VOL. 20 March ISSUE YEAR 2019

Good Vibrations

in Vol. 20 - March Issue - Year 2019
The Evolution of MMF

3D scanning

3D scanning

What MMF means?

Everyone can go on the internet and get a prompt definition like this:
Mass Metal Finishing is a group of manufacturing processes that allow large quantities of parts to be simultaneously finished. The goal of this type of finishing is to burnish, deburr, clean, radius, de-flash, descale, remove rust, polish, brighten, surface harden, prepare parts for further finishing, or break off die cast runners. The two main types of mass finishing are tumble finishing, also known as barrel finishing, and vibratory finishing.1 Both involve the use of a cyclical action to create grinding contact between surfaces. Sometimes the workpieces are finished against each other; however, usually a finishing medium is used. Mass finishing can be performed dry or wet; wet processes have liquid lubricants, cleaners, or abrasives, while dry processes do not. Cycle times can be as short as 10 minutes for nonferrous workpieces or as long as two hours for hardened steel.
Mass finishing processes can be configured as either batch systems, in which batches of workpieces are added, run, and removed before the next batch is run, or as continuous systems, in which the workpieces enter at one end and leave at the other end in the finished state. They may also be sequenced, which involves running the workpieces through multiple different mass finishing processes; usually, the finish becomes progressively finer. Due to the random action of the processes, mass finishing is as much an art as it is a science.2

The Origins About 2500 Years Ago

The origins of Mass Metal Finishing are most probably coming from the gladiators of the Antique Rome that, during their transfers with the chariots, using long jute bags, they placed their weapons, shields and helmets with a large amount of fine sand inside. These bags were left hanging, so as to receive the multiple stresses from the road surface that, in those days, was very sinuous. The sand, in contact with the surface of the metals, kept them smooth and shiny, without great efforts.

Mass Finishing Is As Much An Art As It Is a Science

Who has defined that MMF is as much an art than a science was probably right.
In fact, every scientific environment has rules governed by well-known mathematical formulations related to their own properties or dynamics.
It is also a matter of fact that MMF is only a « sub chapter » of a wider science, which is surface finishing, implemented in the wide courses of surface engineering.
On one hand, there are the implications of the too-many ramifications of these scientific fields and/or of their industrial fields of application.
Just to make an example, excluding coatings and electroplating areas, and trying to compare Surface Finishing fields and Mass Metal Finishing fields, how many are there?
In the MMF area, we may consider:
Barrelling (with rotary barrels, or with centrifugal barrels)
Vibratory finishing batch (with batch circular and trough vibrators)
Vibratory finishing through-feed (with circular vibrators or with linear tub vibrators)
Centrifugal disc finishing
Drag Finishing
Other evolutions of drag finishing, proposed with too many different names

In the SURFACE FINISHING area (excluding coatings and electroplating), we may consider:

Air and wheel blast
Manual airblast and wetblast cabinets
Satellite table blasting machines
Table blasting machines
Frame blasting machines
Pass through blasting machines
Shot peening and blasting cells and automatic systems
Shot blasting machines, cabins and systems

Grinding and buffing
Manual grinding and polishing machines
Rotary table grinding and polishing machines
Through feed grinding and polishing lines
Robotic finishing equipment based on belt grinding and buffing

Laser finishing solutions
Laser peening
Laser polishing
Colour Laser processing
Texturing Laser processing

Industrial Washing
Screw drum washing, rinsing and drying machines
Belt tunnel washing, rinsing and drying machines
Rotary basket washing, rinsing and drying machines
Basket batch washing, rinsing and drying machines
Ultrasonic washing batch cabinets
Ultrasonic through-feed and/or automatic systems

High pressure water jet deburring
High pressure water jet deburring and deflashing
Super High pressure water jet deburring and deflashing

Abrasive flow machining
Abrasive flow machining

Thermal deburring (TEM)
Thermal deburring (TEM)

The above list is just an example to understand how complex the world of surface finishing is (a part of it, excluding coatings and electrochemical) and how small the sub-world of MMF is.
If every scientific environment should have rules governed by well-known mathematical formulations, it is also true that some fields of surface finishing, like belt grinding for example, can rely on institutions and federations of producers of abrasives3 that are providing ISO standards as EN 12413, for Bonded Abrasives or EN 13743 for coated abrasives, or EN 13236 for precision super-abrasives, and so on.
Standard rules and definitions are not only helping safety, which is of course one of the priorities in all processes, but also allow the defining of an essential platform or scientific environment where rules can be governed by well-known mathematical formulations, because of referring to precise factors.
I have already considered these aspects in The « Good Vibrations » Of The Future in Vol.15 – January issue – year 2014, as a contributing Editor of MFN.
Later on, some important projects have started in Europe, with the aim to analyse the MMF process by a scientifically point of view, to define their mathematical models.

Accordingly, soon or later, the MMF could pass from art to science, thanks to the predictive technologies in the course of development - but it is still too early to expect something working at 360° in such a short time.

The Future Of MMF

To merge predictive technology applied to MMF, with the support of Artificial Intelligence, it is possible to enable future virtual tasks that today are related to physical trials and expensive laboratory tests, in order to verify the finishing level achievable in certain conditions on specific surfaces of workpieces.

The elaboration power of today’s computers, available almost to everyone, combined with smart software, could gradually do a couple of things, like:

Elaborate mass metal finishing solutions based on predictive technologies, becoming more and more evolved ;
Implement the predictive solutions perceived, with further options related to the tailor-made requirements of each user or industry (i.e. : based on the quality system issues, with the wish to define a solution according to the required Process Capability Indices Cpk or on the final cleanliness factor required, etc.).

Of course, required information would start from a « QQ W» check list, like Quantity and Quality of what, where « what » is a complex information modality based on 3D scanning, weight, alloy, hardness, surface  roughness, and much further data.

The alloy information, for example, will inform the AI of the elaboration software concerning the explosion risk involved in some kinds of alloys like magnesium, titan and aluminium as well as, in the case of iron components, which will impose certain choices regarding corrosion protection compounds, and so on.

One of the biggest interrogations emerging from the above is « how convenient » will it be to generate the mathematical model of a so « old » finishing technology as MMF, whilst at the same time, continuous evolution is providing innovative alternatives here and there?

And how large would be the strength to try to contain in a single data base all the main mathematical models of the so-complex scenario of machines, media, compounds, environmental issues, risk analysis issues, etc.?

But, also, how to get all the required data or, alternatively, how to create « ideal » models of machines, systems, media and compounds?

Many and more questions will soon arise, to the team working on this project and to any team that in future would like to accept this challenge.

1 Bibliography - Degarmo, E. Paul; Black, J T.; Kohser, Ronald A. (2003), Materials and Processes in Manufacturing (9th ed.), Wiley, ISBN 0-471-65653-4.
2 Source : Wikipedia, the free encyclopedia - References : Mass Finishing Handbook" by LaRoux Gillespie, Society of Manufacturing Engineers, 2007
3 A list is available at: ttps://www.fepa-abrasives.com/abrasive-fepa/members/national-associations

Good Vibrations
by Paolo Redaelli
Contributing Editor MFN and
Rollwasch® Italiana S.p.a.
Tel. +39.0362.930 334
Fax +39.0362.931 440
Email: paolo@mfn.li