CNC machining is traditionally considered a high-precision method. But cutting methods have limits. You simply cannot make a cutting edge perfect enough to compete with a grinding wheel in terms of tolerance and surface finish. However, new techniques and devices are constantly developing. Therefore, we have a significantly new solution that allows CNC machine tools to match the precision of grinding methods. This solution is called diamond machining.
Why diamond machining can improve the surface quality of parts
In machining, the hardness of the cutting tool is one of the most important parameters for machining techniques, and as far as we all know, there is nothing harder than diamond. Artificial diamonds can withstand very high temperatures and cutting conditions. They are relatively cheap and their cutting edge is so fine that you can get a mirror finish with a single edge diamond cutter, and this is the only way to get such a fine surface finish without having to buy the extremely expensive grinding and grinding machines. of polishing. Diamonds can be mounted on simple CNC machine tools and you can achieve excellent results if you optimize the technological system for maximum rigidity. They can machine the hardest metals and achieve mirror-like surface finishes. Diamond turning and milling are among the most widespread technologies currently available for commercial use.
The advantages of diamond processing
Diamond processing has many advantages, the most important of which are:
- Excellent aluminum machining. Diamond tools withstand high cutting speeds and temperatures extremely well. This is why diamond techniques are often used in the mass production of aluminum parts. A single diamond insert can outlast many carbide tools when machining aluminum.
- Production of hard alloys. It is a general law that a harder material can cut a softer material. As there is nothing harder than diamonds, they are very useful for machining carbide, ceramics and other materials with high hardness parameters.
- Diamond polishing. Some diamond grinders are used to polish transparent materials such as glass, polycarbonate and PMMA. This is because the tip of the tool has very fine diamond grains.
- Durability. A diamond insert is 30-50 times more durable compared to a carbide insert.
- Surface quality. By using diamond machining for high-quality machining, you can achieve a better surface finish than any traditional tool. Diamond tools essentially add a small grinding function to machining.
Diamond Processing Techniques
Most machining processes that involve some use of diamonds are grinding and polishing processes. However, there are two processes that can be implemented on CNC equipment, which are more similar to cutting than grinding.
Single point diamond turning
SPDT is a very similar method to simple turning, but the tool used is a diamond cutter. Furthermore, the rigidity of the production system must be much greater. This means short distances between accessories, shorter tool holders and minimal vibration. SPDT is particularly useful for making optical lenses because these are mostly machined parts and it is very convenient to mount them on a lathe and use single-edge diamond inserts to obtain clear, transparent surfaces.
Single point diamond milling
Single-end diamond milling is similar to conventional milling, but the main difference is in the cutting tool and machining parameters. The tool is a milling cutter with diamond-set inserts. Mounted on a 5-axis machining center, this milling cutter is perfect for machining complex glass, PMMA and polycarbonate surfaces. An extremely fast rotating diamond cutter with minimum cutting feed and plenty of lubricant can achieve the best surface finish for automotive lamp lenses, light guides and custom window glass. However, vibrations should always be kept in mind, as they damage the entire surface quality at once. To improve part quality, some SPDM techniques involve machining in only one direction (the cutter machines one path and then returns to the starting side of the part for a passing motion, so that the cutting force is always in one direction) .
What tools are used for diamond processing?
A diamond machining tool is essentially the same as any other cutting tool, except for its use. The insert has a tungsten or carbide base material and a thin layer of diamond is visible on its tip. This layer is extremely hard and lasts up to 50 times longer compared to conventional tools. It is very sharp and provides a very clean cut, resulting in an excellent surface finish.
What materials can be cut with diamonds?
Diamond tools can machine many different materials, including ceramics, silicone, polycarbonate, plexiglass (PMMA), non-ferrous alloys such as aluminum, copper, bronze, titanium, glass, various polymers such as ABS, polyethylene, etc., as well as highly abrasive materials such as concrete, granite and stone. As you can see, the range of materials is very wide, ranging from hard and brittle materials to soft and transparent materials.
If you definitely cannot use diamond machining
A very important note is that diamond tools cannot be used to cut steel or ferrous alloys. The reason for this is that they all contain a significant amount of carbon atoms. Machining is always done at high temperatures and as both diamond and steel contain carbon, the atoms can sinter when heated. This way, the tool can adhere to the workpiece material and both components will be wasted.
Where diamond machining can bring good results
It's always best to discuss where diamond machining stands out using real case studies. Therefore, a list of examples was created
- Lamp lens prototypes. As part of CNC prototyping services, an automotive lamp lens prototype can be made using diamond cutting. The lens is too large and its geometry too complex (in fact, it had to be divided into segments and then glued together to preserve its light-guiding properties) to be ground, but a diamond milling cutter with a 5-axis CNC machine tool can Doing a great job produces a mirror-like surface of the right quality.
- guiding light. Light guides are special tubes and transparent components that can help illuminate specific locations in complex ways. They must have a very fine surface finish, maintaining the complexity of their geometry. With the best 3, 4 or even 5-axis CNC milling machines, Wayke has adopted the latest diamond machining technology with 5-axis micro-milling capability to produce various types of light guides and lenses with excellent optical quality in one standard matrix or freeform.
