Guide to The Process of Plasma Cutting Process
There exist two distinct categories of the metal cutting process in the metal fabrication industry. They include thermal cutting and mechanical cutting. However, plasma cutting is a form of thermal cutting that utilizes ionized gas to cut through metal. At Creatingway, it is an ideal technique for cutting through sheet metal plates. Here is further insight into how plasma cutting works and some of its pros and cons.
How A Plasma Cutter Works
The plasma cutting process utilizes heat to melt and cut through metal. This is different from the mechanical cutting process that uses force to cut. In definition, plasma is an electrically conductive ionized gas-like substance. It shares a similarity to liquid and can flow when exposed to a magnetic or electrical field.
Plasma cutters use a mechanical system that shares a similarity in function. We ionize compressed air or certain gases for example nitrogen in the creation of plasma. Afterward, the electrodes come into contact with the compressed gases causing ionization to occur. Additionally, pressure build-up during this process. The built-up pressure causes a steady stream of plasma to be ejected through the cutting head.
What controls the flow of the plasma stream is the cutting head. We then place this cutting tip on the workpiece for metal cutting to commence. The workpiece stays grounded through the cutting table since the plasma is electrically conductive.
The generated plasma arc contacts the metal workpiece and melts it due to high temperature. Simultaneously, the high speed of the gases blows away the molten metal generated.
Ways in Which the Plasma Cutting Process Starts
The process can begin in three main ways, namely: high-frequency contact, pilot arc, and spring-loaded plasma torch head.
High-frequency contact
This is the low budget version of a plasma cutting system. It involves the use of a high-frequency spark and a high voltage. After the plasma torch comes into contact with the metal, it generates a spark. The spark in turn creates the plasma. However, due to its high frequency, it commonly interferes with CNC equipment and causes malfunctions
Pilot arc
Another great option is using the pilot arc method. We use a high voltage and low current circuit to create a spark inside the torch. A little amount of plasma occurs from the pilot arc. Afterward, the cutting process begins after establishing contact between the workpiece and the pilot arc.
Spring-loaded plasma torch head
This method uses a torch pressed on the workpiece thus creating a short circuit. This makes the current to begin flowing in the plasma cutter. Afterward, the release of the pressure results in the creation of the pilot arc.
Advantages
- Cheaper alternative for medium thickness cuts
- Ability to cut up to a thickness of 150 mm
- Offers a quicker cutting speed than oxyfuel
- Ability to cut through conductive material unlike a flame cutter
Disadvantages
- Does not offer high tolerance when compared to laser cutting
- Not appropriate for thick metal plates
Selecting the Appropriate Cutting Method
The parameters to check when selecting the appropriate cutting method for your project includes the application of the parts, thickness, and type of material. The specifics are below.
- Metal Thickness
Plasma cutting works best with a metal thickness of between 15 mm to 50 mm. However, the recommended upper limit for stainless steel and carbon is about 50 mm. Aluminum on the hand as an upper limit of about 40 mm. Thicknesses above this limit are best cut using a flame cutting machine or waterjet.
- Type of Material
A plasma cutter is more efficient with sheet metals and thin plates. It improves its quality and overall speed.
- Application of Parts
Plasma cutting is a cheaper and quicker alternative for projects with plates around 15 mm. it also provides great quality in a smooth and nice result after [post processing.
Tips for Cutting Using Plasma
- Despite plasma cutters being easy to use, they need a few practices to increase their efficiency. Here are a few examples of those practices:
- Selection of an appropriate tip with the right amperage setting. For instance, using a 70 amp setting with a 40 amp tip results in distortion of the tip orifice. This greatly reduces consumable life. Additionally, we preferably use extended tips in accessing corners, tight areas, and making patterns.
- Before beginning the cutting process, it is a good practice to make a sample cut on the workpiece. This is identifying the optimum setting and travel speed of the plasma cutter.
- Utilize a faster travel speed with the plasma cutter in order to get a cleaner cut. For thicker materials, select a full output with varying travel speed.
In summary, it is important to understand how plasma cutting works to know determine how it will benefit your project. Contact Creatingway now for your plasma cutting needs.
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