PVD Hard Thin Film Coatings

Sutton Tools surface coating facility (Surface Technology Coatings) is Australia’s only company providing a combined coating, nitriding and heat treatment service to industry with ultra-hard thin film coatings based on physical vapour deposition (PVD) technology. Using world-leading technology, coatings are available to solve a wide range of problems relating to friction and wear, thereby improving tool performance and increasing tool life.

Tools or components to be coated are first inspected to insure suitability for coating, and then cleaned using an automatic multi-step process to ensure that they are physically and chemically clean. This is of crucial importance to the success of the coating operation.

Benefits of Surface Technology PVD coatings include:

  • Longer tool life – 300% to 1000% increases are typical compared to uncoated
  • Increased productivity – tools can be run at higher feeds and speeds
  • Uniform thickness – will not alter critical dimensional tolerances of components or parts
  • Corrosion resistant – thermally and chemically stable
  • Not affected by most acids and alkalis
  • Smoother workpiece surfaces – one half the co-efficient of friction of uncoated surfaces results in better surface finish in machining and better mold release in casting operations
  • Lower maintenance costs – the significant increase in tool life means fewer tool changes and less down time
  • More regrinds possible due to the wear land being significantly reduced on coated tools

Preconditions for PVD Coatings

Materials that can be coated include carbides, high speed steels, hot work tool steels, certain copper alloys, stainless steels and nitridable alloy steels. Cold work tool steels can be coated if they are tempered at least three times at the maximum secondary hardening temperature. In general all materials that can withstand a coating temperature of 500ºC, without softening or distortion, can be successfully PVD coated. Certain coatings are applied at 600ºC and these are in general only suitable for carbide substrates. Brazed parts can also be coated if the brazing material is temperature resistant (melting point >600°C) and does not contain cadmium or zinc. Our first recommendation is that each new application should be evaluated using the combined knowledge of the tool user and coating center specialist to choose the best pre-treatment and coating.

Materials that can be coated

  • All secondary hardening tool steels
    – HSS Grades, examples: T-15, M-2, M-35, M-42, ASP Grades
    – Cold Work Tool Steels, examples: D-2, A-2
    – Hot Work Tool Steels, examples: H-13, H-11
  • Stainless Steels – 300 series (Austenitic) stainless, 400 Series (Martensitic) stainless, age hardenable Ph stainless (above H-950) examples: 304, 420, 410C, 17-4 Ph.
  • Carbide and Cermets – All carbide grades are acceptable
  • Carbide Tipped Tools – can be coated when brazing materials are free of Zinc and Cadmium
  • Note: Please consult Surface Technology Coatings before sending carbide tipped tools for coating to verify contents of brazing materials.
  • Pre-hardened steels, example: P20
  • Miscellaneous – Ampcoloy 940, 945 and others, Beryllium coppers, Titanium and Titanium Alloys, Nickel and Nickel Alloys, Inconels, monels, aerospace and refractory metals and alloys

Materials that can be coated but may lose hardness

Heat treated materials such as carbon and low alloy steels with tempering temperatures below 450°C will lose hardness points due to coating temperatures.

Materials that cannot be PVD Hard Thin Film coated

Assemblies, tools or parts that are glued, pinned, pressed or screwed together in a fixed or permanent position.
Any alloy materials which contain Zinc, Tin or Cadmium and other low vapour pressure alloy additions.
Leaded alloys, fusible alloys and most aluminium, zinc and magnesium alloys having low melting points.

Surfaces that are best for PVD Hard Thin Film Coating

Fine ground surfaces with a bright finish are best for maximum coating adhesion.
Ground surfaces should be free of burns, cracking and grinding wheel glazing.
Free cutting CBN grinding wheels produce excellent surfaces for coating due to lower grinding temperatures.

Tool surfaces that can be coated after specialised cleaning

  • Milled or Machined Surfaces
  • EDM Cut Surfaces
  • Surfaces cut by shaving
  • High temperature brazing
  • Black or steam oxide surfaces
  • Nitrided surfaces
  • Polished or lapped surfaces
  • Glass beaded surfaces

These surfaces can be successfully coated. However due to varying surface conditions, testing may be required to achieve the best coating adhesion.

Other surfaces requiring special treatment before coating

  • Rusted surfaces
  • Tools with paint or wax markings
  • Tools with layout die or protective plastic coatings
  • Chrome plated surfaces
  • Nickel plated surfaces
  • Used dies or molds should be free of residual material (dry or wet blast)

Conditions on Components

The components must be held for coating; therefore they must have holes, threads or surfaces that can remain uncoated. In order to coat a component all over generally requires two coats and is charged accordingly. It must be possible to mechanically mask surfaces which are to remain uncoated.

Components with internal surfaces (holes, slots) can also be coated. Depending on the geometry of the component, the coating thickness decreases with the depth of the hole or slot. Blind holes and female threads must be free of hardening salts and other contaminants. It is for this reason vacuum heat treatment is strongly recommended when PVD hard thin film coatings are to be applied.

For components that have been previously used in service prior to coating, please inform our staff as out-gassing is required to optimise coating adhesion.