ABOVE: This Model HZ-85 machine is especially well suited for processing lengthy parts, and can also deburr, finish and polish parts in separate compartments to assure there is no part-on-part contact. The accelerated high-speed method makes it possible to process many parts in cycle times of only a few minutes.
Contributing Editor: Dave Davidson, Deburring/Finishing Technologist | 509.563.9859 | dryfinish@gmail.com | https://dryfinish.wixsite.com/iso-finish
If you have parts that need edge or surface finishing improvement and would like to have FREE sample part processing and a quotation developed for finishing the parts please contact Dave Davidson at dryfinish@gmail.com I can also be reached at 509.230.6821. Information about equipment for bringing Centrifugal Iso-Finishing capability to your facility is also available…
Avoiding Part-on-Part Contact…
Centrifugal Iso-Finishing is an accelerated mass finishing process that utilizes high force to perform deburring, smoothing and polishing rapidly on part edges and surfaces. The high-force of the interaction of abrasive or polishing materials on parts surfaces comes from the 10 G’s (or more) of force that is developed by the centrifugal forces developed by the machine for processing. This force makes it possible to develop edge and surface finish conditions up to ten times more rapidly than traditional mass finishing equipment that is limited to 1 G of media pressure or force against parts or components being finished.
PROBLEM: In small part finishing this centrifugal pressure does not seem to pose much of a problem for the process. Large numbers of parts in jewelry, dental, medical, screw machine and many other industries have been successfully deburred, smoothed and polished for many years without a problem when the finishing media and the parts are correctly loaded into the processing chamber of the machine. In recent years there has been an increasing demand for the fine-finishing and even super-finishing and polishing that this type of process can produce on ever-larger parts. (Some finishes as low as 1 micro-inch and lower have been achieved on certain of these parts). Many of the parts that require this type of fine finish have critical surfaces. Surface impingement arising from a part-on-part collision within the process chamber MUST BE AVOIDED.
SOLUTION. In recent years, some manufacturers have come up with centrifugal iso-finishing machines that are capable of processing large numbers of larger parts that would have posed a problem had the parts been run together in the same processing compartment. This is accomplished by arranging divider inserts to break up the larger processing compartment into sub-compartments so that these critical parts can now be centrifugally finished in its own segregated compartment. Some equipment designs have been modified so that hexagonal processing chambers are longer and now able to accommodate much larger numbers to meet higher production targets.
EXAMPLES: See below a video showing the process on some larger aluminum parts, which are first smoothed in a wet abrasive process and then dry polished for final finish treatment. (This same type of sequential processing is accomplished on ferrous alloys and other harder metals with a three-step sequence. In many cases the process cycle times involved for each step are thirty minutes or under)
Below are some process video footage demonstrations of high-speed centrifugal isotropic finishing. These automated edge and surface finishing methods are capable of producing very refined low micro-inch surfaces that can improve functional part performance and service life.
Centrifugal Iso-finishing Technology
Centrifugal barrel finishing (CBF) is a high-energy finishing method, which has come into widespread acceptance in the last 25-30 years. Similar in some respects to barrel finishing, in that, a drum-type container is partially filled with media and set in motion to create a sliding action of the contents, CBF is different from other finishing methods in some significant ways. Among these are the high pressures developed in terms of media contact with parts, the unique sliding action induced by rotational and centrifugal forces, and accelerated abrading or finishing action. As is true with other high energy processes, because time cycles are much abbreviated, surface finishes can be developed in minutes, which might tie up conventional equipment for many hours.
DIAGRAM: Centrifugal Barrel Finishing principles – high-intensity finishing is performed with barrels mounted on the periphery of a turret. The turret rotates providing the bulk of the centrifugal action, the barrels counter-rotate to provide the sliding abrasive action on parts.
The principle behind CBF is relatively straightforward. Opposing barrels or drums are positioned circumferentially on a turret. (Most systems have either two or four barrels mounted on the turret; some manufacturers favor a vertical and others a horizontal orientation for the turret.) As the turret rotates at high speed, the barrels are counter-rotated, creating very high G-forces or pressures, as well as considerable media sliding action within the drums. Pressures as high as 50 Gs have been claimed for some equipment. The more standard equipment types range in size from 1 ft3 (30 L) to 10 ft3, although much larger equipment has been built for some applications.
Media used in these types of processes tend to be a great deal smaller than the common sizes chosen for the barrel and vibratory processes. The smaller media, in such a high-pressure environment, are capable of performing much more work than would be the case in lower energy equipment. They also enhance access to all areas of the part and contribute to the ability of the equipment to develop very fine finishes. In addition to the ability to produce meaningful surface finish effects rapidly, and to produce fine finishes, CBF has the ability to impart compressive stress into critical parts that require extended metal fatigue resistance. Small and more delicate parts can also be processed with confidence, as the unique sliding action of the process seems to hold parts in position relative to each other, and there is generally little difficulty experienced with part impingement. Dry process media can be used in certain types of equipment and is useful for light deburring, polishing, and producing very refined isotropic super-finishes.
Below: Some additional parts featuring centrifugal iso-finishing and isotropic micro-finishing technology…
Mr. Davidson is a deburring/surface finishing specialist and consultant. He has contributed technical articles to Metal Finishing and other technical and trade publications and is the author of the Mass Finishing section in the current Metal Finishing Guidebook and Directory. He has also written and lectured extensively for the Society of Manufacturing Engineers, Society of Plastics Engineers, American Electroplaters and Surface Finishers Association and the Mass Finishing Job Shops Association. Mr. Davidson’s specialty is finishing process and finishing product development.
About Dave Davidson. I am a deburring and surface finishing specialist, consultant and advisor to SME’s [Society of Manufacturing Engineers] Technical Community Network. The focus of my activity is assisting manufacturers and machine shops with reducing their dependence on hand or manual deburring and finishing methods, and helping them to upgrade the edge and surface finish quality of their parts. I currently work from Norwich, NY but I assist clients nation-wide. I can arrange for free sample processing and process development for your challenging deburring and finishing needs and can provide you with either contract finishing services or the in-house capability to produce improved hands-free finishes on precision parts. I can be contacted at 509.563.9859 or dddavidson@deburring-tech-group.com Let me know if I can be helpful.
Please also take a look at the updated information on our (free) sample processing and process engineering services: https://dryfinish.wordpress.com/2016/08/05/contract-finishing-and-free-sample-part-processing-for-centrifugal-isotropic-finishing-and-polishing/
Free Sample Processing
Contract Deburring and Finishing Services
High Energy Finishing Equipment and Process Development
Mass Finishing Part Applications 