Sursulf Treatment and Lead Screws

Really, can't you do even a smidge of research on your own? If you had taken the time to do EVEN THE MOST RUDIMENTARY search:Tell me about the SURSULF Process

hmmm

I think I already tried that.

Can u tell me about its use in lead screw application?

Hello:

May be by this time you got answer to your queries. Sursulf is a salt bath process. The salt bath is oxidizing in nature and enables diffusion of nitrogen (& carbon !) into the ferrous material / component that is soaked in the bath. Tere are two types of case depths discussed. One is a white layer (so it appears under optical microscope) or compound zone and another is diffusion depth - the depth to which nitrogen has diffused. The compund zone imparts tribological properties on the component surface (resistance to wear, antisiezure,antigalling,antiscuffing, lower coefficient of friction, increased surfae hardness etc and the diffusion depth enhances the fatigue strength by increasing residual compressive stresses. Besides it also increases strength of cross section.

The Surface hardness obtained depends on the composition of th ferrous material treated, more alloying, more is the hardness. The process is carried out at 565 to 570 deg celsius (1065 deg F) for normally upto 120 minutes.

The limitation of Sursulf process are: (1) the treatment is equal to tempering at 1065 deg F and hence core properties are low. (2) Poor brinelling resistance (3) The process temperature can lead to rexlisation annealing of cold worked steel, bringing distortion nd drop in core strength and loss of work hardening effects.

Dr. Gopal / Chennai / India

hi,

u seem to have good knowledge of this treatment.

I am using EN41B (toughened to 25 to 30 HRC) material for nut, which is long & hollow on which sursulf will be done to a case depth of 0.2 mm (hardness 55 to 25 HRC)

The corresponding screw will of AMPCO 18 (al bronze).

WE need to reduce friction between the two under load, also the screw & nut assy is complex so maintenance is difficult. So, we are going for sursulf.

This treatment gives a surface which retains lubricant in the surface pores, so lubrication required is less.

Please comment.

Dear Dr Gopal,

You seem to have good in depth knowledge of the Sursulf Process. Could you please contact me offline on my number...

I am an entrepreneur based in Bangalore. I look forward to hearing from you.

Kind regards.

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Yes this can be done on lead screw - cross sectional strength and core strength are taken care of by design parameters like section thickness/diameter/thread metrology.

Dr. Gopal / Chennai / India