Cavity plating

For applications requiring two different compounds, such as a double hardness sealing ring or a two colour rubber shoe sole, some machines have two injection units. One injects into the bottom/centre mould plate and the other into the parting line. Two injection units on a singlestation vertical press are used in combination with twin rotating cavity plates. 

Other developments have not been as dramatic, but they have nevertheless contributed significantly to the process efficiency. The electric screw drives were replaced by hydraulic motors with a gear box on the reciprocating screw unit. In the future the hydraulic motor may in turn be replaced by a direct hydraulic drive (19). The Introduction of stack molds has also increased productivity. In a stack mold, two cavity plates are placed on top of each other so that the projected area is the same and twice as many parts can be formed with the same clamping tonnage. This technique works best with thin wall, flat parts with short cycle times. 

Rear cavity plate ( B plate) Support plate Ejector retainer plate... 

Duplicate cavity plate n. A removable plate that retains cavities, used where two-plate operation is necessary for loading inserts, etc. 

Hot-runner mold (insulated-runner mold) n. An injection mold for thermoplastics in which the runners and sometimes the secondary sprues are insulated from the chilled cavity plate so that they remain hot during the entire cycle. The plastic in the runners remains molten and is not ejected with the molded part, thus avoiding the normal handling, grinding, and reprocessing of sprues and runners. 

Triple-daylight mold n. A mold having four plates feed plate, floating cavity plate, stripper plate, and moving mold plate. When the mold opens, all the plates move apart making three openings among them. 

Figure 1 Basic variants of injection molds (a) two-plate mold (one cavity) (b) three-plate mold (multi-cavity). Designations a, coupling link b, ejector nxi cl + 2, center rings dl -f- 2, clamping plates e, ejector plate t, ejector pins g, distance plate h, cavity plate i, cavity j, transition plate k, sprue with cone gate 1, runner with 4 sprues m, center bolt n, runner plate o, nozzle rl + 2, insulation plates s, high performance nozzle.

Loaded Q is directly proportional to the plate impedance and controls the other two cavity parameters. Loaded Q = Zp/Xi, where Zp is the cavity plate impedance and X/ is the cavity inductive... 

Sleeve Plates. These are located between the core and cavity plate. It can eject the part itself or contain a number of separately mounted sleeves as required in multicavity molds. Sleeves often are used for circular parts with an undercut in the core section or where core pins prohibit use of ejection pins. The sleeve surrounds the core in a flash free fit. When activated on the opening stroke of the press, the sleeve moves forward beyond the core, stripping the part from the mold. This requires a taper match between the sleeve and core generally about 3-10 deg per side to eliminate wear. 

In this type of insulated runner mold design, the runner plate and cavity plate are bolted together and are only opened to remove the solidified runner after breaks in the molding cycle or to remove fireeze-ups. 

Cavity. Depression in mold the space inside a mold wherein a resin is poured the female portion of a mold that portion of the mold which encloses the molded article which forms the outer surface of the molded article (often referred to as the die) also, the space between matched molds. (Depending on number of such depressions, molds are designated as Single-Cavity or Multiple-Cavity). The cavity plate accommodates the individual mold cavities, which can be separate assemblies mounted into the cavity plate or, in the case of a single-cavity mold, can be machined directly into the cavity plate itself. 

Sleeve Plates. Steel plates located between the core and cavity plate and used for sleeve ejection. The sleeve plate itself can perform the ejection or can contain a number of separately mounted individual sleeves as used in multicavity molds. 

---