Low Stress, Vacuum - Chuck Mounting Techniques For The Diamond Machining Of Thin Substrates

Abstract

Commercially available diamond turning machines offer high levels of accuracy where the full potential of the machine is realised. Unfortunately, surface form accuracy and roughness are dependent on the limiting stiffness of the machine / workpiece environment. Vacuum chuck methods offer a high degree of stiffness combined with the opportunity of mounting substrates in a stress free manner. Thin substrates (4 -12 mm) are relatively easily stressed and the application of vacuum chuck mounting for such components, present many problems. These include deformations due to internal material stress, vibration, and the print -through effect.We have measured the reproducability of deformations caused by the print -through effect and have developed techniques for its elimination. The feasibility of using this print -through mechanism for machining non -rotationally symmetric forms is also discussed. ABSTRACTCommercially available diamond turning machines offer high levels of accuracy where the full potential of the machine is realised. Unfortunately, surface form accuracy and roughness are dependent on the limiting stiffness of the machine/workpiece environment. Vacuum chuck methods offer a high degree of stiffness combined with the opportunity of mounting substrates in a stress free manner. Thin substrates (4-12 mm) are relatively easily stressed and the application of vacuum chuck mounting for such components, present many problems. These include deformations due to internal material stress, vibration, and the print-through effect.We have measured the reproducability of deformations caused by the print-through effect and have developed techniques for its elimination. The feasibility of using this print-through mechanism for machining non-rotationally symmetric forms is also discussed.

Design and fabrication by Selective Laser Melting of a LIDAR reflective unit using Metal Matrix Composite material

“…The polishing operation is the most critical one since the internal structures affect the mirror surface and deteriorate the accuracy [12]. This phenomenon is called print-trough effect or quilting originally studied in [30] and well-known in the vacuum chuck mounting of mirrors [31]. Hence, particular care was addressed to this aspect in the mirror design.…”

Design and Fabrication Technology of Metal Mirrors Based on Additive Manufacturing: A Review

“…The quilting (print-through effect) stems from the influence of mechanical properties during SPDT and polishing [102]. Afterward, the support structures appear on the mirror surface under the FEA, thus deteriorating the surface accuracy (Figure 36).…”