aloutzen
Mechanical
- Jul 10, 2003
- 1
I need some help if possible.
My company uses 2024-T351 as bond arbors for bonding liner to the inside of bearing races. Once the liner is adhered to the ID of the race, a tube shaped bond arbor is inserted into the race and the assembly is placed in an oven. The standard temperature we use is 315 deg F. As the assembly heats up, the bond arbor expands and sets the liner to the ID of the race. It also sets the diameter of the liner due to the amount of expansion that occurs.
This works really well most of the time, BUT after a while, an arbor that has been producing great parts starts to give us failures in the liner. These failures include voids under the liner as well as dimensional problems (undersize/oversize). We have inspected the arbors once they start producing bad parts and the hardness is down, the conductivity is up and the OD is exactly where it was when the parts were new.
As I understand it, the coefficient of thermal expansion does not change with the hardness of the material. Since it is aluminum, the CTE stays as that of aluminum. Is this correct? Would the parts expand faster/slower after repeated heatings? Does the temperature we are using cause the material to be overaged and how does that affect the pressure we would get at a temperature and the expansion of the part?
Basically, I am looking for anything I can get to help understand why these bond arbors "die" after being run through these heat cycles.
Any help you can offer would be greatly appreciated.
Thanks.
Andrew
My company uses 2024-T351 as bond arbors for bonding liner to the inside of bearing races. Once the liner is adhered to the ID of the race, a tube shaped bond arbor is inserted into the race and the assembly is placed in an oven. The standard temperature we use is 315 deg F. As the assembly heats up, the bond arbor expands and sets the liner to the ID of the race. It also sets the diameter of the liner due to the amount of expansion that occurs.
This works really well most of the time, BUT after a while, an arbor that has been producing great parts starts to give us failures in the liner. These failures include voids under the liner as well as dimensional problems (undersize/oversize). We have inspected the arbors once they start producing bad parts and the hardness is down, the conductivity is up and the OD is exactly where it was when the parts were new.
As I understand it, the coefficient of thermal expansion does not change with the hardness of the material. Since it is aluminum, the CTE stays as that of aluminum. Is this correct? Would the parts expand faster/slower after repeated heatings? Does the temperature we are using cause the material to be overaged and how does that affect the pressure we would get at a temperature and the expansion of the part?
Basically, I am looking for anything I can get to help understand why these bond arbors "die" after being run through these heat cycles.
Any help you can offer would be greatly appreciated.
Thanks.
Andrew
