Vol. 16
January Issue
Year 2015

Good Vibrations

in Vol. 16 - January Issue - Year 2015
Evolution of Mass Metal Finishing!

A Wave Finishing unit RoboTEP, with a robot of 220 kg., and a rotary tank of 500 dm3 capacity for dry-finishing task

A Drag Finishing unit TEP-700-SHIFT with two processing tanks automatically shifting and rotary head with 8 satellites

A Centerless Vibratory finishing unit type SMR-D-120-SF, processing an aluminium wheel

A Drag Finishing unit TEP-200-HD with single processing tank and rotary head with 3 satellites

A Centerless Vibratory finishing unit type SMR-D-120-SF, processing a steel gear weighing about 250 kg.

Vibratory finishing, as well as barreling and disc finishing, are related to the so called "Mass Metal Finishing" technology. The meaning is simple and of immediate comprehension, although the use of vibratory finishing, for example, is extended also to non-metallic materials, such as polymers, ceramics, glass, wood, etc.
A sort of exception to the definition "mass" is, moreover, taking place more and more frequently by the increased use of machines for finishing parts "holded" individually by a frame or supported somehow, like the drag-finishing machines.
A similar kind of exception is represented by the "centerless" vibratory finishing machines, holding plates supporting several workpieces, or simply a single big workpiece. This kind of finishing is applied to all that kind of components where a very efficient finishing process is required or where, for some reasons, the pieces cannot be free in the finishing media (i.e.: a very heavy component, like a big gear).
A further kind of exception is represented by the wave finishing machines, holding single or multiple units of workpieces with a robot, or with a mechanical arm, and submerging them in the flowing media in rotation at relatively high speed. This kind of finishing is applied to components of various types, where the finishing cycle is so rapid, that the time to load the parts and unload them from a frame (i.e. of a drag-finishing unit) would be higher than the time required by the finishing. Another good reason to use the robot would be the possibility to expose some areas of the workpieces to the finishing action to the flowing media, instead of others, to achieve the required result.
The finishing tasks with holded workpieces, are not only substituting, for some applications, the "mass finishing" process, but are introducing new opportunities for the finishing of complex areas, special components and part where the finishing need is limited or concentrated in specific areas of the components.
On one hand, this kind of finishing process based on holding the workpieces are still classified as part of the "Mass Metal Finishing" field, because the techniques employed for the finishing process are using similar resources (finishing media, chemical compounds, etc.).
On the other hand, indeed, they are different by the typical "Mass Metal Finishing" process, because they are no more acting as far as the workpieces are concerned in a "mass" dynamic, but in a more precise way. Therefore, a most adequate identification for all these kinds of processes should be identified and applied into modern technical descriptions.
To coin a definition like "Precision Material Removal Finishing" is introducing a definition that could respond to the specific aim to identify the difference passing from a big rotary barrel or a big vibrator moving hundreds of kilograms of workpieces mixed with abrasive media or polishing media, to a robot handling one-by-one components in a precision way, although introducing them into a rotary tank similar to the one of a vibratory finishing machine with media similar to the ones employed in the "Mass Metal Finishing" processes. PMRF is related to processes applied to parts fixes, holded individually.
A definition like "Precision Material Removal Finishing" would make an important distinction of all the new generation technologies like:
Drag finishing;
Centerless vibratory finishing;
Wave finishing;
And all those similar finishing processes, perhaps with different names or identifications, having similar dynamics; the dynamics, to make the limits of this identification, are including finishing media and compounds typical or similar to the ones used in the "Mass Metal Finishing" processes, like barreling, vibratory finishing, disc finishing.
The above series of finishing technologies could be considered the evolution of the "Mass Metal Finishing" technology, which age is indeed quite relevant, being the first rotary barrels with natural stones introduced in Europe around the end of the forties and beginning of the fifties, so, this field is at least 65 � 70 years old.
Unlike the "Mass Metal Finishing", the technologies of "Precision Material Removal Finishing" are covering recent applications, part of which are using robotic technologies, like the Wave Finishing process, and part of which are refined applications of the most recent decennia so, in other words, the innovative and modern frontier of the old "Mass Metal Finishing" field.
The picture above represents the evolution of "Mass Metal Finishing" field since its origin (1948-50) to the current period (end of 2014, beginning of 2015), starting from the selection of natural stones, used in the fifties as the main finishing media, to the most sophisticated technologies of the third millennium, where the robot is acting as main substitute of the operator, to assure automation level and excellent finishing of the workpieces.
The correct use of this new terminology would be helpful for many uses, starting from technical communications such as: technical reviews, journals, web sites, database, exhibitions, etc.
The correct use of this new definition, would help also the manufacturers of machines, systems, media and compounds to identify and separate into the correct directory and category their manufacturing programs of MMF and PMRF machines and processes, support innovation programs such as R&D, Patents, etc., and optimize training courses and didactical activities.

Good Vibrations

by Paolo Redaelli
Contributing Editor MFN and
Rollwasch® Italiana S.p.a.

Author: Paolo Redaelli

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