SAMPE Journal - November/December 2016 - 22

Feature Article
Design Guide Development for Additive
Manufacturing (FDM) of Composite Tooling
T. J. Schniepp
Stratasys, Inc., Eden Prairie, MN
Abstract
The advanced composites industry has a continual need for innovative tooling solutions to enable new applications and product improvements,
as well as address the constant demand for reductions in response (lead) time and costs. Stratasys Fused Deposition Modeling (FDM®) technologies
allow rapid production of highly capable composite tooling across a broad range of tool sizes, complexity, and cure temperatures. This paper will
outline the development efforts, testing, and characterization performed to produce a comprehensive design guide for 3D printed (FDM), high
temperature (>180°C) molds and mandrels for fabrication of composite structures.
Introduction
Fused Deposition Modeling (FDM) is a Stratasyspatented additive manufacturing technology that
builds parts layer-by-layer by heating and extruding
thermoplastic filament. FDM builds in a wide range of
standard, engineering-grade, and high-performance
thermoplastics, such as ABS, PC, and ULTEM™ resins.
FDM is becoming a technology of choice for rapid
production of high temperature (>180°C), low volume
composite lay-up and repair tools, as well as for moderate
(<165°C) temperature production sacrificial (washout) tooling. Relative to traditional tooling materials
and methods, FDM offers significant advantages in
terms of lead time, tool cost, and simplification of tool
design, fabrication, and use while enabling increased
functionality and geometric complexity.
To enable successful implementation and use of
FDM composite molds and mandrels (referred to as
"composite tooling" or "composite lay-up tooling" herein),
Stratasys has developed a comprehensive Design Guide
to address best practices for printed tooling, as well as
to provide relevant performance characterization data
and numerous examples of effective tool designs. A
summary of the development and characterization
efforts are presented herein.
Background and Purpose
Traditional
manufacturing
methods for high
performance fiber-reinforced polymer matrix (FRP)
composite structures require the use of hard tooling for the
mold or mandrel that dictates the shape of the final part.
The mold or mandrel is most commonly made of metallic
materials (aluminum, steel, or Invar alloys), although nonmetallic materials are also utilized (specialized composite
tooling materials, high temperature tooling board, etc.).
Regardless of material, tool fabrication typically requires
significant labor and machining, leading to high costs,
material waste, and long lead times, consisting of many
weeks for even relatively simple part shapes and many
months for more complex tools. The use of additive
manufacturing (or "3D printing"), and specifically FDM,
for composite tooling has demonstrated considerable
cost and lead time reductions while providing numerous
22

other advantages such as immense design freedom and
rapid iteration, nearly regardless of part complexity.
Stratasys FDM technology has been successfully
utilized for low volume composite lay-up and repair
tooling applications for years, but was limited by the
lack of materials capable of withstanding the 180°C cure
temperature frequently required for aerospace and similar
high performance structures, as well as a lack of design
knowledge and guidance. FDM materials ABS (and
ASA), PC, and ULTEM™ 9085 have been demonstrated
to be effective to temperatures up to 85°C, 135°C, and
150°C, respectively. With the introduction of ULTEM™
1010, FDM technology has demonstrated numerous
advantages for fabrication of composite structures
cured at temperatures in excess of 180°C and pressures
of 0.7 MPa.
Scope and Contents
The purpose of the Design Guide is to provide
engineers, designers, and manufacturers of composite
structures with the information and knowledge to
effectively design, produce, and use FDM composite
tooling, regardless of prior experience with or exposure
to additive manufacturing. This paper provides a subset
of the contents of the Design Guide and is intended to
inform readers regarding the general capabilities and
key considerations for FDM composite tooling, although
it will not contain the depth or detailed design aspects
provided in the Design Guide itself.
Tool Design, Production, and Use
Just as design and construction aspects of traditional
composite tooling vary depending on the material of
construction (e.g. Invar vs. carbon/epoxy), there are
factors and "key considerations" that are critical to the
effective design and use of FDM composite tooling. In
particular, in the context of the design and development
of the mold or mandrel, it is important to understand
and consider the processing parameters (e.g. cure
temperature, vacuum bagging scheme, and pressure)
for the composite structure, coefficient of thermal
expansion (CTE), tool/part tolerances, and the intended
use or application (e.g. tooling for small quantities of
SAMPE Journal, Volume 52, No. 6, November/December 2016

Table of Contents for the Digital Edition of SAMPE Journal - November/December 2016