Turbo-Abrasive Machining in the Continuous Flow Environment Dr Michael Massarsky. Turbo-Finish Corporation, 917 518 8205 michael@turbofinish.com turbofinish.wordpress.com

2. Society of Manufacturing Engineers
3rd INTERNATIONAL Machining & Grinding Conference [CONFERENCE & TABLE-TOP EXHIBITS]
OCT. 4-7, 1999, Westin Hotel, Cincinnati, OH
TECHNICAL PAPER
TITLE: Turbo-Abrasive Machining and Turbo-Polishing in the Continuous Flow Manufacturing
Environment.
AUTHORS: Dr. Michael L. Massarsky
David A. Davidson
Turbo-Finish of America, Inc.
44 Kearsarge Street
Bartlett, New Hampshire 03812-0248
(T) 603.374.2341 (F) 603.374.2366
(e) michael@turbofinish.com (e2) ddavidson@mgnh.dyndns.org
(i)www.turbofinish.com
INDEX TERMS: Non-traditional Grinding
Non-traditional Machining
Super-Polishing
Deburring
Edge Contour
Surface Finishing
Loose Abrasive
Edge Finishing
Super-Finishing
Surface Conditioning
ABSTRACT: Turbo-Abrasive Machining and Turbo-Polishing are loose abrasive processes that can
develop functionally important edge and surface effects on rotating and non-rotating
components. The processes are characterized by rapid cycle times, single-piece as
opposed to batch processing, and minimization or elimination of troublesome effluent
steams. The processes facilitate automation of burr removal as well as edge and surface
conditioning of components with complex geometries that present serious challenges to
conventional mechanical finishing methods. This paper outlines process characteristics and
mechanics of both processes, and discusses their application within the context of
enhancing manufacturing flow in the post-machining areas of deburring and edge/surface
final finish.

3. Deburring and surface finishing; still an industry challenge. Deburring and surface conditioning complex machined
and turned parts is one of the most troublesome problems faced by the metalworking industry. In many cases, parts with
complex geometric forms which are manufactured with very
sophisticated computer controlled equipment are deburred,
edge finished and surface conditioned with manual or hand held
power tools. This labor-intensive manual handling often has a
considerable negative impact on manufacturing process flow,
productivity and uniformity of features on the final product, as
well as part-to-part and lot-to-lot uniformity. It has been a long-standing
2
industry-wide paradox that the final surface
conditioning operations utilized on many types of precision parts
have nowhere near the level of sophistication of the preceding
machining operations.
Conventional mechanical finishing methods and unmet
challenges. Mass finishing techniques such as barrel and
vibratory finishing have long been recognized as the primary
tools for metal part deburring and surface conditioning, and as
such, have wide application throughout industry. As
metalworking techniques have evolved in recent years, it seems
that an increasing number of parts require more sophisticated
deburring and surface conditioning methods. Many parts
routinely manufactured now have size and shape considerations
that preclude the use of conventional mass media finishing
techniques. Additionally, manufacturers of high value parts now
prefer manufacturing methodologies in which parts are
processed singly and continuously rather than in batches,
obviating the possibility that large numbers of parts will be
scrapped or reworked due to human error or process
maladjustment.
Another important consideration in evaluating current mass
finishing processes is their wet waste effluent stream; the
treatment cost of which often approaches the cost of the actual
deburring or surface conditioning operations themselves. Industry
has long had strong incentive to seek out mass finishing methods
that could achieve surface finish objectives in a dry abrasive
operation. In contrast with current methods, “TAM” operations
are completely dry, and produce surface effects rapidly, in
single part operations. (Some parts lend themselves to multiple spindle or multiple fixture operations when single part
processing is not an important quality control objective).
TAM combines mechanical finishing simplicity with machining-like sophistication. The “TAM” method provides
manufacturers with the ability to utilize a high-speed precision final machining and finishing method that can
accommodate the current trend toward continuous processing of individual parts. Many larger and more complex
rotationally oriented parts, which pose a severe challenge for conventional mechanical finishing methods, can easily be
processed. Many types of non-rotating parts can
also be processed by fixturing them on disk like
fixtures. Increasingly complex parts are being
fashioned in today’s four and five axis turning and
machining centers and “TAM” technology provides
the method in which needed surface improvements
can be made on these types of parts with a minimum
of direct labor and tooling costs.
“TAM” as a surface conditioning method is a blend
of current machining and surface finishing
technologies. Like machining processes, the energy
used to remove material from the part is
concentrated in the part itself, not the abrasive
material interfacing with part surfaces. Like many
surface-finishing processes, material removal is not
accomplished by a cutting tool with a single point of
contact, but by complete envelopment of the
exterior areas of the part with abrasive materials.
TURBO-ABRASIVE MACHINING CENTER -
Edge Finishing on turbine and compressor disks
is performed by a combination of high-speed part
rotation and a granular abrasive fluidized bed.

