Surface evenness control of laser solid formed thin-walled parts based on the mathematical model of the single cladding layer thickness

Wang, Junhua; Han, Fuzhu; Ying, Weisheng

doi:10.2351/1.5067388

Cited by 4 publications

(2 citation statements)

References 23 publications

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“…When the laser power is too high, the deformation of thin-walled parts increases and the laser can easily burn through the parts; however, when the laser power is too low, a bright white band cannot be formed in the bonding area between the substrate and the alloy material, and the quality requirements of the cladding cannot be met [9]. Many factors affect the quality of thin-walled parts, and determining how to adjust these factors to ensure the quality of the cladding layer and control the deformation of the substrate has become the key to the success of the repair of thin-walled parts [10][11][12]. When repairing thin-walled parts, a large temperature gradient occurs between the cladding layer and the substrate, and there is a difference between the coefficients of thermal expansion of the substrate and the alloy powder; this leads to differences in the thermal expansion and cooling shrinkage of each local area, and cladding stress will occur in the cladding layer [13].…”

Section: Introductionmentioning

confidence: 99%

Study on the Deformation Control and Microstructures of Thin-Walled Parts Repaired by Laser Cladding

Huang

2020

Coatings

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To reduce the deformation and improve the quality of thin-walled parts repaired by laser cladding, a three-factor, three-level orthogonal experimental scheme was employed to clad Ni60 powder on thin-walled parts with a thickness of 3.5 mm. To measure the deformation of the thin-walled parts, a method of combining the meshing of the backs of the thin-walled parts and fixing one end of the parts during cladding was used. The effects of the powder feed rate, laser power, and scanning speed on the deformation of the thin-walled parts were studied via visual analysis and analysis of variance, and the process parameters that resulted in the minimum deformation were determined. The deformation process of the thin-walled parts and the causes of cladding stress were also studied, and the microstructure of the cladding layer with the minimum deformation was analyzed via scanning electron microscopy (SEM). The results reveal that the deformation of the thin-walled parts increased with the increase of laser power. The increases of the scanning speed and powder feed rate were found to reduce the deformation of thin-walled parts; the laser power was found to have a significant effect, and the powder feed rate was found to have no significant effect, on the deformation of thin-walled parts. The order of the influence of factors on the deformation of thin-walled parts from greatest to least was determined to be as follows: laser power > scanning speed > powder feed rate. The optimal parameters to obtain the minimum deformation and good metallurgical bonding of thin-walled parts were found to be a powder feed rate of 1.4 r/min, a laser power of 1100 W, and a scanning speed of 8 mm/s. From the bottom to the top, the crystal structure of the coating with the minimum deformation was found to be coarse dendrite, dendritic crystal, and equiaxed crystal.

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Section: Introductionmentioning

confidence: 99%

Study on the Deformation Control and Microstructures of Thin-Walled Parts Repaired by Laser Cladding

Huang

2020

Coatings

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“…In the ideal case, the z-increment should be equal to the single deposition height to assure the constant defocusing and single deposition height. However, owing the existing the fluctuation and instantaneous defects, the matching relation cannot be ideally assured that has been proved extremely detrimental to the surface quality and precision of thin-wall parts [63,64]. The effect of matching of z-increment and single deposition height on the fabrication of thin-wall is analyzed in the follow section.…”

Section: Surface Quality and Dimension Precisionmentioning

confidence: 99%

Macroscopic and Microstructural Features of Metal Thin-Wall Fabricated by Laser Material Deposition: A Review

et al. 2022

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Owing to the versatility without expanding the machine’s size, thin-wall has been widely used in high-value parts. The investigation of laser additive manufacturing (LAM), which has advantages such as high powder density, easy controllability, and excellent stability, on the fabrication of thin-wall has drawn much attention. In this paper, the research status of macroscopic and microstructural features of metal thin-wall fabricated by LAM has been reviewed. The deposition quality was mainly focused on the effect of process parameters and especially the matching of z-increment and single deposition height. Based on the grain size and growth of columnar, the characteristics of microstructures were analyzed. Considering the structural feature of thin-wall, the effect of grain size and phases on the hardness and distribution of hardness were discussed. The effect of grain size, phases and loading direction on the tensile properties were reviewed. The distribution and modification of thermal stress were presented.

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In situ monitoring of build height during powder-based laser metal deposition

Alam

Vargas-Uscategui

et al. 2022

Int J Adv Manuf Technol

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A powder-based laser metal deposition (LMD) system can fabricate customised three-dimensional (3D) parts, layer by layer, based upon a computer-aided design (CAD) model. However, the deposition will not always feature the expected geometry due to excessive heat input and inconsistent powder flow. Due to the layer-by-layer nature of LMD, geometrical error in one layer is compounded in all following layers and may result in a build failure. Thus, it is critical to monitor online the track and layer height. This study developed an in situ monitoring system integrating a webcam and a narrow bandpass filter. The laser/powder defocus distance was extracted from the melt pool images, and the track/layer height was calculated from the laser/powder defocusing distance and preprogrammed layer spacing. The presented approach does not need additional illumination sources and is a nonintrusive online method. Therefore, it is a potential precursor to a feedback build height control system. It also can be used for measuring omnidirectional height, i.e. height in different build directions relative to the substrate, which has been tested by fabricating two thin-wall structures with customised shapes. These online-measured height data were successfully validated against dimensional measurements from an offline 3D scanner, thus demonstrating the online system’s potential utility in a feedback control system for ensuring acceptable part geometrical accuracy.

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Surface evenness control of laser solid formed thin-walled parts based on the mathematical model of the single cladding layer thickness

Cited by 4 publications

References 23 publications

Study on the Deformation Control and Microstructures of Thin-Walled Parts Repaired by Laser Cladding

Study on the Deformation Control and Microstructures of Thin-Walled Parts Repaired by Laser Cladding

Macroscopic and Microstructural Features of Metal Thin-Wall Fabricated by Laser Material Deposition: A Review

In situ monitoring of build height during powder-based laser metal deposition

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