Letter 290

Surface finish from Roller Burnishing

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I am a manufacturing engineer who would like to learn more about roller burnishing. I am currently developing a new product which will be manufactured from stainless steel. This new product will require a surface finish of 2-10 micron finish. I am attempting to turn a 16 micron finish on a lathe, and then try to burnish the surface to the final 2-10 micron finish. I have considered grinding and electropolishing.

I would be grateful for any input....

Thanks
Robert Shelton
Manufacturing Engineer

BOB SHELTON -

Whether or not electropolishing is required or advisable doesn't primarily hinge on what surface finish is desired, but on how important cleanliness, elimination of slivers, and passivation is is. An electropolished finish will be very smooth at a microscopic level, but it will be wavy if the substrate has not been well polished.

 
Ted Mooney, P.E.
finishing.com - Brick, NJ

What is Burnishing ?

Roller Burnishing is a Super-finishing process. It is a Cold Working process which produces a fine surface finish by the planetary rotation of hardened rollers over a bored or turned metal surface. Since all machined surfaces consist of a series of peaks and valleys of irregular height and spacing, the plastic deformation created by roller burnishing is a displacement of the material in the peaks which cold flows under pressure into the valleys. The result is a mirror-like finish with a tough, work hardened, wear and corrosion resistant surface. Lapping and Honing is eliminated.

ADVANTAGES OF ROLLER BURNISHING

Mirror Finish in One Pass, Accurate Sizing, Close Tolerances, Eliminates Lapping & Honing

Improved Metallurgical Properties - Work Hardened Surface, Increase in fatigue strength,

No Additional Machine Investment - attachable to any Standard Machine Tool Already Present in the Shop

Long Tool Life No Operator Skill Required Low Torque & Power Requirements Maximum Parts Interchangeability

Yashwant Pawar
- Mumbai, MS, India

hai, Iam shankaremarose here.I wish to do project in burnishing . i would be grate ful if somebody answers this . sir ,how to measure the burnishing force. iam using roller type burnishing tool which i have to fabricate.iam mounting the tool in lathe for cylindrical jobs.. moreover iam using hard material as my work piece.could u suggest me some tool material.. thanks

Shankar
student - Chennai, Tamil Nadu, India

Basically you have to mount a pneumatic cylinder on the saddle in the place of the tool post on your lathe at right angles to the work piece. You need also a pressure regulator a flow control valve, a pressure gauge and a lever operated three way poppet valve.This set up will ensure a constant regulated supply of air at your pneumatic cylinder. The cylinder will actuate the roller holdind shaft which is sliding in linear bearings so that there are no friction losses. Just behind the burnishing roller you will place on the shaft your force measuring strain gauges. The signal from the strain gauges is passed to an amplifier and then to a uv recorder. Deflection on the uv recorder show the measuring load at the tool.(You have to calibrate.)
Material for the roller is good a stainles steel . The roller could be radiused or flat. Loads from 400N-2.5 kN.

Mr. Symeon Krezias
- Athens ,Greece

Saw your request for burnishing information.

We found a website from a company called cogsdill and thats what they specialise in - they helped us no end with their technical knowledge.

Regards,

Lee Donaldson
- Nuneaton, Warwickshire, United Kingdom

You can able to measure the burnishing force with help of spring of known stiffness and dial gauge. keep the spring inside the tool. amd place the dial gauge at the end of the tool shank. the deflection of dial gauge multiplied by stiffness of the spring gives the value of burnishing force.
u can use tungsten carbide or diamond as the tool .

Devendra Kumar
Student - Chennai, Tamil Nadu and India

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