Mold-core pin

Althnu to this long hole is what the design in Fig.. 3A requites, the mold (core) pin would be very long and easily bent. ... 

In injection blow mol ding, a parison is injection molded onto a core pin the parison is then rapidly transferred via the core pin to a blow mold, where it is blown by air into an article. This process is appHed to smad and intricate bottles. 

Blind hole In regard to molding products that include holes, it is important to ensure that sufficient material surrounds the holes and melt flows property. A core pin forming blind holes is subjected to the bending forces that exist in the cavity due to the high melt pressures. Calculations can be made for each case by establishing the core pin diameter, its length, and the anticipated pressure conditions in the cavity (3). 

First station usually has multiple preform injection molds where preforms are formed over core pins. The preforms have hemispherical closed ends (resembles a laboratory test tube). The other ends have an open bore, formed by the core pin. External details, such as the thread and neck flange for a screw-top container, are directly produced by injection molding. While the preform is still hot, the injection split mold is opened and the preforms, still on the core pins, are rotated to the blowing station two. Here the preforms are enclosed within the blow mold, and introducing blowing air through the core pins followed with cooling produces the BM. Blow molds opened and the finished products, still on the core pins, are rotated to an ejection station where they are stripped off mechanically and/or air. 

The injection molding with rotation (MWR) is an example of processing at lower temperatures, pressure, etc. It is also called injection spin molding or injection stretched molding. This BM process combines injection molding and IBM, as performed in IBM reviewed, except it has the additional step of with melt orientation (Dow patent). The equipment used is what is commercially available for IM except the mold is modified so that either the core pin or outside cavity rotates. The rotated melt on its preform pin is transferred to a blow mold. The end product can come directly from the I MM mold or be a result of two-stage fabrication malting a parison and BM the parison.164... 

To achieve accurate dimensions in the finished part, the mold cores must be aligned accurately with the cavities. Mold halves have large guide pins in the corners to assure alignment. 

Hydraulic or pneumatic cylinders may be mounted on the mold to actuate horizontal coring members. It is possible to mold angular coring, without the need for costly loose details, by adding angular core pins... 

Machining Core and cavity Slide and inserts Core pins, etc. Mold base... 

The arrows in Fig. 4.49 (p. 78) symbolize the heat flow into, through, and out of the core pin into the cooled mold. There are many ways to internally cool a core pin (often at a relatively high cost) the smaller the size of the pin, the more... 

There are many considerations in specifying the shape of the counterbore. In molding, every hole in a plastic piece is created by a pin (the core pin). The core pins are often subjected to unbalanced side forces, caused by high injection pressures and poor flow conditions in the mold as a result of the gate location, which will deflect these pins. 

The fact that these flaws exist does not mean that design C has never been used, but it should be avoided because of the low productivity of the mold, the increased cost of the molded piece, the possible need for a special screw, and the high cost of upkeep of the mold. As a general rule, a core pin should not project (be unsupported) for more than three to four times its diameter. 

The designer must be always aware that the mold presents the negative of the product shape. This applies not only to core, pins and holes but also to cavities and cores, in general. 

Figure 5.8 The core pin radius (A) is the negative of the radius in the molded part (B)...

Figure 5.9 Chamfer on the end of the core pin (A) creates two steess risers in the plastic for molded) part (B)...

---