Compression molding a charge using vacuum

Claim 1

A method of making a part having a large surface area and providing the part with a smooth surface by compression molding a charge containing a curable resin, said method comprising: (a) opening a mold having an upper die and a lower die with opposing molding surfaces that cooperate to define a mold cavity having a shape corresponding to the desired shape of the part; (b) placing the charge on the molding surface of one of the dies so that the charge covers 40%-80% of the surface area of the molding surface, the charge being in the form of at least one ply of thermosetting sheet molding compound (SMC) containing a heat curable resin and reinforcing fibers therein; (c) moving the dies toward each other to a partially closed condition where the mold cavity is essentially defined but the other die remains spaced from the charge; (d) evacuating the mold cavity; (e) closing the mold so that the dies compress the charge to cause it to fill the mold cavity; (f) allowing the resin to cure; and (g) opening the dies and removing the part.

Claim 2

A method of making a part having a large surface area and providing the part with a smooth surface by compression molding a charge containing a curable resin, said method comprising: (a) opening a mold having an upper die and a lower die with opposing molding surfaces that cooperate to define a mold cavity having a shape corresponding to the desired shape of the part; (b) placing the charge on the molding surface of one of the dies so that the charge covers 40%-80% of the surface area of the molding surface, the charge being in the form of at least one ply of thermosetting sheet molding compound (SMC) containing a heat curable resin and reinforcing fibers therein; (c) moving the dies toward each other to a partially closed condition where the mold cavity is essentially defined but the other die remains spaced from the charge; (d) evacuating the mold cavity; (e) closing the mold so that the dies compress the charge to cause it to fill the mold cavity; (f) allowing the resin to cure; and (g) opening the dies and removing the part.

Claim 4

A method of making an automotive exterior body panel characterized by a large, generally flat surface which is desired to have a smooth finish, said method comprising: (a) opening a mold having an upper die and lower die with opposing molding surfaces cooperating to define a mold cavity having a shape corresponding to the desired shape of the panel; (b) placing a charge of sheet molding compound (SMC) on the molding surface of one of the dies so that the charge covers 40%-80% of the surface area of the molding surface; (c) moving the dies toward each other to a partially closed condition where the mold cavity is essentially defined but the other die remains spaced from the charge; (d) evacuating the mold cavity to at least 10 inches of mercury absolute within a period of less than 10 seconds; (e) closing the mold so that the dies compress the charge causing it to fill the mold cavity; (f) heating the charge to 140-160 degrees Centigrade under a pressure between the dies of 500-1500 psi; and (g) opening the dies and removing the panel.

Claim 5

A method of making an automotive exterior body panel characterized by a large, generally flat surface which is desired to have a smooth finish, said method comprising: (a) opening a mold having an upper die and lower die with opposing molding surfaces cooperating to define a mold cavity having a shape corresponding to the desired shape of the panel; (b) placing a charge of sheet molding compound (SMC) on the molding surface of one of the dies so that the charge covers 40%-80% of the surface area of the molding surface; (c) moving the dies toward each other to a partially closed condition where the mold cavity is essentially defined but the other die remains spaced from the charge; (d) evacuating the mold cavity to at least 10 inches of mercury absolute within a period of less than 10 seconds; (e) closing the mold so that the dies compress the charge causing it to fill the mold cavity; (f) heating the charge to 140-160 degrees Centigrade under a pressure between the dies of 500-1500 psi; and (g) opening the dies and removing the panel.

Claim 8

A method of making a fiber reinforced plastic part, said method comprising: (a) opening a mold having an upper die and a lower die with opposing moldings surfaces that cooperate to define a mold cavity having a shape corresponding to the desired shape of the part; (b) arranging plies of sheet molding compound (SMC) material on the molding surface of the one of the dies so that the plies cover 40-80 percent of the surface area of the molding surface, the maximum thickness of the plies being 1 inch; (c) moving dies toward each to a partially closed position where the mold cavity is essentially defined but the other die remains spaced from the charge; (d) evacuating the mold cavity to at least 5 inches of mercury absolute within a period of less than 5 seconds; (e) continuing the movement of the dies toward each other so that the other die contacts the plies causing the SMC to flow and fill the mold cavity; (f) allowing resin in the SMC to cure; and (g) opening the dies and removing the part.

Claim 9

A method of making a fiber reinforced plastic part, said method comprising: (a) opening a mold having an upper die and a lower die with opposing moldings surfaces that cooperate to define a mold cavity having a shape corresponding to the desired shape of the part; (b) arranging plies of sheet molding compound (SMC) material on the molding surface of the one of the dies so that the plies cover 40-80 percent of the surface area of the molding surface, the maximum thickness of the plies being 1 inch; (c) moving dies toward each to a partially closed position where the mold cavity is essentially defined but the other die remains spaced from the charge; (d) evacuating the mold cavity to at least 5 inches of mercury absolute within a period of less than 5 seconds; (e) continuing the movement of the dies toward each other so that the other die contacts the plies causing the SMC to flow and fill the mold cavity; (f) allowing resin in the SMC to cure; and (g) opening the dies and removing the part.

