Plasma cutter consumables are a group of components directly responsible for achieving an efficient and perfect cut. These parts wear out gradually over time with each of them has a lifetime. These consumable parts reside inside the plasma torch assembly in a specific order and are interrelated. It means that a deficiency or malfunctioning of one of the consumable parts will negatively affect the efficiency of other components. To sustain a plasma cutter's optimum efficiency and to prolong its working life, it is essential to keep records of consumables wear and tear and replace them as and when needed.
In a hand-held plasma cutter, there are five main torch consumables-an electrode, swirl ring, nozzle, shield, and retaining cap. Some torches include optional accessories like a drag shield, wire standoff, two-wheel cutting guide, etc.
Here we will discuss the significance of each consumable in a manual plasma cutter describing their functions in the plasma cutting process.
The electrode is a narrow metal piece typically made of copper or silver. It has an insert or emitter of either hafnium (or tungsten) since they are electrically highly conductive. Initially, the electrode receives a high-intensity electrical current from a cathode inside the torch to which the machine sends the current. The high current produces high-energy sparks and ionizes the plasma gas surrounding the electrode. Then, the electrode focuses the ionized gas through its hafnium/tungsten emitter onto the workpiece, generating an electrical arc. The high electrical current on the electrode causes the ionized gas to form a plasma at a fast pace. Once the plasma takes shape, the electrode settles at the operating electrical current carrying the same throughout the cutting process.
The electrode lives in a medium of excessively heated gas that makes it very hot during cutting. A coolant continuously flows along the electrode during cutting to absorb the excessive heat.
Swirl Ring/Gas Distributor
Some companies refer to the swirl ring as the gas distributor. Typically they are made of ceramic, plastic, or volcanic ash. Some swirl ring variants have an O-ring and small angled holes. The plasma gas comes from the machine, passes through the swirl ring in a spiral motion around the electrode then moves to the nozzle. So the swirl ring controls the plasma gas's spiraling action for centering the arc on the electrode and through the nozzle. The swirl ring also guides the plasma arc to contact suitably with the electrode's emitter. It aligns the electrode's emitter with the nozzle orifice and helps the plasma exit through the nozzle orifice.
The swirl ring protects the nozzle from the electrode by creating an insulation space between them. The swirling action helps the gas to flow at different temperatures. The cool gas stream flows along the outer edge of the plasma and contacts the nozzle protecting it from burnout. Lastly, the swirl ring guides the gas to backward flow facilitating the electrode to dissipate heat.
Nozzle/ Electrode Tip
The nozzle has two jobs. One, it focuses the plasma arc onto the workpiece, and second, it channels the gas flow aiding in shaping and constricting the arc. Nozzles may have varying shapes and widths with an accurately circled orifice. The orifice can also vary in width from nozzles to nozzles. A wider orifice will spread the arc, while a narrow orifice will produce squeezed and focused arc. Larger orifice nozzles are suitable for gauging works, and nozzles with smaller orifices are perfect for detailed, subtle, and intricate cutting jobs.
However, plasma cutting gradually wears out an orifice causing it to get deformed like an egg or oval over time. A worn-out orifice will make the cut less precise and produce rugged edges.
Typically shields are made of copper. Plasma cutting produces plenty of sparks and molten metal. As the name speaks, a shield's job is to protect the torch and inner consumables from excessive heat, sparks, and molten metals by blocking them from reaching backward. So, it burns itself and prevents the rest of the components from costly wear and tear. A shield's design helps to maintain a correct stand-off distance between the nozzle and the workpiece. A drag shield is a type of shield that permits the torch to be placed directly on the workpiece during the cutting process. So, a drag shield allows even an unskilled guy to perform a cut comfortably.
However, a deformed or worn-out shield would result in uneven bevels and low-quality cuts.
Retaining Cap/Outer Retaining Cap
As the name implies, the job of the retaining cap is to hold the rest of the torch consumables stack together. A retaining cap is the frontmost component of a torch, so it is the most highly exposed consumable part to the extreme heat of a plasma stream. Due to this, retaining caps are made from durable materials that can tolerate extreme heat.
The retaining cap has the highest longevity among all consumables. Only physically visible signs of corrosion, clogging, and cracking will require the replacement of a retaining cap.
Inner Retaining Cap
An inner retaining cap upholds inner consumables in appropriate alignment. A worn or distorted inner retaining cap will prevent other components from sitting correctly. It may result in gas flow problems, coolant leaks, and unwanted cut issues.
The standoff guide is an accessory that attaches to the front end of a torch assembly. It serves several purposes. It allows cutting without requiring direct contact between the cutting tip and the workpiece. A standoff guide maintains cutting tips at an exact distance (typically 1-2mm) from the workpiece, helping tips to have an extended working life. Another advantage of the standoff guide is that it gives a user more stability and greater control over the cutting angle. A standoff guide allows a user to steer the plasma torch freely, making the cutting job lots easier.
A standoff guide makes it easy to cut different shapes like curves, circles, straight lines, and many more. Plasma cutter standoff guides can have different designs, like wire standoff guides, straight-edge cutting guides, standoff roller guides, circle cutting guides, two-wheel cutting guides, etc. Standoff guides quickly and easily clip on and off to the torch head.