Elif Temiz, 030070195, 10th Week Definitions- Part3

4- Matched Die Molding

New Definition (Manufacturing Method)

Matched die molding is a pressure method of molding a fiberglass laminate by squeezing catalyzed resin and fiberglass reinforcing materials between two molds (Fig. 8-12). This method is now commonly used for certain types of fiberglass molding. It gives a quality laminate that is smooth and formed on both sides. A proper ratio of resin to glass fiber reinforcement can be maintained. Production is much more rapid than when contact molding is used, especially when the molds are heated to speed up the curing time.

Disadvantages are that it is expensive to tool for matched die molding, and this method is generally limited to fairly small moldings. For example, to date, boat hulls only up to about 20 feet in length have been produced on a regular basis by this method. Experiments have been carried out to determine the feasibility of making even larger hulls and other moldings by this method. Chevrolet Corvette car bodies are made by matched die molding. The first Corvette car bodies were produced by contact molding. Then vacuum bag molding) was used to produce several hundred car bodies before going on to matched die molding, which allows volume production.

Matched die molding does not allow application of a thin color gel coat to the laminate. The Chevrolet Corvette car bodies are painted after they are removed from the matched die molds. It is possible to add a color pigment to all the resin used. The color resin wiII then be throughout the laminate. This method has only limited usefulness, however, as the glass fibers show through the surface.

Matched die molding is practical only when a large number of the same molding is to be produced. The tooling is very expensive and must be amortized by making many moldings. Simple matched die molds can be constructed. Mat and catalyzed resin is applied to one surface of the mold by hand. The matched die mold is be set in place and clamped down in the desired position. Most production equipment does some or all of these jobs automatically.

Modern matched die molding allows rapid molding cycles. A fiberglass sports car top having an area of about 20 square feet has a molding cycle of about five minutes in matched die molding, whereas it commonly takes several hours or more using hand lay-up in a contact mold. Before going to matched die molding, most manufacturers first use molding methods that have less tooling expense to make certain that there is enough demand for the product to justify the high tooling cost required for matched die molding.

(Jack Wiley, The Fiberglass Repair and Construction Handbook, pp.105-106)


There is no previous definition.