Stainless Steel Welding Machine

           Stainless Steel Welding Machine

Stainless steel is not as challenging a metal to weld as aluminum, nickel, magnesium, or the other non-ferrous metals, but neither is it as straightforward as plain steel welding either.

With the chromium in its substance to make it “stainless” – that is, free from rust and corrosion – stainless steel does not take well to careless welding, or to welding techniques that are appropriate for regular steel.

Excessive heat, too great a use of carbon dioxide (CO2) in the shielding gas, and several other factors can all cause the chromium to precipitate out of the metal.

If this happens, the steel will become capable of oxidizing again, and will probably rust in the future – at a particularly bad place for the rust to occur, as well, close to the weld that is holding the pieces together.

The goal when using a stainless steel welding machine is to get a solid weld while preserving the steel’s “stainless” attribute.

A MIG welder is the usual tool used for this purpose, but it is not enough to simply use this kind of welding machine, or the techniques used for regular steel.

Stainless steel welding can be carried out with one of three methods – short-circuit welding, spray-arc welding, or pulsed-arc welding.

                            Short-Circuit Welding of Stainless Steel

Short-circuit welding is carried out by keeping the current at a lower level, and feeding the wire electrode at a lower speed than during ordinary arc welding.

This causes the molten drops of melted electrode wire to bridge the gap between the welding pool and the electrode, which short-circuits the electric arc and puts it out.

However, the welding pool’s surface tension sucks the molten droplet off the electrode almost immediately, and the electrode reignites, only to be put out, reignited, and so on.

This process occurs over 100 times per second – an electrical stutter that is too fast for the human eye to detect, and which therefore looks no different than a regular arc to the operator.

In order to weld stainless steel correctly with short-circuit welding, it is necessary to use the proper shielding gas as well.

More than a trace of carbon dioxide in the gas mixture will lead to loss of “stainless” corrosion resistance, so the proper blend is different from that used with regular steel.

The mixture is a three-part one – 90% argon, 7.5% helium, and 2.5% carbon dioxide.

The welding should be carried out with the “pulling” method on fillet welds, and the “pushing” method on butt welds.

                                  Spray Arc Welding on Stainless Steel

The opposite of short-circuit welding in many ways, spray arc welding uses the most intense current possible – around 300 to 350 amperes is ideal.

This results in the molten metal from the electrode filler wire actually becoming vaporized and sprayed onto the welding surface in an intense, narrow, extremely hot stream.

The weld produced is strong and of high quality, with no spattering onto surrounding surfaces, and a large welding pool.

It is also a rapid method of welding stainless steel. However, this method is usually best for straight, simple joints.

The shielding gas that should be used is 98% argon, 2% oxygen – a very different mixture than that used for short-circuit welding.

The pushing method is best for this technique – the welder should be aware that using the pushing method will expose their hand to fairly intense heat and wear suitably heavy gloves in response, but will make huge gains in visibility, which is crucial for making a good quality weld in this way.

                                  Pulsed Arc Welding of Stainless Steel

Pulsed arc welding involves setting the electric arc so that the current “pulses” up and down between a low current and a high current.

This has the effect of steadily firing single droplets of molten metal from the tip of the electrode into the welding pool. In practical terms, pulsed arc welding provides a good weld penetration without the risk of melt-through – and is therefore good for thinner pieces of stainless steel. The shielding gas mixture most appropriate is 99% argon, 1% oxygen.

With these three methods, it is possible to make successful, high-quality welds that will not degrade the corrosion resistance of this challenging, but commonly-encountered, metal.

                  Steel Welding Machine

Steel has been in use since antiquity, and is perhaps one of the Earth’s most persistent metallurgical substances.

The earliest examples of steel are a few steel daggers made for Middle Eastern potentates and kings – rare items that most people never even saw.

