cryogenic defiashing technology first Invented in the 1950s. In the development process of cryogenic defiashingmachines, it has gone through three important periods. Follow along in this article to gain an overall understanding.
(1) First cryogenic deflashing machine
The frozen drum is used as the working container for frozen edging, and dry ice is initially chosen as the refrigerant. The parts to be repaired are loaded into the drum, possibly with the addition of some conflicting working media. The temperature inside the drum is controlled to reach a state where the edges are brittle while the product itself remains unaffected. In order to achieve this goal, the thickness of the edges should be ≤0.15mm. The drum is the primary component of the equipment and is octagonal in shape. The key is to control the impact point of the ejected media, allowing for a rolling circulation to occur repeatedly.
The drum rotates counterclockwise to tumble, and after a period of time, the flash edges become brittle and the edging process is completed. The defect of the first generation frozen edging is incomplete edging, especially residual flash edges at the ends of the parting line. This is caused by inadequate mold design or excessive thickness of the rubber layer at the parting line (greater than 0.2mm).
（2）The second cryogenic deflashing machine
The second cryogenic deflashing machine has made three improvements based on the first generation. First, the refrigerant is changed to liquid nitrogen. Dry ice, with a sublimation point of -78.5°C, is not suitable for certain low-temperature brittle rubbers, such as silicone rubber. Liquid nitrogen, with a boiling point of -195.8°C, is suitable for all types of rubber. Second, improvements have been made to the container that holds the parts to be trimmed. It is changed from a rotating drum to a trough-shaped conveyor belt as the carrier. This allows the parts to tumble in the groove, significantly reducing the occurrence of dead spots. This not only improves efficiency but also enhances the precision of edging. Third, instead of relying solely on the collision between the parts to remove the flash edges, fine-grained blasting media is introduced. Metal or hard plastic pellets with a particle size of 0.5~2mm are shot at the surface of the parts at a linear speed of 2555m/s, creating a significant impact force. This improvement greatly shortens the cycle time.
（3）The third cryogenic deflashing machine
The third cryogenic deflashing machine is an improvement based on the second generation. The container for the parts to be trimmed is changed to a parts basket with perforated walls. These holes cover the walls of the basket with a diameter of about 5mm (larger than the diameter of the projectiles) to allow the projectiles to pass through the holes smoothly and fall back to the top of the equipment for reuse. This not only expands the effective capacity of the container but also reduces the storage volume of the impact media (projectiles).The parts basket is not vertically positioned in the trimming machine, but has a certain inclination (40°~60°). This inclination angle causes the basket to flip vigorously during the edging process due to the combination of two forces: one is the rotational force provided by the basket itself tumbling, and the other is the centrifugal force generated by the projectile impact. When these two forces are combined, a 360° omnidirectional movement occurs, allowing the parts to remove flash edges uniformly and completely in all directions.
Post time: Aug-08-2023