In the field of metal processing, before precision machining, it is often necessary to cut metal materials. There are several common cutting methods for metal, including grinding wheel cutting, flame cutting, saw cutting, plasma cutting, laser cutting, and waterjet cutting.
Grinding Wheel Cutting:
Using a high-speed rotating grinding wheel to cut steel is a commonly used cutting method. Grinding wheel cutting machines are lightweight, flexible, and convenient to use, widely used in various applications, especially in construction sites and interior decoration, mainly for cutting small-diameter square tubes, round tubes, and profiles.
Saw Cutting:
Saw cutting is a method of cutting workpieces or materials by creating narrow slots using a saw blade. Metal band sawing is the most basic requirement in metal processing, and band saws are standard equipment in the machining industry. The selection of the appropriate saw blade and adjustment of the optimal cutting speed depend on the hardness of the material.
Flame Cutting (Oxy-Fuel Cutting):
Flame cutting is limited to cutting carbon plates and is not suitable for other types of metals like stainless steel or copper-aluminum materials. The main advantage of flame cutting is low cost, but it has a larger heat-affected zone and significant thermal deformation. The cut surface is rough and often has slag. Considering subsequent processing, extra allowances should be added.
Plasma Cutting:
Plasma cutting was invented in the 1950s and uses the heat of a high-temperature plasma arc to locally melt (and evaporate) the metal at the cutting edge and remove the molten metal with high-speed plasma momentum, forming the cutting edge. Plasma cutting is generally used for materials with a thickness of up to 100mm. Unlike flame cutting, plasma cutting is faster, especially when cutting thin carbon steel plates, with speeds up to 5-6 times that of oxy-fuel cutting. It provides smooth cut surfaces, minimal thermal deformation, and a smaller heat-affected zone. Plasma cutting is not limited to cutting carbon plates and can also cut stainless steel, copper-aluminum materials, and nickel-titanium metals.
Laser Cutting:
Laser cutting uses a high-energy laser beam to heat, locally melt, and vaporize the metal to achieve material cutting. It is commonly used for efficient and precise cutting of thin steel plates.
Laser cutting offers excellent cutting quality, fast cutting speed, and high dimensional accuracy (up to ±0.05mm). Due to the laser beam's small spot size, the heat-affected zone is minimal, resulting in minimal workpiece deformation.
Laser cutting quality is superior to plasma cutting, but plasma cutting is faster in terms of cutting speed.
It's worth mentioning that laser cutting equipment can be expensive, with costs ranging from millions to tens of millions of dollars.
Waterjet Cutting:
As the name suggests, waterjet cutting is a processing method that uses water to cut metal. However, ordinary water alone is not powerful enough, and high-pressure water flow is required.
Waterjet cutting can perform one-time cutting of any material with arbitrary curves. The biggest advantage of waterjet cutting is that the generated heat during cutting is immediately taken away by the high-speed flowing water, resulting in no heat-affected zone. Waterjet cutting can even cut bullets without any issues.
Knowing so much about the cutting process, how do we choose the most suitable metal cutting process?
Now the mainstream of these several metal cutting processes, in the cutting thickness, cutting accuracy, metallurgical performance, production efficiency and other aspects have their own characteristics. Before choosing, we must first clarify which needs are the most important for users in the metal processing industry. We can look at equipment acquisition costs, cutting costs per unit of part or length, ease of use, productivity, cutting accuracy, edge quality and metallurgical properties, maintenance requirements.
1.Equipment acquisition cost
The above several cutting methods need to be equipped with different CNC, dust removal equipment, CAD/CAM software, etc. For example, compared to the slower cutting speed of water knives and flames, lasers require higher speed and accuracy on thin sheets. These requirements can directly lead to huge differences in equipment costs
2.Cutting cost per unit of part or length
This cost includes gas, nozzles, electrodes, electricity and water. In some cases, equipment acquisition costs and Labour costs (e.g. loading and unloading) are also shared. So be sure to pay attention to its scope when comparing. Compared with the unit time cost, the unit part or unit length cost covers the cutting speed and production efficiency, and has a practical reference value.
3.Ease of use
This demand is mainly for software (CAM in particular) and CNC numerical control. Learning time and reliance on experience are now reduced by integrating professional experience into the system. For example, Haibao, the leader in the field of plasma cutting, has built the full set of process parameters of Haibao Plasma directly into Haibao's own tooling software and CNC numerical control, so that new users can quickly master it and maintain the same cutting quality and production efficiency as professional veterans. Although this demand is difficult to quantify, it cannot be ignored for actual production.
4.productivity
Productivity is also called production capacity, and cutting speed is often a determinant of production capacity.
5.Accuracy of cutting parts
There are many ways to measure the accuracy of metal parts. Generally, the tolerance requirements for the external contour are lower than those for the inner hole. So now many metal cutting suppliers have introduced higher cutting quality of the inner hole process, such as Haibao integrated bolt hole cutting process. In addition, users usually only measure the upper surface in the measurement, but in fact, because of the impact of the cutting slope, the size of the bottom surface will be very different. For the sake of simplicity, it is recommended to use positive and negative tolerance values for the upper surface measurements, taking into account the cutting slope for each process.
6.Edge quality and metallurgical properties
All of the above processes have different effects on metal machinability, formability and weldability.
7.Maintenance requirement
The long-term cost of use needs to consider the maintenance of these different processes and the difficulty of maintenance.
