Re: 6MT Centre Differential Rebuild Project
Posted: Wed Nov 11, 2015 11:23 pm
Hope I do not lose anybody here.....
Cryogenic heat treatment is useful in high alloy steels where, after heat treatment, residual austenite remains present at room temperatures. Having been heat treated initially through the critical part of the TTT (Time-Temperature-Transformation) curve, the austenite remains stable at room temperatures. However, the martensitic reaction can be continued where the work-piece is subjected to cryogenic temperatures (around -185*C). The residual austenite can continue the transformation into martensite improving the strength and hardness of the material.
Shot peening is a process where the surface of the work-piece is blasted with shot pellets with such force that the skin layer of the material is placed into compression. When the shot peened article is stressed, the outer shin must first negate the residual compressive stresses before going into tension. The effect is that the work-piece can deflect further (greater strain) before the surface can reach tensile force levels where a crack can occur and commence a fatigue failure. When I worked for an Australian automotive supplier the V8 gear parts and the 6-Cyl gear parts were the same. The V8 parts were put through a shot peening process that the 6-Cyl parts did not go through.
Micro Surfacing (also known as superfinishing) involves chemical or other assistance methods to achieve surface finish improvements to enhance wear performance and load bearing characteristics.
The characteristics of the viscous coupling can be changed by tailoring the viscosity of the silicone fluid. The nominal torque rating can be increased by using a higher viscosity fluid at the expense of "bind-up". Likewise be susceptibility to "bind-up" may be reduced by using a lower viscosity fluid, at the expense of all-wheel-drive traction.
Metal components within the centre differential unit are not presently failing, so pursuing technologies that concentrate on making them stronger may not be rewarding? Alternative viscosity fluids will tailor the torque characteristic of the differential. What characteristic were you thinking of upgrading?
Cryogenic heat treatment is useful in high alloy steels where, after heat treatment, residual austenite remains present at room temperatures. Having been heat treated initially through the critical part of the TTT (Time-Temperature-Transformation) curve, the austenite remains stable at room temperatures. However, the martensitic reaction can be continued where the work-piece is subjected to cryogenic temperatures (around -185*C). The residual austenite can continue the transformation into martensite improving the strength and hardness of the material.
Shot peening is a process where the surface of the work-piece is blasted with shot pellets with such force that the skin layer of the material is placed into compression. When the shot peened article is stressed, the outer shin must first negate the residual compressive stresses before going into tension. The effect is that the work-piece can deflect further (greater strain) before the surface can reach tensile force levels where a crack can occur and commence a fatigue failure. When I worked for an Australian automotive supplier the V8 gear parts and the 6-Cyl gear parts were the same. The V8 parts were put through a shot peening process that the 6-Cyl parts did not go through.
Micro Surfacing (also known as superfinishing) involves chemical or other assistance methods to achieve surface finish improvements to enhance wear performance and load bearing characteristics.
The characteristics of the viscous coupling can be changed by tailoring the viscosity of the silicone fluid. The nominal torque rating can be increased by using a higher viscosity fluid at the expense of "bind-up". Likewise be susceptibility to "bind-up" may be reduced by using a lower viscosity fluid, at the expense of all-wheel-drive traction.
Metal components within the centre differential unit are not presently failing, so pursuing technologies that concentrate on making them stronger may not be rewarding? Alternative viscosity fluids will tailor the torque characteristic of the differential. What characteristic were you thinking of upgrading?