Ten common errors on plasma cutting

As we all know,if experienced operator can well operate and maintain plasma cutting equipment,it can save countless workshop downtime and tens of thousands of dollars in operating expenses ,which also can bring higher profits to your cutting business and company.

 

1.Consumables are used until they are scrapped.

Look at your bucket for old parts,you will most likely find that these parts are used until they are scrapped.Use of worn-out parts,not only will it damage the good workpieces,but also it can cause costly cutting torch failures and unnecessary work downtime.It is easy to avoid the mistake of using parts to scrap.There are many signs of wear and tear of consumables;Experienced operators can usually judge the wear of parts by subtle variations in the sound or color of the arc or in the height of the cutting torch.However, the best way to judge the condition of cutting torch parts is to check the cutting edge quality of the workpiece on a regular basis,and check cutting torch parts when cutting quality begins to decline.Record the average life span of parts for a period of time(Arcing times or arc opening times),and according to the current, the material to be cut and its thickness to develop corresponding guidelines of expected service life of components.After confirming the average service life of the components,operators can know when to inspect or replace parts to avoid catastrophic failures.

 

2.Replacement of consumables

If you look at the barrels you have in old parts, you may also find that they are still available.It is a common and costly practice to replace consumables too frequently.When an operator changes parts, he needs to know what to check.If there is a hole inside or outside the nozzle, or if the perforation is worn out, and it’s not round anymore,the nozzle should be replaced.Otherwise, it could be reused.To judge whether the electrode is discarded, check the hafnium pit in the electrode element(Electrode element refers to the silver substance filled in the copper electrode:For air or oxygen plasma systems, it refers to the hafnium core;For a nitrogen or argon hydrogen mixture plasma system, it refers to the tungsten core).Normally,for air and oxygen plasma systems, the hafnium pit depth should not exceed 2 mm,but for nitrogen or argon-hydrogen mixed gas plasma systems, the depth of the hafnium pit should not exceed 3 mm.The swirl ring should be replaced only if dust or oil is found in the perforation, or if there are cracks, arc burn marks or excessive wear, etc..The swirl ring is often replaced too early. It is also the case for the protective cap, which needs to be replaced only when there are signs of physical damage.Normally, the protective cap can be reused after removing metal slag.Normally, the protective cap can be reused after removing metal slag.

  1. The parameters and parts used by the job are incorrect.

The choice of consumables depends on the material and thickness to be cut, the current and plasma gas used, and other cutting parameters.The operating manual will specify the consumables applicable to various types of cutting.Improper use of easily damaged parts can cause shorter service life and lower cutting quality.Running components with the right current is particularly important.When the current is set to 95% of the rated current of the nozzle, the optimum cutting quality and the maximum service life of the components are usually achieved.If the current is too low, the cutting surface will be rough; if the current is too high, the nozzle life will be very short.

  1. Incorrect torch assembly

When assembling the torch, the parts should be properly aligned and tightly stuck together.This ensures good electrical contact and proper airflow and coolant flow through the torch.When changing parts, consumables should be placed on clean workshop rags to avoid dust or metal dust pollution cutting torch.It is important to keep clean during the assembly of the torch,but this is often overlooked.When the O-ring is coated with lubricating oil, it is only necessary to make the O-ring glossy. Too much lubricating oil will lead to the clogging of the swirl ring and the pollution of metal dust to the torch. This may lead to the arc in the plasma chamber being out of control and eventually to the cutting torch failure.Do not apply grease to the cutting torch, or it may cause destructive arc and combustion inside the cutting torch.

 

  1. Neglect of periodic maintenance

As long as it is properly maintained, the cutting torch can last for months or even years.Cutting torch threads must be kept clean, All dust and metal dust in the cutting torch or excessive lubricant on the O-ring should be cleaned. Using cotton swabs and electrical contact cleaners or hydrogen peroxide to clean the torch.

 

Experienced operator operation and maintenance of a good plasma cutting equipment can save countless workshop downtime and thousands of dollars in operating expenses, so that your cutting business and the company to bring higher profits. This period we continue to share with you the following common errors to be avoided in plasma cutting:

 

6.Unchecked airflow and coolant flow

Check gas and coolant flow and pressure every day. If the flow is insufficient, the wearing parts will not cool properly and the service life of the parts will be shortened. Pump wear will lead to filter plugging and low coolant level, resulting in insufficient cooling water flow is part of the fault and cutting torch one of the common reasons. To maintain the cutting arc, it is important to maintain constant pressure. High pressure is one of the common causes of “arcing difficulties”, “arc difficult” refers to the normal operation of all other conditions required to be met when the torch still can not start the arc.

7.Low perforation position

Clearance (the distance between the workpiece and the tip of the cutting torch) is a key element to ensure cutting quality and service life of the components. Even a slight cutting torch height change will affect the angle of the cutting surface. The height of the torch during perforation is particularly important. A common mistake is perforation is too low. This causes the metal slag to splash to the nozzle and the front end of the protective cap, resulting in damage to the parts and subsequent cutting quality problems. If the cutting torch in contact with metal perforation or cutting along the cutting surface drag, may even occur arc “off.” The arc “extinguished” will cause the electrode, the nozzle, the eddy current ring destroys, sometimes may cause the cutting torch to destroy. The recommended cutting height of 1.5 times to twice times the height of perforation can protect the torch and parts from damage.

8.Cutting speed too fast or too slow

Cutting speed too fast or too slow will lead to cutting quality problems. If the speed is too slow, the cutting piece will produce a “slow slag” (large molten slag accumulated along the edge of the bottom). Too slow can also lead to slit widening, the top slag too much. If the speed is too fast, the arc will lag into the slit, resulting in the edge of the groove, slit narrower and along the bottom edge of the workpiece to accumulate small, hard slag beads. High-speed slag is difficult to remove. The minimum slag is produced by maintaining the correct cutting speed. The result is a clean edge, which requires little more than two processing to enter the next step of the manufacturing process directly.

9.”Arc stretching”

If the arc must be “stretched” (deviating from the vertical straight cut path) to find the workpiece, an arc stretching may occur at the beginning and end of the cut. Arc stretching causes the arc to be cut to the nozzle side wall. When performing an edge arc, the nozzle hole should be placed at the center of the workpiece edge to start the plasma arc. It is important to keep this in mind when you are looking for a punch/plasma operation (deviating from the vertical line cut path) for the workpiece. Arc stretching causes the arc to be cut to the nozzle side wall. When performing an edge arc, the nozzle hole should be placed at the center of the workpiece edge to start the plasma arc. It is important to keep this in mind when punching/plasma operation starts from the perforation. In such applications, an arc should be drawn from the edge rather than from the center of the perforation. If the torch has been programmed to deviate from the plate when the arc is opened, or if the “drawing line” follows the last cut of the metal, the arc stretching may occur at the end of the cut. This phenomenon can be minimized by determining the timing of the ARC closing signal and programming the lead line.

10.Cutting Torch collision

“Warping” and collisions will cause irreparable damage to your cutting torch. By programming the graphics cutting system so that it moves around the cutting part (not above the part), you can avoid the cutting torch colliding with the workpiece. In addition, cutting torch height sensor through compensating material changes can also prevent cutting torch collision. However, a voltage-controlled tuning controller may not be able to protect the torch. For example, if the cutting torch follows the slit time is too long, then the cutting end usually occurs “cut torch forward plug.” (Cut the torch to adjust the controller forward to compensate for the tension caused by the voltage increase). This phenomenon can be minimized by careful programming of the extraction line and the cutting torch controller function. Finally, disconnect the torch fixed equipment can help prevent cutting torch in the event of a collision

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