Below you will find a summary of three basic methods of CNC machining. Each method has its own advantages and disadvantages. Therefore, the choice of method always depends on the material, the situation, the costs generated and other factors
Laser cutting
A laser has opened up new fields of application in material processing. Especially in the thin metal sheet sector, mostly laser cutting is used due to the high cutting speeds and low thermal load. The laser processing impresses with its nearly right-angled cutting edges and a minimal cutting gap with achievable tolerances of up to +/- 0.1 mm/m. Even a virtually unlimited variety of materials have made the laser the number one among the cutting tools in many areas. Stainless steel up to 50 mm, steel up to 40 mm and aluminum up to 20 mm can be safely cut. For cutting this type of material are used expensive solutions, such as high power CO2 lasers or multi-diode laser systems.
However, single-diode laser heads are also used for other material groups such as wood, plastic or even paper. It has a low cost and a low weight. It can be easily adapted to an already bought CNC machine as the attachment (it is different from CO2 lasers).
Disadvantages
The disadvantages of laser cutting are that you have to be careful on reflective surfaces and use the appropriate laser for specific material. Others disadvantages:
- high investment costs,
- the limited thickness range of the metal sheet,
- extensive occupational safety measures.
Water cutting
Water jet cutting is an effective alternative to conventional cutting processes and for many users the optimal cutting solution. From foam to hard sapphire, with a high-pressure water jet of up to 6,200 bar, even the hardest materials soften like butter. Especially with heat-sensitive materials, you have to use this cold cutting process, since during the processing no heat occurs and that is why a thermal influence on the material structure by heat is avoided. The latest technology improvements took this innovative process into new levels of accuracy and productivity. The result is a significantly better quality of part tolerance and angular accuracy.
By mixing sharp-edged abrasives such as sand or quartz, the effect of water jet cutting can be further increased, which is why even very thick material can be cut. For example, stainless steel can be cut up to 300 mm and aluminum up to a thickness of 400 mm.
Source: WatechNorwayDisadvantages
- The disadvantages of water jet cutting are:
- the high operating costs,
- risk of corrosion of the manufactured parts,
- slow cutting speed,
- preparation of the cutting water and the disposal of the abrasives.
Plasma cutting
Due to the development of the modern multi-gas burners, plasma cutting becomes popular. It made significant progress in recent years and is one of the most economical cutting processes. Especially for thick Cr-Ni sheets and in the middle steel sector. The cutting quality in the thickness range from 15 mm to 40 mm is similar to that of laser cutting.
This thermal separation process impresses with high cutting speeds, which is why the productivity of the manufacturing process is significantly increased. Especially in the production of components that still need to be welded, turned, milled or further machined during further processing, plasma cutting offers extensive advantages. Plasma cutting machines have a high level of performance and can safely process all electrically conductive materials up to a material thickness of 200 mm.
Disadvantages
The disadvantages of plasma cutting are:
- relatively high operating costs,
- wide cutting gap,
- the high noise level in dry cuts,
- edge zone hardening of the plasma cuts
- post-processing of the finished parts.
Others methods
Milling – you have to use only hard materials, the maintenance costs are relatively low. Usually, you need to finish the edges, you cannot cut elastic materials (textiles, rubber) and small elements, small radius corners. The complex construction of the CNC milling is another disadvantage.
Oscillating knives – the knives blunt very fast. You cannot cut small corners, but you can cut elastic and textile materials
Depending on the cutting task, the advantages of the individual processes come into their own and together they form a smart alliance for a wide variety of applications.
The mentioned methods of material processing have one thing in common. Only highly qualified personnel can do the maintenance of these machines, with which often external service providers are commissioned.
source: Opt Lasers