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Expertise and Capabilities — Abrasive Water Jet Cutting

Light-weighted Core Body for Mirror

Powerful and Precise
ITT operates one of the world's most powerful and precise abrasive waterjet cutting systems for machining lightweight, distortion-free mirror cores used in orbiting observatories, remote sensing satellites and ground-based telescope systems.

The waterjet system was used to cut 4in. diameter hexagonal cells with 0.060 in. (1.5mm) thick walls into a 27.5in. (0.7m) diameter core for the primary mirror on board Space Imaging EOSAT's IKONOS 1 commercial remote sensing satellite. Weighing 29.5 lbs. (13.4 kg), the finished 4in. (100mm) thick concave/convex mirror is part of a three-mirror anastigmat system designed and manufactured by ITT to capture sub-meter resolution Earth imagery.

Our Waterjet System
Our 250 horsepower, CNC-controlled five-axis gantry waterjet cutting system pressurizes water to 55,000 psi, and directs a stream with entrained abrasive particles through a nozzle a few mm in diameter. The effect is a supersonic water knife that slices easily through 8in. (200mm) thick glass materials, such as ULEŽand ZerodurŽ, with a machining accuracy of ą0.010 in (0.25mm). Depending on material depth, ITT can achieve cutting rates as fast as 4in. (100mm) per minute, significantly reducing manufacturing cost and production lead-time.

Our Process

Cutting Complex Designs
Abrasive waterjet cutting enables extensive engineering design and analysis to meet demanding application requirements. ITT has fully integrated the design and analysis tools with the waterjet process. The precision of the cutting action introduces minimal taper or stress in the mirror core walls. This optimizes design flexibility, and enables ITT to machine core structures to any shape or combination of shapes that can be represented mathematically. As a result, designers can overcome the limitations of uniform cell arrays in favor of optimized shapes and structures that give greater control over core stiffness and rigidity. For example:

ITT can rapidly produce mirror cores optimized for particular applications and mounting schemes. This can reduce the cost and complexity of mechanical components in the system.
In ultra-lightweight core designs, ITT can remove 90-95 percent of the glass, leaving strut walls as thin as 0.02in.(0.5mm).
Inside large core structures, ITT can reduce core weight by pocket-milling small cathedral-style supports that provide additional strength in the cells. This type of design can minimize high frequency errors on the mirror surface.

Fusing the Mirror and Core
Once machined with the waterjet cutter, core structures are fused to thin surface plates of the same material to become one contiguous, and thermally stable lightweight optic. See Low-Temperature Fusion Welding.