JEC COMPOSITES MAGAZINE - Issue #135 - July/August 2020 - 22

MANUFACTURlNG method

The importance of FRP process specifications
Process specifications greatly influence the production method, which is
one of the three pillars of FRP (composite) design, together with the final
shape and the material.
Shuichiro Yoshida,
CEO
FRP consultant

he purpose of process specifications
is to manage and record the processes
required to ensure a minimum quality level of FRP products. FRP Consultant
highlights the importance of prioritizing
and defining the process parameters that
are expected to affect the quality of the FRP
product, in addition to data acquisition and
control. Not only does it allow to have a
bird's-eye view of the entire process, being
able to prioritize also helps understanding
the key components of the product, such as
the product drawings and the materials used,
or even what happens after the product is
commercialized.
Roles of FRP process specifications
Process specifications, referred by product
drawings, have two important roles (Figure
1). The first role is the management of key
parameters. Manufacturing FRP products
is a complex process that requires a large
amount of data. Blindly acquiring and
considering all this data is inefficient. It is
necessary to extract the key parameters that
ensure a minimum quality level and to share
the information relevant to both the design
and the manufacturing sides.
The second role is data storage. Whatever

the size of the company, industry, or country,
data storage is often insufficient. This leads to
a decisive issue: the delay in finding the cause
of market problems. Among the companies
supported by FRP Consultant, process specifications are discussed mainly by those that
are already mass producing FRP products
and are facing market problems. How often
key parameters are measured and how long
they are stored is crucial to solve potential
future problems.
Key parameters in FRP
product manufacturing
First, composite product designers need to
define the key parameters. There are two
key parameters that affect the quality of FRP
products: changes invisible from the outside,
and changes due to the environment. For
instance, the first parameter includes temperature and rotation speed when kneading the
FRP matrix resin, temperature and pressure
during moulding, or the amount of foreign
substances introduced during layup. The
changes due to the environment include
environmental parameters such as dust, in
addition to temperature and humidity during
material storage and layup before moulding.
These key parameters affect the properties of
the matrix resin, the occurrence of internal
defects, the moulding dimensions, etc.

Fig. 1: Role of FRP
Process Specs

jec composites magazine / N°135 July - August 2020

The properties of the matrix resin have a
significant influence on the mechanical and
physical properties of the FRP product. In
fact, an incorrect preparation of the matrix
resin is one of the issues encountered on the
market today. This type of internal defect
causes delamination.
As a result of an accelerated curing progress
of the matrix resin due to a condition difference in storage environment, the mould
will not properly close, which may lead to
dimensional irregularities. Also, FRP parts
tend to have large dimensions in addition to
anisotropic torsion, leading to subsequent
assembly issues.
Contents of FRP
process specifications
The conceptual diagram in Figure 2 shows
the basic structure of process specifications,
which includes many parameters. Summary
of key points in process specifications is
mentioned as below.
Pressure, temperature
and machining
Temperature and pressure are basic process
data, considering that the properties of the
matrix resin change due to the thermal history and that the pressure affects the size and
internal defects of the moulded FRP product.
FRP Consultant focus on the need to clarify
the parameters, their acquisition frequency,
and the storage period. In addition, if there is
a recommended moulding programme, the
details of the process parameters should be
specified with tolerances. The sensor system
is calibrated periodically to ensure the validity of the acquired data. It is also necessary
to define the setting related to machining
like rotation speeds because of the risk of

JEC COMPOSITES MAGAZINE - Issue #135 - July/August 2020

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