Compression molding requires relatively inexpensive molds due to the lack of a machined sprue, runner and gate system.
Although the application of chopped carbon fiber composites are relatively new in automobile industry, studies of the SMC
compression molding can actually date back to several decades ago.
It's fabricated in a direct long fiber thermoplastic (DLFT) process from a PP
compression molding compound reinforced with long glass fiber rovings.
West Pharmaceutical India Packaging Private Ltd reported on Wednesday the start of construction on its new
compression molding facility on its 72,800 square meters of land located in Sri City, India.
Extrusion followed by injection molding and SMC followed by
compression molding both have been used to fabricate biocomposites to investigate the influence of processing on their performance.
SMC, formed using the
compression molding process, can now be analyzed by integrated numerical simulation.
Filling the gap between hand lay-up and
compression molding, the Pressure Diaphorm process is said to be ideal for manufacturing sporting goods and military, automotive, and industrial components in lot sizes between 1000 and 100,000.
He adds with more than a bit of understatement: "The throughput is limited by that cycle: that ends up being the bottleneck in the process." By way of comparison, the cycle time for
compression molding an SMC part is 180 seconds.
Compression Molding: A specific amount of liquid plasticizer was added drop-wise onto dried cellulose acetate powder, and the mixture was stirred mechanically in a kitchen mixer for 30 minutes.
Production
compression molding presses are said to be solidly built slab-side presses with steam, hot oil or electric platens up to 100" x 360" and 6,000 tons closing force.
He attributes this to the anisotropic orientation of polymer molecules and fiber reinforcements in extrusion and to the lack of any distributive mixing in
compression molding. Wilkinson cites the example of 30% carbon-fiber/ PEEK compound: "The best extruded samples can achieve a flex modulus of 1.2 million psi, and compression molded samples are under 1 million psi, but we can get 2.5 million psi with our process."
