Rapid Prototyping Journal, Volume 21, Issue 1, January 2015.
Purpose Although Additive Manufacturing (AM), also known popularly as 3D printing, has set a new standard for ease of use and minimal restraint on geometric complexity, the mechanical part properties do not generally compare with conventional manufacturing processes. Contrary to other types of polymer processing, AM systems do not normally use (in-process) pressure during part consolidation. This research investigates the effects on material properties of layer by layer application of pressure during fabrication of polymeric parts by AM. Design/methodology/approach Tensile specimens were produced in Somos 201 using conventional laser sintering and Selective Laser Printing (SLP) - a process under development in the UK, which incorporates the use of pressure to assist layer consolidation. Findings Mechanical testing demonstrated the potential to additively manufacture parts with significantly improved microstructure and mechanical properties which match or exceed conventional processing. For example, the average elongation at break and ultimate tensile strength of a conventionally laser sintered thermoplastic elastomer (Somos 201) increased from 136 ± 28% and 4.9 ± 0.4 MPa, to 513 ± 35% and 10.4 ± 0.4 MPa respectively, when each layer was fused with in-process application of pressure (126 ± 9 kPa) by SLP. Research limitations/implications These results are based on relatively small sample size, but despite this, the trends observed are of significant importance to the elimination of voids and porosity in polymeric parts. Practical implications Layerwise application of pressure should be investigated further for defect elimination in AM. Originality/value This is the first study on the effects of layerwise application of pressure in combination with area-wide fusing.
Purpose Although Additive Manufacturing (AM), also known popularly as 3D printing, has set a new standard for ease of use and minimal restraint on geometric complexity, the mechanical part properties do not generally compare with conventional manufacturing processes. Contrary to other types of polymer processing, AM systems do not normally use (in-process) pressure during part consolidation. This research investigates the effects on material properties of layer by layer application of pressure during fabrication of polymeric parts by AM. Design/methodology/approach Tensile specimens were produced in Somos 201 using conventional laser sintering and Selective Laser Printing (SLP) - a process under development in the UK, which incorporates the use of pressure to assist layer consolidation. Findings Mechanical testing demonstrated the potential to additively manufacture parts with significantly improved microstructure and mechanical properties which match or exceed conventional processing. For example, the average elongation at break and ultimate tensile strength of a conventionally laser sintered thermoplastic elastomer (Somos 201) increased from 136 ± 28% and 4.9 ± 0.4 MPa, to 513 ± 35% and 10.4 ± 0.4 MPa respectively, when each layer was fused with in-process application of pressure (126 ± 9 kPa) by SLP. Research limitations/implications These results are based on relatively small sample size, but despite this, the trends observed are of significant importance to the elimination of voids and porosity in polymeric parts. Practical implications Layerwise application of pressure should be investigated further for defect elimination in AM. Originality/value This is the first study on the effects of layerwise application of pressure in combination with area-wide fusing.