Steel’s use gradually spread, however, due to its strength and usefulness, and by the medieval period, extremely high quality steels had been developed, for use in tools, weapons, and armor. Since then, steel has expanded its role even further, being used as the material for vehicles, devices, parts, machines, containers, construction elements, and even sculptures and jewelry.

Despite the many other metals used in contemporary fabrication, steel is still the most common, and, therefore, the most commonly welded.

Although there are no steel welding machines, in the sense of welders that are designed solely to weld steel, different welding machines may be more or less useful in the steel welding process, just as an alternating-current TIG welder will be more effective with aluminum welds than a direct-current MIG welder.

Whether or not the steel is stainless makes a large difference in the welding process also.

Stainless steel must be welded carefully so that it does not overheat, which will remove the chromium that protects the steel and cause it lose its corrosion resistance – in short, incorrect welding can remove the stainless feature from stainless steel.

                                      Using a Steel welding machine

Both MIG and TIG welders can be used as steel welding machines, although different considerations apply to each, and a TIG welder is generally considered to be better for stainless steel, due to its greater penetration – since stainless steel is more resistant, a more intense welding machine is appropriate for this type of metal.

Stainless steel, and mild steel under most circumstances as well, should have a piece of copper, brass, or aluminum attached to the back side of the work piece, on the far side from the welding area.

This is meant to act as a heat sink.

All of these metals conduct heat very well, and this will draw excess heat away from the steel.

In the case of regular steel, the presence of a heat sink will reduce the chance of rendering the whole area partly molten, which can cause anything from warping to shrinkage to cracking, depending on the specific characteristics of the workpiece.

In the case of stainless steel, the heat sink will prevent chromium depletion and allow the steel to remain corrosion-resistant.

Steel welds will turn out stronger and cleaner if the weld area is prepared with a mixture of ten parts borax to one part sal ammoniac.

The chemical requirements of steel welding extend to the actual welding process itself, since regular and stainless steel need different types of shielding gas to prevent oxidation during welding.

Regular steel is usually welded with a mix of argon and carbon dioxide (CO2), while the most common shielding gas for stainless steel welding is 100% argon.

MIG welding machines are good for welding regular steel, due to their relatively low penetration (meaning that melt-through is less likely) and their general ease of use.

Of course, they will leave dross or slag on the surface of the weld and the adjacent metal, which will need to be scraped off before the weld can be said to be complete.

MIG devices can also be used as a steel welding machine on stainless steel, but they are somewhat less effective than TIG welders – which have the downside of not being as forgiving of imprecisely-fitted welds, and requiring a bit more skill in their use.

Stick welders, with the shielding gas provided by a heavy flux on the consumable electrode, are usable on regular steel, but essentially useless for welding stainless steel.

As with every other task, choosing a steel welding machine and using it properly comes down to a having a modicum of appropriate knowledge, and preparing carefully to make certain everything is in place before the actual welding starts.

Regardless of whether the welder is a part-time amateur or a full-time professional, a small amount of common sense preparation will make it possible to get the needed join when welding steel.

              TIG Welding Machine

When only the best weld quality will do, and welding speed is not an issue, then tungsten inert gas, or TIG, welding is a method that produces very good results.

Welding bicycle and airplane parts are two examples of a situation where TIG welding is needed to create a weld that will not separate under any circumstances.

Because it produces absolutely no surface ‘slag’ on the item being welded, this method can also be used for very exacting, delicate work, such as welding electronics into place.

The bond it produces is both very clean and very strong, so applications such as pressure vessels and pipes can be TIG welded, but it is also suitable for small objects as well.

In TIG welding, a non-consumable tungsten electrode is used to provide the welding arc, with a separate piece of material to use as filler for the arc welding process when necessary.

 An inert gas that will not catch fire or explode when it is in contact with the welding arc’s intense heat – typically a mix of argon and helium – surrounds the welding arc to keep the air away from the weld, where oxygen could damage the bond before it has hardened.

