Tuesday, May 26, 2009

Natural Finishing Media For Great Finishing Of Parts


Finishing media is used in the practice of finishing of parts. When the parts are loaded into the finishing machines – tumbling machines and vibratory finishing machines – along with the media, they rub with each other. The media has an harsh property which results in deburring, smoothing, polishing and cleaning of the parts. Finishing compounds may be used for the duration of the finishing practice to boost the effectiveness of the finishing media. Finishing media can be mostly classified into two categories. One is natural media like corn cob media and walnut shell media. The other category is artificial media like plastic deburring media and ceramic finishing media.

Corn cob media is made by grinding the hard wooden ring of the corn’s cob. It is prepared into an abrasive grit that can flow smoothly. Because it is natural, the corn cob media is environment friendly. This media is suitable for use with both tumbling and vibratory machines. It has great absorbent properties which makes it ideal to clean and dry parts. Corn cob grit can absorb oils, grease, dirt and moisture without causing a score or damaging the surface of the parts in any way. It is exceptional for use as a burnishing agent and is used for burnishing of metals in tumbling machines. Metals such as brass and bronze which are soft in nature get the desired finish with this media.

The corn cob media grit comes from coarse variety to super fine assortment to suit an assortment of parts, based on their mass and nature. This media is strong and does not break down effortlessly; It can be reused again and again and it cost effective. It reduces the cycle time of finishing operations. It is clean and can be incinerated and poses no health or environment danger. It has a soft abrasive action and can be securely used on fragile components to protect micro finishes. It is effective on both metallic and plastic parts.

Walnut shell media is another well-liked natural finishing media. It is equipped by grinding walnut shells that are tough and fibrous into grit – the grit sizes could be large or small based on the necessities. The nature of the parts plus the perforation size of the screen that is used to divide the parts from the media after the finishing process is over establish the grit size. Walnut shell media is also used in blasting machines apart from tumbling and vibratory machines. They are ideal to de-flash plastic parts and polishing and smoothing of metals like aluminium, bronze and brass.

Walnut shell media also comes in practical in oil drilling to avoid clogging during circulation and to impart anti-skid properties to paint which is used about swimming pools and walk ways. This media is angular and multi faceted. It lasts long and is reusable. Being natural, it is non toxic and environmentally protected. It is a soft abrasive that can preserve the primer coat while removing the top coat of paint from parts. It serves to progress the cycle time of the tumbling or vibratory finishing procedure.

Monday, May 25, 2009

Mass Finishing Parts Through Vibratory Finishing Machines

Mass finishing refers to the finishing method on several parts simultaneously. Finishing involves the deburing, polishing, smoothing, cleaning and separating of parts. The finishing method is carried out in a tumbling or vibratory machine, with finishing media, finishing compounds and the parts to be mass finished thrown in collectively.

Depending upon the nature of the parts that call for mass finishing, the finishing machine, finishing media and finishing compounds should be selected. In tumbling machines, parts can be tumbled with or without media. These machines are well suitable for aggressive cutting and producing shimmering polishes; they are good for working on edges and rounded corners. Vibratory machines are suitable for shaking parts and media at a elevated rate of speed; they are secure for use on fragile parts and these machines supply very smooth finishes even in parts with holes and deep recesses. Natural media like corn cob media and walnut shell media are used when a soft abrasive outcome is vital. For heavier abrasive needs, man made media like plastic and ceramic media can be used.

When common deburring has to be completed, ceramic media is very effective. Hard ceramic media are used for light deburring and polishing. Softer ceramic media that have more abrasive ingredients are used when more rapidly cutting is needed. If frail parts are subjected to mass finishing, plastic media can be used to give very smooth finishes without much shine. Because plastic media are much lighter compared to ceramic media, they do not hurt fragile parts. It is essential to use the right quantity of media for the amount of parts being finished so that the parts remain safe. Finishing compounds are used to boost the efficiency of the finishing media being used and to progress finishing cycle times. Compounds could be alkaline or acidic; they are very helpful in de-greasing and de-scaling and they also help in increasing cutting speeds.

Vibratory finishing machines are used in mass finishing of parts. They comprise of tubs called finishing or processing tubs that are vibrated at elevated speeds. The parts to be finished are put into the tub along with finishing media and when the tub vibrates, the parts and media graze against each other. This abrasive action produces the deburring of parts. The cutting action that happens in a vibratory system is precise and thorough. Compounds specially suited for vibratory systems can be used to provide better performance.

The vibratory finishing machines run at high speeds and very short strokes. So, they are powerful; yet, because of the short strokes, they do not place any undue stress on the parts. They can therefore be safely used on large parts like wing spans and landing struts. The vibratory finishing machines easily dislodge material from holes and recesses in parts like bores and can work very fragile parts without causing any damage. The vibratory machines can be automated very easily – a full automation can be done for a finishing process that is sequential in nature. It can also be used as part of a large batch finishing process.