Surfacing of metal: types, technology

Those who are engaged in the operation of various mechanisms, sometimes encounter the need to perform a surfacing on the surface of the part in a particular place. Broken fasteners, worn out during the operation of the part, partially or completely, the edge, worn out sleeve. Each of these cases involves the restoration of a part using a new hardened metal layer to weld onto a worn area. Such processing allows not only to perform restoration, but also to give details new, more valuable properties. For example, by performing a hardfacing using a carbide layer on the base of a low-carbon steel part, it is possible to obtain a part with increased wear resistance or other operational properties.

This simplest, but at the same time, effective method is suitable not only for restoring the fitness (working capacity) of metal parts. With the help of surfacing the metal with an electrode, it is possible to modify the sample, giving it specific features, enhancing the properties of the surface layer, working on strength and wear resistance.

Features and terminology: the basic concept of "surfacing"

What is the secret of this technology, what features does it have and how to implement it in everyday life, we will try to understand together. The reader is hardly interested in industrial technologies, especially with the use of robotic machines. Therefore further we will understand with features of surfacing of metal manually, that is by means of electrodes for welding.

In everyday life, under the concept of metal, a person can have in view of an alloy, for example, steel. If these names can be verbally generalized, then the use of technologies for a particular metal / alloy and the working parts differ.

It is simply unrealistic to consider the topic in detail because of the volume of the material offered, therefore, when starting to familiarize yourself with this process, first specify the details concerning the work with the metal of the chosen type. All that we offer you in the article is recommendations for surfacing.

In general, surfacing of metal has similar features to welding, it does not hurt to get acquainted with the latest technologies applied to the processing of alloys and metals: copper, aluminum, cast iron, stainless steel and others in terms of the specifics of the proposed work.

By surfacing is meant the joining of metals of a heterogeneous character by applying one molten metal to the surface of the other. The filler material is the one applied, the main one being surface treated by the method of welding.

Technological features of the procedure

The mutual penetration of glowing metals into each other occurs at the level of molecules.

To do this, the surface layer is heated to a degree of melting at a shallow depth, and the additive to a liquid state.

Advantages of welding the metal by surfacing include the ability to adjust the thickness of the layer and apply an additive to the sample, regardless of its shape.

The name of the alloy from English comes from the word mixing and in terminology is used as a homogeneous compound. The main characteristics of the alloy include increased reliability, because with the help of mechanical effects, it is impossible to break metals to the initial state.

Basic rules of surfacing

In this work, the fundamental rules of surfacing of metal are distinguished.

The depth of melt of the top layer of the main part should be minimal. This effect can be achieved by an elementary tilt of the electrode, which is made in the direction opposite to the direction of its movement.

With minimal mixing of metals of a heterogeneous nature, the residual stress is reduced, which eliminates the risk of deformation of parts in certain areas.

During the procedure, monitor the amount of additive, because its excess can lead to complications in the future work, which is accompanied by even greater labor and implementation time.

Surfacing technology with electrodes

Before starting to work, pre-clean the metal, which consists of two stages: stripping and degreasing.

Surfacing metal with an electrode is the most common method of obtaining a homogeneous layer. The simplicity of the technology makes it the main application in both production and home environments.

The electrode with a special coating is selected based on the pursued treatment objectives. This choice also depends on the type of metal from which the substrate is smelted. Depending on the brand of electrode, the obtained layer acquires the necessary characteristics.

Connection scheme - direct or reverse. The second option is used more often, because it is convenient. To carry out the work, you need a constant voltage "+" on the coated electrode.

Features of the procedure

The shape features and the thickness of the layer depend on the cross section of the electrode. To ensure high-quality surfacing, the voltage and amperage of the arc must be minimized, but this requires correct coordination. Practical skills are acquired with experience and in the future do not cause working difficulties.

Surfacing: small secrets

When the voltage rises, the scar begins to increase not in volume, but in width, which increases the length of the arc. Each of the types of electrodes has its own peculiarities of use. For example, do you know how important it is to preheat the substrate? When working with lowallergenic steel, this condition is not always necessary. Which mode is best to cool the part? And what level of current should I set? All technological details of surfacing are noted in the accompanying documentation for the type of electrodes you have chosen. With regard to the quality of surfacing, it increases with the temperature of heating, the value of which for all types of electrodes is approximately the same and is + 300 ° C. Carrying out work related to surfacing the house, you will have to acquire a thermo-furnace, for example, an electrical chamber.

Features of plasma surfacing of metal

Strong practically unbroken under any force of pressure nodes are produced using plasma surfacing. With the help of such processing, each of the products that have passed through the procedure acquires the necessary dielectric, thermal, physical and other properties. In other words, the products are hardened in the process of surfacing. Cutting of metal, as well as its processing is performed using a special cutter with a hot plasma flow.

Products made using overlay welding plasma arc, are characterized by wear resistance, heat resistance, acid resistance, etc.

In comparison with surfacing with an electrode, plasma surfacing has several advantages, but it can be used only in production conditions. To mount a special installation and purchase equipment for working with such units at home is at least an expensive pleasure. So once again think whether there is a need to purchase a tool for rare use at home or there is a place for applying an old good electrode, which will be more profitable financially, but not the worst option.

Surfacing seams and their types

To get a high-quality coating of the base part with another alloy, start laying the next scar on the opposite side of the product. In this case, overlaying layers are superimposed not sequentially (one after another), but arbitrarily - then on one, then on another site. The use of such a technology for surfacing the metal will help avoid partial deformation of the substrate during overheating.

Surfacing seams, depending on technology and purpose, are divided into several categories.

Depending on the type of workpiece used, one of the schemes of the arrangement of scars is used:

• A helical line formed from rollers of a homogeneous alloy;
• A series of closed circles, created from welded scars;
• The metal streaks along the generatrix.

With the first of the methods most often work when carrying out work in conditions of mechanized production. Therefore, we will not go into this process. With the rest of the techniques of processing of flat and three-dimensional parts, let's take a closer look, having studied their specifics and scope.

Seams for flat surfaces

When processing planes, one of the technologies for applying a homogeneous layer is used: narrow or wide scars, a continuous layer. We will become acquainted with these types of surfacing of metal.

Narrow hatching

Method of application - narrow scars. They are laid with overlapping about 1/3 of the entire length of the seam.

Application of wide rollers

The processing procedure with the help of wide rollers consists in a smooth perpendicular movement of the electrode relative to the axis of surfacing. At the same time, oscillatory motions are performed, the configuration of which is selected based on the volumes of the main part.

Combined surfacing

The use of combined treatment is appropriate in those cases where it is required to obtain a continuous homogeneous layer. For this, surfacing is produced by narrow scars, which are located at a distance slightly less than their width. After the application of the first layer, the base is cleaned, getting rid of the slag, and another layer of molten metal is applied to the remaining voids.

For cylindrical surfaces

In addition to the above, another popular welding technique is used when using electrodes - in a protected gas environment. The principle of processing is not difficult. In fact, it is in another - the purchase of a cylinder filled with a special gas mixture: argon, helium, any other, depending on the type of filler material used for surfacing. This option is best for a small home workshop.

Although buying a gas cylinder for working with metals at home is unlikely to be appropriate. It is easier to perform welding with electrodes by means of electrodes, as we saw in the article.

I would like to hope that here you have found all the answers to the questions of interest, figured out the concept of the technological process and clarified for yourself how to properly weld surfacing at home.