It is well known that calcining electrodes in a furnace is an important procedure. It must be done before welding.
If you refuse preliminary heat treatment, you may encounter problems during the work process, such as poor ignition and sticking of the rod, poor quality and unreliability of the seam, and an unsatisfactory appearance of the finished product.
The above are just the most common problems that are often encountered; in fact, there are even more of them.
Calcination of electrodes before welding: purpose
Calcination of welding electrodes is one of the stages of heat treatment. The purpose of this process is to reduce the liquid content of the coating materials. The presence of moisture can negatively affect the work: poor ignition of the electrode, its sticking, and shedding of the layer.
However, there are other reasons: long-term storage, unpacking a new pack (the technician most often does not know under what conditions the electrodes were kept), and during operation signs of the presence of liquid are detected. The calcination procedure helps to achieve better results and has a positive effect on the quality of the finished product.
Welding slag on a seam made with a raw electrode
Can we measure it?
So, the shelf life of welding electrodes – can we measure it? Storage conditions directly affect the shelf life of electrodes. Welding materials, like goods used in everyday life, have a shelf life.
If all the above parameters are observed, the rods can be stored for an almost unlimited period of time. All features of contents and packaging must be observed in accordance with the standards of GOST 9467-75 and GOST 9466-75. This rule applies both to manufacturers who store rods in a warehouse before shipping to the customer, and to end users who hold welding consumables immediately before use.
Calcination requirements
The main indicators during calcination are the following parameters: the need for a drying procedure, its modes and the number of calcinations.
Lack of heat treatment can lead to increased consumption of materials, poor-quality seams, loss of time, and sometimes to redoing the entire job. Therefore, if there is uncertainty about the conditions and duration of storage of the electrodes or there is moisture in the coating, then calcination must be carried out .
- The optimal drying mode for materials is indicated on the packaging or in the technical documentation.
- The electrodes are factory calcined, so they can be processed again no more than three times.
More details about the calcination process in a separate article.
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Features of calcination at home
So, from all of the above it is clear that calcination and drying of electrodes is an important stage in preparation for welding work. The quality of the resulting connection depends on the correctness of this procedure.
Heat treatment parameters are determined by the type of rods. This information is usually indicated on the packaging.
Electrode calcination temperature.
Amateurs, of course, often do not have professional equipment for calcination. For example, when performing any work in the country, the need to purchase special devices is simply unprofitable. You can do this operation yourself.
The material can be processed in the oven. It is necessary to set the temperature from 190 to 210 degrees and hold the rods for 30 minutes. Some welders recommend using higher temperatures, up to 300 degrees.
Many are also faced with the question of how to dry welding electrodes at home? An excellent option for performing such a procedure would be to use a boiler. The rods just need to be left in it for one to two months, after which they should be wrapped in cling film.
The described option is suitable for drying in the winter, and in the spring you can safely start working.
In fact, in the process of heat treatment at home, you can use any heating device or any homemade electric dryer.
It is also worth considering that if the rod has been severely damaged by moisture, then under no circumstances should it be immediately exposed to high temperatures. Before calcination, it must be kept at 100°C for at least two hours, after which the temperature must be increased.
This is due to the fact that with rapid heating, the moisture will evaporate and leave a coating of salt and lime on the electrodes.
Electrode calcination log
The calcination log is an official regulatory document that records all processes of preparing welding materials.
The information is presented in the form of a table, which includes several sections: calcination date; serial number of calcination; type of electrodes; mass of calcined material, kg; calcination temperature; time of processing; responsible for calcination; person performing control.
The journal is kept in one copy, laced, numbered, sealed and certified by the signature of the person responsible for office work at the facility.
The magazine can be purchased at a printing house for a fee or you can view a sample document on the Internet.
Bottom line
Proper preparation for welding work is the key to its reliable and high-quality performance. This also applies to electrodes, which must be dried and calcined, especially when welding critical metal structures or obtaining sealed seams.
At the same time, do not forget how many times you can heat treat them, because it is not recommended to calcinate the electrodes more than twice. This is due to the fact that the electrode coating may be destroyed and the rods will become unusable.
https://youtu.be/neMXjs3dtng
Equipment for calcining electrodes
There are several types of calcination equipment.
Furnaces
1. A stationary furnace is a metal cabinet with special trays for electrodes. To maintain the required temperature, the walls are lined with heat-insulating materials. It is equipped with a thermostat with a temperature limit from 60 to 500 degrees. This guarantees uniform heating and maintaining the set temperature throughout the processing of materials.
