Choosing the right welding process parameters is very important to improve welding quality and increase production efficiency. The welding process parameters (welding specifications) refer to the physical quantities selected during welding to ensure the quality of the weld. 1. Selection of welding power source type and polarity Nylon Insert Locknuts,Nylon Insert Nuts,Hex Flange Nylon Nuts,Stainless Steel Nylon Insert Nut Kunshan Liyue Hardware Products Co.,Ltd , https://www.fixlyhardware.com
Types of welding power supply: AC, DC polarity selection: positive connection, reverse connection: the welding piece is connected to the positive pole of the power supply, and the welding rod is connected to the negative pole of the power supply.
Reverse connection: the welding piece is connected to the negative pole of the power supply, and the welding rod is connected to the positive pole of the power supply.
Polarity selection principle: Basic electrode is often reversed by DC, otherwise the arc combustion is unstable.
The splash is severe and the noise is high. When the acid electrode uses DC power, DC is usually connected.
2, the diameter of the electrode
It can be selected according to the thickness of the weldment. Generally, the larger the thickness, the thicker the diameter of the selected electrode, and the relationship between the diameter of the electrode and the weldment is shown in the following table:
Weldment thickness (mm)
2
3
4-5
6-12
>13
Welding rod diameter (mm)
2
3.2
3.2-4
4-5
4-6
3, the choice of welding current
There are many factors to consider when selecting the welding current, such as: electrode diameter, coating type, workpiece thickness, joint type, welding position, weld bead level, etc. However, it is mainly determined by the diameter of the electrode, the position of the weld, and the level of the weld bead.
(1) Welding rod diameter The thicker the welding rod diameter, the larger the welding current. The table below is for reference
Welding rod diameter (mm)
1.6
2.0
2.5
3.2
4.0
5.0
6.0
Welding current (A)
25-45
40-65
50-80
100-130
160-210
260-270
260-300
(2) When welding position flat welding position, some welding current can be selected to be larger. When the position is horizontal, vertical and overhead, the welding current should be 10~20% smaller than the flat welding position. The fillet welding current is slightly larger than the flat welding current.
(3) weld bead level
Bottom and single-sided welding are formed on both sides, and the current used is smaller.
The welding current used for the alkaline electrode is about 10% smaller than that of the acid electrode. The welding current of the stainless steel electrode is smaller than that of the carbon steel electrode.
In short, if the current is too large or too small, it is easy to produce welding defects. When the current is too large, the welding rod is prone to redness, which deteriorates the coating, and it is easy to cause undercuts and craters to cause defects, and at the same time, the weld seam is overheated and the crystal grains are coarsened.
(4) Arc voltage
The arc voltage is mainly determined by the arc length. If the arc is long, the arc voltage is high; otherwise, it is low.
During the welding process, it is generally desirable to keep the arc length consistent and to use short arc welding as much as possible. The so-called short arc refers to the diameter of the arc length of the electrode is 0.5 to 1.0 times, and beyond this limit, it is a long arc.
(5) Welding speed
Under the premise of ensuring the required size and quality of the weld, the operator is flexible. The speed is too slow, the heat-affected zone is widened, the grain is coarse, and the deformation is also large; the speed is too fast, and it is easy to cause defects such as incomplete penetration, unfusion, and poor weld formation.
(6) Speed ​​and voltage are not mandatory for the welder's hauling habit, but according to the empirical formula, it can be seen that when the current is less than 600A, the voltage is 20+0.04I. When the current is greater than 600A, the voltage is 44V.