Page 200 - Chalcogenide Glasses for Infrared Optics

176 Cha pte r Se v e n

framework was welded together and attached to a wall. The units
were bolted together and bolted to the framework. The first extrusion
took place in July, using scrap Amtir 1 glass. Nitrogen pressure was
used to power the piston. The extruded rods were allowed to grow in
length almost to the floor before being cut off at the cylinder exit and
stacked with the others. The run was ended after the glass was
exhausted in the cylinder. Rods were cut into manageable lengths,
stacked, and glued together to be gang-cut to required lengths using
the diamond ID saw. Individual units had to be polished on both
ends. AMI purchased two small planetary polishers for the job. Plastic
plates with many holes the diameter of the rods were the polishing
gigs. Each small cut piece was placed in a hole on the plate, and then
the plate was placed on the rotating polishing pad. One pad was
coarse polish, and one was fine polish. The polishing process was
very fast. Hundreds of pieces could be produced each day. Tom Loretz
was present at the first run. He pointed out the unit was pneumatic,
not nearly as good as a unit in which the piston was powered by a
jackscrew. Using a pneumatic system would result in poor diameter
control. We could see that in volume production with Thermoscan
we would need an excellent system. We placed an order with CES to
design and build an extrusion unit based on a computer-controlled
jackscrew. Delivery would take quite a while.
Meanwhile we continued working with Thermoscan to produce
extruded parts from C1 core glass they could evaluate. Using the C1
glass was much easier than using Amtir 1 because of the lower soft-
ening point. By late September, AMI could build a case for being able
to produce 50,000 parts per month at a price of less than $2 each.
Unfortunately, Thermoscan was bought by Gillete. Jacob Fraden lost
control of technical decisions. Management used the threat of our
glass light pipes to force their present supplier to cut his price consid-
erably. By the end of 1993, it was apparent that there would be no
volume rod sales by AMI to Thermoscan.
The system designed by Tom Loretz was delivered in the spring
of 1995 and placed in operation. Figure 7.18 shows a diagram of the
computer-controlled system. On the left, the system is shown using
the tractor attachment that moves small-diameter rods, 1 to 5 mm in
diameter, from the die. On the right is the twin rail attachment that
both moves and supports the larger-diameter rods, say, 0.5 to 1.0 in.
The design and results of applications were described by Loretz
15
et al. at SPIE. AMI continued to develop the production methods,
concentrating on C1 glass drawing rods and plates. Figure 7.19 shows
a photograph of extruded rods and plate sections.
The rods were made for Peter Melling of Remspec. His intention
was to use long rods in place of ATR crystals in order to gain sensitivity
because of increased surface contact and many more reflections from
the inner surface.