In Figure 4 Fully Automated SMC line The SMC

In compression molding of thermosetting compounds, the hardening
process involves a chemical reaction called curing. Curing is irreversible in
nature due to cross linking of polymer chains. This chemical bond formation
requires application of heat. Once solidified, further heating does not lead to
melting but causes thermal decomposition of the compound. Hence, they cannot be
reshaped. They require low internal mold pressures of 40-100 bar and pressure
build up time of about 1 second. Due to curing, the forming process is
relatively slower with lower press velocities and longer cycle times (60-180
seconds).

Dieffenbacher provides complete production lines for the
following thermoset forming processes:

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1.     
SMC

SMC stands for sheet molding compound which is a compression molding process as
well as a fiber reinforced composite. The compound is composed of carbon or
glass fiber reinforcements in an epoxy resin matrix. It is tacky, plastic and
flexible in nature and supplied as continuous sheets. Figure x represents a
typical Dieffenbacher SMC Duroline.

Figure 4 Fully Automated SMC line

The SMC Duroline is a near
unmanned complete production line including milling, drilling and water-jet
cutting stations (11) for finishing the formed SMC components. SMC sheets are
unwounded at the unwinding station (1) and reduced to desired shapes and sizes
at the cutting station (2). The feeding robot with gripper (5) transfers the
cut sheets from the conveyor (3) onto a stacking table (4). The stacking table
monitors the weight of the stack to control volume of SMC material according to
predefined requirements. The feeding robot then transfers the SMC stack into
the mold cavity (8) of the high precision press (7). The unloading robot (9)
transfers the finished components onto a cooling station (14). The mold
cleaning robot (10) enables automatic press mold cleaning after a fixed number
of cycles.

SMC is suitable for manufacturing
automotive components which require excellent surface qualities like bumpers, air
deflectors, fenders, front panels etc.

2.     
D-SMC

The SMC Directline process provides
higher process stability and higher material quality by elimination of semi-finished
processes. In D-SMC, the semi-finished product is directly manufactured in the production
line before processing. This provides higher flexibility in recipe formulation and
helps in reducing storage and transportation costs. Further processing is similar
to a conventional SMC production line.