The Resource Guide To Metal Finishing With Equipment And Media
The finish of a product speaks volumes about it and hence it assumes a lot of importance.
How to achieve the best possible finish? Using walnut shell media and corn cob media and
finishing compounds, of course! Finishing media and finishing compounds as the names
suggest are materials used for providing the desired ‘finish’ or ‘polish’ to an object or part
using vibratory finishing machines and centrifugal barrel machines and more.
Finishing compounds come in 2 main varieties – wet compounds and dry compounds.
There products for different purposes including cleaning, rust proofing, burnishing, colouring
and ferrous cutting. These finishing compounds also come in standard packaging sizes of 5
gallons and 55 gallons. Dry finishing compounds (which are in powder form) are typically
used in burnishing, colouring, cleaning and cutting. BC-311 produces heavy lather and is
used in tumbling barrels for burnishing all kinds of equipment like deburring machines and
centrifugal barrel machines. Mass finishing can be best described as processes in which a
number of parts are simultaneously finished. The mass finishing involves burnishing,
deburring, cleaning, removing rust, polishing etc of the parts. The two main types of mass
finishing are tumbling barrels or barrel finishing and vibratory finishing machines.
Mass finishing is an art while being a science because the processes involve random
action. The mass finishing process could be organized as batch processes, continuous
processes or sequential processes. Media are used in mass finishing to accomplish one of
four things - cut, luster, parts separation and scrubbing of surfaces. The media could be
aluminium media, preformed walnut shell media, preformed resin bonded media, preformed
shapes in steel, synthetic random shaped media, natural media in random shapes like
rocks, corn cob media, ceramic etc. Vibratory finishing machines are used in the
vibratory finishing machines process. This vibratory finishing machines process involves
using components like water, finishing media and finishing compounds. Vibratory finishing
machines are designed to produce highly smooth surfaces and can act inside deep cavities
like tubes. It can be used on varied parts - for delicate parts or large surfaces, which may
not be possible in a tumbling barrels process. Loading and unloading vibratory finishing
machines is easy. They also have the advantage of lesser cycle times, better cleaning and
better color maintenance. Vibratory finishing machines typically do not have speed control;
however, a few of them do. The usual speed is 1700 vibrations per second; for lesser
speeds, the parts may sink to the bottom making the finishing process less effective.
Vibratory finishing machines work at optimum level when they are between 75% and
90% full. Three parts walnut shell media to every part metal can be used for delicate parts.
Finishing media and finishing compounds can be defined as material that are used to
remove sharp edges and burrs from parts to make them smooth and provide a good finish
and polish effect. There are deburring machines, vibratory finishing machines, mass
finishing machines, tumblers and spinning machines among others that are used to produce
the finish. The finishing compounds and corn cob media are used in these machines for
varying periods of time to give the desired finish or polish.

Corn cob media come under the dry finishing media type. It is treated corn cob media that
is powdered to different dimensions depending on the finish requirements including
vibratory finishing machines. They can be used to achieve very fine finishes in the 1 Ra
range and meet any requirements for a decorative finish. Corn cob media is environment
friendly as it is made from the hardened cob ring and is organic in nature. It has the
advantage of being capable of use in tumbling barrels and vibratory finishing machines and
can absorb oils, grease and dirt. It can be used to dry parts while keeping their surface safe.
Corn cob media also finds use as a burnishing grit for soft metals like brass and bronze.
The weight and type of the part to be finished determine the size of the corn grit in the
corn cob media.
The corn cob media are re-usable and long lasting as they do not break down easily.
Deburring machines is the process of removing jagged edges or protrusions from parts,
mostly wooden and metal parts. Deburring machines are used to accomplish the process
of deburring. Primarily two types of deburring machines used – tumbling barrels or
centrifugal barrel machines and vibratory finishing machines. Tumblers are used for mass
finishing of parts. They can be used for wet as well as dry finishing. These systems are well
suited for fast and efficient deburring of plastic and metal parts or components. There are
models that are available in different sizes from compact bench models to big barrels that
can be fixed on floors. Tumbling barrels systems are very important deburring machines in
use. They are typically used where heavy deburring is required. Barrels are ideal for heavy
loads. Dry tumbling barrels is used when delicate deburring machines are called for and
produces a smooth finish. Wet barrelling is used for metal processing to remove excess
material as well as to provide a polish.
Vibratory deburring machines are also used for mass finishing. They function by shaking
or vibrating the processing vessel, which causes the walnut shell media and parts to scrape
against each other thus accomplishing a deburr and producing a polish. These deburing
machines are precise and can deburr even recesses in the parts and hence they are very
well adapted for delicate and intricate components. They can also be used on large surfaces
because they have very short strokes and high speeds. These centrifugal barrel machines
can be automated quite easily compared to tumblers. Walnut shell media come under the
category of dry finishing media. The walnut shell media can be used in cleaning and
finishing applications. They are ideal for tumble finishing of metals like brass, bronze and
aluminium. Walnut shell grit finds use in oil well drilling, to keep the circulation going.
Walnut shell media is made by crushing the walnut – it is hard and fibrous in nature. They
are long lasting, angular and have many faces. They are mildly abrasive. The main
advantage of walnut shell media is bio degradability. It is there fore environment friendly
and non toxic. It can be reused many times over. It suits both tumbling barrels and
vibratory finishing machines and reduces finishing operations time substantially.