What are the reasons for the unstable wire feeding speed of MIG welding machine?

1. Factors related to wire feeding mechanism
1. Wire feeding wheel problem
Wear: After long-term use, the tooth shape of the wire feeding wheel will gradually wear. The worn wire feeding wheel cannot apply stable pressure to the welding wire, resulting in uneven friction during wire feeding, which causes unstable wire feeding speed. For example, when the teeth of the wire feeding wheel are worn to a certain extent, the welding wire is easy to slip between the teeth, making the wire feeding speed fast and slow.
Improper pressure: If the pressure of the wire feeding wheel on the welding wire is too large or too small, it will affect the stability of the wire feeding speed. Excessive pressure may cause the welding wire to deform or even be flattened, increase the friction between the wire feeding wheel and the wire guide tube, and cause poor wire feeding; too little pressure will cause insufficient friction between the welding wire and the wire feeding wheel, which is prone to slippage and unstable wire feeding speed.
2. Wire guide tube problem
Blockage: During the welding process, impurities such as debris, dust, and oil stains of the welding wire may enter the wire guide tube and gradually accumulate, causing the wire guide tube to be blocked. In addition, too much anti-rust oil on the surface of the welding wire may also form oil stains in the wire guide tube, affecting the smooth passage of the welding wire. When the wire guide tube is blocked, the resistance of the welding wire in the tube increases and is uneven, resulting in unstable wire feeding speed.
Bending or deformation: If the wire guide tube is improperly installed or squeezed by external force, it may bend or deform. This will change the running trajectory of the welding wire in the tube, increase the friction between the welding wire and the tube wall, and affect the wire feeding speed and cause fluctuations.
2. Failure of the electrical system of the welding machine
1. Failure of the wire feeding motor
The performance degradation or damage of the wire feeding motor will directly affect the wire feeding speed. For example, the wear of the motor brush will cause the motor speed to be unstable, and then the wire feeding speed will be unstable. In addition, the short circuit or open circuit of the motor winding will also make the motor unable to work normally, causing abnormal wire feeding speed.
2. Problems with the control circuit of the welding machine
The control circuit of the welding machine is responsible for adjusting the wire feeding speed. If the components in the circuit (such as potentiometers, controller chips, etc.) fail, the control signal of the wire feeding speed may be unstable. For example, if the potentiometer is worn or has poor contact due to long-term use, the set wire feeding speed cannot be accurately transmitted to the wire feeding motor, causing fluctuations in the wire feeding speed.
3. Factors related to welding wire
1. Welding wire quality issues
Uneven diameter of welding wire will lead to unstable wire feeding speed. If there is a diameter deviation in the production process of welding wire, the thicker part will have greater resistance when passing through the wire feeding wheel and the wire guide tube, while the thinner part will have less resistance, which will cause fluctuations in wire feeding speed.
Uneven hardness of welding wire will also affect wire feeding. For example, if the heat treatment of welding wire is uneven during the manufacturing process, the deformation and friction of parts with different hardness during the wire feeding process will be different, which will lead to unstable wire feeding speed.
2. Surface state of welding wire
When there is oil, rust or other impurities on the surface of welding wire, the friction of welding wire will increase during wire feeding. These impurities may make the friction between welding wire and wire feeding wheel uneven, or form obstacles in wire guide tube, making wire feeding speed unstable.
4. Other external factors
1. Power supply voltage fluctuation
If the power supply voltage of the welding machine is unstable, it will affect the working state of wire feeding motor. When the voltage is too high or too low, the motor speed will change, which will lead to unstable wire feeding speed. For example, in an environment where the grid voltage fluctuates greatly, the welding machine may be affected, especially some welding machines that are more sensitive to voltage fluctuations.
2. External interference
Electromagnetic interference in the surrounding environment may affect the control circuit of the welding machine and the normal operation of the wire feeding motor. For example, the electromagnetic field generated by large motors, electric welding machines and other equipment at work nearby may interfere with the electronic components of the welding machine, affect the control signal of the wire feeding speed, and cause unstable wire feeding speed.