Welding thrust current
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Many friends who weld with alkaline electrodes often encounter the problem that the electrodes tend to stick to the workpiece. Most of them try to adjust parameters such as the welding current or voltage, but the effect is not significant. Many experienced technicians will tell you to increase the thrust a bit. The thrust mentioned here actually refers to the thrust current; the main reason for stickiness is that the thrust current is too low. So what exactly is thrust current? Below, I will explain what the thrust current does, as well as its advantages and disadvantages. As is well known, current controls the penetration depth, while voltage controls the width of fusion. The greater the current, the deeper the penetration; the greater the voltage, the wider the molten pool. Correct usage of thrust current: When starting welding, the circuit is in a short-circuit state, the voltage drops sharply, and a large current is required ； After arc initiation, it is necessary to stabilize the arc; at this stage, the electrode and the molten iron in the pool are still in a short-circuit transition state, the voltage continues to drop, while the current remains high ； After the transition is complete, it enters a normal welding state, with the voltage rising and the current falling. There are three currents that can be adjusted in manual arc welding: the starting current, the welding current, and the push current. The arc starting current is the maximum current that a welding machine can output when starting a weld. Each time arcing occurs, the applied voltage is increased for a short period to make the arcing current larger, thereby facilitating arcing. Thrust current is a current that the welding machine applies in addition during the short-circuit transition of the molten iron while welding, thereby enabling a stable transition of the molten iron and preventing sticking. Thrust current is the characteristic that increases the output current when the output voltage is below 15V; especially during a short circuit, this phenomenon prevents the welding rod from sticking. The welding current is the working current supplied by the welder during normal welding. Acidic electrodes do not require a pushing force, while for alkaline electrodes, under normal continuous welding conditions, the pushing current can be set at around level 3, or approximately 30 amperes. In spot welding, the thrust current can be increased, which helps to prevent stick-soldering. Skilled welders, when welding and finding that the solder stick tends to stick, may find that the thrust setting is too low; increasing the thrust should resolve this issue. The advantage of the thrust current is that it eliminates stick-soldering. So how does the thrust current eliminate \"sticking\"? The principle is as follows: when welding with a low current, the arc voltage is low (below 15V), and the electrode tends to stick significantly (at this point the voltage is close to 0V). In such cases, the thrust current increases immediately, providing sufficient arc energy to facilitate rapid transfer of the molten droplets and thus preventing sticking during welding. The disadvantage of thrust current is that it tends to cause spattering: the main reason is that thrust current accelerates the transition speed of the droplets, causing them to separate from the tip of the electrode rapidly. This separation leads to fragmentation and thus spattering. Therefore, some instances of spattering are caused by an excessive amount of thrust current; reducing this current accordingly can help minimize spattering. For beginners just starting out with sticking strips, it’s likely not due to a lack of thrust, but rather because they are unable to control the arc length. An arc that varies in length can also easily cause sticking.
The push current in welding is actually a special dynamic power supply adjustment function, primarily used during manual arc welding, especially when welding alkaline electrodes, to prevent the electrode from sticking to the workpiece. When the arc is in a short-circuit state, or in other words when the electrodes come into contact with the molten pool, the power supply can automatically increase the current to facilitate the smooth transfer of droplets from the electrodes into the molten pool, thereby preventing stickage. This thrust current is activated during arc short circuits or when the electrode makes contact with the molten pool, increasing the output current to maintain welding stability. In simple terms, the function of the thrust current is to help the welder quickly move through the short-circuit state at the start of welding, thereby transitioning to a stable welding condition. This is achieved by briefly increasing the output current under a short-circuit condition, allowing the droplets to be rapidly transferred to the workpiece under the force of the arc, rather than remaining on the welding electrode and causing sticking. The advantages of thrust current are mainly as follows: 1. Reducing stickiness: It prevents sticking that occurs when the welding electrode is too close to or in contact with the molten pool, due to insufficient current. 2. Stable transition: It can provide sufficient current during the short-circuit transition phase to maintain the stability of the welding process. The disadvantages of thrust current include: 1. Increased spatter: Since thrust current increases the transfer speed of the droplets, it may lead to more spatter during welding. 2. Improper use may affect weld formation: If the thrust current is set too high, it may cause instability during welding, thereby affecting the quality of the weld. Therefore, properly setting and using the thrust current is crucial for optimizing the welding process. It is necessary to adjust the thrust current value based on the specific welding conditions and the type of welding material in order to achieve the best welding results. For beginners, in addition to adjusting the thrust current, it is also necessary to learn how to control the arc length and master stable handling techniques in order to avoid strip sticking caused by inadequate skill. .