SAMPE Journal - July/August 2011 - 37

Rapid/Affordable Composite Tooling Strategies Utilizing Fused Deposition Modeling
B. Macy Stratasys Inc., Eden Prairie, MN E-Mail: bill.macy@stratasys.com Abstract The need to reduce costs and cycle times while maintaining or improving quality and repeatability is a well appreciated challenge across manufacturing at-large. This challenge is even more evident in composite part fabrication. This paper will discuss practical examples that demonstrate solutions across the composite part manufacturing value stream. Fused deposition modeling (FDM) has been effectively used to provide solutions for patterns, molds, pre-forms, intensifiers, caul plates, lay-up tools, high strength soluble mandrels, trim & drill tools, and even secondary processes like bonding fixtures. In addition to tooling, FDM is also being successfully used for consumable cores that are being laminated or enveloped as an integral part of the final composite part. The ability to combine solid modeling with a digitally mastered, lights-out, environmentally friendly manufacturing process, which can produce everything from tooling to parts, enables new options for design, manufacturing and production. With these capabilities, companies can take advantage of the flexibility to rapidly respond to a wide range of needs. Today’s composite manufacturing market is dynamic and demands new solutions. This paper presents specific case studies in which FDM has been utilized to provide beneficial solutions for composite tooling and manufacturing. Introduction Current manufacturing challenges are well appreciated and many composite manufactures are looking for new methods to reduce product development cycle times. At the same time, manufacturers are looking to minimize the invested cost of tooling. FDM has been widely used for prototyping for many years, but specific case studies for composite applications and how the FDM technology can be utilized in composite fabrication is needed. This paper documents the application knowledge gathered from three case studies. These case studies provide real technical requirements in conjunction with the desire for reduced cycle times and minimized tooling costs. The results provide insight into how FDM can be used to obtain rapid/affordable tooling for composite applications. FDM Applications for Composite Manufacture FDM can be applied to many aspects of composite part fabrication at different stages of manufacture. Figure 1 shows an overview of the variety of applications FDM can address. Technical Introduction For FDM to be used successfully in composite applications the following parameters must be considered and correctly accounted for, including mechanical properties, service temperature, and coefficient of thermal expansion (CTE). FDM offers a variety of material options so the user must consider which material provides the best performance and cost trade for the application. Current material options are ABSM30, polycarbonate (PC), ULTEM 9085, and polyphenylsulfone (PPSF). Based on each material’s strength and heat deflection properties, as shown in Figure 2, the materials were evaluated for different applications. The findings of these evaluations are reported by service temperature and application in Figure 3. Service Temperatures The combination of material strength and heat deflection temperatures establishes what service temperatures each FDM material is capable of supporting. Figure 3 provides the application trial results that exposed tools to stated service temperatures, vacuum bagging, and autoclave pressures. Figure 3 displays that FDM can provide solutions for a wide range of composite tooling applications. Coefficient of Thermal Expansion (CTE) Composite tooling applications must allow for adequate temperature resistance to the cure cycle of the resin system as well as accommodate the resulting thermal growth of tooling at the cure temperature. Failure to account for these properties can result in poor quality parts or broken tools. Because FDM materials are thermoplastic in nature, their CTE is large relative to tradition tooling materials. Therefore, it is imperative that thermal growth be factored into the tooling plan. Ideally, FDM should be applied in applications where thermal expansion can be easily compensated, such as low temperature cure resins, smaller tools, or longer tools where thermal growth can be accounted for in final
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Figure 1. FDM composite applications.
SAMPE Journal, Volume 47, No. 4, July/August 2011

SAMPE Journal - July/August 2011

Table of Contents for the Digital Edition of SAMPE Journal - July/August 2011