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Advanced in-situ thermal control for predictable and precise high speed sintering

High speed sintering (HSS) is an additive manufacturing process for polymers initially discovered and developed under EPSRC funded research. HSS is similar to laser sintering but replaces the laser with a combination of an inkjet print head and an infrared (IR) lamp. Instead of a laser moving across the cross-sectional area, the print head deposits radiation absorbing material (RAM) in the desired shape and the entire print bed is then irradiated with the IR lamp. Only areas which are covered in RAM absorb enough energy to sinter, the rest of the powder bed acts as a support for the next layer of powder. Replacing the laser can lead to considerable time savings as layer print time is independent of cross-sectional area.

Student

Joe Eastwood

Supervisor

Professor Richard Leach
Dr Simon Lawes

The HSS machine set up1.

Figure 1: The HSS machine set-up1.

HSS is now being commercialised by a number of companies including Xaar 3D from its 3D Printing Centre on Nottingham Science Park. The process requires measurement and control techniques to ensure reliability, repeatability and tight geometric tolerances of the parts made. HSS requires the development of non-contact methods of thermal measurement, using emissivity values from the build area. Key challenges lie in the simultaneous use of different build materials with differing emissivity and further temporal changes in emissivity observed during phase changes that are inherent to the process.

The aim of this project is to develop in-situ, non-contact measurement methods for the temperatures generated during the HSS process and consequently to develop the in-process control of these temperatures.

[1]   Thomas HR, Majewski CE, Oduye D and Hopkinson N. Effect of infra-red power level on the sintering behaviour in the high speed sintering process. Rapid Prototyping Journal, 14(3):155–160, 2008.

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