The presence of these gases means that welders using a TIG machine must be careful and wear proper protective equipment, however, because argon can destroy the human brain or lungs in cases of heavy exposure.

History and applications of TIG welding

TIG welding is an effective but painstaking procedure, so it must be carried out manually by someone experienced in this demanding skill.

This is the reason that other welding methods are used for many applications, despite the all-round excellence of TIG welds.

 The technique was originally developed to be used in building aircraft during the 1930s and 1940s, when there was both a need for this type of welding to hold together materials that were going to be subjected to the massive stresses of flying, and when the gas shielding technology had become advanced enough to make TIG welding efficient.

 Pure helium was the initial gas used, giving the method its original name of “Heliarc,” but argon soon supplanted helium as the main ingredient, since it is cheaper and just as effective.

A TIG welding machine can be employed to weld nearly any weldable metal, although slightly different settings are needed for some types of metal. For most metals, the best power source for the electrode that heats and melts the filler metal is direct current (DC).

However, aluminum welding sometimes requires the use of alternating current (AC) for best results, so a TIG welding machine able to power its electrode with alternating current is used in some applications.

TIG welding machines today

There are numerous TIG welding machines available to the modern welder, many of which include the latest welding technology and digital controls for maintaining a stable arc. Some of these welding machines are large and powerful, mounted on wheels and therefore best for workshop floor use, while others are compact designs that the welder can carry with them onto scaffolding or ladders thanks to their lightness and small dimensions. Modern TIG welding machines are also designed to operate over a large voltage range – even a small, “micro-TIG” can have a voltage range of 138 to 265 volts, meaning that it can be applied to welding everything from unalloyed to high alloy steel, cast aluminum, nickel alloy, copper, and the like.

Although originally designed for aircraft construction, the TIG welding machine has become a versatile, compact tool that is available for nearly every professional welding job imaginable, from aerospace applications to building computers to bicycle construction and repair.

TIG Welding Machines

The fine hand work of a skilled artisan is something that is appreciated in many different fields, but people seldom realize that certain types of welding and welding machines are designed specifically to be used by skilled welders to produce welds of extremely high quality. Images of robotic welders assembling cars in Japan have become such a commonplace of the world’s mental landscape that the human factor is often lost sight of in the welding industry, at least in the eyes of the general public. However, TIG welding machines are used manually for high-quality hand welding, and can handle some of the most complicated joints and toughest applications in metal fabrication.

TIG welding is slower and more costly than other types of welding that can be fully automated, or handled by barely-trained welding operators, but it compensates for this with the excellence of its results. High-pressure applications such as welding on boilers and aircraft parts is often handled with TIG welding machines, and indeed, the first TIG devices were developed around the time of World War II for aircraft construction.

A TIG welder is a “Tungsten Inert Gas” welder that features a permanent tungsten electrode for arc welding, uses an inert or semi-inert gas such as argon or a mixture of argon and helium to shield the welding site from oxygen to prevent oxidation of the weld, and, when necessary, uses a separate feed of filler metal as the ‘solder’ for the welding process. TIG welding machines require a skilled user, and a closer look at some TIG welding techniques reveals more about the operation of these extremely flexible machines.

TIG welding techniques

When a person is making a weld with a TIG welding machine, there are several different options for the welding technique to be employed. The three methods available to the welder are the push technique, the pull technique, and the perpendicular technique. Each is defined by the position of the welding gun and electrode relative to the point of welding and the welding pool (which is the pool of liquid metal present at the exact point where the welding is taking place). The push method is the most frequently used, although all have applications depending on the type of metal being welded, the thickness of the pieces, and so on.

The push method involves holding the welding gun and electrode behind the welding point, slanting forward past the end of the already welded area. Holding the welding gun in this fashion gives the welder excellent visibility to the point where they are welding, and has several other advantages as well. The shielding gas blown from the nozzle covers the area of the joint before the heat is even applied, meaning that the welding pool is always covered completely by shielding gas and accidental corrosion or oxidation is practically nonexistent. The push method results in a wide, shallow-penetration weld that is good for thinner metal types. The weld is also very low-lying and smooth.

