1. Look: The selection of industrial sewing machines mainly to see whether the nose is bright, there is no paint and bumps phenomenon, needle plate, push plate, panel, round wheel and other electroplating layer is intact, whether the plate is straight, paint surface has no cracks or local discoloration, rack is not broken, paint, crooked;
2. Test: First use two layers of thin cloth to test the seam, check whether the pins are flat, uniform.
Then use thick material to test the seam, to see whether the length of the pin can reach 3.6mm, no jumper and jump needle situation, adjustment should be flexible and convenient.
3. Check: Unload the belt, the plate to press the foot, gently turn the wheel, to see if it is running freely, the needle is not in the needle plate hole in the middle of the lifting.
4. Listen: In the idling and with the load when listening to the motor, the machine parts in the operation of the sound, normal sound should be uniform, stable, soft irregular noise and strange sound is not