To achieve the shiny metal surface, not necessarily material varnish.One can resort to polishing metal, which is used as a decorative appearance workpiece after coating or during processing of the product.In one case, enough sawdust metal file, in another - the surface should be brought to light by electropolishing.All of these manipulations can be done independently at home.
- Purpose polishing
- Benefits metal electropolishing Electropolishing
- with circles
- Polishing wheels
- Electrochemical polishing
- Micro- and macro-polishing
- electrolytes and solvents
- Baths for electropolishing
polishing of metal parts are initially smooth, shiny surface.But it eventually fades and operation scratched.For the hidden details, of course, appearance is not a big deal, but when the metal parts are placed in plain sight, then they should look properly.That is how it will look glossy surface, after you have spent po
Polishing metal is also intended to improve the smoothness and cleanliness of the surface of metal parts and eliminate traces of past treatments - unevenness, scratches and dents.Polishing parts is carried out with emery wheels, grinding powder, a special lime paste, polishing solution or electrolyte.
trim surfaces of metal parts, not only to give them an attractive appearance, but also to protect against rust, corrosion by alkalis and acids.Good polishing susceptible metals such as brass, bronze and copper.Stainless steel gloss finish will not work, but give it a matt gloss - easily.
Based on the foregoing, it can be argued that the polish comes in two types - preliminary and final.Pre-polished metal used for mechanical removal of irregularities, and the final - to create a perfectly smooth and glossy finish state metal surfaces and protect it from environmental factors.
separate branch polishing is electropolished steel.The procedure has a positive effect on the physical and chemical, electrical and magnetic properties of metal surfaces, facilitating deep drawing and stamping of certain metals, and also increases the level of corrosion resistance.This explains the widespread use of electric polishing of metals in laboratory studies and in industry.
Electropolishing has a long list of advantages over mechanical polishing with respect to simplicity, flexibility and speed.For example, stainless steel mechanical polishing techniques is difficult because it is a long and expensive operation.Electropolishing of stainless steel is going for a few minutes, the procedure is cheap and allows you to obtain a surface with better reflectivity.
Electropolishing reduces processing time in comparison with the product of mechanical technology is almost 5 times, although it improves the surface smoothness of only 1 - 2 class.In the mechanical polishing can achieve higher surface finish, but the process of electropolishing indispensable when handling complex product profile with internal cavities, diesel fuel system components and springs which are inconvenient and complicated in shape for machining.
Electropolishing is the best method of surface preparation before plating because it shows a high adhesive strength of the protective coating with a polished base.This technique is used to improve the machining of parts for sliding materials that come into contact with the polished surface, for example, the yarn feeders in textile machines, for sharpening the cutting tool in the production of measuring tools.
Electropolishing but eliminate time-consuming and hazardous mechanical grinding and polishing operations, eliminates difficulties which are caused by the hardness or toughness of polished products, and the operation of degreasing products, which are essential in mechanical polishing.High performance procedure is not dependent on the hardness of the metal.Electrolytic polishing equally well to aluminum and soft red copper, hardened steel and cemented carbide tools.
downside is the increased power consumption.Some disadvantages are associated with the fact that almost every metal requires its electrolyte composition.The duration of the process, regardless of the current density is 20 - 30 minutes.Typically, when such manipulations removed the metal layer that has a thickness of 2 - 5 microns.
Electro using circles
for grinding and polishing work made using special polishing machines with the shaft of the electric motor, which is extended on both sides to secure the polishing tool.These machines have a control that lets you adjust the speed of the brushes and community significantly.
products and details, which can be electropolished, should not be too deep scratches and scrapes because their output using this technique is extremely difficult and often nearly impossible.Remember, the softer metal, which is subject to polishing, the easier it is to take off his coat, but more difficult to achieve a uniform surface.Polishing taken hold solid metal with high specific pressure on the surface.
as polishing wheels used felt discs, leather, wool and cotton fabrics.To take mechanical polishing brushes made of bristles or brass.For further use such a polishing mixture or slurry.Typically, polishing metal must be two rounds - a felt disc for coarse cloth for polishing and fine.
Felt polishing discs for electropolishing of stainless steel or aluminum are made up of several layers of felt, which have a thickness of up to 4 centimeters, fastened together with glue.The layers of felt in the manufacture of sanding disc tightly pressed against each other and put under the press.
Once they are glued and the adhesive has dried, taken in the middle of the circle prodelyvat hole.Thereafter circle Electrosharpener fixed on the shaft by means of two nuts and washers.This grinding wheel is also easily fixed in the drill chuck or electric drill.
Cloth disc can be cut from cotton, cloth, calico, or fustian, then the layers are sewn together in a disc multiple layers.Crosslinked circles need to glue together, leaving the edge of 3-4 cm.The disc cartridge is pushed onto the drilling device in a manner like a felt disc was attached.
Press the metal surface of a spinning disc to start the electropolishing at home.Working surface during polishing wheels to periodically lubricate the special blend of polishing, and to a certain dosage.
Remember that the circle is "tig" item with an excess of the mixture, with its lack of range of wear quickly, and the metal will not get the desired brightness.Therefore, lubrication-free polishing wheels polishing mixture leave about a quarter of the working surface.
Resilient wheels must turn and cling to detail with a certain force, the very polished item must in relation to the range to move freely.Electropolishing using mixtures can be carried out end or periphery of the circle.Moving products made directly special tool or by hand.
Speed range for polishing machines is 2000-2800 rpm.Polishing machines with high-speed laps used when required significant processing quality.In order to achieve high gloss aluminum electropolishing is carried out at lower frequencies.
If the product to be exposed to polishing, have a simple shape - flat or square, you can process them on the universal electric machine that is running buff straight profile.To perform rough machining are hard and tight circles to fine - soft.
