Mass finishing can be best described as processes in which a number of parts are simultaneously finished. The finishing involves burnishing, deburring, cleaning, removing rust, polishing etc of the parts. The two main types of mass finishing are tumble or barrel finishing and vibratory finishing. In both types, a cyclical action is used to create a grinding action between the various surfaces. Some times, the parts are finished by rubbing against each other. But more often than not, some media is used to achieve finishing. The finishing process can be wet or dry. For a wet finishing, a liquid is used as a cleaner or abrasive. For a dry process plastic, ceramic or dry compounds are used as media. Finishing times vary with the composition of parts. For non ferrous materials, it could be just 10 minutes and for hardened steel, it could take more than 2 hours.
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. In batch process, a batch of parts are input, worked on and pulled out; the next batch is now input and so on. In a continuous process, the parts are fed and pulled out continuously. In a sequential process, the parts are put through a sequence of processes one after the other. Normally, after every sequence, the part is in a better finished state.
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 ceramic media, preformed resin bonded media, preformed shapes in steel, synthetic random shaped media, natural media in random shapes like rocks, cob meal, walnut shells etc. Compounds are used in mass finishing to aid in deburring, cutting, burnishing and so on.
Vibratory finishing machines are used in the vibratory finishing process. The 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 process. Loading and unloading vibratory finishing machines is easy. They also have the advantage of lesser cycle times, better cleaning and better color maintenance. These machines are easier to maintain as compared to tumblers. They can mass finish more parts and have less wear on media. Automating or semi automating them is easier compared to tumblers.
Vibrators 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 media to every part metal can be used for delicate parts. For more aggressive finishing, parts can be used without media. http://gravcollc.com/ will provide further details.
Posted 1 year, 3 months ago at 8:44 pm. Add a comment
Finishing media is a term used to describe material or materials that alters the appearance of a part by cutting off rough edges or deburring them. Finishing media is also used in cleaning, burnishing and polishing of parts and their surfaces. Further, they are used in anti rusting and coloring also. There are many types of finishing media like plastic finishing media, ceramic finishing media, Dry finishing media and wet and dry finishing compounds. There are machines like vibratory system, tumblers and spinning systems in which the finishing is carried out – by putting the finishing media and the parts together. The media rubs against the parts, effectively deburring them. The degree of finish can be manipulated by increasing or decreasing the speed of these machines. It can also be controlled by the type, size and shape of the media being used.
Walnut shells come under the category of dry finishing media; they are nothing but treated walnut shells. The shells are grounded to grit of varying dimensions to suit different needs (depending on the nature and weight of the part being finished). 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. It is also mixed with abrasive paints used typically around swimming pools, in walkways etc where they act as anti skid agents.
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 and vibratory systems and reduces finishing operations time substantially. Because it is only mildly abrasive, it retains micro finishes; while removing the top layer of paints, it protects the base coating of paints.
Deburring can be defined as a finishing method typically used in manufacturing and industrial units. Metals are made into parts of different shapes and sizes by welding, molding or casting etc. The resulting pieces have jagged edges called burrs. The process of removing the burrs is called deburring. It is essential to make high quality parts that are smooth and functional while being aesthetically appealing too. Abrasive materials are normally used as deburring media. The process of deburring is applied in the wood industry, for wood pieces too. Deburring media varies in composition, shape and size depending on the part being deburred. Ceramic deburring media is used for heavy metals, synthetic or plastic media is most suited for less aggressive needs, precision media that come as small pins and spheres are used on surfaces and parts that need precise and delicate handling, natural media like corn cob and walnut shells for non abrasive deburring and finishing compounds for deburring with a good polishing effect. For further details, log on to http://gravcollc.com/
Posted 1 year, 3 months ago at 8:25 pm. Add a comment
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 vibrators, tumblers and spinning machines among others that are used to produce the finish. The finishing media and compounds 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 that is powdered to different dimensions depending on the finish requirements. 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 as tumbling and vibratory media 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. They are bio degradable and organic in nature; they can be burned. They are very clean and pose no environmental threats. They can be used effectively on plastics as well as metal surfaces for giving a good finish. They are capable of absorbing water and oils and are effective cleaners. They can be used even on parts with micro finishes as the corn cob media does not harm the surfaces. They are very cost effective too.
Vibratory systems impart a cutting and finishing action by vibrating the processing tub at certain speeds which causes the media or vibratory compounds to scrub against the parts. The scrubbing action in turn removes or cuts sharp edges and provides a smooth finish on the parts. The vibratory compounds can be used in places where precise finishing is required. For instance, to remove excess material embedded in the recesses of a bore, they can be used effectively. They can also be used on large surfaces without worrying about the surface safety as they are gentle even on delicate parts. By controlling the speed of the vibratory system, it can be used on smaller or larger surfaces. BC-300X is one of the wet vibratory compounds and is used for burnishing of parts. It is acidic in nature and can be used on all metals. It is very effective with steel media. It is super effective in cleaning and imparts a corrosion inhibitor for all metals. BC-320 is a wet burnishing compound that works well in vibratory machines. It is specifically for use on aluminium metal and produces a very bright finish. For more information on finishing media, go to http://gravcollc.com/
Posted 1 year, 3 months ago at 8:00 pm. Add a comment