Titanium Nitride (TiN) coating running against ?

[SoilentG]

Hi, we have a gear set that was designed by a contractor that selected 300 series gears running against 300 series gears... doh! Yes, their is galling! We've tried switching to TiN coating on both parts but the friction is greatly increased.

I was thinking of changing one of the gears to a different material but haven't seen many published values of friction values and wear values for TiN vs. ?

Does anyone have any suggestions?

Thanks,

Jeff

 

[swall]

A little more information would be helpful.First of all, is stainless required for the application? Do the gears get any lubrication? How highly loaded are they?

 

[SoilentG]

Gears: Very lightly loaded.

Environment: Non-corrosive office type.

Lubrication: Grease only, if any. Not sealed for oil.

 

[israelkk]

Use Aluminum 2024-T4 or 7075-T6 see PIC Design, Berg or SDP catalogs. The should be uncoated. Either machine tem after chromic anodize or mask them during coating.

 

[israelkk]

Are you sure you do not have binding due to incorrect center distance? This cab start galling. Can you provide more info on the gears?

 

[SoilentG]

Yes, we found that the alignment is a big issue but the SS vs. SS is also an issue. Coating them with TiN has increased the friction significantly. The good news is that the motors are so lightly loaded that in continuous operation before coating, they never got warm. So we can increase the current to offset the friction.

So, Aluminum vs. TiN is a good combo? Do you have any friction coefficients for this combo?

 

[swall]

I would be inclined to change one of the gears to 360 leaded brass.

 

[JTreglio]

TiN is a good hard coating, but if you want to prevent galling, consider sputter-deposited solid lubricants, such as MoS2, WS2, and WC/C. These materials will give you very low friction coefficients -- below 0.1.

Jim Treglio
Molecular Metallurgy, Inc.