During compression moulding of sheet moulding compound (SMC), voids are formed .. “Design for Success – A Design & Technology Manual for SMC/BMC”. Premix manufactures Sheet Molding Compounds (SMC) that are primarily used in compression molding. Premix offers SMC’s that are suitable for molding a. Most compression molding presses require that both the loading of SMC into the metals and even other polyesters such as bulk molding compound (BMC).

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Suitable applications are typically structural in nature with no flammability requirements.

Sheet Molding Compound, Bulk Molding Compound

Construction Applications — Composites. The straight plunger-type mold allows for some inaccuracy in the charge of plastic and produces a vertical flash. Design Engineer, Bus Manufacturer.

One significant example are automotive applications where the leading technologies are long fibre reinforced thermoplastics LFT and glass fiber mat reinforced thermoplastics GMT. With the latest of electronic servo motor to high pressure hydraulic pump users save considerable energy and the greatest in speed, distance, pressure, dwell time and burping movements. Ability to create complex parts, including B-side geometry? The operator would then stretch the bottle at the neck over the core to free the bottle.

Trimming and finishing costs are minimal. As a side note, remember not to allow any undercuts on the shape, it will make ejection especially difficult. The platens of the presses were steam heated. Compression-molding is also suitable for ultra-large basic shape production in sizes beyond the capacity of extrusion techniques. Complete Composite Solutions Request Information.

This method of molding is greatly used in manufacturing automotive parts such as hoods, fenders, scoops, spoilers, as well as smaller more intricate parts. LFI produces Class-A finishes right out of the mold. The mold was then pushed into the press. Combined with the straightforward nature and short production cycle of the compression molding process, parts made using SMC can be created in similarly high volume in a small amount of time.


No problem — LFI can even mimic fine textures such as stone and wood grain.

Compression molding

It is sturdy and durable, capable of resisting impact even at high speeds. The landed plunger type mold must have an accurate charge of plastic, and no flash is produced.

LFI consists of polyurethane mixed with chopped glass fibers — as the name suggests, longer fibers are used for greater strength and reinforcement. SMC feed material usually is cut to conform to the surface area of the mold. The start button hydraulically closed the vertical press to full pressure. The heat sheets removed from the mold were then transported to a die station.

Also, it is one of anf lowest cost molding methods compared with other methods such as transfer molding and injection molding ; moreover it wastes relatively little material, giving it an advantage when working with expensive compounds. For example; Molding water bottles used msc cut sheets from a roller die.

Compression molding – Wikipedia

The paste is spread uniformly onto the bottom film. Our off-the-shelf SMC can eliminate or reduce development time, translating to cost savings. Therein, the heat sheet all molded parts from that cycle were joined together by a parting line rind flash were placed in a transfer cart. Pre-heated SMC is placed into the lower half of the mold. Thermoplastic matrices are commonplace in mass production industries.

BMC is available in bulk bags as well as slug form.

Compression Molding Process / SMC

Terms of Use Privacy Policy. Ideal for applications where non-flammability is crucial. Designed-in ribs can add enhanced stiffness to your SMC part. All articles with unsourced statements Articles with unsourced statements from March Articles with unsourced statements from August Lastly, sheet molding compound is an extremely economical choice.

Intended for use in automotive or transportation body panels that require painting. The flash type mold must have an accurate charge of plastic and produces a horizontal flash excess material protruding from the mold.


The mixing operation can be done in a number of ways. Newsletter Sign up for our monthly newsletter! Compression molding was first developed to manufacture composite parts for metal replacement applications, compression molding is typically used to make larger flat or moderately curved parts. Bulk Molding Compound Offers Excellent Flow Characteristics Bulk Molding Compound BMC is a thermoset plastic resin blend of various inert fillers, fiber reinforcement, catalysts, stabilizers, and pigments that form a viscous, ‘puttylike’ injection molding compound.

Processing of SMC of is typically done by compression or injection molding. Manufacturers can save money on all aspects of the production process, from minimal labor costs to reduced waste.

In compression molding there are six important considerations that an engineer should bear in mind [ citation needed ]:. Guidance for light-weighting mass reduction of products mouldinf advanced moulving materials. Structural Thermoset Composites Structural thermosets are high-performance composites that are distinguished from standard compounds andd the use of more specialized resins both liquid and solid vinylester, epoxy, benzoxazine, etc.

Compression molding is also widely used to produce sandwich structures that incorporate a core material such as a honeycomb or polymer foam. Appearance critical parts that require a Class A paintable finish and structural applications that require high strength and stiffness but are not appearance critical. Compression molding is a high-volume, high-pressure method suitable for molding complex, high-strength fiberglass reinforcements. The first sheet was placed- one below a core and one sheet of equal size above the core, and then the top of the mold lowered by hand or by hoist to near shut.

The resin is applied in the form of a paste to a film; next, the fibers are cut and added to the paste. Materials that are typically manufactured through compression molding include: The start button moved the lower platen back into the press and the cure cycle bagan again.