Modification of various designs, parts and functional elements is often carried out by completely changing the structure of materials. For this, means of deep thermal, plasma and chemical treatment are used. But there is a wide segment of methods for changing operational properties due to external coatings. Such methods include vacuum metallization, due to which it is possible to improve decorative, conductive, reflective and other characteristics of materials.
Technology Overview
The essence of the method is the deposition of metal particles on a work surface. The process of forming a new coating occurs due to the evaporation of donor metals in a vacuum. The technological cycle involves the implementation of several stages of structural change of the target base and coating elements. In particular, the processes of evaporation, condensation, absorption and crystallization are distinguished. The key procedure can be called the interaction of metal particles with the surface in a special gas environment. At this stage, vacuum metallization technology provides diffusion and particle attachment processes to the structure of the workpiece. Depending on the spraying conditions, the characteristics of the coating and the type of workpiece, various effects can be obtained at the output. Modern technical means allow not only to improve the individual performance of the product, but also with high accuracy to differentiate the surface properties in individual areas.
Applied Equipment
There are three main groups of machines used for this technology. This equipment is continuous, semi-continuous and batch. Accordingly, they differ in terms of the general organization of the processing process. Aggregates with continuous operation are often used in serial production where in-line vacuum metallization is required. Equipment of this type can be single- and multi-chamber. In the first case, the units focus on the implementation of metallization directly. But multi-chamber models also provide for the possibility of implementing additional procedures - initial product preparation, control, heat treatment, etc. This approach allows us to optimize the manufacturing process. Machines for batch and semi-continuous metallization, as a rule, have one main chamber. It is due to the irregularity of production that they are used for a specific procedure, and preparatory operations and the same quality control are carried out in a separate order - sometimes in manual mode without automated lines. Now it is worthwhile to consider in more detail what nodes such units consist of.
The device for metallization
In addition to the main chamber, where the spraying processes take place, the equipment includes many auxiliary systems and functional components. First of all, it is worth highlighting directly the sources of sprayed material, the communications of which are connected with the gas distribution complex. So that the vacuum metallization plant can provide the parameters necessary for a specific processing task, the supplying spraying channels with regulators allow, in particular, to adjust the temperature level, flow direction velocity and volumes. In particular, this infrastructure is formed by leakages, pumps, valves, flange elements and other fittings.
In modern installations, sensors connected to a microprocessor unit are used for the same regulation of operating parameters. Given the given requirements and fixing the current actual values, the equipment without operator intervention can adjust the processing modes. Also, to facilitate operation processes, the equipment is supplemented by in-chamber cleaning and calibration systems. Thanks to this equipment, the repair of the vacuum metallization of the machine is simplified, since continuous and timely cleaning minimizes the risks of overloading of air motors, manipulators and communication circuits. The latter are considered at all as a consumable part, the replacement of which in continuous units is carried out on a regular maintenance basis.
Target materials for metallization
First of all, metal billets are subjected to the procedure, which can be made including from special alloys. Additional coating is required to provide an anti-corrosion layer, to improve the quality of electrical wiring or to change the decorative properties. In recent years, vacuum metallization is increasingly used in relation to polymer products. This process has its own specificity, due to the characteristics of the structure of objects of this kind. Less commonly, technology is applied to products that have low hardness values. This applies to wood and some synthetic materials.
Features of plating plastics
Spraying on the surface of plastic parts can also change its electrical, physical and chemical properties. Often metallization is also used as a means of improving the optical qualities of such blanks. The main problem in performing such operations is the process of intense thermal evaporation, which inevitably exerts pressure on the flows of particles spraying the surface of the element. Therefore, special modes of regulation of the diffusion of the main material and the spent mass are required.
Vacuum metallization of plastics, which have a rigid structure, has its own specifics. In this case, the presence of protective and primer varnishes will matter. To maintain a sufficient level of adhesion while overcoming the barriers of these films, it may be necessary to increase the energy of thermal action. But here again the problem arises with the risks of destruction of the plastic structure under the influence of heat fluxes. As a result, in order to relieve excessive stress in the working medium, modifying components such as plasticizers and solvents are introduced to keep the shape of the workpiece in optimal condition, regardless of the temperature regime.
Features of the processing of film materials
Manufacturing technologies for packaging materials include the use of metallization for PET films. This process provides aluminization of the surface, due to which the workpiece is endowed with higher strength and resistance to external influences. Depending on the processing parameters and the final coating requirements, different methods of heat removal can be used. Since the film is temperature sensitive, an additional deposition procedure is introduced. As in the case of plastics, it allows you to adjust the thermal balance, while maintaining the optimal environment for the workpiece. The thickness of the films, which are processed by the method of vacuum roll metallization, can be from 3 to 50 microns. Technologies are gradually being introduced that provide similar coatings on the surfaces of materials with a thickness of 0.9 microns, but for the most part this is only experimental practice.
Reflector Metallization
This is also a separate area of metallization use. The target in this case are car headlights. Their design provides for the presence of reflectors, which over time lose their operational qualities - they grow dull, rust and, as a result, become unusable. In addition, even a new headlamp may receive accidental damage, which will require its repair and restoration. It is precisely for this task that the vacuum metallization of reflectors is oriented, providing wear-resistant spraying on a mirror surface. Filling the external structure with metallized particles eliminates minor defects on the one hand, and acts as a protective coating on the other, preventing possible damage in the future.
Organization of the process at home
Without special equipment, surface chemical coating technology can be applied, but vacuum treatment will require an appropriate chamber anyway. At the first stage, the workpiece itself is prepared - it should be cleaned, degreased and, if necessary, performed grinding. Next, the object is placed in a vacuum metallization chamber. With your own hands, you can also perform special equipment on rails from profile elements. This will be a convenient way to load and unload material if processing is planned on a regular basis. As a source of metallization particles, so-called ingots are used - from aluminum, brass, copper, etc. After that, the camera is tuned to the optimal processing mode and the spraying process begins. The finished product immediately after metallization can be manually coated with auxiliary protective coatings based on varnishes.
Positive feedback on technology
The method has many positive qualities that are noted by users of finished products in different areas. In particular, the high protective properties of the coating, which prevents the processes of corrosion and mechanical destruction of the substrate, are indicated. The ordinary consumers of products that underwent vacuum metallization in order to improve or change decorative qualities also respond positively. Experts also emphasize the environmental safety of technology.
Negative reviews
The disadvantages of this method of processing products include the complexity of the technical organization of the process and high requirements for preparatory activities for the procurement. And this, not to mention the use of high-tech equipment. Only with its help you can get high-quality spraying. Cost is also included in the list of disadvantages of vacuum metallization. The processing price of one item can be 5-10 thousand rubles. depending on the area of the target area and the thickness of the coating. Another thing is that serial metallization reduces the cost of a single product.
Finally
Changing the technical, physical and decorative properties of certain materials expands the possibilities of their further application. The development of the vacuum metallization method has led to the emergence of special areas of processing with a focus on specific performance. Technologists are also working to simplify the spraying process itself, which already manifests itself in the form of reducing the dimensions of equipment and shortening post-processing procedures. As for the application of the technique at home, this is the most problematic way of covering, since it requires the contractor to have special skills, not to mention technical means. On the other hand, more affordable spraying methods do not allow obtaining coatings of the same quality - whether it be a protective layer or decorative stylization.