If these two devices are compared, who will be better? What’s the difference between turret punch and laser cuttting?
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1. Laser cutting machine
Laser is a kind of light. Like other natural light, it is produced by the transition of atoms (molecules or ions, etc.).
But different from ordinary light, laser only depends on spontaneous emission in a very short time at first, and then the process is completely determined by stimulated emission.
Therefore, the laser has very pure color, almost no divergent directivity, high luminous intensity and high coherence.
During the cutting process of the laser cutting machine, the beam is focused into a small focus through the lens of the cutting head, so that the focus reaches a high power density, in which the cutting head is fixed on the z-axis.
At this time, the input heat of the beam far exceeds the part of the heat reflected, conducted or diffused by the material, and the material is quickly heated to the melting and vaporization temperature.
At the same time, a high-speed air flow blows out the melted and vaporized material from the coaxial or non coaxial side to form holes for material cutting.
With the relative movement between the focus and the material, the hole forms a continuous slit with very narrow width to complete the cutting of the material.
During slit cutting, the process parameters (cutting speed, laser power, gas pressure, etc.) and motion trajectory are controlled by the numerical control system, and the slag at the slit is blown away by a certain pressure auxiliary gas.
However, the laser beam has a certain divergence angle and is “conical”. When the “conical” height changes (equivalent to the change of the optical path length of the laser cutter), the beam cross-sectional area on the surface of the focusing lens will also change.
In addition, light also has the property of the wave, so diffraction is inevitable.
Diffraction will cause the beam to expand laterally in the process of propagation.
This phenomenon exists in all optical systems and can determine the theoretical limit value of these systems in terms of performance.
Due to the “cone” of Gaussian beam and the diffraction of light wave, when the optical path length changes, the beam diameter acting on the lens surface changes at all times, which will cause the change of focus size and depth, but has little effect on the focus position.
If the focus size and depth change during continuous processing, it will inevitably have a great impact on the processing. For example, it will cause inconsistent cutting seam width, impervious cutting or ablation of plates under the same cutting power.
This is a processing disadvantage caused by the principle of laser cutting machine.
2. Servo CNC turret punch
CNC turret punch can be used for processing all kinds of sheet metal parts, and can automatically complete a variety of complex holes and shallow stretch forming at one time.
According to the requirements, the holes of different shapes with different sizes and hole spacing can be processed automatically.
The large round holes, square holes, waist holes and various shape curve contours can also be punched by small die in step.
Special processing can also be carried out, such as louver, shallow stretching, counterbore, flanging hole, stiffener, embossing, etc.
Through simple die combination, compared with traditional stamping:
- It has high machining precision and stable machining quality;
- Its processing format is large: the processing format of 1.5m × 5m can be completed at one time;
- It can carry out multi coordinate linkage, process parts with complex shapes, and can be used for shear forming, etc;
- When machining parts are changed, generally only the NC program needs to be changed, which can save production preparation time;
- The punch itself has high precision and rigidity, can choose favorable processing dosage and high productivity;
- The punch has a high degree of automation, which can reduce the labor intensity;
- Simple operation, with certain basic computer knowledge, can be started after 2 ~ 3 days of training;
- It can save a lot of mold costs, and can use low cost and short cycle to process small batch and diversified products;
- It has a large processing range and processing capacity, so as to adapt to the changes of market and products in time.
Processing mode of servo turret CNC punch:
(1) Single punching: punching is completed in a single time, including linear distribution, arc distribution, circumferential distribution and punching of grid holes.
(2) Continuous blanking in the same direction: the method of partial overlapping processing of rectangular die can be used to process long holes, trimming, etc.
(3) Multi-direction continuous blanking: the processing method of machining large holes with small molds.
(4) Nibbling: continuous arc punching with small round die in small steps.
(5) Single forming: the processing method of one-time shallow stretch forming according to the mold shape.
(6) Continuous forming: forming processing methods that are larger than the die size, such as large-size louver, rolling rib, rolling step and so on.
(7) Array forming: machining multiple identical or different workpieces on a large plate.
3. Laser cutting vs CNC punch
Both laser cutting and CNC punch are indispensable processing mean in production and processing.
We need to master their different characteristics in order to select the best and most economical processing method.
Through my experience, the two have the following characteristics and differences:
- CNC punch mainly cuts the straight line, square hole, round hole and OB hole, and the pattern is simple and fixed;
- The main materials are carbon steel plate and aluminum plate below 6mm;
- CNC punch is not recommended for stainless steel plates with a thickness of more than 2mm;
- Because the material has high viscosity so it has high hardness;
- The phenomenon of material jumping and knife sticking is serious, and the consumption of mold is also large.
- The processing speed of NC punch is fast, and the die is fixed;
- If a new mold needs to be developed, the cycle is at least three weeks and the cost is high;
- The degree of flexibility is not high;
- It is troublesome to remove the burr at the connection point, and the knife joint mark is obvious;
- For parts with length less than 500mm, the machining accuracy is about + / – 0.10mm;
- Laser cutting is more flexible;
- Faster cutting speed and high production efficiency;
- Short production cycle;
- No deformation during processing;
- No mold required;
- Any shape can be precision formed at one time;
- For parts with length less than 500mm, the machining accuracy is about + / – 0.05mm;
- However, compared with the punch cost, the blanking cost of simple graphics is higher;
- The slag around the cutting line affects the surface quality;
- Rolling rib, knock down hole, shutter and other three-dimensional special-shaped parts cannot be manufactured by laser cutting machine.
Anyway, in the actual production, it is necessary to select the appropriate processing means according to the part drawing in order to obtain the best result.