(Materials for machining with monocrystalline diamond)

Electo-optics manufacturers require complex geometries combined with dimensional accuracy in the sub-micrometre range. The optical surface qualities needed are beyond the limits of conventional cutting tools.

However, ultra-precision machining using single crystalline diamond tools allows:

  • the manufacture of complex geometries
  • surface roughnesses in the nanometer range
  • dimensional accuracies in the sub-m range
  • the machining of a broad material spectrum of non-ferrous metals, plastics and crystals

Materials suitable for diamond machining:

Metals: Aluminum Alloys(1100, 2011, 2017, 2024, 5086, 5186, 6061, 7051); Brass; Copper(OFHC); Gold; Magnesium; Nickel (electroless and electrolytic plating); Silver; Tin; Zinc.

Polymers
: Acetal; Acrylic; Fluoroplastic; Nylon; Polycarbonate; Polystyrene; Polysulfane; Zeonex.

Crystals: Amtir; Barium Fluoride; Calcium Fluoride; Cesium Iodide; Gallium Arsenide; Germanium; KDP; Lithium Niobate; Potassium Bromide; Potassium-Dihydrogen-Phosphate; Silicon; Zinc Selenide; Zinc Sulfide (and Cleartran , a water-free form of Zinc Sulfide).

KDP is a water-soluble, nonlinear optical crystal often used as a frequency converter for short-pulse lasers.
It is part of a class of optical crystals which are difficult to polish because they are soft and water-soluble.
Single point diamond turning (SPDT) is the current state-of-the-art process for finishing KDP.
Spraymisting is used to achieve exceptionally high-quality optical surfaces.
(The mineral spraymist oil is removed with toluene or xylene.)

Materials not suitable for diamond machining:

Problems occur when SPDT processes are used with materials containing carbon e.g. optical glass, ceramics, ferrous metals etc

A chemical reaction (graphitization) occurs between the carbon and diamond tool due to the high temperatures of machining, and this rapidly destroys the cutting edge of the diamond tool. No real solution to this problem exists at this time and the potential value of e.g. cryogenic coolants is dubious (not cost-effective in production.)

Single crystal diamonds are the only material which can offer a tool edge radius of less than 50 nm and a cutting edge without notches, so various types of glass, ceramic, tungsten carbide etc are more suited to machining by grinding rather than by single point diamond turning.

Parameters for Optoform and Nanoform Ultra-Precision Machining Systems

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