Claim 10

A method of compression molding a part so that it exhibits an extremely smooth surface finish that can be painted without substantial visualization of surface imperfections, said method comprising: (a) opening a mold having an upper die and a lower die with opposing molding surfaces that cooperate to define a mold cavity having a shape corresponding to the desired shape of the part; (b) placing a sheet molding compound charge on a molding surface of the lower die so that the charge covers 40-80 percent of the surface area of the molding surface of the lower die; (c) lowering the upper die towards the lower die to a partially closed position where the mold cavity is sealed but the upper die remains spaced from the charge; (d) evacuating the mold cavity before the upper die contacts the charge; (e) compressing the SMC charge with the upper die to cause the SMC charge to flow and fill the mold cavity; (f) opening the dies and removing the part; and (g) painting the part whereby the surface quality of the painted part is aesthetically pleasing.

Claim 11

A method of compression molding a part so that it exhibits an extremely smooth surface finish that can be painted without substantial visualization of surface imperfections, said method comprising: (a) opening a mold having an upper die and a lower die with opposing molding surfaces that cooperate to define a mold cavity having a shape corresponding to the desired shape of the part; (b) placing a sheet molding compound charge on a molding surface of the lower die so that the charge covers 40-80 percent of the surface area of the molding surface of the lower die; (c) lowering the upper die towards the lower die to a partially closed position where the mold cavity is sealed but the upper die remains spaced from the charge; (d) evacuating the mold cavity before the upper die contacts the charge; (e) compressing the SMC charge with the upper die to cause the SMC charge to flow and fill the mold cavity; (f) opening the dies and removing the part; and (g) painting the part whereby the surface quality of the painted part is aesthetically pleasing.

Claim 16

A method of making an automotive exterior body panel capable of being painted without requiring a previous in-mold coating processing step, said method comprising: opening a compression mold having an upper die and a lower die with opposing molding surfaces that cooperate to define a mold cavity having a shape corresponding to the desired shape of the panel; heating the dies to a temperature of at least 140° C.; placing not more than 4 plies of a sheet molding compound (SMC) charge on the lower die so that the charge covers 50-75 percent of the molding surface of the lower die; lowering the upper die towards the lower die to a partially closed position where the mold cavity is essentially defined and sealed but the upper die remains spaced from the charge; evacuating the mold cavity to at least 5 inches of mercury absolute within a period of less than 5 seconds; lowering the upper die until it contacts the charge and compresses it at a pressure of 500-1500 psi to cause the charge to flow and fill the mold cavity; opening the dies and removing the part; and painting the panel without requiring an in-mold coating step.

Claim 17

A method of making an automotive exterior body panel capable of being painted without requiring a previous in-mold coating processing step, said method comprising: opening a compression mold having an upper die and a lower die with opposing molding surfaces that cooperate to define a mold cavity having a shape corresponding to the desired shape of the panel; heating the dies to a temperature of at least 140° C.; placing not more than 4 plies of a sheet molding compound (SMC) charge on the lower die so that the charge covers 50-75 percent of the molding surface of the lower die; lowering the upper die towards the lower die to a partially closed position where the mold cavity is essentially defined and sealed but the upper die remains spaced from the charge; evacuating the mold cavity to at least 5 inches of mercury absolute within a period of less than 5 seconds; lowering the upper die until it contacts the charge and compresses it at a pressure of 500-1500 psi to cause the charge to flow and fill the mold cavity; opening the dies and removing the part; and painting the panel without requiring an in-mold coating step.

Claim 18

A method of making a fiber reinforced part with a large surface so that the surface is extremely smooth while the part remains structurally strong, said method comprising: (a) opening a mold having an upper die and a lower die with opposing molding surfaces that cooperate to define a mold cavity having a shape corresponding to the desired shape of the part, said mold further including a sealing ring surrounding the upper die; (b) placing a charge on the molding surface of the one of dies so that the charges covers 40-80 percent of the surface area of the molding surface, the charge being in the form of at least one ply of thermosetting sheet molding compound (SMC) containing a heat curable resin and reinforcing fibers therein; (c) lowering the upper die and sealing ring toward the lower die to a partially closed position where the sealing ring provides a vacuum seal around the mold cavity while the upper die remains spaced from the charge; (d) evacuating the mold cavity; (e) lowering the upper die so that it compresses the charge causing the charge to flow and fill the mold cavity; (f) allowing the resin to cure; and (g) opening the dies and removing the part.

Claim 19

A method of making a fiber reinforced part with a large surface so that the surface is extremely smooth while the part remains structurally strong, said method comprising: (a) opening a mold having an upper die and a lower die with opposing molding surfaces that cooperate to define a mold cavity having a shape corresponding to the desired shape of the part, said mold further including a sealing ring surrounding the upper die; (b) placing a charge on the molding surface of the one of dies so that the charges covers 40-80 percent of the surface area of the molding surface, the charge being in the form of at least one ply of thermosetting sheet molding compound (SMC) containing a heat curable resin and reinforcing fibers therein; (c) lowering the upper die and sealing ring toward the lower die to a partially closed position where the sealing ring provides a vacuum seal around the mold cavity while the upper die remains spaced from the charge; (d) evacuating the mold cavity; (e) lowering the upper die so that it compresses the charge causing the charge to flow and fill the mold cavity; (f) allowing the resin to cure; and (g) opening the dies and removing the part.