Examples of budget models of calcination furnaces: EPSE-10/400 “NOVEL”, PSPE-40/400 ZSO “Ten and K plus”.
Video
A small video that clearly demonstrates the PSPE-40/400 oven.
More about stoves on this page.
Pencil cases
2. Welding work is often carried out outdoors. To warm up the electrodes outdoors, pencil cases have been created: they are sealed, have thermal insulation, and facilitate long-term storage of the electrodes in a dry state. There are two types of pencil cases, depending on the type of design: thermos pencil cases and thermal pencil cases . They do not heat, but only maintain in a dry and, if necessary, heated state. [ads-pc-3][ads-mob-3]
Thermal cases
Thermos cases are compact in size, have a heat-insulating internal coating, and are equipped with heating elements and a thermostat. All these advantages allow calcination to be carried out directly on site.
Examples of the most popular models of pencil case thermoses: P-5 “BRIMA”, PT-5 “BARS”.
Thermal cases perform two functions :
- – creating a certain temperature level for storing electrodes;
- – heating of materials.
Thermal pencil case is a design in the form of a small box with a door, the average weight is approximately three kilograms. Inside there is a special thermal device, which is finished with a layer of insulation. The temperature that the thermal pen can produce varies in the range from 0 to 120 degrees.
Storage rules
As you can imagine, proper storage directly affects the shelf life of welding electrodes, so take this seriously.
We wrote above that the rules are established by GOST. All manufacturers, suppliers, sellers and welders are required to comply with it. Electrodes deteriorate most during transportation, so inspect them carefully after opening the package.
How to properly store electrodes? According to the rules, the rods must be stored in a dry, warm room.
The optimal air temperature is 14-16 degrees Celsius, and the optimal humidity is no more than 50%. Use special devices to control temperature and humidity. They can be either hand-held, portable or stationary, mounted on a wall indoors.
The room itself must be thoroughly waterproofed.
Do not have open openings through which snow, rain or wind can enter the room. If the room has windows and doors, they must have seals. The presence of large gaps between window or door openings and the wall is excluded.
The ideal option is an insulated, waterproofed warehouse, with an electronic temperature and humidity control system. But this option is not possible if you are engaged in home welding. Therefore, use your garage or storage room as a warehouse, install an outdoor thermometer on the wall and purchase a psychrometer.
Electrodes are stored at a constant temperature; changes are also unacceptable. The electrode coating easily absorbs moisture or becomes dry, which may shorten the shelf life. The shelf life of welding electrodes can be increased if you follow our recommendations:
- Store electrodes in boxes or boxes made of thick cardboard, do not place them on the floor or open ground. It is better to put them on shelves or pallets. This will protect the rods from excessive condensation.
- Do not leave open packaging outside. If you do not have this opportunity (for example, you carry out welding work outside the workshop or garage), then protect the packaging from moisture and dust by wrapping it in thick paper or putting it in a box.
- Immediately close the package containing the electrodes.
If you usually use few materials, then the shelf life of welding electrodes can be increased by making a special case for them from PVC pipe. Below is a training video on how to make such a pencil case.
How to see that welding electrodes have passed their expiration date
If there is concern that optimal maintenance conditions have not been observed, a visual inspection of the welding materials should be carried out. This will determine whether they are suitable for use.
Do not use materials with chipped coating
There are several options for the condition of consumables :
1. The electrodes are externally in normal condition and are ready for use without preliminary preparation (unless the welding mode requires it).
The mode of preliminary procedures is indicated on the packaging
2. There are some defects that can be eliminated by carrying out preparatory procedures, such as cleaning, drying, etc.
3. The materials have completely deteriorated and are not suitable for use. In this case, they must be disposed of. They can also be used as training consumables and as additives.
How is drying done?
The temperature and holding time are different for different electrodes, so before you start drying, carefully study the packaging. Foreign manufacturers do not always indicate drying parameters on their boxes; to find them out, you need to go to the manufacturer’s website, where more detailed technical specifications are posted. Since cellulose electrodes must have the lowest moisture content in the coating during operation, they are packaged in metal cans and it is not recommended to calcinate this type of electrodes. In practice, they can be calcined at a temperature no higher than 70 degrees, otherwise the coating will collapse.
Special devices have been developed for this:
- bake;
- closet;
- pencil case.
In addition, there are “folk” methods - how to dry electrodes without the use of special equipment. It is recommended to carry out calcination and drying no more than 3 times. Practice has shown that with a greater number of calcinations, the coating crumbles and crumbles.
