Increasing the power of a laser cutting machine does not necessarily increase production efficiency. Whether to purchase a high-power laser source should be analyzed according to its specific situation.
People all want to make money with laser cutting machines, which is obvious. Many people think that increasing the power of lasers will increase their income – sometimes it does, but sometimes it does not.
If we consider how increasing power will affect revenue, then we should discuss this issue in detail. When the power range is relatively low, any increase in power is directly reflected in overall efficiency.
As power increases, cutting speed also increases proportionally. However, when parts are small, the cutting speed may not necessarily take full advantage of what the laser power can achieve.
Increasing power on small parts is not effective, so increasing power has no meaning when cutting thin sheets and small details.
All of these considerations apply to cutting in argon gas: after the material being cut reaches a certain thickness, it must transition to using oxygen for cutting.
However, when cutting with oxygen, the cutting speed is much slower, and this speed does not increase with the increase of power. This means that increasing power only makes sense for medium-thick plates.
For example, when the power is 6 kW, the maximum thickness that can be cut in nitrogen is 6 mm. Once the thickness exceeds this value, oxygen should be used for cutting. At this time, the cutting speed will be slower, thus reducing overall efficiency.
When the power increases to 8 kW, the maximum thickness that can be cut in nitrogen is 8 mm; the maximum thickness that 10 kW can cut is 10 mm; the maximum thickness that 12 kW can cut is 12 mm.
High laser power only makes sense when cutting materials of medium thickness.
For thin sheets, high-power cutting cannot be used because it is limited by machine power. When faced with thick sheets, cutting speed will be limited by oxygen cutting technology.
Therefore, if most of the cutting task involves metal plates with a thickness of 8 mm, a laser with a power of at least 8 kW should be used, and if the thickness is 12 mm, a laser with a power of 12 kW should be used, and so on.
The above dependence relationship shows that further increasing power, such as increasing it to 15 kW or 20 kW, should almost completely eliminate cutting thick plates in oxygen.
Laboratory research has confirmed this, but is the industry ready to use such high power?
Challenges of Using High-Power Cutting
In recent years, the rapid development of fiber laser sources has led to the emergence of high-power products on the market, up to 20 kW or even 30 kW.
However, the reality is that applying these high-power lasers to cutting equipment is not as simple as it may seem. Offering extremely high power may look great in advertising, but with its high purchase cost, can it really provide a return on investment?
The biggest problem is energy absorption and loss in the cutting head, which can cause overheating of optical elements. The higher the laser power, the more detrimental the thermal effects will be.
To make the cutting process run smoothly, many parameters of this process must be controlled. One of these is the height of the focus, which must be accurately pre-set for each type and thickness of cutting material.
Due to the optical properties of the glass used for the optical elements in the cutting head, the position of the focus will change with an increase in temperature, which affects the cutting process – this effect is called focus shift.
Focus shift is difficult to control because the lenses are cold at the start of the cut, but as time goes on, they warm up and the focus shifts, leading to a decrease in cutting quality or even stopping the cutting process altogether.
The effect of focus shift increases with laser power. For powers up to 6 kW, this effect can be ignored, but at higher powers, focus shift becomes a very noticeable problem.
Using special aspheric lenses with low-absorption anti-reflective coatings can alleviate some of the focus shift problems to a certain extent.
However, absorption and overheating problems will increase over time because optical elements degrade quickly when working at high power, with higher powers leading to faster degradation rates.
In addition, when installing or changing protective glass, invisible impurities may enter the cutting head, causing damage to the optical elements. The higher the laser power, the greater the risk of serious malfunctions due to operator error or improper operation.
At low power, damaging one optical element does not damage neighboring elements.
However, at high power, the rate of optical element destruction is so fast that it may trigger a chain reaction, destroying all parts of the laser head, including the fiber, before the operator can react.
The above phenomena mean that many companies decide to buy lasers with very high power, hoping to significantly improve efficiency, but they cannot fully utilize such high power.
In reality, overheating and downtime caused by failures of optical elements result in huge costs. Users of such lasers often have to reduce the laser power to a level where it can operate stably.
Typically, the actual power used may be only half of what they paid for.
It should also be remembered that although doubling the power can double the linear cutting speed, this does not translate into doubling the total production efficiency.
Besides, as mentioned earlier, increasing power does not linearly increase the number of parts produced in a single shift. Improving laser power cannot shorten the time it takes for parts to move quickly, reduce the time needed to replace trays or prepare activities, or shorten the lunch break of operators.
If a 1.5 kW laser is chosen instead of a 6 kW laser, the price of the laser may be doubled. However, considering the entire material thickness range calculated by the number of components cut, the average production efficiency of the entire machine will only increase by about 30%.
Therefore, it has been proven that buying two 6 kW lasers with the same amount of money can improve production efficiency by 100%. It should also be remembered that if two lasers are used, in the event of downtime, the other laser can continue cutting to ensure continuity of production.
In summary, providing high laser power can indeed create excitement and a “wow” effect.
However, this does not directly translate into expected results, just as a 1000 horsepower car will not necessarily drive through a city faster than a 100 horsepower car.
The rationality of purchasing a laser with very high power should be analyzed separately. In many cases, it may be found that high power significantly increases both the purchase and operating costs without necessarily improving production efficiency.