Welding elective: masters share secrets of working

our website experts talk about the nuances and characteristics of manual arc welding

Welding is considered one of the most common technologies of metal compounds. Without welding does not do any construction, and welding machine is an indispensable thing in the arsenal of any handyman. Cook the gate, fence, reinforcement cage, welded loop, collect a basis for the greenhouse, dog cage, put the gate - there will always welding application.

Also welding is one of the key technological elements cold forging. But where to start welding, and most importantly - what the nuances necessary to pay attention to? In this material, we will answer the following questions:

• How to choose a welding machine
• On what current cooking
• What need accessories
• How to get high-quality welds
• How to cook different metals

welding – the necessary theoretical minimum

Learn welding needed for the most common technology - manual arc welding (MMA briefly - from the «Manual Metal Arc» English abbreviations). Moreover, it is necessary to cook, using the inverter welding machine. Why inverter? Inverter outputs a constant current with a high degree of stabilization. They are lightweight, portable (can be transferred by throwing shoulder strap). Allow to carry out all the settings "under him" even the novice welder. Inventors, in contrast to conventional welding transformer, well-maintained voltage drops, and in the process do not "squander" weak electrical networks.

There are also more advanced welding technology. For example, TIG (short for Tungsten Insert Gas). This - manual arc welding with non-consumable electrode in an inert protective gas atmosphere (argon).

And MIG-MAG (Metal Inert / Active Gas). This - manual arc welding with automatic feeding melting metal electrode (filler wire) in a protective inert / active gas.

These types of welding, because of the high prices for used equipment and tooling and requirements welder qualification, are more suitable for professional work in repair shops or enterprises. For example, for vehicle body repair, restoration work, welding of thin metal and non-ferrous metal compound with high requirements for weld quality.

To perform most of the work "in the country" best suited manual arc welding using inverter welding machine.

But despite the apparent ease (bought inverter and boil), there are many nuances that must be considered for high-quality and durable weld. We must start with the selection of the welding machine. How to do it?

On the dacha often have to deal with welding so-called "black" metals. Hence: it is first determined with the kind and thickness of metal which is supposed to boil. From this it depends on the type and diameter of the welding electrode. The diameter of the welding electrode determines the magnitude of the welding current. And then, depending on this value, select the welding inverter.

The dependence of the diameter of the electrode from the metal thickness is represented in the following table.

The thicker the metal, the greater the diameter of the electrode is taken, and the greater must be the current at the welding machine. Each electrode (depending on its diameter) is a lower limit current. If you reduce the current below this limit, the quality of the weld will not get. For clarity, the setting of the welding current is reduced in this table.

On average, depending on the proposed works, for every 1 mm diameter electrode requires a current of 25-30 amps.

Before welding should also estimate the permissible load on your electrical network.

When current of about 110A, inverter power consumption amount of 3 to 4 kW. In the conventional electric network are safety machines 16A, 3.5 kW. Accordingly, when exceeding these values, the machine will shut off the electricity. Conclusion: either do not exceed the allowable capacity or, if there is a need to cook at high currents, for example, the electrode is 5 mm so called "Five", to put a more powerful machine and increase the cross-section wiring.

For the majority of works in the construction of suitable welding machine with a maximum welding current of 140 amps (the apparatus is better to take with a small margin over current at 160-165A, rather than butt). The power of the inverter for the eyes is enough to to weld one of the most popular of the electrodes 3 mm in diameter - the so-called.. "Troika".

Another factor that affects not only the choice of the inverter, but also the convenience of working with him - it is PV (duty factor). Why is it important to pay attention to this indicator? PV is defined as the ratio of the operating time of the welding machine under a load (net welding time) to the total cycle period of welding time (welding time + pause time).

For general welding cycle is generally accepted:

• According to European standards - 5 minutes at 40 ° C.
• In Russia - 10 minutes at 20 ° C.

The optimal value is 60% MF. T. e. work 6 minutes (at 10 minute cycle) - 4 minutes rest. If the PV is less than 60%, for example, is only 15%, this means that after 1.5 minutes of work required to make rest for 8-9 minutes. This will result in downtime at work. Trying to increase the continuous operating time triggers the thermal protection device.

If px welding apparatus is 60% at maximum current, then this is more than enough to work even at an elevated temperature. In practice, the welding is not conducted continuously during the 6 minutes (electrode as off), and with intermittently required for electrode replacement, the working seam cleaning slag visual inspection welded parts.

Practice Welding

Quality Welding starts with the preparation of the workplace and the necessary tools. The best thing to do to get a welding table. On it are placed metal blank and fastening device:.. Clamps, brackets, etc., which are fixed via welded parts.

