The electrolyte-plasma processing of electrically conductive materials is mainly applied in final polishing.
Electrolyte-plasma metal processing not only possesses significant advantages over the analogues, but also allows you to combine several technological processes simultaneously. The use of the electrolyte-plasma polishing method is justified in cases where it is necessary to obtain the following effects.
- final polishing of a metal with accuracy class 14 (roughness value reduction to Ra=0,01 micron)
- improvement of surface reflective properties to 70%
Metal surface cleaning
- quick surface decontamination (from 30 seconds)
- a stage in a continuous polishing process
- removal of various contaminations (paints, oils, scales, rust/oxides, abrasive impurities)
- giving hygienic properties to implants
- layerwise removal of any metal coatings
Blunting and deburring
- quick removal of burrs with length up to 3 mm (up to 30 seconds)
- weld processing
- cleaning of intricate parts
- processing of large production lots of casting/stamping lines
- fast cleaning of products from ferrous metals (up to 10 seconds)
- a stage in a continuous process of surface preparation for coating
Preparation for coating
- cleaning and defatting
- surface activation
- effective removal of defective coatings for repeated coating
- significant improvement of surface wettability
- thinning by grinding the superhard materials without heating
- finishing of cutting tools by thinning the cutting edges
final grinding of tools for surgery/microsurgery:
- removal of microburrs
- removal of microbarbs
- removal of contaminants and impurities
- grinding and polishing at one technological stage
- preparing of a backing surface for epitaxy
- reduction of "crystal imperfection" in large lots
- improvement of a single crystal silicon surface with an accuracy class 14 (roughness value reduction up to 0.01 microns)
Polishing of precious metals
- alteration of products' reflective properties: from a mirror — to mat surface
- nonwaste polishing of precious metals recovery of removed metal without lossless
- removal of incrusted elements from a surface (removal of diamond deposition)
Electrolyte-plasma processing: promising application fields
Tasks of metal products' polishing consist not only in giving products a decorative finish. By plasma processing of industrial parts, improvement of products' performance characteristics (durability, reliability, hygiene and etc.) becomes a pressing task.
Electrolyte-plasma processing application for increasing the reliability of parts
It is known that the reduction of metal mechanical properties through adsorption in the presence of stressed state (Rehbinder effect) often disables springs and other parts operating in the conditions of chemically active medium, and disables appliances, devices, valves by alternating loads. Plasma processing of such parts in neutral electrolytes allows to increase the reliability and durability of the processed products in several times.
Increasing the reliability of parts after hardening
Technology of electrolyte-plasma polishing was used to improve the reliability of large-size heat-treated springs made from stainless steel 3X13. Polishing was carried out in an ammonium sulphate solution supplemented with ammonium chloride at a voltage of 340 V. As a result, the removal of a fragile scale surface layer which was formed during quenching, and the removal of a defective metal surface layer took place. After plasma processing, the springs acquired shiny appearance, and removing an adsorption layer led to an increase in corrosion resistance of a metal and reduced the stress level in a surface layer.
Increasing the functionality of parts by increasing the extent of their streamlining
Practice has shown that electrolyte-plasma processing improves the performance of turbine blades for gas and steam power plants, and the performance of pump impellers and compressors. At the same time not only the increase of resistance to fatigue alternating loads takes place, but also the reduction of hydrodynamic resistance (increase in streamlining) in gas and liquid environments, thus resulting in less energy wasted and device performance increased.
Improving the hygienic properties of metal products by plasma processing
Positive results were achieved by the processing of structural details of the dairy industry equipment. Electrolyte-plasma polishing of large-size milk separator plates increases the operating properties and durability, and improves the equipment performance. As milk circulation in drum is improved, the quality of separation, hygiene parameters and corrosion resistance are also improved. Plasma polishing of milking unit stainless steel parts not only improves the aesthetic parameters of products, but also improves their health characteristics and leads to an increase in longevity of a unit.
Reducing the wear of friction pairs
Reducing the value of the friction pair surface roughness from 1.5 micron to 0.5 micron significantly reduces wear (up to 68%) by the same operation time. The cleaner the friction pair surface, the greater load it can bear and the greater durability it has. It was found out, that plasma polishing of inclined Archimedean screw pump parts for pumping chemically active liquid significantly affects the durability and performance of such pumps. This is due to the fact, that, after polishing a 1.5 m screw with a hard chrome coating, the wear of the external cylinder from special rubber, having a contact with a screw, significantly decreases.
Improving the metal surface layer at the expense of vacuum removal
Polishing of various kinds of molds for manufacturing plastic parts and for high-pressure casting of aluminum parts increases the molds' durability, and, moreover, improves the quality of workpiece surfaces and the surface layer structure due to the elimination of possible voids. However, the molds' relief complexity requires the further study of the way how the electrolyte flows' instability affects on the surface quality to be done.
Improvement of chromic coatings and their decoating
Widely used chromium galvanic coatings in many cases, except enhancing the operational properties of parts, must create decorative effect. However, it is not always possible. Chromium coatings, obtained from tetrachromatic electrolyte, have a range of high performance characteristics, however, due to the dark colour and surface haze, do not have a decorative effect. Plasma processing (for example, in an aqueous solution of ammonium sulfate) can significantly extend the application of chromium coatings on motorcycle and bicycle parts. Electrolyte processing of various structural elements of vehicles, such as exhaust pipe parts, trunk parts, steering wheel parts and other, showed a sharp increase in light reflectivity of polished parts, fixed some surface defects, and made it possible to remove the defective coatings for their re-application.
Cleaning surfaces of stamped products
Our technology is also efficiently applied for polishing stainless steel tapes in rolls weighing up to 1,000 kg, and for polishing band saws (for cutting wood) - after heat treatment a scale layer is formed on their surface. Plasma polishing of these products not only creates a decorative effect, but also facilitates the subsequent operation of tape forming and increases product service life period. The polished saw surface during operation experiences less friction and less heat, which leads to less tarring and simplifies the periodic cleaning of a saw surface by solvents.
The application of metal plasma processing in medicine
Enterprise, manufacturing denture products, surgical and other medical instruments, display high interest in the electrolytic-plasma polishing. Since, being created by lamp rays, the glitter from an instrument sometimes dazzles medical staff, it became required to provide surgical instruments with polished, but matte surface. That is why matting is carried out after tool polishing. Such medical products are made of stainless chromium ferritic-martensitic steels, and their polishing requires using electrolytes with composition, which is different from solutions used for polishing of austenitic non-magnetic stainless steels.
Jewellery polishing and plasma processing of nonferrous metals
Electrolyte-plasma processing is very promising in terms of improving performance properties of jewellery, watch cases, bracelets and other similar products of complex shapes, as well as in terms of surface preparation for galvanic coating. Such parts are usually made from special non-ferrous alloys: gold, copper, silver, nickel, zinc, lead, which are polished in special electrolytes based on organic compounds: thiourea, Trilon B, citric acid and others. Moreover, the polishing quality is sometimes very dependent on the small content of alloying elements in the alloy (in an amount of 1-2%). For example, alloying of brass with lead in an amount of 2.1% makes it impossible to polish watch cases from this alloy in solutions, which are used for polishing lead-free brass.