As I've had several request for alternative methods and materials for deburring radiusing surface polishing

of metals in general . I will be completing an article I've been working on ,which has expert opinions

techniques and accumulated experiences of well over a century from top professionals

in their respected fields . I will complete it this weekend and post parts pertaining too our forum needs

early next week . Hopefully the majority of you will find it useful and informative .

I'll be looking forward to that!

I had better start out by giving typical mesh size of abrasive materials in other words Grit Size

which are not always interchangeable between the two terminologies !. 12-2000 grit are commonly available .

An industry standard measurement is 400 grit 30 microns which equals 0.0012" 12000 micro mesh or 2 micron

equals 0.0001" . Which machinist will recognize as finer than frog hair on a baby's ass !.


This metal finishing article will be broken into a few different segments , so as to cover what would be practical

for our forum members in general .

De burring metal : When a process such as this is undertaken it’s generally to remove rough nibs unwanted appendages

from a surface . There are a few different methods in which to achieve this , grinding , filing ,shot blasting or peening

as well as mechanical vibratory abrasion . As many of you use tumblers and vibratory media for polishing metals

cases for the most part , we shall stick with abrasive metal removal .Deburring ,Radiusing , surface smoothing

polishing burnishing polish , degreasing and surface cleaning with media .

Known too the industry as Mechanical surface finishing sometimes referred too as mass economical vibratory

finishing processes . Keys to successful as well as repeatable metal surface finishes , start with choosing the correct

media and shape of media for the task at hand .

Days long gone by media was crushed grinding wheels , river stones , slag , corn cob , walnut and other shell hulls

Including ocean sea shells along with silica ( sand ) . Welcome too the 21 St. Century and modern media .

Ceramic , porcelain , Plastic polyester , urea formaldehyde , steel hardened , SS, silica beads ,aluminum oxide

silicon carbide , Zirconium and some of the old organics walnut , cob . I shall not venture into Diamonds or other

Highly expensive types of media for our forum proposes .

This may surprise some of you that 85-92% of media consists of ceramic or plastic resin either extruded or pressed .

Shapes are VERY IMPORTANT as is selecting the correct media and mesh or abrasive grit for a particular task .

Cleaning metals for any deburring or polishing process is very important . Ultrasonic is preferable with a degreasing agent

Or high pressure solution and rinse . It also can be accomplished in an agitation tub or tumbler , vibratory hopper and by

hand . Depending on circumstances either dry or wet . Let me point out a couple of benefits of wet slurry or Compound

Cleaning . Water serves as a coolant absorbs dust evenly disperses media in the working vessel and is the

Universal Solvent . A strong surfactant with detergent and fine abrasive degreases cleans , with little to no hand effort .

It also serves to keep media clean so as to work much more effectively and in many cases far quicker .

Media generates desired surface finishes , de burring , radiusing , smoothing , polishing . Constant media contact

with your parts not only accomplishes this but cushions parts from themselves avoiding impingement .

Media Shapes ; triangle, star , pyramid ,cylinder ,rhomboid ,parabolic ,ellipse ,ball , oval

cone ,and a few others I’ve surely forgotten .

Weight ; Ceramic 95-110 lb cu ft. , Plastic media 55– 85 lb cu ft. ,

Steel media 200-260 lb cu ft. Organic media Walnut shell Corn. cob 80-90 lb cu ft.

For aggressive grinding on tough metals ceramic media is generally material of choice .

Ceramics depending on parts shape as well as shape of media chosen can fracture or chip

and lodge in holes or undercuts of parts . Deburring example triangular cone pyramid or arrow

-head may be chosen .

Plastic media ; One I personally prefer too polish brass cases or aluminum ,zinc the softer

metals . Spherical ,cylinders , triangle or rhomboid combination in the smaller sizes

Seems to produce excellent polishing results . ( I mix 55-30-15 in the order listed ) .

Any combination of plastic ceramic and organic may be used as a “ Complex Media “.

Walnut corncob are normally used for drying media ( Yes they can also be used as polishing

media , we all know that ) in industrial application metal treatments if they are used at all .

Media shape is generally dictated by parts geometry ( This is VERY IMPORTANT to remember )

Small media produces a smoother finish , has more surface contact area also requires a longer

processing time . Large media faster removal of burs also for radiusing produces rougher

finishes . So required finish dictates media size ,material shape and type of abrasive .

Abrasive types Silica de burring ,deflashing of softer metals . Silicon carbide aggressive

grinding for tougher metals as is aluminum oxide . Zirconium mainly used in plastic media

for fine grinding . Media cost verses wear rate , lower the media wear rate lower your media cost .

Polishing Media can always be enhanced either by Compounds wet or semi dry paste rouge

or waxes . More on those at a later date .

I would like to thank ; Eugen Holzknecht for his

contribution on materials for this article as well as his dedication of service too the Industry

for over a quarter century .