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Laser metal deposition (LMD) is an important additive manufacturing (AM) technology, but the metallurgical defects, such as cracks and porosities, produced in LMD process…
Laser metal deposition (LMD) is an important additive manufacturing (AM) technology, but the metallurgical defects, such as cracks and porosities, produced in LMD process will seriously affect the mechanical properties of the parts. The purpose of this paper is to propose a novel in-process defects detection method based on infrared scanning for LMD.
The defects detection principle is that, after every three to five layers have been deposited, the optical head of a high-precision infrared two-color pyrometer is driven to scan the defects by measuring the abnormal temperature peaks on the deposited surface. The experiments for verifying the defects detection principle were carried out.
The relationship between the temperature peak value and the dimensions of the defect was analyzed based on the heat conduction theory and curves of temperature peak value versus crack width or diameter of porosity.
This method can effectively improve the detection accuracy and the defects can be precisely located, which can meet the requirement of laser targeting re-melting and elimination of the defects.
This paper seeks to describe the development of an inexpensive stereolithography (SL) system with high power ultraviolet light‐emitting diode (UV‐LED) curing light source…
This paper seeks to describe the development of an inexpensive stereolithography (SL) system with high power ultraviolet light‐emitting diode (UV‐LED) curing light source. The advantages of UV‐LED light source will be investigated and the results presented.
The working principle of the UV‐LED light‐based SL system (LED‐SL) and its characteristics were explicated; the effect of beam divergence angle on the shape of a single cured line was analyzed; and the effects of the shapes of single cured lines shone by different light sources on the fabrication accuracy were compared.
LED‐SL has significantly higher part fabrication efficiency and accuracy than UV lamplight‐based prototyping systems. Furthermore, the UV‐LED energy consumption is much lower than laser and UV lamp sources, which conforms to the requirement of Green Manufacturing.
In increasing the scanning speed, the vibration of the focusing lens set has an obvious effect on the scanning accuracy; therefore, further research is needed.
This research verified the feasibility of adopting high power UV‐LED as the light source for a rapid prototyping system and enhanced the versatility of conventional UV‐SL technology.