Having a private house or cottage, from time to time you are faced with the need to weld something. It is expensive to pay a welder for services each time, especially since many jobs do not require special qualifications. Then there is a desire to purchase a welding machine and learn how to weld it yourself. The easiest way to learn welding is with inverter welding machines. They are controlled electronically, thanks to which they have several functions that make life much easier for a novice welder. These units allow you to get a high-quality seam even without much experience. Now it’s a small matter: you need to find out how to choose a welding inverter.
How to choose a welding inverter for your home or cottage if there are dozens of brands?
What wire should I use to weld thin metal?
They use welding wire
with a diameter of 0.8 - 1.6 mm.
Due to the fact that it has no coating, a shielding gas is supplied to the weld pool area (the area where the burning arc and molten metal
), which does not allow air oxygen to come into contact with the molten
metal
.
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Additional functions of inverter welding machines
The presence or absence of service functions is not critical, but it makes life a lot easier, especially for a beginner. Their set is usually standard:
- “Hot start” HOT START - affects the ignition of the arc. When igniting, an additional impulse is given, which makes it easy to start welding.
- “Arc Force” - ARC FORCE - when the electrode suddenly approaches the metal, the welding current automatically increases. This prevents the electrode from sticking.
- “Anti-stick” - ANTI STICK - turns off the power when the electrode gets stuck, turns it on after it comes off. A convenient function, especially relevant for novice welders.
There are some other useful features. For example, indication and automatic shutdown when overheating. This is a useful addition - it is not always possible to keep track of the time or the overheating indicator. Automatic shutdown saves you from burnout and expensive repairs.
A welding machine for manual electric arc welding allows you to weld almost all metals, except non-ferrous ones
Pay attention to the package: in addition to the welding machine, there is usually a power cable (sometimes it is removable, sometimes it is stationary), two welding cables - one with a clamp for attaching to the part, the second with an electrode holder. It is better if the cables are light, flexible and long. But such luxury is not always available. More often, working cables are about 2 meters long, which is not always convenient. When looking at the cables, pay attention to how they are terminated, soldered (preferably) or clamped/rolled.
Pay attention to the warranty period, as well as how close the nearest service center is to your home/dacha. The lack of a service network is an alarming sign. This means that even if there is a warranty breakdown, you will have to repair it yourself, for money. You won’t send your device for repairs across half of our rather large country...
Scope of application of the inverter (Device class)
Conventionally, welding inverters can be divided into household (amateur), professional (for commercial use) and industrial.
- Domestic class (hobby class) inverters – welding in domestic conditions (at the dacha, in the garage). Quality requirements are standard. The operating mode is short-term. This type of inverter welding machine is used for small volumes of work or one-time jobs. The welding current of the inverter is usually from 120 to 200A.
- Professional-grade inverters - repair of communications, pipes, installation work in housing and communal services, production and assembly of frame structures, etc. The requirements for quality and reliability are high. The operating mode is long. Operating conditions are more stringent. The welding current of the inverter is usually from 200 to 300A. Used for commercial purposes.
- Industrial-grade inverters – welding of critical metal structures during the installation of pipelines, in the construction of industrial and infrastructure facilities. Operating mode: continuous (shift work). The volume of work is large, the quality requirements are high. The welding current of the inverter is usually from 300 to 500A.
Each class corresponds to certain tasks, quality, volume and duration of welding work, and operating conditions of the inverter welding machine. Its price and reliability directly depend on the class of the device. Methods for selecting an inverter will be different depending on its class.
What determines the correct selection of the mode?
A correctly set idle mode ensures high-quality combustion of the electrode and a clearly defined droplet transfer of metal into the weld pool, forming a reliable connection with weld root penetration. The formation of spatter when igniting and breaking the arc is minimal; the surface of the parts being welded in the weld area requires almost no additional cleaning. One of the main signs of a correctly selected mode is the characteristic hissing sound when the arc burns.
Three-phase welding rectifier with no-load voltage regulation by sectioning the turns of the transformer windings.
Some models of welding inverter have an additional protective function against electric shock to the welder at increased open circuit voltage. The device automatically reduces the voltage to a safe value when an emergency occurs and restores it when it disappears. Devices with increased open circuit voltage are used when welding with electrodes with refractory coating used to work with specific alloys.
Certain inverter models are equipped with a welding oscillator circuit for better arc ignition. Such devices were used on transformer welding machines with alternating and direct current. The oscillator converts the mains supply voltage into a voltage of 2.5-3 kV with a frequency of 150-300 kHz and outputs it to the output terminals in pulses lasting several tens of milliseconds. The oscillator consists of a step-up low-frequency transformer connected to an oscillating circuit and a spark gap with tungsten contacts. At the output there are capacitors that pass high-frequency currents and limit the low-frequency current from the welding machine.
Such devices also provide protection against electric shock. The power consumption of the oscillators is 250-300 W, which slightly increases the total power consumption of the welding inverter. Oscillators can be purchased as a separate unit or made independently.
DC and AC inverters
Device and difference
Let's look at the operating principle of an AC inverter
. The conversion of mains voltage into welding voltage occurs in the following sequence. First, it is rectified and fed to a converter, which generates a high-frequency pulse sequence. The main idea is to supply a 220 volt network voltage to the step-down transformer with a frequency of not 50 Hz, but 30 - 70 kHz.
In this case, the dimensions and weight of the transformer are significantly reduced. To help you imagine this colossal difference, let's give an example: a transformer with a power of about 5000 W, converting a voltage with a frequency of 50 Hz, will weigh about 20 kilograms. A transformer of the same power, but operating at a frequency of 50 kHz, will weigh 250 grams. What will you choose?
Next, the voltage reduced to 60 volts is supplied to the welding electrode from the output of the transformer.
DC inverter
for the most part repeats the circuit of an AC inverter. But a rectifier is added at the output, which converts the output AC voltage to DC.
What to choose
We have dealt with the differences in the design of these types of power sources for welding processes. But, by and large, for most users the power supply device is of little interest. More important for him is the purpose of the various sources and their areas of application. This will ultimately be decisive in your choice.
Try to choose a welding power source that can be connected to the existing network without the risk of overloading it. In addition, the purpose of the source must correspond to the work that you intend to perform with its help. To make the right choice, familiarize yourself with the features of welding various metals.
About categories and prices
All inverter manual arc welding machines working with consumable electrodes, designated MMA, can be divided into two large groups:
- Household - for occasional use and simple work. If you are not planning a large-scale construction project, you will need the device once every two to three months to repair something, weld something, etc., then the working life of the units of this group is sufficient. These are the cheapest of the inverter welders. They cost 3-5 thousand rubles or so, produced in China.
- Professional - for long hours of daily work. This is an option for those who will use an inverter in production or are planning large-scale construction: build a dacha or house, weld a metal fence and stairs. The cost of these units is about $300-400.
There is also an intermediate class - semi-professional. In terms of characteristics and price, they are approximately in the middle. This is a good choice for those who love to make things and also love a good tool. All gradations are very arbitrary, but if you tell the seller what class you want the device to be, he will understand you and offer several options.
There are also universal or combined welding inverters. They can weld in several modes, one of which is usually manual arc welding. These units belong to the professional class and are convenient for their versatility - some can also work as a cutter, as well as cook in an environment of inert gases, which allows you to weld thin metal and stainless steel without any problems. This equipment will be useful if you also have a car - you can do repairs yourself, as well as cook all sorts of small things around the house.
