What is Stick Welding Process?
Stick welding process [also known as shielded metal arc welding (SMAW) or manual metal arc welding or simply arc welding] is a type of welding process which uses consumable solid electrodes that deposit on the weld surface with the help of high ampere and low voltage current.
The components used in stick welding process are mentioned below.
- AC or DC power source
- Welding electrode (or welding stick)
- Cables for connecting the components
- Workpiece to be welded
Principle of Stick Welding (or Arc Welding)
The principle of stick welding is similar to the principle of electric fuse.
You might be knowing that in an electric bulb, if the higher current is passed through the circuit, then the fuse overheats and blows.
The exact principle is used in the stick welding process.
The only difference here is that the fuse (i.e electrode) is fed continuously and the short circuit keeps on occurring over and over again.
Because of this, the filler material is deposited continuously on the workpiece.
In simple words, when the electrode strikes the weld surface, the heat is generated which melts the welding electrode, and finally the filler metal is deposited on the workpiece.
The weld deposition takes place at relatively lower voltage and higher current ranges.
Stick Welding Process (Shielded Metal Arc Welding, SMAW)
Stick Welding Process (or Shielded Metal Arc Welding Process or SMAW process) is a common and versatile method which is used for joining shapes that cannot be welded using automated processes.
The Shielded Metal Arc Welding diagram is shown in the above picture.
In shielded metal arc welding process, the stick electrode (or welding electrode) is used as a filler material between the weld grooves.
The stick electrode consists of an inner core wire and the outer coating material which is also known as flux coating.
In SMAW process, the electric arc shown in the above diagram is the luminous electrical discharge that is produced between the positive and negative terminal.
The arc formation takes place when the electrode is stuck with the workpiece surface.
When the arc is formed, the electrode is moved along the weld groove which deposits the filler material along the weld groove. After solidification of the filler material, the final welded joint is obtained.
13 Important things you should know about stick welding process
How is the stick welding current selected?
The stick welding current selection depends on the following factors.
- Electrode diameter
- Type of electrode
- Type of workpiece, etc.
What type of electrodes are used in stick welding process?
The electrodes used in stick welding process contain inner core metallic wire which is covered with a flux coating material (also known as electrode coating).
The electrode coating materials can be of 6 types.
- Cellulose type
- Rutile type
- Acid type
- Acid rutile type
- Oxidizing type
- Basic type
What weld movements are used in Shielded Metal Arc Welding?
In order to get the perfect weld, neither wider nor narrow and dipper penetration is required. But it is necessary to give movement to the welding torch during the ongoing welding process.
The welding motion can be back and forth, or oval motion. The picture given above represents the different welding movements for SMAW process.
Which power source does stick welding use? AC or DC? And why?
With a shielded metal arc welding (SMAW) process, both AC and DC power sources can be used.
But mostly DC power source is suitable for all types of electrodes.
The arc produced by non-ferrous type electrodes may not be perfect when an AC power source is used.
On the other hand, starting and maintaining the arc using a DC power source is easier.
Also, overhead weldings can be easily done using a DC power source.
In DC power source, the straight polarity (i.e electrode negative) can be used for welding of all steels, but it is not suitable for welding of non-ferrous metals.
When the reverse polarity (i.e electrode positive) is used with basic low hydrogen electrodes, non-ferrous metal can be welded easily.
For welding of sheet metals, the DC straight polarity is used, which minimizes the burn-through problems because of less penetration of arc.
For stick welding process, the power source with constant current having dropping characteristics is preferred over the constant voltage type.
What size of stick welding rod should you use based on metal thickness?
In stick welding process (SMAW), various sizes of welding rods are used depending upon different thickness of metals as well as different current ranges.
- For lightweight metals, small size electrodes of 1.6 mm to 2 mm can be used with current ranging from 25 amp to 40 amp.
- For heavy work where more fusion is necessary, the electrode having larger size (i.e 5 mm to 6.3 mm) with high current capacity (i.e 240 amp to 320 amp) is used.
What is the core wire of a welding rod made of?
The core wire used in stick welding is made up of rimming quality steel.
Rimming is nothing but the method of deoxidizing the steel during its final stage of manufacturing.
The semi killed as well as fully killed steel is also used as a core wire because it gives good performance as well as it is cheap to manufacture.
- In rimmed steel, the silicon content is 0.03%.
- In semi killed steel, silicon content varies from 0.03% to 0.1%.
- In fully killed steel, silicon content is over 0.1%.
The rimming quality steel gives good arc stability, uniform melting of the core wire, as well as fine globular metal transfer.
The proportion of sulfur should be around 0.03%. More sulfur content may lead to hot cracking.
Having said that, now let’s discuss the advantages and disadvantages of stick welding.
Advantages of stick welding process
The advantages of stick welding process are mentioned below.
- Stick welding process is the simplest process as compared to other arc welding processes.
- Wide range of metals and their alloys can be welded by using a stick welding process.
- The stick welding process can be carried out in horizontal, vertical as well as overhead positions.
- The equipments used in stick welding are easily portable.
- The cost of welding by using SMAW process is also comparatively less than the other types of welding processes.
- Also by using this process, different varieties of electrodes can be used as per the requirements of the welding process.
Disadvantages of stick welding process
Disadvantages of stick welding process are mentioned below.
- In SMAW process, the length of electrode is fixed, so the electrode needs to be replaced after it is finished.
- For welding longer joints, the electrodes get finished and the next electrode is used. Due to the use of next electrode, the slag inclusion or incomplete penetration or any other type of welding defects may occur at the place where welding starts with the new electrode.
- The stick arc welding process is comparatively slower than TIG process and MIG process.
- The welding electrodes have the flux coating, so there are more changes of slag inclusion during the welding process. While the slag inclusion defect is seen less in other welding processes like TIG and MIG welding.