Today's welding requirements have become more stringent with regard to
the quality and appearance of a typical weld. Manufacturers are addressing
quality and consistency issues by looking more closely at all parts of
their welding operations. Here, we look at welding system components,
and focus on those that may have been ignored in the past, but are vital
to producing small parts.
Weld Quality--Today's Expectations
Quality in all manufacturing areas is now demanded, rather than hoped
for or applauded when received. Welding, the last process in the manufacturing
cycle, is also subject to this demand and has been making its own changes
to keep up with changing times.
It also seems to be a general trend that most modern products are becoming
more physically compact. Thus, it is incumbent upon the welding process
to be more precise and to apply the right amount of heat in exactly the
right place. In short the modern world requires precision welding, welding
that can be repeatedly executed within a close set of tolerances.
What Kinds of Miniature Parts Require Precision Welding?
A surprisingly large number of products, including batteries, capacitors,
sensors, pressure devices, light bulb filaments, metal bellows and seals,
and surgical tools, require precision welding to seal, shape, or join
to complete the manufacturing process. Not only must these welds be extremely
reliable because of the product's critical nature, they must also be created
without compromising the device's function.
Welding is considered by many to be more of an art rather than a true
mathematical science. It seems to change gradually rather than quickly,
and often lags behind the other manufacturing processes in investigating
the full details of its own technologies. Progressive manufacturers are
now changing this thought paradigm and are willing to investigate any
technology that can improve output consistency.
The science of welding is extremely complicated with an immense number
of variables to consider, not only in the welding processes and equipment
available, but also in the detail of consumable elements and how they
affect the welded output.
Joining & Welding Processes: A Quick Review
In the manufacturing industry, the two most popular methods used for
precision joining are the TIG and plasma weld processes.
TIG and plasma welding processes were originally developed to provide
a means to produce acceptable weld quality on a variety of metal materials
and alloys. Advances in power supplies, welding techniques, and process
controls have allowed for greater weld accuracy. The process is now used
in even more precision and miniature applications.
In the Gas Tungsten Arc Welding process (GTAW), also referred to as the
Tungsten Inert Gas process (TIG), an electric arc is established between
a tungsten electrode and the part to be welded. To start the arc, high
voltage breaks down the insulating gas between the electrode and the workpiece.
Current is then transferred through the electrode to create an electrode
arc. The metal to be welded is melted by the arc's intense heat and fuses
together. The plasma weld process is a TIG welding variant with an additional
copper housing around the electrode that directs and further constricts
the arc. Both processes use a Tungsten electrode ground to a point both
as the source of the arc ignition and as an transfer medium.
Welding System Elements
A typical welding system consists of the following elements:
- Welding power supply
- Arc starter
- Welding torch
- Tungsten welding electrode
- Welding parameters
Welding Power Supply: Historically, welding power supplies were
often large crude devices to deliver electrical power to a welding arc.
Power supplies have been improved, and now offer faster response, with
accuracy and reliability in a more compact design.
Arc Starters: High frequency arc starters were the primary means
of starting a TIG arc. Now, the welding industry also offers DC arc starters.
These devices offer better arc starting, longer electrode life, and less
electrical noise that may cause interference with other electrical or
control systems near the welding system.