4. 3
Consequently, deburring, edge finishing, surface
blending and smoothing and surface conditioning
are performed on all features of the part
identically and simultaneously. Many metal parts
that are machined by being held in rotational
work-holding devices (for example: chucks,
between centers, rotary tables, etc.) are
potential candidates for “TAM” processes. In
many cases these final deburring and surface
conditioning operations can be performed in
minutes if not seconds.
TURBO-ABRASIVE MACHINING CONCEPT.
The basic concept underlying TAM operations is
the placement of a rotating or oscillating metal
component or work piece in a low-speed air-abrasive
stream (fluidized bed) that is contained
by a specially designed chamber. Surface
finishes and effects can be generated on the
entire exterior of complex parts, and specially fixtured non-rotational components. (Simple interior channels on some
parts can also be processed). Various surface finish effects can be obtained by controlling variables of the process such
as rotational part speed, part positioning, cycle times, abrasive particle size and characteristics and others. Additional
surface effects can be developed by utilizing processes that make use of sequential abrasive and/or polishing media
combinations. Several machine designs have been
developed which can accommodate parts as small as 2-3
inches (50mm) in diameter to very large and cumbersome
rotational parts up to four feet (1200mm) in diameter and
larger.
High intensity abrasive effect. Surface finish effects are
generated by the high peripheral speed of rotating parts
and the large number and intensity of abrasive particle to
part surface contacts or impacts in a given unit of time
(200-500 per mm2/sec. or 129, 000 to 323,000 per in-
2/sec.) These factors make this equipment capable of
generating one of the highest rates of metal removal to
be found in any type of free abrasive surface finishing -
operation today. Yet, with proper media selection and
process adjustments, very refined finishes can be achieved.
Parts with an initial surface roughness profile of 2-5 μm
Ra (80 - 200 μinch Ra) have been reduced to 0.2-0.4 μm
Ra (7-15 μinch Ra) in single operation in time cycles of
only a few minutes. It should be
noted, that surface finish effects
developed from this process depart
significantly from those obtained
from air or wheel blasting. TAM
processes can produce much more
refined surfaces by virtue of the fact
that the rotational movement of parts
processed develop a very fine finish
pattern and a much more level
surface profile than is possible from
pressure and impact methods.
Random finish pattern vs. linear
grinding patterns. Another very
important functional aspect of TAM
technology is its ability to develop
needed surface finishes in a low
temperature operation, (in contrast
with conventional wheel and belt
grinding methods), with no phase or
structural changes in the surface layer
of the metal. A further feature of the

