2002 (Backfills for previous years) / DB reference years
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Author Boris Fritz, Rafiq Noorani, Integrated Systems and Aerostructures, Air Combat Systems, Northrop Grumman Corporation, Pico Rivera, CA USA bfritz@sll.northrop.com
Source Rapid Prototyping & Manufacturing 2000
Abstract Much research is being done to increase the mechanical properties of Rapid Prototyping (RP) Materials. The possibility of increased yield strength, thermal stability, stress relief and improved wear or abrasive resistance of existing RP materials would be very desirable. All these characteristics describe the effect of cryogenics processing on materials. However, almost all of this research has been done on metals. The little research that has been done in the plastics industry indicates that cryogenics processing can be effective and should be investigated for RP materials.
The term cryogenics refers generally to temperatures below -150 C (-238 F, or 123 K). In the following study, cryogenic processing is accomplished by slowly ramping the part temperature down to below -184 C (-300 F), keeping the part at that temperature for an extended period of time and then slowly ramping back up to room temperature.
The goal is to apply cryogenic processing to Ciba SL5220 and DSM Somos8110 photopolymer epoxy resins as well as to Stratasys' ABS thermoplastic material to see if they will benefit from this process. It is hoped that the materials to be tested will show greater wear resistance, abrasion resistance, fatigue resistance, and reduction in internal stresses. It may also make the materials less brittle without affecting hardness. A further goal is to see if cryogenic processing will protect a model from the distortion which occurs during thermal cure, and possibly obviate the need for a thermal cure. (Thermal cure is used to maximize the high temperature capability of a photopolymer).
Initial limited results of tensile test samples and impact test samples of the RP materials show promising results with the Photopolymers but not yet with the ABS material. XX