Metal arc welding with covered electrodes:
- 111 welding,
- MMA welding,
- SMAV welding.
Welding with covered electrodes became widespread in the early 20th century. Originally, fusible electrodes were used, which consisted of a steel wire shielded by a mixture of calcium and clay, or silicates or carbonates. Despite the fact that it is the oldest welding technique currently available on the market, it continues to be very popular with a wide range of enthusiasts.
What determines the universality of the MMA method?
First and foremost, versatility. Welding with covered electrodes is generally considered to be the most versatile welding technique. Its advantages are, above all, its versatility, the possibility of working in any position and in field conditions, the relatively low cost of purchasing welding equipment, and the fact that MMA equipment is simple to operate, so many years' experience is not a requirement to start welding with the 111 method.
Arc welding techniques
We distinguish between covered electrode welding by welding position, such as:
- (PA) - sub-field (the easiest of the positions);
- (PB) - collateral;
- (PC) - wall-mounted;
- (PD) - eaves;
- (EP) - ceiling;
- (PF type) - vertical from bottom to top;
- (PH type) - vertical from bottom to top;
- (PG type) - vertical from top to bottom;
- (PJ type) - vertical from top to bottom.
During the commissioned work, it is very important to adhere to the technical symbols for the weld markings as, firstly, this will make welding easier and, secondly, it will result in a high-quality end product.
How to choose the best welding machine?
The main thing we should pay attention to when choosing a welding machine is the specific amperage, i.e. the maximum welding current available to the model in question. The power is a determinant of the thickness of the material to be processed, as well as the type of electrodes optimal for the welding process. In addition to this, the duty cycle is also an important consideration in choosing a welding machine, telling us how long we can weld without taking breaks. Inverter welding machines have various functions that optimise the work, such as:
- Hot StartThis is a function that makes it considerably easier for us to start work. While normally, after the arc is struck, the welding current is temporarily increased and then the parameter returns to the set value, thanks to the Hot Start the melt will be properly shaped right from the start.
- Anti Stick, an anti-short-circuit function; when the electrode sticks to the material, the current will automatically be reduced to the lowest value, making it easier to detach the electrode from the material without the risk of distortion.
- Arc Force, a function that stabilises the arc when the arc length changes and the current increases during shortening.
Basic parameters of covered electrode welding:
- arc voltage;
- arc length;
- current intensity,
- diameter and position of the electrode relative to the joint;
- welding speed.
Strengths and weaknesses of covered electrode welding
|Very thick as well as relatively thin (even from 1.5 mm) parts can be joined;
Possibility of working in any conceivable position and under difficult weather or spatial conditions;
A very versatile method that allows different grades of steel to be joined;
Use of relatively easy-to-use and low-cost welding machines (very light and mobile);
Fairly high weld quality (with skilled welding) and considerable strength.
|High sensitivity to moisture due to hygroscopic properties (especially when working with alkaline lagged electrodes);
Not very high working capacity (less than 5 kg of binder/h);
Time-consuming work, which has to be interrupted quite often to install a fresh electrode and remove accumulating slag;
High vapour emissions
Low welding speed.
Questions and Answers
Which welding machine to choose?
Recommended welders available on the welding market include the Magnum Snake 200PS, Magnum Viper 205A, Sherman ARC 200 C and Dedra Desti 203P.
What are the disadvantages of welding with covered electrodes?
The negative aspects of SMAV welding can include: slow welding speed, time-consuming work, high volumes of fumes and vapours emitted and high sensitivity to moisture.