Industry information

The mold exhaust is not good. the impact of the product and the solution

2021-07-26
The mold exhaust is not good, the impact of the product and the solution!
In a sense, the injection mold is also a displacement device, ie the plastic melt enters the cavity, and is simultaneously replaced out of the air in the mold cavity. In fact, the air in the mold is not limited to the cavity, especially the three-plate injection mold, cannot be ignored to the air present in the flow path. Further, the plastic melt produces a trace decomposition gas. These gases must be discharged in time.
  
If the exhaust performance difference of the mold is prone to bubbles, silver, cloud, recregnor, surface focal, intermittent injection, etc. Therefore, there is a reasonable exhaust structure to be equipped on the mold to avoid poor exhaust gas.
01 Common Several Mold Exhaust Ways

1) Mold exhaust tank exhaust
For molds that are large, medium-sized plastic parts, the amount of gas is required to exclude, usually, the venting grooves are usually opened on the side of the finish. The position of the exhaust tank is good at not in the melt flow, and the exhaust tank size is smoothly discharged by the gas smoothly and does not overflow. The venting groove width is generally about 3-5mm, and the front end of the exhaust tank is less than 0.05mm, and the length is generally 0.7-1.0mm.
 

2) Mold field exhaust
For small molds, the slot gap can be utilized, but the dividing surface must be located at the melt flow.

3) Mold tunnel gap exhaust
For a combined die or cavity, it can be utilized for a gap exhaust.

4) Mold pusher gap exhaust
With the push rod and the template or core, the gap is exhausted, or the gap of the push rod and the template is intentionally.

5) Powder unburned combined gold block exhaust
Powder unburned binding is a material that is sintered with a spherical particulate alloy, a poor intensity, but is loose, allowing gas to pass. The exclusion requirement to reach the exhaust gas in the portion where the exhaust is required, but the bottom air hole diameter is not too large to prevent the cavity pressure from extruding it.

6) Exhaust well exhaust
On the outside of the plastic melt convergence, a hole is provided to discharge the gas into it, and a good exhaust effect can also be obtained.

7) Mandatory exhaust
In the portion of the closed gas, the exhaust rod is provided, which is good in this method but will leave the rod traces on the plastic parts, so the exhaust rod should be located in the concealed place of the plastic parts.
02 Molds should pay attention to when exhaust design
1. When the exhaust is extremely difficult, use a squeezed structure. If some molds are not easy to open the exhaust tank, first should change the mold to a pattern without affecting the appearance and precision of the product, which is not only conducive to processing. Exhaust gas can also improve the original processing difficulty and easy maintenance.
2. At the closed shape of the plastic product, it is necessary to increase the thir to exhaust, prevent burns and integration.
3. For the product mold of the complex geometry, the opening of the exhaust tank is preferably concluded after several trimming.

4. The more thin-walled products, the more away from the gate of the gate, and the opening of the exhaust tank is especially important.

5. Also pay attention to the opening of the exhaust tank for small or precision parts, as it can eliminate the various defects of the article in addition to the lack of burns and injections of the product.

03 summary
Suitably opens the exhaust tank to greatly reduce the injection pressure, injection time, pressure deposit time, and lockup pressure, so that the molding of the plastic parts is easier, thereby increasing production efficiency, reducing production cost, and reducing the energy consumption of the machine.
Details determine success or failure, the details of the mold must be carefully handled!