JEC COMPOSITES MAGAZINE - Issue #131 - Novembre/December 2019 - 57

machine SOLUTlONS

Composites increase machine
performance, operating speeds and accuracy

Ondrej Uher,
Research and development director
CompoTech

T

he reality, however, is that
composite parts can play
a vital role in revolutionising machine performance,
increasing operating speeds, accuracy and repeatability. This is
largely due to a modern, highly-automated manufacturing
process - axial fibre placement
- that offers particular advantages in the production of composite beams and tubes used in
machine tool and automation
systems.

In automation and machine tool applications, carbon fibre-reinforced
composite materials can offer significant productivity, quality and lifecycle cost benefits. Yet their adoption in the manufacturing sector has been
relatively slow. In part, this can be attributed to design engineers that
are unfamiliar with the properties of composites, underestimating their
benefits while overestimating the cost and complexity of their application; and to some extent, there has been a natural reluctance to change
from what is perceived as established manufacturing methods to a new
way of machine design and construction.

These can outperform their
traditional metal counterparts
across multiple dimensions,
while remaining extremely
cost-competitive.
Machine tool
performance requirements
Manufacturers of industrial
machine tools and automation
systems are facing pressure
from end users to continually
improve capacity, quality, and
throughput. These requirements translate into a number

Focus
The characteristics of carbon fibre-reinforced composite materials are well known:
-- High specific strength and stiffness allow the creation of parts
that offer excellent structural properties and low weight;
-- Composite structures can be manufactured in complex
shapes;
-- Alterations in material composition and lay-up allow the
physical properties of the end product to be tuned to match
the application's needs.
These characteristics have led to the widespread adoption of
carbon-reinforced materials in applications such as aerospace
and defence, motorsport and high-end automotive products, and
sporting goods.
Increasingly, however, users in the industrial sector are also
turning to carbon fibre materials as a route to improved machine
performance.

of potential competing performance requirements:
-- Larger machines, with moving elements that may be
several metres in length;
-- Motion systems capable of
high speeds and rapid levels
of acceleration and deceleration;
-- A high degree of stability,
accuracy and repeatability.
In addition to the challenges
inherent in the provision of
motion and control systems
on these large, high-performance machines, designers
must also select suitable structural elements.
These parts need to have a low
weight, while still offering sufficient strength and stiffness
to support both static and
dynamic loads with minimal
deflection.
Whichever material a designer
selects, the physical requirements of large, high-performance machines call for hollow section beams with large
cross sections and thin walls.
Structures of this type provide
the required stiffness and low
weight, but they can have oth-

N°131 November - December 2019

er characteristics that adversely
affect machine performance:
-- Vibration: If the natural
frequency of the member
itself, or its walls, is too close
to the machine's operating
frequencies, the resulting
resonance can significantly
impair performance, leading
to instability or inaccuracy
in use;
-- Thermal stability: A machine
may have to operate across
a wide temperature range,
due to changes in ambient
conditions, heat from the
workpiece or heat generated
during cutting, machining
or welding operations. Over
a large span, the resulting
thermal expansion can lead
to significant distortion;
-- Machine integration: Regardless of their inherent
characteristics, the members
have to integrate effectively
into the overall structure of
the machine. This means
they must accommodate
appropriate fixing points
for ancillary equipment,
brackets for axles or bearings,
or tracks for other moving
components.

/ jec composites magazine

57
JEC COMPOSITES MAGAZINE - Issue #131 - Novembre/December 2019

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