1. Heat transfer
The print head of a 3D printer has two types of heat transfer: heat conduction and heat convection. During the printing process, the solid print material is heated into a liquid by the heating cavity to maintain a molten state with good adhesion mobility, proper filament width and good adhesion properties to ensure the quality of the specimen, i.e. the heat transfer process.
In order for the printing process to be completed smoothly and the specimen to meet standards, the heating chamber temperature needs to be kept at a constant temperature in order to avoid being too low or too high, and when the temperature is too high, the air conditioning needs to be turned on to reduce the temperature, i.e. the thermal convection process.
2. Temperature sensor
The temperature sensor is a device that converts the temperature signal perceived by the outside world into a useful electrical signal in the circuit. Temperature sensors include metal RTDs, thermocouples, new integrated temperature sensors and so on. Metal RTDs or thermocouples are commonly used in industrial temperature control systems, while new integrated temperature sensors are mostly used in small temperature measurement circuits.
The temperature sensor chosen for 3D printers is related to the material used for printing. Currently, the materials commonly used in 3D printing are PVC, PBS, ABS, etc. These polymer materials have a temperature range of 100 to 280 degrees Celsius.
In terms of temperature measurement range, copper resistors are unsatisfactory and thermocouples have a large temperature measurement range, but their measurement accuracy is not sufficient considering the low temperature measurement. Therefore, platinum resistance was used as a temperature control sensor for the print head of the 3D printer.
3. Closed-loop temperature control system
The temperature control system in a 3D printer is essential, not only to monitor the proper functioning of the printer, but also directly related to the print results and quality. The print material is heated to a molten state in the heating chamber and extruded from the print head at the start of printing. As different materials have different melting points, different temperatures have to be set.
In addition, the print material should always be melted during the printing process, otherwise the print result will be affected. If the temperature is too high, the nozzle outlet will become sticky and affect the result of the specimen, even leading to deformation of the specimen; if the temperature is too low, it will accelerate the solidification of the material and will not be able to bond completely with other materials, even leading to the material not being ejected and the print not being completed successfully.