An analytical method to predict and compensate for residual stress-induced deformation in overhanging regions of internal channels fabricated using powder bed fusion

Kamat, Amar M.; Pei, Yu

doi:10.1016/j.addma.2019.100796

Cited by 26 publications

(29 citation statements)

References 49 publications

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“…Reference [13] In addition, thermal distortion is influenced by the scanning strategy and scanning time and can be improved by adjusting them. References [14][15][16] Kamat and Pei analytically calculated deformations due to residual stresses in parts with internal channels, which can be used to compensate for deformations [17]. To compensate for shrinkage effects, different scaling factors are applied to the individual 2D layers.…”

Section: Classical Methods To Compensate For Deviations In Additive Mmentioning

confidence: 99%

Compensation for Geometrical Deviations in Additive Manufacturing

et al. 2019

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The design of additive manufacturing processes, especially for batch production in industrial practice, is of high importance for the propagation of new additive manufacturing technology. Manual redesign procedures of the additive manufactured parts based on discrete measurement data or numerical meshes are error prone and hardly automatable. To achieve the required final accuracy of the parts, often, various iterations are necessary. To address these issues, a data-driven geometrical compensation approach is proposed that adapts concepts from forming technology. The measurement information of a first calibration cycle of manufactured parts is the basis of the approach. Through non-rigid transformations of the part geometry, a new shape for the subsequent additive manufacturing process was derived in a systematic way. Based on a purely geometrical approach, the systematic portion of part deviations can be compensated. The proposed concept is presented first and was applied to a sample fin-shaped part. The deviation data of three manufacturing cycles was utilised for validation and verification.

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Section: Classical Methods To Compensate For Deviations In Additive Mmentioning

confidence: 99%

Compensation for Geometrical Deviations in Additive Manufacturing

et al. 2019

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“…When θ > 45°, the effect of warp deformation on the contour offset has to be taken into account, as shown in Figure 9d and e. The warp deformation mainly induces shape deviations in the vertical direction while its effect in the horizontal direction is negligible. The vertical offset of layer i + 1 with respect to layer i was estimated by Kamat et al (Kamat and Pei 2019) to be:…”

Section: Effect Of Warp Deformation Of the Overhang Regionmentioning

confidence: 99%

“…The local melting/ cooling induces large temperature gradients in and around the melt pool causing intensive thermal stresses in the solidified layers. Thermal stress-induced warping does not deform the solid regions appreciably since these regions are constrained by many layers below; on the other hand, the overhang regions are unconstrained and suffer significant deflection due to stress relief during the process (Kamat and Pei 2019). Moreover, the melt depth is larger than the layer thickness (since previous layers are also remelted to ensure sufficient bonding between the built layers [Yadroitsev et al 2013;Kamath et al 2014]), which induces a shape deviation (such as dross [Charles et al 2020;Feng et al 2020]) since the solidified thickness is larger than the designed one.…”

Section: Introductionmentioning

confidence: 99%

“…The overhang angle (θ, measured with respect to the build direction) is a crucial parameter that affects the warp deflection of overhang regions as well as the surface roughness (Kamat and Pei 2019;Mingear et al 2019). An overhang angle of θ ∼ 45°is generally agreed upon as the critical value up to which overhang regions can be printed without support structures (Pakkanen et al 2016;Kadirgama et al 2018).…”

Section: Introductionmentioning

confidence: 99%

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Experimental and numerical investigation of the origin of surface roughness in laser powder bed fused overhang regions

Feng

Kamat

Sabooni

et al. 2021

Virtual and Physical Prototyping

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Surface roughness of laser powder bed fusion (L-PBF) printed overhang regions is a major contributor to deteriorated shape accuracy/surface quality. This study investigates the mechanisms behind the evolution of surface roughness (R a) in overhang regions. The evolution of surface morphology is the result of a combination of border track contour, powder adhesion, warp deformation, and dross formation, which is strongly related to the overhang angle (θ). When 0°≤ θ ≤ 15°, the overhang angle does not affect R a significantly since only a small area of the melt pool boundaries contacts the powder bed resulting in slight powder adhesion. When 15°< θ ≤ 50°, powder adhesion is enhanced by the melt pool sinking and the increased contact area between the melt pool boundary and powder bed. When θ > 50°, large waviness of the overhang contour, adhesion of powder clusters, severe warp deformation and dross formation increase R a sharply.

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“…The shape deviation of an L-PBF printed internal channel depends on its printing orientation, with horizontally printed channels suffering the most severe deformation and vertically printed ones the least [21]. For a horizontally printed circular channel, the cross-sectional shape deforms to an ellipse due to thermal stress-induced warp [21]. The critical overhang angle (with respect to the build direction) is often recognized as 45 • [22] beyond which support structures are usually required.…”

Section: Introductionmentioning

confidence: 99%

Investigation on shape deviation of horizontal interior circular channels fabricated by laser powder bed fusion

Feng

Chen

Kamat

et al. 2020

Additive Manufacturing

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The fabrication of horizontal interior circular channels poses some unique challenges to the laser powder bed fusion (L-PBF) process. The engineering challenge is to be able to print horizontal interior channels using L-PBF without using support structures, while the scientific challenge is to predict the shape deviation in the horizontal channel. This paper studies the geometric fidelity (roundness and shape deviation) of L-PBF printed horizontal interior circular channels (diameters 1− 3 mm) by developing experiment-based regression models and a preliminary computational fluid dynamics (CFD) simulation model. The roundness error is found to be affected by the shape/size of the melt pool, thermal stresses, beam offset, and the slicing algorithm. It is recommended that to decrease the roundness error, in addition to choosing a proper beam offset, the width/depth of the melt pool should be minimized by minimizing the volumetric energy density (smaller laser power or higher scanning speed). Shape deviation in overhanging structures is determined by the thermo-mechanical driven molten flow in the melt pool. Hanging structures with irregular profiles (dross) are formed due to the sinking of the melt pool on an unconsolidated powder bed under the effect of gravity, surface tension, and poor thermal conductivity. (Partially) unmelted powder randomly adheres to the edges of the melt pool enlarging the hanging structure and roughening the profile. Small laser power or large scanning speed benefits reducing the roundness error and hang-diameter ratio. 0 • or 45 • rotational linear scanning strategy can be selected for minimizing the roundness error or the hang-diameter ratio, respectively.

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An analytical method to predict and compensate for residual stress-induced deformation in overhanging regions of internal channels fabricated using powder bed fusion

Abstract: An analytical method to predict and compensate for residual stressinduced deformation in overhanging regions of internal channels fabricated using powder bed fusion.

Cited by 26 publications

References 49 publications

Compensation for Geometrical Deviations in Additive Manufacturing

Compensation for Geometrical Deviations in Additive Manufacturing

Experimental and numerical investigation of the origin of surface roughness in laser powder bed fused overhang regions

Investigation on shape deviation of horizontal interior circular channels fabricated by laser powder bed fusion

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