The pull method positions the welding gun ahead of the welding point, slanting back towards it, and moves away, ‘pulling’ the weld along with it. This method does not protect the welding pool from the atmosphere as well and may result in light contamination of the weld (or at least soot on its surface). The pull method produces narrow, deep-penetration welds, suitable for workpieces made out of thick metal and joints that need a very strong weld. The perpendicular method witnesses the welding gun held at right angles to the workpiece, pointing directly at the welding pool, and has effects midway between those of the push and pull methods.

These three methods are the basic building blocks from which the versatile applications of TIG welding are derived. The welder can choose the technique best suited to the needs of the job, the thickness of the metal, and the depth of weld needed, and adjust the results simply by the orientation of their welding gun.

Ultrasonic Welding Machine

The device sounds like one from science fiction – a welding machine that can weld plastic or metal using ultrasound to bond the two materials together – yet the fact is that ultrasonic welding machines exist in our prosaic modern-day world and not in an interstellar civilization filled with spaceships, exotic weapons, thinking robots, strange perils, and alien adventures. The first ultrasonic welding machine was developed and patented in 1960, and the technique gradually gained ground over the following several decades. Recently, ultrasonic welding has become sharply more common, but research is ongoing into how to utilize and improve this method of assembly, making it, in some ways, an even fresher technique than laser welding.

Ultrasonic welding operates by causing focused, mechanical vibrations at the same point in two pieces of plastic or metal that are to be joined. A completely different ultrasonic welding machine design is needed for welding plastic and for welding metal. The process can also be used to embed metal parts into plastic, by softening the plastic to the extent that the metal will sink into it at the precise point desired. The main uses are bonding plastic to plastic or metal to metal, however.

An ultrasonic welding machine’s design may vary depending on the substance it is meant to weld, but some features are common to all of the machines.  Most include an anvil – a surface on which the work is positioned for welding – and a sonotrode – the “hammer” which clamps onto the other side of the work and emits the ultrasonic pulse that causes welding. Small, portable ultrasonic welding machines omit the anvil, and feature a hand-held sonotrode, which is pressed to the two sheets of work material (usually, fairly thin plastic) that have already been clamped firmly together.

Welding plastics with an Ultrasonic welding machine

Ultrasonic welding machines that are designed to weld plastic parts together into a single workpiece fires its pulse of intense ultrasound vertically, straight through both pieces of plastic. The plastics should have close to, or exactly, the same melting points for the ultrasonic welding process to offer its best results. High-frequency vibrations are used to produce the sharpest and most intense vibration possible in the plastics, with sound frequencies anywhere from 20 to 70 kilohertz. These are outside the range of human hearing, but will probably raise the hackles on any dog unlucky enough to be nearby.

The vibrations, together with the friction between the two pieces of plastic as they rebound against each other, melt both pieces of plastic at the point where the ultrasound is concentrated. The liquefied plastic of the two pieces mixes together, then cools and hardens almost immediately, creating a very strong, clean bond between the parts.  Weld time is often no more than a single second, and there are no byproducts such as heat or fumes.

Welding metals as well

Metals can also be welded using an ultrasonic welding machine, although, in this case, the metal is not actually melted to create the weld. The sonotrode is built to introduce the oscillations horizontally, in the same plane as the two pieces of metal to be joined rather than at right angles to them.  The metal is under pressure, and the shock of sound along its horizontal plane disrupts the structure of both pieces of metal enough so that they ‘diffuse’ into each other – that is, they literally merge together without melting. Different kinds of metal can be welded in this way, and the bond is strong and lasting. This type of ultrasonic welding requires very precise control, however, and at the moment, it is practically limited to very large welding operations with technicians and many resources.

