The leakage of the melt in the hot runner system into the manifold plate is a common concern for mold manufacturers. In most cases, the leakage of the hot runner system is not due to poor design, but is not manipulated according to design parameters. Typically, the leakage occurs at the seal between the hot nozzle and the manifold. In addition, leakage may occur in the case of excessive heating. In this case, in addition to the leakage of the system, the system will be damaged, and the pressure will be irreparably damaged due to excessive pressure, so the hot nozzle needs to be replaced.
Since the preloading of the hot nozzle and the manifold is very important, the dimensional and tolerance requirements provided by the hot runner supplier must be strictly observed to effectively prevent system leakage. Through expert analysis and multiple tests, the hot nozzle was finally improved to prevent leakage. Let's take a look at several hot nozzle designs:
The first is to fix the back of the hot nozzle on the manifold, and the high-temperature bolts that fix the nozzle to the manifold can prevent leakage under cooling conditions. Although this method prevents the leakage of the melt from the hot nozzle to the manifold, it does not prevent thermal expansion of the component under overheating conditions, and the operating temperature range is 230 ± 27 °C.
The second method is an economical and effective method for preventing leakage, which can be applied to a small cavity number system. Since the hot nozzle fixed to the splitter plate by the bolt can be moved together with the splitter plate, this design has a minimum length requirement for the hot nozzle and a limitation on the cavity spacing.
The third is that the edge of the nozzle is elastic rather than steel, and the elastic edge provides preload under cooling conditions and prevents damage to the system. If it is overheated by accident, it can also absorb thermal expansion, and its operating temperature range can be extended to 230 ± 110 °C.
Usually, it is difficult to find out whether the hot runner is leaking or not, because it is not visible from the outside of the mold. But if you look carefully, you can still find some leaks through some signs. Another sign of leakage is that some of the cavity or product charge is incomplete during handling. This is because some of the injected melt leaked into the manifold groove, resulting in insufficient injection molding of the product. This situation is shown as a sudden change in process parameters.
If the operator suspects that there is a leak, the injection molding machine should be closed immediately and the system should be inspected after cooling. After clearing the system and detecting the cause of the leak, all parts should also be inspected. Damage to components may occur due to overheating temperatures or cleaning procedures. If the part is found to be damaged, the part should be replaced in time.
Finally, it is worth mentioning that customers should fully understand the design and performance of various hot runners when purchasing hot runners to ensure the processing accuracy of important parameters and provide necessary technical training for relevant staff.
Huijie Steel Pipe provide variety of Profile Steel Tubes for automotive parts,,engineering machinery,agricultural
machinery,furniture,construction materials,Supplied as DIN,ASTM,ASME,EN,BS,JIS,GOST,GB etc standard
including the Seamless special pipes/SMLS profile steel pipes/ERW profile steel pipes,
We can offer the profile Steel Tubes:
Seamless/ERW Rectangle Steel Tubes,
Seamless/ERW Rectangle Steel Pipes,
Seamless/ERW Square Steel Tubes,
Seamless/ERW Square Steel Pipes,
Seamless/ERW Omega Steel Tube,
Seamless/ERW Omega Steel Pipes,
Seamless/ERW Hexagonal Steel Tube
Outside Hexagonal and Inside Round Steel Tube,
Outside Round and Inside Hexagonal Steel Tube,
Seamless/ERW elliptical steel tube,
Seamless/ERW Oval Steel Tube,
The special profile steel tubing can be produced by customer drawing.
Profile Steel Tubes
Oval Steel Tubes,Hexagon Steel Tubes,Seamless Square Tubes,Seamless Hexagon Pipes
Ningbo Huijie Steel Pipe Manufacturing Co.,Ltd , https://www.hjbearingtube.com