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[ Mold News ] the experimental application of permeable mold (Published:2015-4-14)
To carry out the use of die steel in the air in the plastic mold industry can effectively solve the problem of plastic mold industry, improve the production efficiency and market competitiveness of products, with good prospects for industrial applications. Mainly displays in: 1) reduce the injection pressure, reduce the forming and holding pressure time; 2) improve the mold parting surface tight degree, improving the performance of an ejector rod and insert, without using a parting surface or other exhaust system, avoid the waste edge generation; 3) can make the gate bias, wall unevenness, thin wall molding products difficult problems are solved and ease.

1 the experimental application of permeable mold

1.1 preparation of materials

The Haining Feida metallurgical powder Co., the production of grade 304L stainless steel powder as raw material [3], the suppression of a diameter of cylindrical specimens of 8cm, sintering furnace, sintering temperature is 1100-1300 DEG C, holding 1 hours. The basic parameters of the sample prepared as in table 1.

The basic physical parameters of Table 1 hole cylindrical compacts

Fig. 1 SEM photo of material surface

Fig. 2 SEM photo materials section

The experimental sample pictures of SEM as shown in Figure 1, 2. Figure 1 is the experimental specimen surface of SEM photos, the figure can clearly see the irregular black areas, these areas are the surface pore. Figure 2 is the experimental section of the SEM images, can be seen from the internal complex pore channel [4].

1.2 simple mold inspection

Experimental design of the injection molding experiment device of [5] as shown in figure 3. The EDM process in porous mould steel processing cavity body, the volume of the cavity filling resin is 12.8cm3; and fixture design and assembly of the sealing rubber ring cavity is completely closed, air mould main part; then the injection cylinder and air mould main body assembly of a full set of injection molding equipment.

By tensile test machine to control the injection pressure and speed in the experiment, barrel and die by holding furnace heating.

1.2.1 injection molding process

Selection of ABS resin in the experiment, in the injection cylinder is heated to 170 DEG C, the cavity temperature heated to 40 DEG C, respectively in 20MPa, 15MPa two kinds of injection molding experiments under pressure, injection time is about 10s, after the filling pressure of 5min.

Control of tension and compression testing machine pressure injection. The injection molding process can be observed in many oil leakage mode specifically, along the wall flow aggregation to the bottom edge, this is because the mould cavity is completely closed, the gas in the cavity during the injection process only by the ventilation mode specific through. The injection mold cavity filling period, once completed, the machine pressure value will increase sharply, while maintaining a predetermined pressure value of the pressure. 5 minutes after the holding time can be obtained after mold, mold piece with a breathable plastic die steel.

Figure 3 injection molding experiment device

1.2.2 stripping process

The release of the die steel has not been installed to release device, as shown in Figure 4, depending on the device the diagram of the rubber gasket seal cavity effective permeability. High pressure pump to access 20MPa, plastic can be ejected smoothly. After stripping the plastic parts as shown in figure 5.

Figure 4 the demoulding device

Figure 5 are obtained under the conditions of different injection pressure, injection molding parts

1.2.3 experimental results and conclusions

The permeability of the design of the mould the successful completion of the injection molding experiments, good performance, the following conclusions are obtained from which we can:

1) prepared by air die steel material has the advantages of good permeability experiment, the use of this material was prepared by mold permeability under certain conditions can play a good effect of the exhaust gas in the cavity, eliminate all, injection molding filling completely, as shown in figure 5;

2) respectively in the experiment in 20MPa, plastic parts for injection molding experiment shown in Figure two 15MPa pressure condition after 5 shows, including the injection molding parts, under the condition of 20MPa filling completely, the injection molding of 15MPa under the condition of incomplete, filling, molding conditions that 20MPa can meet the injection molding production, to solve the problem of gas gas, and the injection production pressure required values are generally higher than this value, which makes the permeability of the mold application prospect is extremely good.

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