Page 26 - 3D Metal Printing Fall 2019

3D FEATURE
Automated Calibration
More lasers in a 3D metal printing setup can increase processing speed, but also can introduce complications distinct from those of printing with a single laser. These include scan-field alignment, the thermal state of the AM system, laser utilization and soot management. BY DR. ZACH MUPHREE
Manufacturers often experience an inverse relationship between speed and quality, but when making parts for aerospace, medical devices and other complex applications, quality is fundamental. Any gains in out- put that compromise the safety or utility of the part aren’t gains at all.
In the interest of faster production, additive manufacturing (AM)-equipment makers have been moving toward two-, and sometimes even four-laser setups. However, adding lasers can introduce complications quantitatively and quali- tatively distinct from those of printing with a single laser.
Laser Alignment
The addition of a second (or more) laser to an AM setup can raise concerns with scan-field alignment, particularly
Dr. Zach Muphree is vice president-tech- nical partnerships at Velo3D, Campbell, CA; www.velo3d.com.
Optimizes Multi-Laser System Performance
Fig. 1—In most systems, precisely aligning two laser spots requires external hardware, a tedious procedure often consisting of burning marks on a substrate and measuring the outcome. And, calibration must be performed at the build plane, as any change in the distance between the scan head and the measurement plane causes a corresponding alignment shift.
with aerospace components and other large parts. While one laser can individu- ally print many types of smaller medical parts, such as orthopedic replacements, printing larger parts that take up most of the build plate often requires multiple lasers to work in concert. Any slight laser misalignment can have big consequences. In engineering terms, that means that each scanning system must accurately align to the other within less than 50 microns difference throughout the build plate.
In most systems, precisely aligning two laser spots (Fig. 1) requires external hard- ware. The alignment procedure often con- sists of burning marks on a substrate and measuring the outcome, a tedious process. In addition, AM shops must perform the calibration at the build plane, since any change in the distance between the scan head and the measurement plane will cause a corresponding alignment shift.
The System’s Thermal State
...represents another important vari-
24 | 3D METAL PRINTING • FALL 2019
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