5. process is that it produces a more random pattern of surface
tracks than the linear abrasive methods such as wheel grinding or
belt grinding. The non-linear finish pattern that results often
enhances the surface in such a way as to make it much more
receptive as a bonding substrate for subsequent coating and
even plating operations.
Metal improvement and peening. TAM processes have strong
application on certain types of parts, which have critical metal
surface improvement requirements of a functional nature.
Significant metal improvement has been realized in processes
developed with both abrasive and non-abrasive media material.
Because of the intense nature of media particle contact with
exposed features, it has been observed that residual
compressive stresses of up to 400-600 MPa can be created in
selected critical areas. Tests performed on rotating parts for the
aerospace industry that were processed with this method
demonstrated a 40%-200% increase in metal fatigue resistance
when tested under working conditions, when compared with parts
which had been deburred and edge finished with less
sophisticated manual treatment protocols.
The Physics of Turbo-Abrasive Finishing Process
Figure 1 - Electronic Microscope photo of
TAM abrasive tracks at 400X
In turbo-abrasive machining, while the part is rotating in a fluidized bed of abrasive grain, the part surfaces are
subjected to a microimpact effect, which develops from high-speed collision and interaction of abrasive grain and part
surfaces themselves. It has been proven that metal removal intensity in TAM machining greatly depends on a parts
rotational speed. High rotational speeds (RPM=1000-5000) and small area of abrasive grain contact cause metal
stress exceeding the Gf fluidity limit. Owing to this, a surface plastic deformation takes place, while exceeding metal
fatigue strength limit leads to micro cutting itself. These results have been confirmed by an electronic scan microscope
study of mark tracks on polished part samples (Fig.1). The above mentioned mark tracks have confirmed that a surface
formation is accompanied by the physical processes of micro cutting with prevailing plastic deformation of the metal
FIGURE 2
Metal removal dependence on part orientation angle in fluidized bed
degrees Qm, micron/min
4
2.8
2.4
2
1.6
1.2
0.8
0.4
0
30 45 60 75 90
2 3 1
Brass Bronze Steel

6. surface. During repeated collisions of abrasive grains and plastically altered metal, the latter is either subjected to micro
cutting for the second time, or is recurrently altered and then refined as a result of mass interaction of abrasive grain
with the material being machined.
Depending on abrasive material and its shape either
abrasive cutting or plastic deformation takes place in the
finishing process; or both processes may work together. For
example, micro cutting process prevails with silicon carbide
abrasive media, while plastic deformation of thin metal layers
is a result of treatment by electric corundum or zirconium
corundum abrasive grain.
[Ed. Note: Turbo-Abrasive Machined surfaces are
characterized by a randomly oriented pattern of abrasive
tracks. Although the abrasive materials utilized in TAM are
similar to the material utilized in conventional pressure blast
processes, the nature of abrasive media/part surface contact
is quite different, as is the nature of the resulting surface
effects. Blasting is a very directionalized process where
media contact is almost entirely of a perpendicular nature.
The primary surface effect is generated by the overlap of
high-speed impact craters in the part surface. In TAM the
primary abrasive to surface contact is of a rolling or linear
nature caused by the rotational movement of the part. This
rolling, linear method of contact produces micro-abrasive
tracks with raised edges or ridges on the longitudinal edge of
the track. The plastic deformation referred to above is a
reference to the developing of; and then removal of these
raised edges by subsequent abrasive contact. TAM surfaces
are created by an iterative process in which these raised
exposed micro-edges or ridges are continuously being
created and then removed.]
The rising airflow presses pulsating abrasive particles onto the surface being treated/machined with a normal force Py
and abrasively scores it in the depth h. The relation between normal force Py and abrasive track depth h can be shown
as
Radius rounding off (edges) Rz, Rx and Ry dependence on
5
h = bPyn
[1],
where b and n are plasticity constants,
0.024
0.016
0.008
0
FIGURE 4
abrasive grain size Dg and different RPM
1. Dg - 80, 2. Dg - 46, 3. Dg - 30 mech
1000 1500 2000 RPM
Rz
1 2 3
0.048
0.036
0.024
0.012
0
1000 1500 2000 RPM
Rx
1 2 3
0.08
0.064
0.048
0.032
0.016
0
1000 1500 2000 RPM
Ry
1 2 3
Figure 3 – TAM edge finish effects and edge
orientation in relation to vector.

