1. In the tensile test, the fracture of the sample is always broken on both sides.

2. The sensitivity of the dial pointer is poor, the position of the pendulum is abnormal, and the pendulum bar of the impact tester is not allowed to be marked vertically.

3. The hammer return is abnormal, fast and slow. The passive needle can't stop well at any position, and it doesn't coincide with the main needle.

4. During loading, the oil system leaks oil seriously or the oil pipe breaks.

5. After the sample breaks, the pendulum falls back quickly, causing impact.