay for appropriate cooling
when welding is completed. The Fan As Needed feature maintains a relatively
uniform temperature on critical internal components, minimizing thermal
stress cycles that can reduce the service life of those components.
In contrast, the Miller Syncrowave uses a Fan On Demand™ system
that is tied to a thermostat found in the transformer windings. When
the temperature rises to a preset rated temperature level of the machine,
the fan turns on. The problem with this technique is that the machine
is constantly going through rapid heating and cooling cycles during
welding - even when not welding at the maximum rated output level
of the machine. This repeated thermal cycling stresses the unit's
internal components.
Air Flow Design
Lincoln's innovative design for its Precision TIG models uses only
rear air flow louvers that bring clean air in from the top of the
unit and exhaust it out the bottom. In this way, less dirt is drawn
into the machine. To further minimize dirt contamination and build-up,
Lincoln uses an air pattern inside the machine that creates a higher
velocity horizontal flow over main power components that require cooling,
such as the transformer, choke and rectifier. The benefit to users
is that this airflow provides for better cooling and higher ratings
than the competitor's unit. Compare this clean environment to Miller's
Syncrowave, which intakes air through base louvers next to the shop
floor, drawing in dirt and debris in a manner similar to a vacuum
cleaner.
Separate PC Compartment
Precision TIG 275 and 375 PC boards are housed in a separate compartment
that keeps contaminants out and provides shielding from disturbances
of TIG high frequency. The control leads entering the board are also
shielded from electrical noise. And if that's not enough, the board
is selectively potted and dipped in a environmental sealant to further
protect it.
But don't think the separate compartment of the PC board makes it
difficult to access. By simply removing two screws on the front panel
of the machine, the operator can easily get into this area if required
- there is no need to remove the sheet metal case.
High Frequency Arc Starter Compartment
From talking with customers and maintenance personnel during the development
of this unit, it was noted that the number one maintenance item on
a TIG machine is cleaning and adjusting the spark gap. So, to make
this task easier, Lincoln developed a compartment to house the high
frequency arc starter. Located at the side, it is easy to access with
a removable panel that eliminates the need to remove the entire case
side. Also, this isolated and shielded compartment minimizes the high-frequency
arc emissions from getting out of the spark gap area and into other
areas of the machine. Furthermore, the separate compartment helps
protect the High Frequency spark gap from dust and dirt. Miller's
TIG units have an access panel but do not have separate compartments
for the arc starter.
TIG Torch Connection Box
Another separate compartment that the Lincoln Precision TIG has built
in for convenience and reliability is a TIG torch connection box.
This box, located at the side of the machine, helps operators make
connections easily in a standing position, but also isolates water
lines from the main transformer compartment should a leak ever develop.
Making the connections is a simple, intuitive process. The operator
connects the color-coded input water and gas fittings at the back
of the torch connection box. TIG torch connections are made at the
front, or output side, of the connection box with convenient wrench
access.
Cooler
The Precision TIG's optional cooler is housed in a slide out drawer
under the unit that makes it easy to service and maintain. It also
uses a Pro-Con® brand water pump with a heavy-duty motor. Pro-Con
is widely recognized as a leader of reliable pump components in the
cooler industry.
Construction Highlights
Not only do the Precision TIG 275 and 375 machines offer innovative
design features not found on competitive units, but these TIG welders
are also constructed to exacting standards so that purchasers can
expect long service life out of the machine. Here are some of the
construction highlights that set them apart:
Durable Switches
Lincoln's design ensures the best possible electrical connections.
To do this, the company uses durable switches that make positive electrical
and mechanical contact. The operator switch leaves no question whether
the switch is in the correct position. This also reduces intermittent
electrical contact that can cause switches to fail.
No Direct Mechanical Connections of Aluminum to Dissimilar Metals
Lincoln's stringent design standards specify that there are no connections
made to dissimilar metals such as bare aluminum to copper, without
plating the connection. In contrast, the Miller Syncrowave makes a
connection of bare aluminum from the high frequency transformer to
bare copper at the output stud. However, aluminum to dissimilar metal
connections can promote the formation of aluminum oxides, which act
as an insulator and reduce electrical conductivity. Miller also falls
short by using input lead connections made of aluminum - for customers
who typically use copper wire to connect power to the machine, this
also could lead to the formation of aluminum oxide.