7. experimentally determined for different materials. Part rotation creates tangential force Pz. (Tangential force Pz is a
result of a part rotation).
Taking into account the fact that abrasive grain in the fluidized bed (besides mostly having a vertically oriented
circulation) travels intensively in a pulsating manner, reminiscent of the Brownian type of movement. One can come to a
conclusion that the surface being machined is undergoing (or is subjected to) particle collision impact ranging from 0 up
to 90 degrees. Along with this, part of the abrasive media (besides the cutting and sliding processes), while rotating on
the surface, creates substantial rotating moment, which causes micro-layer of metal to be plasticized by the abrasive
grains’ cutting edges.
The most efficient interaction is determined by the correlation of forces Py / Pz, which depends on the physical and
mechanical properties of the metal being treated, as well as abrasive properties of the media and grain sharpness.
Here, kinetic energy of abrasive grain would be most fully used at an angle of approximately α=45°, when the
tangential and the normal components of a cutting force have the highest values.
The above mentioned facts have been proven experimentally for steel and brass materials, where the maximum intensity
of metal removal process is achieved at the angles of α=30–60° ( SEE Fig 2 ABOVE).
Special experiments have shown that the most intensive metal removal takes place when a part speed vector doesn’t
coincide in its direction with a part’s longitudinal roughness;
otherwise, due to the polydispersion of the fluidized bed, the
abrasive grain not only works on the peaks of micro surface
roughness, but also in their cavities.
After having being treated by TAM a surface has an unoriented or random microrelief, consisting of a large number of
short scratches or abrasive tracks. This gives the surface high adhesion properties as a substrate, allowing for strong
bonding with different types of coating, such as plasmatic, galvanic, lacquer polishing, etc.
6
As one can see, extensive research shows that the metal
removal process in TAM can involve the following:
- micro-cutting;
- micro plastic deformation;
- residual fatigue removal of metal.
The outcome of the above described interaction between
the abrasive grain and the surface being treated has
become a foundation for developing processes and
designing industrial equipment for TAM of complex part
surfaces, as well as for the processes of deburring,
rounding off sharp edges and preparation for different
coatings.
Automated Deburring and Edge Contouring of Complex
Rotating Parts
Extensive experimentation has shown that TAM process is
one of the most technologically advanced methods to be
used for automation of deburring processes and rounding off sharp edges. At the present time many of these operations
are performed by conventional methods, requiring significant use of skilled manual labor (for example, in the
aerospace industry).
A study of the interaction between
abrasive grain and differently
oriented part edges was
conducted both on turbine and
compressor disks.
In order to evaluate the uniformity
of the TAM process, the radii of
part edges coinciding with the
direction of coordinate axes have
been controlled: (refer to Fig 3
diagram above).
Figure 5 - Uniform edge contour effects produced by TAM in 3-4
minutes of machine time, replace multi-hour manual procedures.
Figure 6 - Radius effects produced both broach
slot and counter-bore features of turbine disk

8. 7
- Axis X is parallel to disk rotational spin;
- Axis Y is parallel to radius direction;
- Axis Z is parallel to speed vector.
The part edges positioned at an angle of α=30-90° in relation to part vector Vsp are rounded off more intensively
than edges parallel to Vsp. For example, titanium alloy disks after having been treated with zirconium corundum grain
[ZA – 1548 /36] mesh during four minutes at RPM - 1800 reached the following values:
- Rx = .018 - .025 (rounding off radius on edge x
[Rx], parallel to part spin axis).
- Ry = .025 - .045 (edge Y parallel to part radius).
- As Rz = . 007 - . 01 (edge Z parallel to vector
Vsp).
Figure 7 - TAM processes have removed burrs and radiused
features, including difficult to access slot areas on this titanium disk
The same radii values were obtained on heat-resistant nickel alloy disks, as well as stainless steel disks.
The grain size influence on the radius of rounding off edges is demonstrated on figure 4.
Increasing the abrasive grain size from 80 mesh to 30 mesh causes Rx and Ry to grow 2.2 – 2.8 times. The following
values were received while abrasive grain size 30 mesh was being used, at RPM = 2000:
- Rz = .02 - .03, Rx and Ry = .05 - .06
This effect of grain influence is connected with the fact that the impact energy of grain and the surface being machined
is proportional to the mass of abrasive grain (i.e., ~Dg, where Dg is an average grain size). Radius formation process on
nickel turbine disks being treated with TAM is demonstrated in Figure 5.
Figure 6 presents test results, which were achieved at the Turbo-Finish Lab Center in cooperation with United
Technologies. Here, one can clearly see the radius formed after a nickel alloy turbine disk has been treated with TAM
process. Geometric parameter measurements have shown that the process does not push the part out of tolerance.
Therefore, this is one of the definite advantages of TAM process where controlling technological parameters allows for
regulation of disk edge radius within tolerance limits.
Figure 7 illustrates post TAM radius formation on a turbine disk made of titanium alloy. Thus, the turbo abrasive
technology can be successfully applied to treat metals with different physical-mechanical and physical-chemical
properties. Solid, fragile and those of high plasticity materials can be machined and finished equally well with the turbo
abrasive process.
Summary: TAM processes can be easily justified in many types of applications where part size and shape
considerations make applying other surface and edge conditioning technologies difficult. The process
deburrs and develops needed edge and surface finish requirements very rapidly in an entirely dry abrasive
environment. In contrast with other technologies that utilize single point of contact cutting methods, TAM’s
combination of complete abrasive envelopment and rotational motion give each feature in a given symmetry
of rotating parts identical and simultaneous processing. When used as a final machining or conditioning
method exceptional feature-to-feature uniformity can be developed.
.
Significant TAM process characteristics:
(1) Very rapid process cycle times, well suited for single piece continuous flow operations.

