Prototype molding

IE-. [Innovative Engineering of Mich.] Polyurethane engineering elastomer for rollers, pallets, prototypes, molds, fixtures, wheels, bun peis, metal forming pads. 

In vacuum-bag molding the reinforcement and the resin mixed with catalyst are placed in a mold, as in the hand layup method, and an airtight flexible bag (frequently rubber) is place over it. As air is exhausted from the bag, atmospheric air forces the bag against the mold (Figure 2.46). The resin and reinforcement mix now takes the contours of the mold. If the bag is placed in an autoclave or pressure chamber, higher pressure can be obtained on the surface. After the resin hardens, the vacuum is destroyed, the bag opened and removed, and the molded part obtained. The technique has been used to make automobile body, aircraft component, and prototype molds. 

Low-cost molds for contact and low-pressure molding can be made from reinforced TS polyester or epoxy compounds with glass fiber and/ or mineral filler reinforcement. These constructions have also been used to make prototype molds for compression and injection molding, with the advantages that they can be produced quickly and at low cost (often in-house) and can readily be modified. Latest technology uses blocks of resin-based compounds that can be machined by computerized instructions, for production of protot5 e molds. 

Note, however, that prototype molds still introduce another variable cooling rate. The less similar the cooling rate of the material inside the prototype mold vs. inside the production mold, the less realistic the... 

The economic compromise for a prototype mold material is often aluminum or epoxy filled with aluminum powder. The latter material has a thermal conductivity approaching that of solid aluminum, which is nearly five times that of mold grade steel (and therefore introduces a variant into the prototype process). Either material can be machined into the correct cavity shape filled epoxy has the additional capability to be cast around a part form. 

Projected surface area Propagation Proportional Umit Prototype mold... 

Prototype mold n. A temporary or experimental mold used to make a few samples to test product design or obtain market reactions. Such a mold is often made from a low-melting metal-casting alloy or from a filled and reinforced epoxy resin. 

Recently, prototype molds are being fabricated from particle-filled polyurethane and epoxy syntactic foams using computer-aided multiaxis routers. Plugs, used to mechanically prestretch polymer sheet, are also usually machined from syntactic foams. For certain pol5miers, heated aluminum plugs or solid nylon plugs are desired. 

Aluminum or Kirksite can be used to construct prototype molds. However, molds from these materials will never produce close tolerance parts with finished edges since telescoping edges cannot be produced in these soft metals. Flash-free... 

An inexpensive, satisfactory prototype mold can be made by casting aluminum to an undersized shape and finishing the casting with aluminum powder filled epoxy or polyester. This type mold will produce accurate prototype parts and can easily accommodate design changes. The parts, however, will not be flash-free. 

Prototype Mold. A simplified mold construction often made from a light metal casting alloy, such as aluminum, used to obtain information for the final mold and/or part design. 

If the prototype needs to be molded in an injection, compression, transfer, or blowmolding process, it is possible to create a hard cavity shell by first coating the silicone rubber cavity with a release agent and then metal spray plating the cavity surface. When the plated coating is sufficiently thick, it is removed from the elastomeric cavity and backed up with liquid epoxy and appropriate reinforcing stiffeners to create a prototype mold that, with care, can be used to mold parts in the plastic intended for final part. Time from art to part may be merely a few weeks, as compared with the several months generally required for conventional machined steel production molds. 

The mold is an important cost factor in the calculation of a plastic product. Mold modifications are usually associated with high costs and big risks. For proper functioning of compression molds, it is important that a technical drawing suitable for production be made before designing the mold. In some cases, it may be necessary to investigate and prove the manufacturability of a part with a prototype mold before manufacturing the production mold. 

The prototype mold (for technical parts made from aluminum) has established itself in the area of continuously improved CAD/CAM technology (for mold making). 

Due to the high temperature loads when producing rotomolded plastic parts, it is almost impossible to use cheap prototype molds. A rotational mold has to have a certain thermal conductivity and has to constantly withstand changes in heating and cooling. 

In the construction of prototypes, molds are used where the mold shells are manufactured in the metal spraying procedure. This is only possible for easy and flat contours due to the metal spraying procedure. 

FIGURE 1.176 Prototype mold with carbon fiber molded shells... 

An alternative in prototype molding is the use of carbon fiber shells, which are manufactured in an autoclave. The advantage of this application is that there are almost no restrictions for mold design. The disadvantages are the high production costs and limited lifetime. 

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