The unstable operation of the plastic tensile testing machine may be caused by various factors such as mechanical structure, electrical control, environmental factors, operation, use, and maintenance. The following is a detailed introduction:

1、 In terms of mechanical structure of plastic tensile testing machine:

1. Wear and tear of transmission components

Wear of screw pair: The screw and nut are important components of the testing machine transmission, and after long-term use, the clearance between them will increase. For example, during frequent tensile tests, the screw rod rotates continuously and the nut moves back and forth on it. After multiple cycles, the threads of the screw rod and the nut will wear, resulting in a decrease in transmission accuracy, shaking, and unstable operation of the testing machine.

Gear wear: If the testing machine adopts gear transmission, the tooth surface of the gear will gradually wear due to friction. When the gears are severely worn, the meshing clearance between the gears increases, which can cause impact and vibration during the transmission process, affecting the smooth operation of the testing machine.

2. Loose components

Loose connectors: The testing machine may be subjected to various forces during operation, such as tension, vibration, etc., which may cause some connectors, such as bolts, nuts, etc., to loosen. For example, if the connecting bolts between the upper and lower fixtures of the testing machine and the crossbeam become loose, the fixtures will shake during the tensile test, which will affect the smooth operation of the entire testing machine.

Loose bearings: Bearings are key components that support the rotating parts of the testing machine. If the bearings are not securely installed or become loose during use, they can cause the rotating parts to become eccentric during operation, resulting in unstable operation of the testing machine.

3. Guidance mechanism malfunction

Wear or deformation of guide rail: The guide rail is an important component that ensures the linear motion of the moving parts of the testing machine. If the surface of the guide rail is severely worn or deformed due to external impact, it will cause the moving parts to experience jamming, jumping, and other phenomena during the movement, which will affect the smooth operation of the testing machine.

Damage to guide wheels: Some testing machines use guide wheels to guide the movement of moving parts. If the guide wheels are worn, stuck, or improperly installed, it can cause the moving parts to move unevenly, resulting in unstable operation of the testing machine.

2、 In terms of electrical control of plastic tensile testing machine:

1. Motor malfunction

Unstable motor speed: The fluctuation of motor speed will directly affect the smooth operation of the testing machine. For example, wear of the carbon brush of the motor, uneven surface of the commutator, or internal winding faults of the motor can all lead to unstable motor speed, causing the testing machine to experience ups and downs during operation.

Insufficient motor power: If the motor power equipped on the testing machine is too low, the motor may not be able to provide sufficient power when stretching plastic samples with high force values, resulting in difficult operation of the testing machine, shaking or instability.

2. Control system issues

Decreased sensor accuracy: Sensors are key components for measuring force and displacement in testing machines. If the accuracy of sensors decreases or malfunctions, it can lead to inaccurate measurement data, which in turn affects the normal operation of the control system. For example, if the force sensor is damaged or its performance deteriorates after long-term use, the measured force value may deviate from the actual value, and the control system adjusts based on the incorrect force signal, it may cause the testing machine to operate unstably.

Unreasonable control algorithm: The control system of the testing machine usually uses a certain control algorithm to achieve precise control of the testing process. If the control algorithm is unreasonable or the parameter settings are improper, it may cause oscillation, overshoot and other phenomena during the operation of the testing machine, affecting the smoothness of operation.