Ceramics are a type of inorganic, non-metallic material made from natural or synthetic compounds through forming and high-temperature
sintering. It is a functional material with a high melting point, high hardness, high wear resistance, and oxidation resistance. It is characterized
by high hardness, high rigidity, high strength, no plasticity, high thermal stability, and high chemical stability. It is also a good insulator and is
often used in military, aerospace, high-end PCB, and other fields. The ceramics used in the military, aerospace, and 3C industries are mainly
oxide ceramics, carbide ceramics, metal ceramics, nitride ceramics, etc., which have special mechanical, optical, acoustic, electrical,
magnetic and thermal properties.
However, ceramic materials are limited by process conditions during mechanical processing and cannot accurately reserve various holes,
grooves, and edges for assembly. Therefore, drilling processing for engineering ceramic products is often required in production, and it is also
an important technology for ceramic processing. The high hardness, high brittleness, and easy breakage of ceramic materials require good
processing technology for precision drilling of ceramics, especially small and micro-hole processing, forming processing, thread processing,
etc., in order to expand the range of material machinability and enable it to be more widely used. At present, the main technologies for drilling
holes in ceramic materials include mechanical processing, ultrasonic processing, laser processing, and other methods. Today, we will briefly
introduce them.
Mechanical drilling is the most widely used method. This method uses a diamond hollow drill, which uses the rotation of the hollow drill to grind
and continuously cut into the ceramic material until it penetrates. This method is particularly suitable for the processing of circular holes with a
diameter of more than a few millimeters.
Advantages:
(1) The process is mature and easy to operate;
(2) High processing efficiency and simple equipment.
Disadvantages:
(1) Due to the high hardness of ceramics, the drill bit wears severely;
(2) Ceramics are brittle, and it is easy to produce chipping at the entrance and exit of the hole, affecting the processing quality of the hole;
(3) A large amount of debris and dust is generated during the processing, and the processing environment needs to be improved.
Ultrasonic drilling is one of the most suitable and effective methods for ceramic materials with low tensile strength. Ultrasonic processing is a
process in which an ultrasonic generator converts electrical energy into ultrasonic frequency oscillations and fixes them on an amplitude
amplification tool to generate ultrasonic vibrations, so that the liquid abrasive between the tool and the workpiece continuously impacts and
grinds the processed surface at a high speed and acceleration. Therefore, processing efficiency is related to the ultrasonic output power,
abrasive type, processing speed, etc.
Advantages:
(1) It can process points and insulating materials;
(2) It is not limited by the hardness of the material and can process complex 3D structures;
(3) The processing tool does not need to rotate, so it can process holes with special contours;
(4) The processing speed is fast and there is no thermal effect.
Disadvantages:
(1) It is troublesome to replace the processing tool;
(2) The processing quality is subtly affected by factors such as changes in tool quality or force conduction caused by processing;
(3) Its processing accuracy is limited by its processing amplitude. It is more suitable for surface cutting and complex three-dimensional surface
processing and cannot meet the needs of high-precision micro-hole processing at the level of hundreds of microns.
Laser drilling is also effective in processing small holes in superhard materials such as ceramics. Laser processing generally uses a pulsed
laser. The laser beam is focused on the ceramic workpiece through an optical system. The laser pulse with high energy density
(106~109W/cm2) is used to melt, gasify and evaporate the processed surface, thereby removing the material to achieve small-hole
processing.
Advantages:
(1) It is a non-contact process that will not cause mechanical extrusion or mechanical stress to the material and is safe and reliable;
(2) It is simple to operate, with fast processing speed and high efficiency, and it is easy to achieve mechanization with computer control;
(3) It has high precision, low processing costs, and a high process level.
The laser focus spot can be converged to the wavelength level, concentrating high energy in a very small area, which is particularly suitable for
processing fine, deep holes. The minimum aperture is only a few microns, and the hole depth and aperture ratio can be greater than 50. Laser
drilling is mainly used for parts of the ceramic body, such as the shell earpiece and antenna drilling, earphone drilling, etc. It has the
advantages of high efficiency, low cost, small deformation and wide application range. By optimizing the laser processing parameters, higher-
quality micro-holes can be processed. Therefore, compared with ceramic materials, the laser drilling process has a very comprehensive
advantage.