What did the H-K9L optical glass cutting test measure?
The test measured total thickness variation (TTV), average thickness deviation, surface roughness Ra, and edge chipping on ten 6 x 70 x 70 mm sheets cut from a 70 x 70 x 70 mm H-K9L optical glass block. The material was cut on an ESO-GM machine with a 0.45 mm fully coated endless diamond wire.
What TTV result did the test achieve?
TTV ranged from 0.003 to 0.015 mm. Eight of the ten samples were at or below 0.010 mm. TTV is the difference between the highest and lowest measured thickness on a sample, so it should be reviewed together with the average thickness deviation.
What was the thickness tolerance?
Average thickness values ranged from 5.992 to 6.008 mm around the 6.000 mm nominal target. The largest positive and negative deviations were both 0.008 mm, keeping the sample averages within a +/-0.010 mm target.
What surface roughness and chipping results were recorded?
Average Ra values ranged from 0.72 to 0.94 micrometers, with an overall mean of 0.82 micrometers. Maximum edge chipping stayed below 10 micrometers for every sample. These results indicate a suitable starting surface for later grinding and polishing, subject to the customer's final optical specification.
Which process conditions supported the result?
The test used a 5 mm/min feed rate, 24 m/s linear wire speed, 160 N wire tension, cutting oil, and a 60 second wire-bowing step. The new wire was pre-run without load for 20 minutes, and wire-diameter compensation was adjusted from 0.47 to 0.48 mm as wear developed.
Read the complete original report
See Ensoll's full H-K9L optical glass cutting test report for the nine-point data tables, equipment images, and measurement methods.