Dough molding compound (DMC)

Dough molding compound (DMC)

Lay-up and filament winding methods of shaping composites are far too slow and labor-intensive to compete with steel pressings for car body panels and other enclosures. Sheet molding compounds (SMCs) and dough (or bulk) molding compounds (DMCs or BMCs) overcome this by allowing molding in a single operation between heated dies. To make SMC, polyester resin containing thickening agents and cheap particulates like calcium carbonate or silica dust is mixed with chopped fibers -- usually glass -- to form a sheet. The fibers lie more or less parallel to the plane of the sheet, but are randomly oriented in-plane, with a volume fraction between 15% and 40%. DMC is made in a similar way, but the mix has a higher concentration of filler and a lower volume fraction of chopped fiber (10% to 25%), which are randomly oriented in 3-dimensions. This makes a "pre-preg" with leather or dough-like consistency. When SMC sheet is pressed between hot dies it polymerizes, giving a strong, stiff sheet molding. DMC is molded in closed, heated dies to make more complex shapes - door handles, shaped levers, parts for washing machines and the like.

Source:
"Dough (Bulk) molding compound, DMC (BMC), polyester matrix", Granta CES Edupack 2018, accessed June 2020

General Applications: Car battery cases; door handles and window winders; washing machine parts such as lids; automotive vents, distributor caps and other small moldings; casings for telephones, gas and electricity meters.

Related Processes: Flexible Adhesives|Autoclave molding|Pultrusion|Resin transfer molding (RTM)|Vacuum and pressure bag molding|Vacuum assisted resin transfer molding (VARTM)|BMC (DMC) molding|Filament winding|Band sawing|Drilling|Milling|Turning/Boring/Parting|Abrasive jet machining and cutting|Laser cutting|Water-jet cutting|Cubic printing|Organic solvent-based painting|Pad printing|Silk screen printing|Water-based painting|Texturing|Vapor metallizing (PVD)

''

Record number: 1024