Iven

user FORUMHOUSE

From personal experience I can say that welding is sometimes very necessary to the plane, ie. E. smooth surface on which to cook something. We need to be tied to this plane. His first welding table I made of sheet metal 1250h2500h3 mm, a height of 75 cm. As used legs profiled pipe 20h40h2 mm.

As countertop may be any piece of metal. For example, take the sheet 1000h2000h4 mm - it will worktop. From another sheet smaller - 1000h2000h2 mm - make the middle shelf.

Go ahead. The first officer of any welder - it's all kinds clamps, assembly accessories and corners. Without them it is impossible to fix the parts to be welded on the table, keep the necessary tolerances and geometry of the product. Members FORUMHOUSE prefer clamp factory-built home-made made for each case of welding. This is justified for large volumes of work.

Sergeyb3

user FORUMHOUSE

Welding work is meant weld channel, angle, pipes and so on. D. In each case the clamp is unique.

Well-designed and made clamp turns into a third, a truly universal "hand" of the welder.

One of the main difficulties of any novice welder - observance of right angles at the welded parts. Cases when carefully marked and cut the workpiece (e.g., rectangular metal carcass) After welding "leads", and it turns into a parallelogram. How to avoid it?

Metal contracts when cooled. Which side of longer stitches, and where they are thicker there and lead metal. Therefore, we first need to temporarily grab welded products, rather than cooking each side completely. To fix the angles at 90 degrees instead of the metal parts can be used "gusset" or jib of the profile pipe. And jib butt welded are not, and overlap.

Another rule of thumb: if the corners and clamp to help withstand a right angle, the flatness of the products can only provide the assembly on a flat surface. Before starting the fusion, check the diagonal, if they left, appropriate adjustments are made. To control the angles can be used homemade squares.

Also when welding space, do not carry the increased load of structures - a rescue dog, skeleton under a greenhouse, etc... - do not get involved provarkoy total of all places, that to 1 mm² weld can withstand a load of about 40 kg... The fewer seams in such structures (within reason), the lower the probability that after cooling they will lead metal.

Nikola1

user FORUMHOUSE

I cooked the loop at the gate. First picked up two half wings, checked the ease of opening - open easily. Then scalded continuous loop suture, check ease of opening - open tight. What have I done wrong?

This may be due to the fact that the axis is not coincided upper and lower hinge, led metal, loop during welding overheated, lost its geometry.

svar4ik

user FORUMHOUSE

If the tack gates opened without problems and after provarkoy not - hence, the loop pulls due to the occurrence of residual welding stresses.

We struggle with this as follows:

• first loop welded to the gate, where they lie on the assembly table;
• We have a right and we catch all the details;
• We are laying the respective gaps (about 2 mm) between the loop and the pole;
• loops must be 2 on each side (and not 3 or 4), so it is easier to observe the alignment;
• to compensate for welding deformation boil the hinges to the door leaf carton and crosswise.

cast iron welding

cast iron welding is considered to be a daunting task. In most arc welding of cast iron is carried out "hot" method. For this purpose the workpiece to be welded is preheated to 600-650 ° C. In summer conditions, for sealing is not particularly critical structures may be used ie. N. "Cold" welding technique - without preliminary heating parts and using special electrodes.

Klez

user FORUMHOUSE

Cast iron can be welded to stainless steel electrodes. How much do I cooked them, not cracked nothing, flew off. "Uonkami" to "direct" the same polarity is brewed, but if rutile, the welding is bursting at the seams.

For more details about the kinds of electrodes described in the article,"Additional elements for welding".

Mictlayotl

user FORUMHOUSE

I have to weld cast iron so: We clean the welding place, carve edge and welded parts or TSCH4 or UONIIyami. By changing the polarity of the difference is not seen. The welding current is lead at a minimum, periodically cooling the welded parts to the air.

When welding iron "the cold" can not prevent overheating of the welded components. Therefore welding are short sections, 30-40 mm in length, not provarivaya entire part at a time, with careful forging hammer received stitches. metal forging removes residual stress in the metal that prevents cracks in the welded seam.

It is also important to prepare the piece prior to welding - make butchering cracks.

makar4ic

user FORUMHOUSE

I once dropped on the floor cast iron cauldron. There was a crack in the 5 cm, it seemed a pity to throw away, I decided to make it.

Validating done so:

• I found the crack tip;
• Drill crack tip drill 4 mm and butchered crack (removed chamfer angle) grinder, a disk 3 mm thick;
• CN electrode welding was conducted with a diameter of 3 mm;
•  Validating the resulting seam smoothed out with a grinder Grinding Discs.

