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Machine Performance Evaluation
Published in Richard Leach, Simone Carmignato, Precision Metal Additive Manufacturing, 2020
The overall part geometry is mostly insensitive to error motions of the recoating axis, but certain error motions directly impact layer thickness and, therefore, process stability and consistency. The recoating system of a PBF machine is often an actuator that resembles actuators on a machine tool, either a linear actuator or a rotary stage. Again, tests similar to those conducted on machine tools are likely warranted. For a linear motion recoating system, only two error motions impact the geometry of the top layer of powder: straightness in the Z-direction (EZR) and roll (EAR) (see Figure 8.5).
Diagnostic and other applications of MTF equipment
Published in Tom L. Williams, The Optical Transfer Function of Imaging Systems, 2018
The basic MTF equipment in which the techniques described here were implemented, is illustrated in figure 12.1. The object generator consists of a slit illuminated with radiation modulated at a fixed frequency by a mechanical chopping disc. The slit is mounted on a small linear stage and can be moved perpendicular to itself and to the optical axis of the equipment, by a stepper motor. The complete object generator is mounted on a rotary stage, also driven by a stepper motor, that can rotate it about the optical axis in order to vary the azimuth of the slit.
Fabrication, Assembly, and Metrology of the Neutron Imaging Pinhole
Published in Fusion Science and Technology, 2018
John I. Martinez, Derek W. Schmidt, Thomas H. Day, Christopher Wilson, Valerie E. Fatherley
A key requirement of the program is the inspection of both the front and back of the 200-mm pinhole assembly. An OGP Quest 300 OCMM with a rotary stage was used to inspect the front and back of the pinhole. The accuracy of the rotary stage is 10 arc s; this results in a 5-µm variability at each end of the pinhole inspection. A fixture was used to hold on to the pinhole assembly using the same bolt pattern that will be used for final mounting at the National Ignition Facility (see Fig. 2b). The inspection coordinate system was set using the outer four penumbra profiles on both ends and creating an axis down the center of the four penumbra from one end to the other. The penumbra profiles were two half-circles mating together to create a circle. Each half of the penumbra half-circle was independently inspected, with the difference in centers reported as well. Inspection of each triangle groove reported the three corners and the circle inscribed by the three sides. External inspection references to tie the OCMM inspection at LANL to the coordinate measuring machine inspection at Lawrence Livermore National Laboratory (LLNL) were used. Ruby half-spheres were used for assembly surfaces at LLNL. These rubies were also optically and laser scanned as part of the inspection process for cross referencing.