9. (2) High intensity, small media operation allows for access into intricate part geometries
(3) Completely dry abrasive operation creates both edge and surface finish effects.
(4) Metal improvement and peening effects are possible for increased metal fatigue resistance.
(5) No part on part contact
(6) Modest tooling requirements.
(7) Primarily an external surface preparation method, though some simpler interior channels can
8
also be processed
(8) Many types of symmetrical rotating components can be processed; non-rotational components
can be processed also when attached to disk like fixtures.
(9) Very refined surface and edge effects can be developed in multi-step processes that utilize
successively finer abrasive materials sequentially.

10. 9
Turbo-Polishing
Turbo-Polishing is a term coined by the authors
to describe a group of processes which has
been developed to produce super-polish and
super-finish surfaces on critical hardware. Like
TAM processes, these processes utilize free
abrasive material and rotational motion to
produce specific edge and surface effects.
Unlike TAM processes, parts are processed in
a non-fixtured random media environment. The
method is useful as a single-piece continuous
flow style of final surface machining in that: (1)
the parts are isolated within their own processing chamber, with multiple part processing possible in
machinery equipped with multiple chambers, (2) relatively rapid cycle times make it possible to
accommodate cellular and flow-line production.
The method utilizes both high-pressure
centrifugal and
reciprocating motion to produce
significant improvement in part
surfaces that have demanding
surface texture and surface
integrity requirements. It is
possible to produce functionally
valuable surfaces by subjecting
critical hardware to a multi-step
process in which a series of
successively finer abrasive
materials are used in sequence.
These processes are a variant
of batch processes originally
developed to produce very refined “near-buff” surface finishes on a variety of consumer articles requiring
highly reflective surfaces for aesthetic reasons. Previously, most of these smaller parts required manual
buffing to produce the high-quality cosmetic or decorative surface finishes required. Although, not
immediately appreciated, the development of this technology also enabled the development of an
automated, uniform and consistent method for producing very low Ra surfaces. Sequentially finer abrasive
steps, using this method, can produce exceptional surface quality with even with the very high Ra
initial surface condition common to castings, forgings and coarsely machined parts.
Orbital Pressure Finishing Principles
Based on “ferris wheel” physics, four processing chambers are located in
opposing positions at the periphery of a rotating turret. Barrels rotate in
the opposite direction of the turret rotation, combining a vigorous sliding
motion of loose abrasive with the high-pressure contact of media and
parts generated from the centrifugal forces of the turret spin. An
additional reciprocating movement can be added to this mix, by
deliberately mounting the processing chambers at an angle from the
horizontal. This added reciprocating movement is useful for developing
special edge and surface effects in a number of applications. The high
centrifugal forces and high-speed reciprocating slide zones make it
practical to develop super-polished and super-finished surfaces that
would be impractical with other methods because of the extensive time
cycles that would be involved. As the entire part exterior is subjected to the same abrasive, polish or
burnishing protocol, it is possible to produce a much more uniform surface on the overall part than is possible

