Thermal cutting is one of the most important production processes in the metal producing and metalworking industries (e.g. in Structural engineering, machine fabrication, Energy equipment manufacturing shipbuilding and plant manufacturing etc.).
Thermal cutting primarily means the use of energy in various forms to cut virtually any shape from iron and nonferrous materials out of sheets or large slabs. These are the grades of the material which are usually referred as “Flats” in the metal processing industries. The other type of metals is available in angle, channel, beams, pipes, rods etc. which are called as “Longs”. The series of article would cover primarily the cutting of the Flats & at a later date Longs.
Thermal cutting can be categorized on the following requirements
1. Type of material to be cut & its thicknesses:
The selection of thermal cutting process would primarily be depending upon the type of material Ferrous, nonferrous & its thicknesses
We are representing the selection bubble diagram of Ferrous material so based on the thickness of the material the cutting process can be identified. The diagrams are having certain overlapping areas where 2 process can be fit in. There would be more criteria to used to further narrow down on the actual process.
The tolerance of the various types of thermal cutting processes are each dedicated to the process basics, expressions, quality and dimensional tolerance. The quality characteristics, perpendicularity and angularity tolerances and the permissible calculated depth of roughness are set separately for the different cutting. One of the examples of tolerance is also mentioned in the above figures, similarly all other criteria would be covered in the subsequent articles.
3. Physics of the cutting process & its effects on the material:
We can distinctly separate the cutting by physics, which can be burning (chemical reaction) by oxidation, cutting by melting and vapourisation cutting (also called as sublimation). The selection of the process would make an effect on the type of the material to be cut, its tolerances, chemical & physical reaction post cutting.
4. Type of production:
In various industries the type of production is categorized as cutting by manually operated tools, semi- mechanised cutting, fully mechanised cutting and automatic cutting. The volume of the production can also have a bearing on the selection of the process. The location of the cutting in the production like in- situ production , on site, open yard, enclosed area or normal factory site affects the process that can be used.
5. Post cutting operations desired:
The thermally cut parts which are parted from the mother plate are further taken for the post cut operations. In some of the operations there would be direct fitment, welding, grinding or bending, heat treatment etc. The process is greatly influenced by the post cutting operation desired.
6. The energy carrier:
The energy carrier is terminology used for the method in which the energy is used for metal removal it can be hot gases, electric gas discharge or by beam energy like light. They would be easily connected in the above sequence for gas, plasma & Laser. The usage of various energy carriers have direct implication on several physically & mechanical effects on the cut parts.
7. Application of the cut part:
The application of the cut parts as mentioned in the point no 5 can be further explained to understand that whether the part is subjected to mechanical stress, chemical reaction or fatigue etc , this would directly determine the thermal cutting process to be used.