One
of the most antiquated technologies found in many manufacturing
plants today is mechanical (mass) finishing equipment. In some cases,
this is so because the old process is still the best for a particular
application. In many other cases, the process is simply not updated
because it is not understood. Mechanical finishing is often regarded
as a “black magic.” As we know, since engineers work with
variables not potions, the old process is left alone. It is also
regarded as a dirty, noisy process that is operated by the least
experienced and trained people in the plant but is often dominated
by a single “seasoned” employee who knows the process
and what to do to fix it if necessary.
Because
of this, one of the best opportunities for savings in the manufacturing
process can be found in deburring, radiusing, edge breaking, surface
improving, burnishing, polishing or de-flashing processes.
First,
are you improving an existing process or are you exploring alternatives
for a new part and process?
To
upgrade a current process, time must be spent identifying and understanding
your process. By using the following parameter list, record the
values associated with your current process and determine the cost
(per load, hour, day, part). Besides giving you the information
you need to start seeking improvements, this exercise will make
you familiar with mechanical finishing in general, and you will
become more capable of managing this process. As you identify the
values for the above parameters, you will also identify variables
unique to your plant and process.
Often
overlooked is the consistency of the part coming to the mechanical
finishing process. The mechanical finishing process is often unfairly
expected to “remove a burr,” “refine a surface”
or “remove heat treat scale.” This becomes unfair when
the burr height or location, value of the surface or amount of scale
is not clearly defined. When defining a process with samples that
have a 0.002-inch burr height, you should expect this process to
effectively address this size burr with a small variance. In too
many cases, production produces larger burrs by trying to get more
parts out of tooling or various other reasons, and still expects
the finishing process to remove the larger burr in the same process
time under the same conditions. To make the finishing process repetitive,
understanding the condition of the incoming part is critical. If
you are trying to determine why parts are not exiting your finishing
process as expected, you must first confirm that they are entering
the process as expected.
A finishing
process will also be easier to maintain if the problems it addresses
are minimized as the part is produced. This does not mean you can
prevent a process from creating a burr, but you can minimize the
burr and make sure it is consistent by controlling the process that
creates the burr. This is the single most important consideration
in designing an efficient and manageable finishing process. Paying
attention to the location of the burr produced will also simplify
your quest for the best mechanical finish. This, of course, also
applies to operations that produce scale, such as heat treat or
welding, or certain surfaces from grinding. All of these processes
must be designed so that the problems they produce are consistent
and can be handled repetitively by the mechanical finishing process.
To
start we must have an understanding of the following:
- The
manufacturing problem you are addressing with your mechanical
finishing process.
- The
parameters that can effect a finishing process.
- Your
process parameters and the values of each.
- The
technologies are available for your mechanical finishing process.
Finishing
Requirements
- Deburring
- Deflashing
- Radius/Edge
Break
- Surface
Improvement (Preparation for another process)
- Pre-polish,
pre-plate, painting preparation
- Surface
Improvement (Performance)
- Achieve
certain surface value, remove defects
- Burnish
- Polish
- Clean
Parameters
for Mechanical Finishing
A.
Part Parameters
- Finish
requirement (burr height range, required edge break, R value of
surface needed)
- Part
dimension
- Part
weight
- Production
numbers
- Material
used to make part
- Special
concerns, including but not limited to the following:
-Location
of burr (internal burr?)
-Holes, corners, etc., where lodging can occur
-Rust, corrosion, oxidizing
-Surface finish requirements for debur or radiusing processes
B.
Process Parameters Equipment
- Type
of equipment
- Cost
of equipment
- Type
of action created
- Speed/amplitude
- Energy
requirements
- Maintenance
and upkeep
- Process
time
- Floor
to floor time
- Adaptability
to handling parts to and from equipment
- Percent
of time used for separation and unload
Operator
- Requirements
of time
- Requirements
such as lifting, is height a factor for loading, inspection, etc.
- Training
Media
- Cost
per pound
- Attrition
(% weight per hour)
- Metal
removal rate (% weight per hour)
Compound
-
Cost per gallon
-
Concentration requirements and use per hour
-
Water use requirements
C.
Additional Parameters to Consider
- Waste
disposal cost (additional equipment or disposal)
-
Inspection
-
Pre-process concerns (washing, conveying, queuing)
- Post-operation
concerns (inhibiting, washing, drying)
When
investigating your alternatives for a new mechanical finishing process,
it is best to employ the help of an experienced lab. Most mechanical
finishing equipment suppliers have invested in the facilities to
test your samples and develop a process. The advantage a lab offers
is that it has multiple technologies to investigate and the range
of media and compounds needed to test effectively. Also, it has
from 15-40 years of experience developing processes for mechanical
finishing. There are very few plants that have the variation of
machinery, media and compounds in house that are needed to adequately
test for the best process to finish a part.
When
providing samples to the lab, ensure the following:
-
Collect and provide all available parameters. Record the parameters
in a spreadsheet and send them with the samples you would like
tested.
-
Send a sample of the finish you require, when possible.
- Provide
prints showing requirements and restrictions.
-
Make sure your samples reflect what your production will produce.
When
possible, sample testing should be followed by additional tests
using estimated production numbers in the equipment recommended.
This testing cost is minimal and allows you to address and minimize
concerns on the vendors’ floor where problems and improvements
can be handled quickly and cost effectively. An experienced operator
and maintenance personnel can add value to a visit and reduce the
cost of addressing problems and making improvements on your plant
floor.
Serving
the Finishing Industries. Since 1936.
PF Onine and all contents are properties of Gardner Publications,
Inc.
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