JEC COMPOSITES MAGAZINE - Issue #79 - March 2013 - 109

Figure 3 shows the effect of reducing cycle
time on the total cost of a carbon fibre hood
outer panel. At a volume of 35,000 parts per
year, the total cost of a carbon fibre hood
outer panel ranges from $70-100, depending
on the cycle time.4 The carbon fibre itself
makes up 85-90% of the total part cost and is
the most significant cost component. However, reducing cycle time decreases the number of tools required, and therefore reduces
the total cost of the part by up to 27%.

Conclusions

Fig. 2: RTM resin viscosities of 5-minute (System A) and 2-minute (System B) curing systems

fully within 2 minutes at 115°C. As seen
from the figure, both systems have very
low and almost constant viscosity at the
recommended processing temperatures for
60 seconds.
At this temperature, even large and complex
parts can typically be impregnated fully
by using advanced RTM manufacturing
technologies, such as HP-RTM. System A
provides a bit more latency while System B
requires a higher level of temperature and
process control during the moulding cycle
to guarantee full cure. However, by using
higher temperatures or completing the cure
step outside the press-tool, cycle times can
be reduced substantially below the 2 minute
marker with the EPIKOTE 05475/EPIKURE 05500 system.

Cost considerations
Cycle time (fast curing) is an important factor in the total cost of a part, and affects how
many parts can be produced from a single
tool in a given time period. To meet annual
volume demands, a manufacturer may
require multiple sets of tools and presses,
adding significantly to their investment
and part costs. A number of studies have
compared the cost of composites with that
of steel and other automotive materials.3
The advent of new composite processing
equipment and resin systems, however,
means most of these studies’ assumed composite cycle times are outdated. Therefore,
previously-held notions about the viability
of composites for higher volume production
should be reconsidered.

New VOC-free and non-toxic liquid
moulding epoxy resin systems have been
developed that offer unique processing characteristics while providing fast overall cycle
times. These new systems cure so rapidly
that cycle times of about 2 minutes can be
attained utilizing modern manufacturing
technologies. With carbon fibre composites,
the cost of carbon fibre itself is the major
contributor to total cost. However, reduced
cycle time epoxy resin systems can help to
substantially reduce the manufacturing cost,
enabling further development of lightweight
automotive solutions. n
More information:
TRAC@momentive.com
www.momentive.com
References
1. Reichwein, Heinz-Gunter, Paul Langemeier, Tareq Hasson,
Michael Schendzielorz, “Light, Strong and Economical –
Epoxy Fiber-Reinforced Structures for Automotive Mass
Production”, http://www.speautomotive.com/SPEA_CD/
SPEA2010/pdf/TS/TS8.pdf, Society of Plastics Engineers
Automotive Composites Conference and Exhibition, Troy,
Michigan, USA (September 2010).
2. Sloan, Jeff, “Auto Composites Quest: One-Minute Cycle
Time?”, Composites Technology Magazine, http://short.
compositesworld.com/G651LhR0, Cincinnati, Ohio, USA
(August 2012).
3. Das, Sujit, “The Cost of Automotive Polymer Composites: A Review and Assessment of DOE’s Lightweight
Materials Composites Research”, http://www.ornl.
gov/~webworkscppr/y2001/rpt/108590.pdf, Energy Division,
Oak Ridge National Laboratory, United States Department of
Energy, Oak Ridge, Tennessee, USA (January 2001).
4. Ball, Cedric, Francis Defoor, Sigrid ter Heide, Roman
Hillermeier, “Material and Process Cost Comparison Model
(Internal Document), Momentive Specialty Chemicals, http://
www.momentive.com/Industry/automotive.aspx?id=73,

Fig. 3: Effect of cycle time reduction on total part cost - Example

Columbus, Ohio, USA (August 2012).

No79 March 2013

/ jec composites magazine 109

http://www.momentive.com http://www.speautomotive.com/SPEA_CD/SPEA2010/pdf/TS/TS8.pdf http://www.speautomotive.com/SPEA_CD/SPEA2010/pdf/TS/TS8.pdf http://short.compositesworld.com/G651LhR0 http://short.compositesworld.com/G651LhR0 http://www.ornl.gov/~webworkscppr/y2001/rpt/108590.pdf http://www.ornl.gov/~webworkscppr/y2001/rpt/108590.pdf http://www.momentive.com/Industry/automotive.aspx?id=73 http://www.momentive.com/Industry/automotive.aspx?id=73

JEC COMPOSITES MAGAZINE - Issue #79 - March 2013

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