What are the pros and cons of microporous ceramic engraving and milling machine processing and laser drilling?

Making a small hole in a component is a common thing. However, if the requirements of hard materials, such as in the carbide on a large number of 0.1 mm to several micron diameter holes, with ordinary machining tools is not easy to do, even if you can do, the processing cost will be very high. Existing machining technology in the material to play miniature holes is used tens of thousands of revolutions per minute or hundreds of thousands of revolutions of high-speed rotary drill processing, with this approach can only be processed in a hole diameter of more than 0.25 millimeters of small holes. In today's industrial production is often required to process holes with a diameter smaller than this. For example, in the electronics industry, the production of multi-layer printed circuit boards, the requirements of the board drilled thousands of small holes with a diameter of about 0.1 to 0.3 millimeters. Obviously, the use of the drill just mentioned to process, the difficulties encountered is relatively large, processing quality is not easy to ensure that the processing cost is not low. As early as after the 1960s of this century, scientists in the laboratory with a laser in the steel blade to play a micro-miniature holes, after nearly 30 years of improvement and development, and now use the laser in the material to play a tiny diameter of small holes has been no difficulty, and the processing quality is good. The holes are punched with regular walls and no burrs. Punching speed and very fast, about one-thousandth of a second time can be punched out a hole.

The reasoning behind laser drilling of small holes in materials is simple (laser drilling) and the practice is not complicated.

Lasers are very coherent, and optical systems can focus them into very small diameters (less than 1 micron), which are equivalent to "micro-drills" for drilling. Secondly, the laser's brightness is very high, in the focus of the focus of the laser energy density (average energy per square centimeter area) will be very high, ordinary laser output of a laser, the energy generated can be as high as 109 Joules / cm2, enough to make the material melting and vaporization, leaving a small hole in the material, and drilling out of a drill like.

How to use the laser "drill", laser scientists have done a lot of research. They found that, with the emission of many light pulses per second (usually called high repetition rate laser pulses) to do "drill", out of the small hole quality than with a single light pulse, or a few light pulses per second time out of the hole better. The reasoning goes something like this: when drilling with a single pulse or a few pulses per second, the laser energy required for each pulse is high enough to heat the material to the point of melting in order to drill the hole. However, the melted material is not able to vaporize sufficiently, but heats up and vaporizes the material in its vicinity, and as a result, the small holes punched out are less regular in shape and size. If a high repetition rate laser is used to output light pulses, the average energy of each light pulse is not very high, but the power level is not low due to the narrow width of the light pulse. As a result, not much melt is formed on the material per laser pulse, and mainly vaporization occurs. Since there is very little melt when the material near the hole is heated, the same thing does not happen when the hole is punched with a single pulse. The shape and size of the punched hole is much more regular.

To make a high quality of punched holes, but also need to pay attention to the choice of laser focus position. The principle of choosing the focus position is roughly like this: for thicker materials, the laser beam focus position should be located inside the workpiece, if the material is thin, the laser beam focus needs to be placed on the surface of the workpiece above. This arrangement will make the punched holes are basically the same size above and below, without "barrel-shaped" holes.

Laser drilling in the material, drilling out the hole quality is not only very good, especially in playing a large number of the same hole, but also to ensure that the size and shape of a number of small holes in the shape of uniformity, and drilling speed, high productivity. Therefore, in addition to laser drilling in the production of the electronics industry, many other sectors of industrial production are being used, such as small holes in ordinary cigarette filters, small holes on the sprayer valve, but also in the use of laser processing. Sprayer cans and bottle necks are used to control the flow of compressed substances (such as deodorants, oils, or other liquids), the performance of the valve use is determined by this small hole on the sprayer. This small hole has a diameter of 10 microns to 40 microns, with other mechanical processing methods are not so good to do, with the laser to process, can ensure quality, but also to ensure speed.