CNC drilling machines and CNC milling machines are important equipment in PCB processing. This equipment is expensive. The selection of CNC machine tools is not only important for operation, process setting and maintenance, but also for the quality of produced products.
As a craftsman, for pure technical and operational considerations, the selection indicators of CNC machine tools generally start from the following aspects:
1. Rigidity And Stability of The Machine Table:
In order to make the machine tool have sufficient stability and rigidity to avoid vibration, many manufacturers use marble as the material for the bed, and some Japanese manufacturers use steel as the bed. Because the deformation of steel at different temperatures is larger than that of marble, it is unstable. Manufacturers use compensation in the software to eliminate the loss of accuracy caused by deformation. At present, most manufacturers use natural marble or artificial marble as the bed. It is recommended to use the equipment for the marble bed. The marble should be cleaned with detergent and water during daily maintenance, and alcohol should not be used. After wiping, dry it with a dry cloth and wait for the water to evaporate completely before you can work.
2. The Speed and Stability of The Shaft:
At present, there are two kinds of rotating shafts. One is rolling bearing with a maximum speed of 80,000 rpm, and the other is an air bearing with a maximum speed of 120,000 rpm. If it is a milling machine, rolling bearings should be used, because the longitudinal load is better than that of air bearings, and the purchase of the drill chuck is also the focus of the investigation. Replacement is expensive, and some are time consuming with daily maintenance. The presser foot of the rotating shaft is also another, and its unreasonable life and design will also cause great trouble. For example, there is no seal between the shaft and the presser foot, which causes the vacuum cleaner to require a lot of power, resulting in a waste of money for the purchase of the vacuum cleaner or the power of central vacuuming waste, and may cause poor chip evacuation in the circuit board hole.
3. The Movement Accuracy And Displacement Repeatability of the Tabletop:
This is the most important point when selecting, and it cannot be seen through pictures or ordinary operations. It can only be certified after testing after purchase. The current equipment can meet the design standards when it leaves the factory. The key is to run for one to two years later. Whether the accuracy is very stable, the machine tools produced in Europe do better in this regard.
4. Feed Rate of X, Y, Z axis:
The current feed rate generally uses a screw stepping motor with a speed of 25 meters per minute, while the new product has adopted a servo motor, and the high feed rate can increase the production capacity by 20%-40%. The material being drilled affects the feed rate and has little effect on production efficiency.
5. The Moving and Fixing Device of The Table:
The moving load of the tabletop is mainly based on guide rails in the past, and there is also air flotation as the load-bearing of the table moving. The air flotation table is used for flexible movement and convenient maintenance, so it is the first choice when purchasing. The device for fixing the circuit board on the table is generally a pneumatic chuck. The design of the chuck has an important impact on the replacement of the equipment in the future. Generally, it is not easy to wear and tear, because it is one of the most severely worn parts of the equipment when it is worn. Once worn, replacement and debugging should be simple, including the debugging of the positioning accuracy of the machine tool (for the template for milling machines). At present, many manufacturers provide automatic clamping devices. If you do not have a good equipment maintenance engineer, it is best not to use it, because the use of automatic loading and unloading devices has high requirements for maintenance engineers, and the current circuit board drilling sometimes takes more than 1 hour at a time. It is generally not necessary to use it in China.
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