Solid circles intensely polished, but quickly salted, particularly in the processing of soft base and precious metal or an alloy.Soft elastic in the following preliminary operations are ineffective and can deform and flatten while being pressed strongly against the workpiece.
Periodically take away from the metal part of the drive to assess the quality produced polishing.When the appearance of the metal you will be satisfied, and the item will be perfectly smooth, shiny and smooth, you can stop the process.Thereafter, repeat the procedure on the rag drive which is capable to remove residues from the metal surface polishing agent.
Electrochemical polishing is a process which is characterized by a chemical reaction between the workpiece and the electrolyte by an electric current.This procedure reduces the occurrence of roughness and gloss.
micro- and macro-polishing
For electrochemical polishing of the workpiece, which anode is connected to a plus power source, were placed in a bath of electrolyte.The second electrode - copper cathodes.Due to the special composition of the electrolyte for electropolishing and to create conditions (film formation of high resistance) fixed uneven dissolution.
First will dissolve the most exposed points, thereby reducing the surface roughness, and then disappear completely, and the surface of the parts will be shiny and smooth.Selective dissolution of these elements takes place at the same time sticking to give shine.
process to remove large protrusions called macro-polishing, and the dissolution of small irregularities - micro-polishing.If these two processes occur simultaneously, the metal surface will acquire smoothness and gloss.There are times when these qualities are unrelated to each other, that is achieved without smoothing shine and vice versa.
In the process of electrochemical polishing on the surface of the anode or hydroxy-formed oxide film.If it covers the surface uniformly, the conditions that are necessary for the micro-polishing.The outer part of this film is continuously dissolved in the electrolyte.
Therefore for successful procedures required conditions in which there is an equilibrium between the rates of formation of the oxide film and its chemical solution to the film thickness was changed.The presence of the film involves the possibility of making the exchange of electrons between the polished part and the electrolyte ions without the risk of destroying the aggressive electrolyte metal.
macro-polishing process depends on the presence of the anode film, which is thicker in the recesses and protrusions on the fine.This film facilitates the rapid dissolution of the projections, so that they create a high current density and resistivity over them will be lower than over the various grooves.
The effectiveness of the anode of the film increases with its internal resistance.Electrolytes which contain complex salts or salts slabodissotsiiruyuschih acids capable of improving the anode resistance film.
electrolytes and solvents
on during the process of electro-apart anode film have an effect, and other factors such as the movement of the anode, which is the mechanical mixing of the electrolyte.Electrolytes a composition can function normally only when heated.The general rule lies in the following: an increase in temperature is able to reduce the rate of neutralization and increase the rate of dissolution of the film.
important factors that affect the procedures for electrochemical polishing, perform voltage and current density.Depending on the treated metal and the electrolyte composition made to conduct polishing under conditions that correspond to different parts of the curve.For example, the polishing of the copper in the phosphoric acid is conducted at a current limit mode without the formation of oxygen.
The most widely used electrolytes are made on the basis of sulfuric, chromic and phosphoric acid.To increase the viscosity of the solution is introduced into it methylcellulose and glycerol.As inhibitors of etching adopted to add electrolyte and triethanolamine sulfoureid.
for cleaning products electropolishing after the procedure is common to use solvents that are made on the basis of chlorinated hydrocarbons - trichlorethylene and perchlorethylene.
These substances are non-combustible, their ability to remove greasy soils and paste products with higher than that of ethanol or gasoline.Products need to download the bath, a soft hair brush handle, overload the vessel with hot ammonia which removes residual paste and fat.
as alkaline detergent used lye (potassium hydroxide, sodium hydroxide), potash, soda and ammonia.In recent years, more and more popular use detergent compositions based on the kinds of surfactants.With the success of the bath can be used, in which the cleaning process is carried out in the ultrasound field, which greatly increases the performance and quality of the surface cleaning.
electropolishing for the electrochemical polishing decided to make a special bath.Remember, they are very dangerous for health, especially at high temperatures.For the polishing of ferrous and non-ferrous metals, in particular carbon steel, the most popular is the universal electrolyte.
Its composition is as follows: Orthophosphoric acid (65%), sulfuric acid (15%), chromic anhydride (6%), water (14%).Mode of operation: the temperature is about 70-90 degrees Celsius, the voltage of 6-8 V, the anodic current density of about 40-80 A / dm2, the shutter 5-10 minutes.
electropolished stainless steel - and CrNi hromonikelmolibdenovoy taken hold in the following solution: phosphoric acid (65%), sulfuric acid (15%), chromic anhydride (6%), glycerol (12%), water (13%).
mode of this solution: the temperature of about 45-70 degrees Celsius, the anode current density is close to 6.7 A / dm 2, the voltage level of 4.5-6 V. Maintain the item in a bath for 30 minutes 4: enough for presswork4-6 minutes for the parts after heat treatment or welding 10-12 minutes to cast otpeskostruennyh steel products - half an hour.
For polishing products made of aluminum or an alloy used a well-established structure of the electrolyte: phosphoric acid (65-70%), chromic anhydride (8-10%), water (20-27%).Operating mode: the temperature at 70-80 degrees, freshly prepared solution must achieve a current density of 10-30 A / dm 2, in a saturated salt solution - 10-20 A / dm2.Withstand item 5 minutes or more.For electropolishing
parts of duralumin need such solution composition: sulfuric acid (40%), phosphoric acid (45%), chromic anhydride (3%), water (11%).Mode of operation: The temperature in the range of 60-80 degrees Celsius, the anodic current density at the level of 30-40 A / dm 2, the voltage level of 15-18 V, an excerpt - a couple of minutes.