Graving is well known throughout the ages. This method is used to give a unique texture to different solid materials, but most commonly it is made on metal. Since the dawn of time with the use of graving, different items were decorated, but for a long time, the first place was for guns (firstly blade weapons, then hand weapons). For this reason, scarcely needed to be a wonder that one of the oldest and respected schools in Russia was created at the Tula armory.
If for a long time, this method was exclusively manual and demanded a supreme mastery, touched upon the art, then nowadays for graving machine-tools with numeric control is used increasingly. A combination of industrial and computing technologies lets to force the process as well as make it cheaper. Thanks to this, items decorated with graving became available for a wide range of customers that was instantly estimated by the business owners.
Nowadays machine-tools with numeric control are widely used in the production of following items:
- different advertising platforms;
- printed circuits for electronics;
- souvenir gifts;
- inner décor elements.
Such widespread of this method is because it has a wide range of undeniable advantages compared to manual graving. Among them are following:
- Temporary cost savings
Coating of an image using machine-tool takes dozens and sometimes even a hundred-fold less of times that in its turn positively reflects upon efficiency and allows choke off a net cost of output product.
- Deskilling effect
It might take near 5 years to prepare a high-quality engraver. CNC operator can master it in a matter of months.
- Wider range of used materials.
Use of machine-tools, allowing to vary at a greater range delivery, revolutions, and even cutting tools, to engrave not only metal but also many different materials that previously were “out of the engraver league”. Among them is glass, a plastic, a ceramic and even wood (despite its structural imperfection).
- Repeatability of result.
Experienced and talented as the master is, still it will be difficult to precisely reproduce the same pattern if needed (for example the front of the furniture). For CNC machine-tools there are no such a problem. The final result is a perfect appearance. Essentially you can get an infinite number of absolutely identical copies.
Variety of engraving
Nowadays this term specifies two kinds of working: mechanical (also known as milling) and laser. As a matter of fact, there is a little in common between them. Drastically differs both technological process and used equipment.
During the mechanical engraving milling machine where the cutting tool is so-called graver is used. The question is about a unique variety of small milling cutters that have a right or a conical working surface and also a cylindrical type shank.
Engravers differ from each other by the whole number of characteristics, the most important is cutting point profile and a sharpening angle. The final choice depends on the specific nature of the picture that has to be move on a solid surface, and also on the work material properties.
The majority of engravers qualify as single cut type. This means that there is no spiral flute used for cutting chip exiting. The absence of it is since such kind of equipment is used only when the operating depth in one cut is not more than 0,5 mm.
However in cases, when it is necessary to work with different types of nonferrous materials as well as with its allegations, quite often it is necessary to use dual-lead engraver, equipped with spiral flute.
Right engravers have a considerably tight range of use. As a rule, thanks to it, advertising materials, based on double-layer plastic, is made. The conical type of such a tool is notable for its generality. However using this tool one should pay attention to the sharpening angle: the choice depends on a wide variety of choices: depth of work, the hardness of raw parts, etc. Besides, it should be taken into account a wide row of additional factors, including growth in width and a spot of engraving.
Laser engraving based on the use of powerful light output supplanted the cutting tool. The density of its energy is such that on contact with the working surface, laser rays melt it off or even causes evaporation of a part of the material. In such a way, its power is the main factor affecting the work. Pulse time is also very important as well as how a power density allocates in a blot of focusing.
Another group of factors that must be taken into the consideration is physical characteristics of work material, including its thermal diffusion, ability to reflex and deflection, melting temperature, etc.
Machine tools used for application of a laser engraving, differs by multiple criteria, among them are:
- The power of a laser ray;
- stub design;
- work field dimension;
- coverage rate;
- resolution ability;
- autofocus system availability.
The modern machine tool for laser engraving allows us to create both vector-based and pixel images. Moreover, the resolution can reach 200 lines per millimeter. Besides, using such a tool allows equally effective process a flat and cam surfaces. Even more, laser engraving is suited for the creation of a picture right in the layer of the material (if it has necessary transparency). Similar flexibility allowed us to use laser engraving in different fields. First of all, it is worth mentioning the output of different souvenir and memento products. Simultaneously it is effectively used in such a conservative area as a jewelry production. Besides, through laser engraving, serial numbers are applied to the parts of different equipment. Just to name a few.
Difference between cutting and engraving
Because both processes use similar equipment they are commonly confused. As a matter of fact, cutting and engraving are quite similar. The basis is the mechanical impact on the surface, allowing to remove a part of the material from it, that way creating pimple of the required shape.
Again there is a quite significant difference. If during the cutting the item is created form the pill, engraving, on the other hand, is more of a final step of production that allows lending for the item more appealing appearance have nowhere near the influence over its functionality.
It is worth mentioning that modern cutting-engraved CNC machine tools can perform both operations, but on a condition that its design allows changing tools during the working process. Thanks to this, the ability to create and program a continuous technological cycle is available, including all necessary operations: shaping, trimcut, and applying the image. To do that one should only create a CNC code, but this is a separate and definitely feasible problem.
In summary it would be nice to pitch upon a mechanical engraving during the surface machining of the cam surface. Many believe that this task is impossible, however in fact that is not quite the case. Modern CNC machine tools allow to solve tasks of any complexity. This is thanks to use of special indicator, called probe. It measures the height of inequality, that might be on the surface of an item, spots dots and creates on its basis a unique map that will be used later on during the applying the image (for its creation interpolation algorithm is used). The perfect final result will be provided by the CNC code. Operator must firstly to estimate the best possible scan step.