Welding Machine Parts

 

welding machines are used for hard work and for that reason, they are built tough so that they will survive years of use in good working condition. However, the very conditions of the workplace where welding machines are usually used – constantly serving as the circuit for a powerful electrical arc, heated intensely by the welding process, and often used in a workshop with other heavy, hard objects that can potentially fall on them or strike them – means that no matter how durable a welding machine is, something will break or wear out eventually.

A welding machine user should inspect their machine regularly, in fact, to catch wear or parts fatigue early rather than when it causes a major problem. The electrical wiring is the first thing that should be inspected, to catch fraying, cracking, or other damage before it results in a damaging short circuit. The rollers which feed filler wire from the spool, if present, should also be inspected to make certain they are moving properly and not becoming loose. The hose leading to the welding gun should be checked for minor cracking that might lead to a burst hose. All contacts should be cleaned, possibly ground if they are thickly coated with residue, and replaced if necessary.

In the event that something does break or need to be replaced, there are many businesses on the Internet which offer replacement parts for both new and older models of welding machines. These businesses are a quick, efficient way to get welding machine parts if you are unable to buy spare parts anywhere in your vicinity.

What welding machine parts are available

Companies that sell welding machine parts typically have large stocks of parts for very recent models of welding machine (those still in current production), and smaller selections of parts for out-of-production models. The websites can typically be searched by the make, model number, and sometimes the part number as well. If you are having difficulty finding the specific part you need, many of these companies also offer a toll-free number to call. These numbers will put you in touch with someone who will conduct a physical search for the part you need, and may be able to turn up better results for an obscure part than the website can.

These companies also often sell manuals for the welding machines also, which makes the process of diagnosing problems and repairing them quicker, easier, and more effective. Those who are buying a used or refurbished welding machine are well-advised to seek out and buy a manual at around the same time as they purchase the machine. This ensures they will know how to care for their machine, lessening the chance of problems to begin with, and will be prepared to cope with a need for welding machine parts should it arise.

            Welding Machinery

Nothing exists in complete isolation, especially in a workshop, where one form of effort flows naturally into another, the end of one process is often the beginning of a second. welding machines of various kinds – MIG or TIG arc welders, plasma welders, spot welders, and so on – are extremely useful in their own right, but even they need accessories to function properly. At a minimum, a welding table capable of supporting an electric circuit through the work and the welding machine is required as the substrate for the project. Many other pieces of welding machinery exist to make the welding process easier and more versatile.

There are literally hundreds of different tools, accessories, and machines that are useful in one or another in the welding workshop. A few of the more common pieces of welding machinery include :

  • Welding positioners – these table-like devices use a wide range of attachments to hold welding projects at the correct angle for the weld that needs to be made. Not all welds are straightforward, and during the process of metal fabrication, it is often necessary to approach a piece from several different angles. Welding positioners hold the piece at nearly any angle, depending on their construction – some of the types include rotary tilt tables, gear-powered elevators, tilting turntables, and “sky hooks.”
  • Welding lathes – welding lathes are useful for those who frequently make welds around the circumference of round metal objects. The lathe rotates the workpiece at a pace appropriate for welding, and a weld can be applied around the circumference of the item in a single motion, rather than needing to be turned manually. Many welding lathes include support for automatic welding, completing one join and then moving to the next preprogrammed position for the next join.
  • Welding manipulators – a large, dramatic, upright piece of welding machinery, welding manipulators include a vertical tower and horizontal boom, and can be used to lift heavy workpieces into a position where a long seam can be welded. Many of these manipulators can be fitted out with additional equipment to move the work piece for the welder’s convenience during the welding process.
  • Floor turntables – these heavy-duty, rotating tables can accommodate extremely heavy workpieces of half a ton or more, and rotate either continuously or when a foot pedal is pressed for greater manual control of positioning. The rotation of these turntables moves different parts of the workpiece close to the welder in a regular cycle. The turntable can be used for either manual or automatic welding.
  • Vacuum welding chamber – resembling either a large, industrial mushroom with a square stalk and a skylight, or some type of strange, domed UFO, the vacuum welding chamber is a work table that includes a completely enclosed, domed-over top that can be used to exclude the air to completely prevent all risk of welding contamination. No oxidation or rusting will occur in such a sealed welding chamber, while a typical model includes two sets of vacuum glove ports, a vacuum pump, and various instruments for monitoring and controlling conditions inside the chamber. The chamber can be used to produce welds of exceptional quality and purity.

