What are the common problems of heat shrink packing machine?

This time, let’s talk about the control principle, electrical failure and maintenance of automatic sealing shrink packing machine. Heat shrink packing machine is a highly automated equipment, which is widely used in medicine, food, beverage, household chemical industry and other industries. This kind of machine can greatly reduce the material and labor costs of medium box packaging, and is of great economic significance. Therefore, it is very necessary for manufacturers to master troubleshooting and simple self-maintenance.


1. Principle of machine.

Automatic shrink packing machine is a kind of automatic packing machine controlled by PLC and other peripheral lines, which combines electronic components and mechanical device. The brief function summary of PLC is to receive signals and transmit signals. After receiving the signals sent by photoelectric or other sensors, the corresponding signal instructions are transmitted logically, so as to control the actions of each subsystem to achieve the effect of full automation.

For example, after receiving the photoelectric detection of the product, start the transportation and seal off; or after receiving the sensor signal of mis-cutting and product blockage, stop and alarm the system and indicate the cause of the fault. Therefore, after understanding the principle of the equipment, we can quickly analyze and troubleshoot the problems that may occur in the machine.

2. Fault and maintenance.

2.1 PLC or photoelectric failure.

The main faults of PLC are designated transfer point and signal access point. For example, if the output point controls the motor, the fault phenomenon is that after the motor starts with a signal, the motor is transported and rotated, but after the stop signal is sent, the motor does not stop running, and when the plc power is cut off, the motor stops running. If the point controls the solenoid valve. The reason for the obstacle is that the solenoid valve coil is not broken and the cylinder is not reset. If the external force hits the plc to separate the bonding point, it can help determine the cause. There are two ways to maintain an plc output point failure. A more convenient way is to use the programmer to modify the program and change the damaged output point to standby. Use the output point while adjusting the line, or replace the PLC. Signal access point fault detection can manually trigger the corresponding signals such as photoelectric, sensors, access switches, etc., check whether the point indicator is displayed to determine whether the signal fault and PLC fault.

2.2 proximity switch failure.

The shrink packing machine has a number of proximity switches, some for blades protection and some for controlling the film receiving / releasing motor. The latter is used to control the knife. Occasionally mis-operating the protection switch once or twice will interrupt the normal operation process, and because of the small number of faults and short time, it brings some difficulties in fault analysis and troubleshooting. Its typical performance is that the occasional fall of the sealing knife is not in place and is raised automatically. The reason for the failure is that the sealing knife did not encounter the product in the falling process, but lost the signal due to the proximity switch sensed by the position, just like the contact between the protective plate and the packaging or the sealing knife and the packaging. The fault maintenance method can first use manual induction to check whether the corresponding signal instructions are normal and whether the command transmission can be triggered to enable the corresponding next action to start; if not, the proximity switch of the same model can be replaced.

2.3 Magnetic switch failure.

The magnetic switch is used to detect the position of the cylinder and control the stroke of the cylinder. The stacking, pushing and blade lifting of the cylinder are related to each other. the main fault of using the magnetic switch to detect its position is to track the cylinder. Because of the high speed of the cylinder, the magnetic switch can’t detect the signal. The fault maintenance method can save the throttle valve and its solenoid valve on the cylinder, reduce the compressed air flow and reduce the running speed of the cylinder until the magnetic switch detects the signal. Or replace the magnetic switch (if it is determined that the switch is damaged)

2.4 Solenoid valve failure.

The main fault of the solenoid valve is that the cylinder does not move or does not reset, because the cylinder solenoid valve cannot change direction or gas. If the solenoid valve due to poor air passage, or the air pressure of the machine can’t reach the working pressure, the tool holder can’t rise. The tool holder protection proximity switch can’t work, the normal condition of the whole machine operation is invalid, and the machine can’t operate, which is easy to be confused with electrical faults. The solenoid valve has air leakage. By listening carefully to the sound source and finding the air leakage point by hand, it is usually easy to find the solenoid valve that flows through the air.


As there are too many automatic machine control components, please forgive the author-SNCPACK can’t give a comprehensive overview of all the causes of faults, so here only some equipment prone to failure and miscalculation to make some descriptions, it is convenient for users to quickly define and judge the machine downtime or failure, so as to eliminate and solve the problem. If you encounter complicated causes or damage to other key components, you are advised to find a professional electrical engineer for inspection, or contact a professional engineer at SNCPACK for analysis and judgment, please call + 86 18928379199 (whatsapp) or contact us by email sales@sncpack.com.Next we will also explain other packaging machine problems, please follow our social media numbers or website news, and sincerely hope to receive other suggestions and guidance, thank you