Ultrasonic Polishing - Tips and Process
The advantages of ultrasonic polishing: The tool moves with a stroke length of 40 μm up to 30,000 times a second. We therefore have a very short stroke that moves incredibly rapidly. This offers 2 crucial advantages:
- Ultra-short stroke, allows very precise control in difficult areas.
- High pulse frequency, which requires a broad, uniform movement in order to evenly process the area to be worked.
How does the ultrasonic system work?
A piezo-ceramic is located inside the ultrasonic handpiece, which expands to a maximum of 40 μm and contracts again. The entire process is governed by the control unit such that the expansion and contraction occurs 30,000 times a second. The piezo-ceramic generates a maximum of 45 watts of output. You can however suppress this performance by excessive pressure, thereby inhibiting this power output.
You need to ensure the following when using the ultrasonic polisher:
- Always work with uniform movements in order to avoid distorting the surface.
- Work with light contact pressure. The tool works considerably more efficiently as a result and the ultrasonic handpiece is not overloaded.
- It is absolutely essential to ensure that the contact surfaces are clean and free of grease in order to Prevent clogging of the stones and lessening the cutting effect, sintered stones need lubricating.
How do we use ultrasound in practice?
The best results are achieved with ceramic- fibre files for removal of hard erosion skin.
Depending on the task, you will need to shorten the file to the required length. According to the u/s polishing unit recommendation Ceramic-fibre stones must only be cut using a diamond cutting disc. If the tools are shortened with pliers, the fibres in the synthetic matrix are crushed and consequently loosened. The fibre files lose their strength and you will end up with a "paintbrush" that no longer works effectively. Dress the front face of the ceramic fibre file on a diamond film or a grit size 400 diamond file.
Which tools are suitable for ultrasound?
- Ceramic-fibre files and ultrasonic polishing systems are the perfect match. Using these tools, a really good surface finish can be obtained with very high stock removal for removing the erosion structure.
Three grades of ceramic-fibre file are available:
- Standard Ceramic fibres are used in this case.
- Standard interspersed with diamond. The stock removal is enhanced by the incorporated diamonds. Particularly useful for hard materials such as carbide.
- Crystal fibre files allow you to obtain a further increase in the crystalline fibre structure stock removal performance. They are the most modern fibre files on the market.
All ceramic-fibre files achieve very uniform surfaces. The surface values are altogether finer than the grit size used would allow one to expect. Ceramic-fibre files are always used dry except when using diamond compound on the fine stones.
- Diamond files - Galvanic and sintered tools can be used. Sintered diamond files are extremely hard. You should be sure to familiarise yourself with their use in order to ensure that you do not cause any damage to your mould.
- Polishing woods - Both soft and hard wood can be used. If you set the output too high, it may occur that your wood burns. Turn down the output in this case.
- Brass or copper sheet - These tools are used with coarse diamond compound (e.g. 25 μm) for removing the erosion skin.
- Ceramic-fibre files with diamond compounds - Take for example a thin fine grit-sized fibre file (grit size 1.200) and 6 μm diamond compound. The fibre file is elastic. This allows you to apply the necessary pressure and for example very easily process narrow slots.
- Sintered Mould Polishing Stones up to 3 mm can be readily clamped using the right holder. Preferably work wet and you will obtain within a very short time finely evened surfaces, above all in problem areas.