We are well aware that there are several processes that can be used for varied kinds of cutting applications i.e. laser, plasma cutting, oxyfuel cutting, waterjet cutting and other mechanical methods of cutting.
Some factors to evaluate before deciding the cutting method to be used are – material to be cut, productivity, operating cost that will be incurred, cost of capital equipment and environmental considerations. In Part 1, we will be evaluating some of the factors that influence the choice of the cutting process.
Type of Material
Some methods of cutting can be used to cut only specific kinds of material. For example, plasma cutting can be used to cut only metals that are electrically conductive, oxyfuel cutting can be employed to cut carbon steel, whereas laser and waterjet cutting methods can be utilised to cut a wide range of materials.
Thickness of the Material
The efficiency of the cutting process depends on the thickness of the material to be cut. Typically, plasma cutting is used to cut metals of medium to thick range, laser cutting is generally used to cut thinner materials and oxyfuel cutting can be used to cut carbon steel that is quite thick. Waterjet cutting can be used for cutting materials of varied thicknesses.
Commonly, productivity is measured by the cutting speed. However, this is not the case and there are other factors that must be considered to evaluate productivity. The criteria are:
- Amount of time taken to set-up the job on the cutting machine
- Time required for programming
- Time needed to prepare the machine for cutting i.e. time for preheating, etc.
- Number of cutting heads the cutting system can accommodate
- Facility to unload the parts safely when the system is in operation
- Productivity of the nesting software and the capability to reduce unnecessary motion of the cutting head and at the same time minimise the time taken to cut
- Capability to undertake several processes on one machine i.e. cutting holes, slots, contours, bevelling, etc.
- Time needed for secondary operations like finishing, grinding, etc. that can be reduced by improving the quality of the finished parts
Total System Cost
The cost of the torch or cutting head, the cost of the cutting table or the robot used for cutting, CNC, software for programming, products used for the purpose of water treatment, fume control, recycling and abrasive removal, the cost of electricity used in the cutting process, etc. all contribute to the total system cost. Typically, oxyfuel cutting systems incur the lowest capital cost, the cost of plasma and waterjet comes next while laser systems require the highest capital outlay.
A point to consider is that the total cost of a certain kind of cutting system can differ widely from another. For example, the cost of cutting tables may be considerably different if they belong to different manufacturers despite having the same configuration. It is important for you to understand the causes for these differences before making a final purchase decision.
Each process of cutting has its pros and cons which you must take into consideration before finally deciding which kind of cutting to use. Sometimes, you may need to use a combination of cutting methods for a particular cutting application. We will be looking at some more factors in the second part of the series.