Mechanical Crimping and Soldering
Heavy current carrying connections and power lead lugs in the Precision
TIG units are mechanically crimped and soldered. Additionally, care
is taken to be sure lugs are not crimped over the top of the insulation;
all leads are stripped before they are crimped. These leads are also
routed neatly through the Precision TIG machines and fastened securely
so that the leads cannot loosen over time and come in contact with
hot surfaces over time.
Secured Sleeves
Lincoln provides secured sleeves for bundles of leads. The sleeves
are mechanically secured so they will not loosen over time. These
measures also ensure the leads are not subject to abrasion against
sharp components or insulation inside the machine. Miller's competitive
machine has SCR gate leads that are not secured and may come in contact
with the main transformer coil. To alleviate high frequency leakage,
Lincoln provides insulating sleeves for the high frequency circuit
leads, which Miller does not.
Adequate Electrical Spacing
The Precision TIG 275 and 375 units use a transformer construction
that maintains adequate electrical spacing and tracking distances
between transformer windings and lamination. To do this, molded insulated
coil spacers are used.
By comparison, Miller Electric's comparable machines use wooden spacers
wedged in between transformer windings and lamination. Wooden spacers
are subject to swelling with moisture, and subsequent shrinking as
they dry out. Over time, this can cause the spacer to loosen, thereby
introducing the possibility of vibration, electrical shorting and
more serious transformer failure.
Mechanical Fastening
To avoid, the Precision TIG 275 and 375 units have mechanical locking
tabs on the electrical PC board connectors, which are specifically
designed to eliminate mechanical loosening that can, in turn, be a
cause of subsequent electrical failure. In addition, the pins are
treated with corrosion-resistant grease. The Miller unit uses no independent
fastening and relies on the engagement friction of the connectors.
Testing
Not only do Lincoln's innovative design and construction practices
make the Precision TIG 275 and 375 stand apart from the competition,
but rigorous testing conducted before the machines are put into production
ensure the utmost quality. Some of these tests include:
 |
| Vibration Test |
 |
| Jerk Test |
 |
| Environmental Test |
Drop Test
The TIG units are dropped at different orientations to a flat concrete
floor from a 12 inch height.
Jerk Test
The integrity of the lift bail designed for overhead crane lifting
is checked by dropping the machine 12 inches and then stopping it
in mid-air. This test is performed multiple times to look for signs
of damage to the structural integrity of the lift bail assembly.
Vibration Test
As part of the regiment of stress tests, the Precision TIG unit is
put on a vibration table to test its ability to withstand vibration.
This test is meant to simulate the vibrations of common use over the
intended life cycle of the product as well as the vibration generated
by transport over various road conditions, as might be experienced
during shipping.
Environment Test
The machine is put in a chamber to test if malfunctions occur when
exposed to extreme conditions, as might be experienced in the real
world, including abrasive and conductive dust, humidity, moisture
and fluctuating temperatures.
Undercarriage Test
At the job site or in the fabrication shop, the machine may be moved
from location to location as projects and plant layouts change. Considering
this type of use, Lincoln engineers determined to test the stability
of the machine when fully loaded with its typical accessories. For
example, in this case, Lincoln adds shielding gas bottles and, with
a variety of repeated stress test conditions, takes it up and down
obstacles at different angles to verify stability and integrity of
the wheeled undercarriage.
Shipping Test
Lincoln tests the integrity of the packaging to International Safe
Transit Association (ISTA) standards so consumers and distributors
can be sure they will receive an undamaged unit.
Life Testing
After the machines have survived the above battery of mechanical stress
tests, Precision TIG units undergo cycling tests at full capacity
and maximum load for an extended period of time to verify continued
functionality.
Electrical Stress Testing
This testing checks for proper functionality of the Precision TIG
when exposed to high voltage surge pulses on the input lines. Also,
tests are run to check immunity to various types of electromagnetic
interference (EMI) and RF, as well as how much EMI the machine itself
emits.
Field Testing
Before selling to customers, Lincoln put several Precision TIG machines
into 'real world' field testing for a six month period. To do this,
key customers weld with the new unit for an extended period of time
and report their findings back to the Lincoln design team. These "testers"
look at such things as performance, design and reliability.
Conclusion
A rugged, reliable design, serviceable features, outstanding construction
and strigent testing that goes beyond the norm - Add these to the
long list of other attributes such as superior arc performance, value
added features, easy set-up, more power and output range delivered
at a low price and now you have the full story of how the Precision
TIG family gives you the Power to Perform!
