Shotpeening and case hardening do have very little in common, but so does
grit or bead blasting and shotpeening. I'll explain:
- Case hardening is a heat-treat process whereby the outer layer of material
(metal) is made harder than the remaining substrate. This gives the item
strength, but makes it less brittle than if the whole part was heat-treated
to the harder value.
- Grit blasting or bead blasting is a mechanical means of removing paint,
cad plating, dirt, etc.
- Stress relief is normally done by baking metalic parts to alleviate the
residual stresses that build up over time as load cycles take their toll.
- Shotpeening is a process where metalic shot is directed under air pressure
to add a compressive layer to the surface of a metallic part. It is not
used to remove paint, etc. It is normally done to highly stressed parts
after the stress relief bake when a part is undergoing overhaul, and during
original manufacture. Its use helps to prevent cracks that form due to
tensile stress.
I am an engineer in the aircraft business - we use these processes
frequently. These processes are also very common in the automotive business
as well.
Michael Altomare
'77 Triumph Spitfire 1500
-----Original Message-----
From: Ryan Smith <shmitty99@hotmail.com>
To: spitdrvr@camalott.com <spitdrvr@camalott.com>
Cc: spitfires@autox.team.net <spitfires@autox.team.net>
Date: Monday, July 19, 1999 3:38 PM
Subject: Re: rebuilding the engine, with more than one question
>
>Actually shot peening and case hardening have very little in common. Shot
>peening is just a means of removing surface defects from the material. It
>does not make it harder in any way like heat treating or case hardening
>does. The purpose of shot peening is to remove the potential starting
place
>for a fracture. Fractures propigate from the weakest place in the surface
>so if the surface is made uniform the chance of a fatigue fracture is
>lessened.
>
>Ryan Smith
>72 Emerald Green Spitfire
>
>
>>From: "N.A. Campiglia III" <spitdrvr@camalott.com>
>>Patrick,
>> > 1) what is shot peening?
>>This is a process of relieving stress in metal structures. A regular
>...cut...
>Think of it this way, shot pening forms a kind of
>>toughened skin on the outside of the part sorta like case hardening...
>
>
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