The main problem of welding of cast iron that has a malleable cast iron, gray, high strength. Additionally, in the seam increases the brittleness of the metal. Therefore, each case requires individual approach.

If no special electrodes, it can be self-made, navivaya top electrode for welding steel (13/45 UONI ANO-4), a spiral copper wire diameter of 1.2-2 mm.

Welding galvanized metal

Timakval

user FORUMHOUSE

I decided to cook a galvanized pipe stairs. Faced with the problem - it is impossible to boil the details right the first time. Zinc shot before welding Cleaning disc. What else have secrets?

Dashnik:

user FORUMHOUSE

Galvanized pipe - is a black metal coated only with zinc. Position of welding necessary to strip a gloss completely removing the layer of zinc. The place clings "crocodile", must also be cleaned and securely fixed on the tube.

It is important to remember that in the process of welding the zinc evaporates rapidly. Escaping zinc vapors are hazardous to health. Therefore, welding galvanized products necessary to maintain, or in an area equipped with forced ventilation, or outdoors.

If the zinc can not be removed, it is necessary to carefully approach the selection of the electrodes. For better welding of carbon steels used with rutile electrodes. For example:

• ANO-4
• IR-3
• OZS-4

For welding alloy steels - the basic type electrodes coated:

• UONI-13/45
• SSSI-13/55
• DSK-50

Cook, making electrode reciprocates. This facilitates advance of zinc burning. If the zinc layer on the workpiece is more than 40 microns, to obtain a quality weld zinc layer must be completely removed.

Extension for welding inverter

It is often necessary to conduct welding work at a great distance from the power supply (for example, when welding the fence). Extension needs for 30-50 meters, or even more. What is the wire cross-section selected for the normal operation of the welding inverter? Relying on the experience members of the forum, we can conclude that we take for extension copper flexible (stranded) two-wire cable. The cross section of wire strands - 2.5 mm². If you plan to ground, then take trohzhilny wire of the same section. The load is connected to a separate circuit breaker 16 or 20A.

Timakval

I made myself Extension of wires PVA 2h2.5 mm², 40 meters long. For instant control voltage on the network and choice of welding current applied digital voltmeter. Spark held out of two such extensions of up to 70 meters. Judging by the voltmeter, voltage losses were no more than 15-17V.

Before connecting the load to the coil wire extension cord must be completely unwinding. Otherwise, due to the phenomenon of self-induction, it may overheat.

And at the end of the article - Memo for the novice welder by FORUMHOUSE:

• Start learning to cook the best performing seam on a horizontal surface, in the lower position. This allows you to quickly get the hand and learn to control the welding process.
• Before welding metal must be cleaned of dirt, rust, paint, or not achieve high-quality weld.
• Electrodes keep dry. Composition of the core should be similar to the composition of the weld metal.
• The slope of the electrode during welding was held at about 45 degrees, the distance from the electrode to the metal - 2-3 mm.
• Lead electrode may be forward and backward angle angle. If the electrode lead angle ago, the penetration will be deeper. If the forward angle, the penetration will be lower, and wider than the seam.

Butt welding connection. If the thickness of metal at the abutting preforms greater than 5 mm, the workpieces before welding should be removed from the chamfer. At butt welded parts stand a gap of 1-2 mm. First, we catch the workpiece, using jigs, and then boil them along the entire length.

Angular / T-weld joint. The weld has the form of a triangle. For quality weld, its thickness must be equal to the thickness of the base metal. If a single pass can not boil necessary seam thickness (thicker metal) make several passes.

Vertical welding seam. In this type of compound exhibited lower current (adjusted individually) than, for example, by welding horizontally. Otherwise, the metal will overheat and will flow, and the high-quality seam will not work. Electrode lead better upwards t. K. In this case, the molten metal is held already solidified metal from below.

Welding on the forward and reverse polarity. Direct polarity: to "+" Inverter connected mass. Derzhak connected to "-".

Reverse polarity: the mass is connected to the "-". Derzhak - to "+".

When welding at a reverse polarity at the electrode will stand out more heat and heating of the workpiece is reduced. This means that in the normal polarity is better to cook a thick metal. And vice versa - reverse polarity best suited for welding thin metal.

How to choose a welding machineYou can learn from this thread. Which electrodes are not worth buyingIs told here. Understand, how to buy a mask for weldingYou can read this topic. And yet - welding life hacking for newbies.

By what criteria to select the welding machine, explains in this video. all the benefits of working with welding inverter you can learn from this a movie.

Subscribe to the channel! Share on social networks! Join FORUMHOUSE!