SAMPE Journal - November/December 2016 - 28

Feature Article
As can be seen, there is very little dimensional change
and the inherent variability and accuracy limits of the
3D metrology system itself certainly come into play as a
likely source of the observed variation.
Moisture Exposure
As expected, moisture exposure testing demonstrated
that tools dried (4 hours at 125°C) prior to use produce
laminates of acceptable quality (no significant porosity
or other obvious issues). Results for the evaluation of
laminates produced on moisture saturated tools without
drying prior to lay-up and cure was not complete at time
of publication.
Tool Life
The empirical portion of tool life characterization
(as described previously) was not complete at time of
publication. As a result, only the analytical test data
is presented. As described, DMA was performed to
evaluate creep resulting from flexural loading (0.7 MPa)
at 180°C, 195°C, and 205°C. TTS was then used to
project long-term behavior. The resulting relationship
is shown in Figure 6. Again, it is important to note that
this data was obtained under flexural loading conditions
and is expected to be a significantly harsher loading
condition than the actual cyclic compressive loading that

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28

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composite tooling experiences in reality. That said, the
results support that an ULTEM™ 1010 composite tool
is capable of performing well beyond the requirements
of prototyping volumes. The flexural strain at failure
for ULTEM™ 1010 was determined to be 3.5% (tested
per ASTM D790)3. Even a very low strain of 0.1% is
not predicted to occur until 80+ hours of exposure at
180°C and 0.7 MPa. Refer to Conclusions for additional
information.
Conclusions
Stratasys FDM technology has been successfully
utilized for low volume composite lay-up and repair
tooling applications for years. More recently, the
introduction of ULTEM™ 1010 has enabled expansion of
the technology into tooling for high temperature (180°C)
cure composite structures. A comprehensive Design
Guide has been developed to provide the information
and knowledge to assist in unlocking the potential value
of FDM composite tooling. A sub-set of the information
assembled for the Design Guide was presented herein,
including an introduction to the "key considerations" for
FDM tooling, as well as some important characterization
data.
Of particular importance, the tool life characterization
work performed to date was found to be very encouraging.
Given that the flexural strain at failure is 3.5% and even
using a much lower threshold for acceptance, ULTEM™
1010 demonstrates the ability to perform under harsher
loading conditions (flex) for the equivalent of dozens
of high temperature, high pressure autoclave cycles,
perhaps even 100+ cycles (refer to Figure 6). And of
course, use of lower pressure (and/or lower temperature)
cure cycles will only extend the usable life. This data
also suggests that for use with the relatively low loading
produced in vacuum-bag only cycles, tool life is not a
significant concern for typical aerospace industry part
volumes (at least from the perspective of creep-induced
tool deformation). Further testing is necessary to confirm
and develop a more comprehensive understanding and
additional tool life characterization continues to be point
of emphasis. Future development data will be included
in subsequent versions of the Design Guide.
References
1. TA Instruments. "Application of Time-Temperature
Superposition Principles to DMA." Thermal Analysis
Application Brief, number TA-144. 29 January 2016.
www.tainstruments.com.
2. A.V. Tobolsky. Properties and Structures of Polymers.
Wiley, New York, 1960.
3. Stratasys, Inc. "ULTEM 1010 Resin Spec Sheet." 29
January 2016. www.stratasys.com.

SAMPE Journal, Volume 52, No. 6, November/December 2016
http://www.tainstruments.com http://www.acrolab.com http://www.stratasys.com
Table of Contents for the Digital Edition of SAMPE Journal - November/December 2016
