Top 5 Hand Held Plasma Cutting Components

Why is regular maintenance of your hand held plasma cutter essential

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Whether you are a Do It Yourself, DIY, person or a manufacturing unit, you will definitely agree on the efficacy of the plasma cutter.

The power, the precision and the cut it makes set it apart from the other mundane tools in your tool kit.

In bygone years, the plasma cutters where huge and bulky; but thanks to advancements in technology hand held cutters are in vogue now.

The hand held plasma cutter follows the conventional plasma systems wherein the general air in the workplace is used as a substitute for plasma gas and the plasma arc measures between 12-20k amps per square inch. Here the size of the orifice of the nozzle determines the shape of the arc.

Working of the Plasma Cutter

How does a hand held plasma cutter work? As you know there is an electrode present in the plasma torch; when the trigger is in “OFF” position the electrode and the nozzle of the plasma torch are in contact.

Once you switch on the torch and press the trigger, the DC current that flows through the instrument launches the flow of the plasma gas.

Gradually, pressure builds in the compartment and this will force the electrode and the nozzle to separate creating an electric spark in the process.

This spark creates the plasma jet which is directed to the surface of the metal.

The spark comes out in the form of an arc, if the orifice is small the kerf, the width of the arc will be less and if the orifice is big, the kerf too will be big.

Components of the handheld plasma cutters

What are the main components of the cutter?

  • Shield
  • Retaining cap
  • Nozzle
  • Electrode
  • Swirl ring

Shield

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As the name suggests is a protection for the inner parts of the plasma torch from the sparks and the molten metal which result during plasma cutting.

Retaining Cap

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Its main function is to keep all the consumables together

Nozzle​

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The nozzle directs the plasma arc. The width of the arc is dependent on the size of the orifice- wider arc is needed in gouging applications while smaller arc is useful for intricate designing and cutting.

The nozzle also funnels the flow of gas and in that process controls the shape of the arc.

Electrode

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The electrodes are made of copper or silver and contain tungsten or hafnium most often. Tungsten and hafnium are good conductors of electricity and that is why they find a place in the electrode.

When the DC current starts flowing to the torch, the current enters the cathode of the electrode and through the tungsten filament reaches the nozzle in the shape of an arc.

The nozzle focuses the arc to the metal for cutting. There is a cooling device attached to the back of the electrode to transfer the heat out of the electrode.

Swirl Ring

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The gas is channeled in various directions by the swirl ring.

It is because of the swirl ring that the gas goes in spiral manner around the electrode, the arc, the nozzle and finally through the torch to the plate.

The main purpose of the swirl ring is to keep the gas at different temperatures thus the gas that is cool is outside and near the nozzle and prevents it from burning up.

The swirl also channels the gas back through the electrode and out thereby maintains the heat in the torch.​

How to identify if any of the consumablesare faulty

Nozzle: This is the first of the consumables that will start showing signs of trouble when you notice

  1. The orifice is out of shape and not round any more
  2. The orifice is very hot
  3. The arc is distorted
  4. Cut speed gets slow
  5. The kerf gets wider.

Electrode: During heating, the pieces of the tungsten or the hafnium melt and are blown through the nozzle creating a pit in the electrode. Change the electrode when the

  1. Pit depth is 1/32
  2. The resultant arc looks green and ugly

Swirl ring: This doesn’t need to be changed unless it cracksbecause then the cooling of the torch gets affected.

It is always a good idea to change the electrode and the nozzle together so that you don’t compromise on the cut quality. For every five to ten sets of electrodes and nozzles you can change the swirl ring once.

Change the other components, like the retaining cap when it develops cracks due to falls and exposes the underlying consumables; ensure that there is no slag on the shield as it will restrict the airflow.

Maintenance of the plasma cutter

Your plasma cutter has to be maintained properly and regularly to ensure that it cuts precisely and neatly. Those who live in areas prone to dust moisture and dirt should increase their inspection routine frequency. Schedule a periodic maintenance of the machine to ensure it works well for a long time.

It is also crucial to know that even if one part of the cutter malfunctions than the rest of the components will follow.

Will maintenance ensure long life?

Even with proper maintenance when inexperienced hands operate the cutter, the life of the machine reduces considerably because they do not know to control the amperage and the speed required to cut through material. When you cut too slowly or with too much power you end up damaging the consumables. Typically hand held cutters are air cooled and when they are dropped the swirl ring breaks and the cooling gets affected which in turn reduces the life of the instrument.

Remember these tips

  • It is important to match the consumables with whatever application you are using to lengthen their life and to get the desire quality of cut. Any discrepancy in amperage and the material to be cut will strain the consumables.
  • The presence of oil and water in the torch is detrimental to the health of the consumables.
  • Remember to keep the torch at proper distance from the work piece to prevent over heating of the nozzle
  • Cutting at the right speed is paramount for consumable life

References:

  • April 3, 2017
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