Effect of infra-red power level on the sintering behaviour in the high speed sintering process

• Published in: Rapid prototyping journal 2008-05, Vol.14 (3), p.155-160
• Main Authors: Majewski, C.E., Oduye, D., Thomas, H.R., Hopkinson, N.
• Format: Article
• Language: English
• Subjects: High speed; Islands; Lasers; Lean manufacturing; Manufacturing; Mechanical engineering; Mechanical properties; Methods; Microscopy; Optical microscopy; Powder beds; Production methods; Rapid prototyping; Sintering (powder metallurgy); Studies; Thickness
• ISSN: 1355-2546; 1758-7670
• DOI: 10.1108/13552540810878012

Purpose - To investigate the effects of the infra-red power level on sintering behaviour in the high speed sintering (HSS) process.Design methodology approach - Single-layer parts were produced using the HSS process, in order to determine the effect of the infra-red power level on the maximum achievable layer thickness, and the degree of sintering. The parts were examined using both optical microscopy and contact methods.Findings - It was initially expected that an increase in the infra-red lamp powder might allow an increase in the depth of sintering that could be achieved, as a result of increased thermal transfer through the powder. However, results in fact indicated that there is a maximum layer thickness that can be achieved, as a result of part shrinkage in the z direction. Optical microscopy images have shown that a greater degree of sintering occurs at higher power levels, which would be expected to correspond to an improvement in the mechanical properties of the parts produced. These images also indicate that the radiation absorbing material forms in small "islands" on the powder bed surface. As sintering progresses, these islands begin to merge; this occurs to a greater extent at higher infra-red lamp powers.Research limitations implications - These results are based only on single layer parts. Further work will examine the sintering characteristics of multiple layer parts.Practical implications - Results have shown that, whilst it is not possible to increase the achievable layer thickness of the parts produced by modifying the infra-red lamp power, the degree of sintering can be improved greatly by increasing the power.Originality value - HSS is an entirely new process which is currently still under development; the results presented here will directly impact the direction of further development and research into this process.