These items represent only a few of the more flexible pieces of welding machinery currently offered to aid the welding efforts of the contemporary welder. Whatever the exact needs of a particular welding situation, there is likely to be a piece of welding machinery that will help to achieve the desired results in a way that is as smooth, convenient, and problem-free as possible.

              Wire Welding Machine

Some welding tasks are complex because many long welds of very different shapes must be made on a single work piece. Some of these may be best welded by a human welder due to the flexibility of a living welder over a pre-programmed machine. However, some welding jobs are complex in a different way – because hundreds or even thousands of identical welds must be made quickly and precisely on the same work piece. Although a living welder can handle these jobs as well, it takes them dozens of times longer than an automated process would, and produces considerably lower quality simply because people are not as precise as machines.

A prime example of one of these welding jobs is wire mesh. Whether it is meant to be used as part of a fence which will help to keep live animals on a farm from wandering away through the fields and woods, as the door of a pet carrier, as the reinforcement for concrete construction work, as the sides of supermarket carts that will soon be filled with boxed cereal and canned tuna as they are wheeled to the checkout, or for making retail display racks or garden items, wire is a very useful item – but one which involves thousands of welded joints in each roll.

Wire welding machines are large, complicated welders capable of precise calibration to be able to weld different thicknesses and mesh sizes of wire. They are unlikely to be found in a home welder’s garage, or indeed anywhere except a wire factory, but wire welding machines are interesting examples of specialized welding technology and a vital link in maintaining a working infrastructure as well.

How a wire welding machine works

A wire mesh welding machine may be dedicated to a certain size of wire – for example, 1” by 1” spaces, 3” by 1”, or whatever other pattern is desired. In this case, the wire welding machine is constructed as an industrial roller-and-die system. Dozens of wires are pulled forward parallel to each other by a toothed drum at one end of the machine, which pulls the wires forward the distance necessary to make the next weld.

For example, if the wire mesh is 1”x1”, the drum will turn enough to pull the wire forward in one inch increments. The wire is pulled between two bars, which are fitted with welding dies, also at 1” intervals. As the wires are moved forward, another wire is fed across them at right angles, the welding dies clamp down and fuse the cross-wire to the other wires, then open as the strands are pulled forward another inch, and so on. This rapidly welds wires into a sheet of the desired mesh size.

Modern wire welding machines also offer more sophisticated, servo-driven, computer-controlled welding as well. These machines move a huge welding frame with dozens of welding heads over the wires or rods that are being welded, in response to pre-programmed welding patterns. This allows extremely complex welds to be made, such as those used for concrete reinforcement, specialized wire patterns to be used in additional fabrication processes, and countless other uses that the simple roller-and-die arrangement cannot handle. The welding frame is shunted to and fro by the servo motors almost like the shuttle on a loom, except that in place of thread, it is ‘weaving’ wire and rod, and using highly accurate automatic welds to fasten the ‘fabric’ together.

The application of modern computer technology to wire welding machines has increased the flexibility of these devices greatly, allowing a single machine to be reprogrammed for a wide variety of different tasks. This makes it efficient for a single operation to create wire mesh for every purpose from making the door that will keep Fluffy in her crate while she is under her owner’s seat on the aircraft, to the critically important wires that will be used in the structural reinforced concrete that will allow a new skyscraper to soar high into the winds, rivaling the height of other famous structures around the world and speaking of its home nation’s pride.

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