Galvanized mold

High-quality and also expensive molds can be manufactured using the porous nickel-galvanos. In the special procedures, porous galvanic molds with thicknesses up to 2 mm can be manufactured. These molds are backfilled, and if necessary provided with temperature control tubes. 

Figure 4.47 schematically shows an example of the construction of a galvanized mold on a micropipette to be produced with injection molding. The galvanized mold insert is molded in a galvanic way after a so-called positive model , meaning the model... 

Generally speaking, the wear behavior of nickel, depending on the composition and hardness, almost reaches the wear behavior of hard chrome. Usually galvanized mold inserts for injection molding are used with a nickel hardness of 44 to 48 HRC. For other applications, such as in the aviation industry or in the slush technology, sulfamate nickel is used with a hardness of about 25 HRC. 

Fine contours of the model surface are accurately transferred to the galvanized mold inserts through electroplating, such as genuine leather grains, skin texture, fine diamond cuts as used in micro-reflectors, high-gloss polish, etc. 

The requirements on the surface characteristics of the galvanized molds are very different. In dolls parts and toy animals, satin matte surfaces are desirable. To this end, the most strongly undercut galvanized molds are sand blasted with corundum or other abrasives. For textured or smooth surfaces a surface treatment by etching or special blasting with different material mix is necessary. 

FIGURE 4.50 Galvanic molds for the manufacture of doll parts made from PVC using... 

The possibly attainable lifetimes of the galvanized mold inserts correspond well to the lifetimes of the steel molds. The galvanized mold is often superior to the steel mold due to the high corrosion resistance as compared to deposition products, which are created during the processing of PVC. However, a prerequisite is the right fit in properly sized master molds, i.e., they cannot spring back under the injection pressure. 

The production time is dependent on the relatively low deposition rates of the special electrolyte. Hence, the mold designer must not make the walls of the galvanized molds too thick and should consult the galvanic designer if in doubt ... 

Galvanized molds made from hard nickel are particularly vulnerable to bending stress. 

In the past, it was very difficult to repair galvanized molds. The only repair measures were the placement of pins, the time-consuming post-electroplating, or the... 

FIGURE 4.53 Galvanized mold with a subsequently inserted slider brakethrough and injection channel... 

Galvanized Molds for Other Plastics Processing Methods... 

The previous discussions refer mainly to the use of galvanized mold inserts in injection molds. Figure 4.54 shows an application example. The extensive field of rotational molding and the so-called slush technology is discussed in detail in... 

FIGURE 4.54 Injection molding galvanized mold inserts for impeller and spreading disc... 

Using the galvanized molds, the mold structure is as follows ... 

FIGURE 4.55 Galvanized mold inserts integrated into a steel body for foaming control buttons... 

FIGURE 4.58 Galvanic mold for aircraft engine cowling, mounted on a steel frame... 

FIGURE 4.59 Galvanic mold with rear section for helicopters cowling when measuring and adjusting... 

C and to be vacuum-tight at the same time. In addition to molds made from steel or aluminum, galvanic molds made from sulfamate nickel with integrated steel inserts, via which a mounting on a mobile tubular frame is done, have proved to be very effective (Figures 4.58 and 4.59). 

The design of the positive models is of particular importance, because large-sized galvanized molds are often used in the aerospace industry, and mold shells of up to 9 m long and 3 m wide are currently manufactured in Germany. Bath models... 

The following advantages of galvanized molds are offered to the design engineer in the aerospace mold making ... 

Vacuum systems are often used in the so-called RTM process. The mold load is therefore extremely low and galvanized molds can be manufactured in a lightweight design, i.e., the galvanized molds with wall thicknesses from 3 to 5 mm are fixed to the tubular steel frame using inserts such as the molds for the aerospace industry. The pipe system for the temperature control is inserted and covered by a 10 to 15 mm thick cast resin laminate layer. This mold manufacturing method is very inexpensive. It was successfully used for the production of car body parts. 

The galvanized mold is, as usual, mounted on a steel or aluminum frame with a vacuum-compatible resin-based backing material, and can be used on conventional thermoforming machines. 

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