GUIDE FOR IONITRIDING
- Materials that can be Ionitrided
include High Speed Steels, Mould, Tool & Die Steels, Stainless Steels, Alloy Machine
Steels, Carbon Steels and Cast Irons.
- Brazed and silver soldered parts
containing volatile metals( cadmium and zinc) must be avoided; silver brazed parts suffer
from reduced strength after Ionitriding.
- Select material and a hardness level
that during Ionitriding will not change dimensionally or drop in hardness. A part hardened
and double tempered at 1050 F, or higher, ensures stability in Ionitriding. To achieve the
optimum hardness for a material it should be used in a heat treated condition. For
hardening use only a vacuum furnace.
- Specify stress tempering before final
machining at 1050 F to ensure minimum distortion in lonitriding, especially on thin,
asymmetrical and heavily machined parts.
- For maximum stability of air
hardening High Speed Steels, Mould, Tool & Die Steels and Stainless Steels a Cryogenic
Treatment should be incorporated into the hardening process, usually after the first
temper.
- Indicate areas to be lonitrided,
masked and where optional; threads are masked unless otherwise specified. Critical
surfaces to be Ionitrided must be clean bare metal, free from burrs, very fine sharp
edges, de-carb and any form of treatment oxide or residue; lonitriding an RMS 15-30
surface is more effective than a rough or mirror finish.
- E.D.M. machined surfaces to be
lonitrided must be free of re-cast layer and after E.D.M. machining all parts must be
stress tempered; E.D.M. surfaces can be polished or given a fine abrasive grit blast to
remove oxides.
- When a polished finish is required,
use a water soluble polishing compound, preferably a diamond paste. Do not use compounds
containing silicones.
- Incorporate features to allow
stacking and handling lugs or threaded holes in heavy parts. Avoid sections with less than
30 degree angles, narrow slots, small blind holes and holes that exceed a ratio of length
10 times diameter.
- Blow out all threaded & blind
holes and areas that may hold dirt or metal fragments. Do not supply parts contaminated
with paint, plastics, rubber, residual salts from heat treat, chrome plating or containing
volatile metals, i.e., Brass, Zinc alloys and plating.
- Packaging must be provided to prevent
parts being damaged during transportation. A light coating of water soluble oil should be
applied to prevent parts rusting. Highly-polished surfaces should also be wrapped with a
plastic packaging film( food wrap).
- Purchase orders should state
lonitriding specifications, materials, part and serial numbers, history of previous
processes and note when dis-colouration is not permitted, e.g., Part # S-187, 4140 Rc
28-32, lonitride 0.010" - 0.015" T.C.D., Surface Hardness Hv 550-653 per AMS
2759/8.
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GUIDE
FOR P.V.D. COATING
- Materials that can be coated include
Carbides, High Speed Steels, Mould, Tool & Die Steels, Stainless Steels, and some
grades of Aluminum Bronze, Beryllium Copper, Carbon Steels, Nickel & Nickel Alloys and
Titanium & Titanium Alloys.
- Brazed and silver soldered parts
containing volatile metals( cadmium and zinc) must be avoided; silver brazed parts suffer
from reduced strength after the coating process.
- Select material and a hardness level
that during coating will not change dimensionally or drop in hardness. A part hardened and
double or triple tempered at 950F-975F, or higher, ensures stability in coating. For
hardening use only a vacuum furnace.
- Specify stress tempering before final
machining at 975F to ensure minimum distortion in the coating process, especially on thin,
asymmetrical and heavily machined parts.
- For maximum stability of air
hardening High Speed Steels, Mould, Tool & Die Steels and Stainless Steels a Cryogenic
Treatment should be incorporated into the hardening process, usually after the first
temper.
- Indicate areas to be coated, masked
and where optional; critical surfaces to be coated must be clean bare metal free from
burrs, de-carb and any form of treatment oxide or residue, including grinding burns,
cracks and glazing.
- To achieve optimum coating adhesion,
fine ground surfaces are necessary. The best surfaces for coating can be produced with CBN
grinding wheels, Alumina grinding wheels are not recommended. All parts require full
de-magnetizing before coating.
- E.D.M. machined surfaces to be coated
must be free of re-cast layer and after E.D.M. machining all parts must be stress
tempered; E.D.M. surfaces can be polished or given a fine abrasive grit blast to remove
oxides.
- When a polished finish is required,
use a water soluble polishing compound, preferably a diamond paste. Do not use compounds
containing silicones.
- Incorporate features to allow
stacking and handling lugs or threaded holes in heavy parts; avoid sections to be coated
with narrow slots and small blind holes.
- Blow out all threaded & blind
holes and areas that may hold dirt or metal fragments. Do not supply parts contaminated
with paint, plastics, rubber, residual salts from heat treat, chrome plating or containing
volatile metals, i.e., Brass, Zinc alloys and plating.
- Packaging must be provided to prevent
parts being damaged during transportation. A light coating of water soluble oil should be
applied to prevent parts rusting. Highly-polished surfaces should also be wrapped with a
plastic packaging film( food wrap).
- Purchase orders should state required
coating(s), thickness, material(s), part and serial number(s) and a history of heat
treatment and previous coatings. e.g., Part # S-287, D2 Rc 56-58 double tempered, TiCN
coat, 2-3 microns.
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MATERIAL GUIDE
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