11. with single point of contact methods such as hand-held grinding or belt, buff or polish methods. Once process
parameters have been established it is also possible to achieve a part-to-part and lot-to-lot consistency of
result not possible where manual abrasive methods are utilized. Both TAM and Turbo-polishing are useful
tools in developing specific surfaces where important surface texture and surface integrity requirements are
an issue for the functionality of critical hardware. An example of this would be the super-polishing or super-finishing
10
of turbine blade foil surfaces.
This photograph was taken with
an electron microscope at 500x
magnification. It shows the
surface of a raw unfinished “as
cast” turbine blade. The rough
initial surface finish as measured
by profilometer was in the 75 –
90 Ra (μin.) As is typical of most
cast, ground, turned, milled,
EDM and forged surfaces this
surface shows a positive Rsk [Rsk
– skewness – the measure of
surface symmetry about the mean line of a profilometer graph. Unfinished parts usually display a heavy
concentration of surface peaks above this mean line, generally considered to be an undesirable surface
finish characteristic from a functional viewpoint.]
This SEM photomicrograph (500X
magnification) was taken after
processing the same turbine
blade in a multi-step procedure
utilizing orbital pressure methods
with both grinding and polishing
free abrasive materials in
sequence. The surface profile has
been reduced from the original
75 – 90 Ra (μin.) to the 5-9 Ra
(μin.) range. Additionally, there
has been a plateauing of the foil
surface, and the resultant
smoother surface manifests a
negative skew (Rsk) instead of a
positive skew. This type of surface
is considered to be very
“functional” in both the fluid and
aerodynamic sense. The smooth,
less turbulent flow created by this
type of super-polished surface is
preferred in most aerodynamic
applications. Another important
consideration the
photomicrographs indicate is that
surface and sub-surface fractures
seem to have been removed.
Observations with backscatter
emission with a scanning electron
microscope (SEM) gave no
indication of residual fractures.
Profilometer tape readings on
this and other parts are shown
in the APPENDIX
Before and after examples of turbine blade super-polishing using a
multi-step recipro-orbital pressure method

12. 11
REFERENCES:
1. Dr. M. L. Massarsky and D. A. Davidson, “Turbo-Abrasive Machining Theory and Application,”
SME Technical Paper MR95-271, Proceedings of the 1st International Machining & Grinding
Conference; Society of Manufacturing Engineers, Dearborn, MI, Sept. 12-14, 1995
2. Dr. M. L. Massarsky and D. A. Davidson, “Turbo-Abrasive Finishing,” SME Technical Paper,
Proceedings of the Deburring and Surface Conditioning Symposium; Society of Manufacturing
Engineers; Dearborn, MI.; Oct. 26-27, 1993
3. Massarsky, M. L., Davidson, D. A. “Turbo-Abrasive Machining and Finishing”, METAL FINISHING,
White Plains, NY: Elsevier Science, p. 29-31, July, 1997
4. Massarsky, M. L., Davidson, D. A. “Turbo-Abrasive Machining – Dry Process Mechanical
Finishing for Today’s Complex Components”, FINISHER’S MANAGEMENT, August 1997
5. “Dry Mechanical Finishing for Rotating Components”, SURFACE ENGINEERING, England:
Institute of Metals, p. 363-364, 1997, Vol 13, No. 5
6. Massarsky, M.L., The Peculiarities of Part Treatment in Fluidized Bed of Abrasive Grains. - In
collection "Progressivnye methody of obrabotki detalej". - LDNTP, [Russian],1977, p.79-84.
7. Massarskiy M.L., Guzel V.Z., Surface Quality at a New Method of Part Treatment is Turbo-
Abrasive Grinding. - In collection "Physika i Tchnologia Uprochenia Poverchnosti Metalla". -
Materials of seminar, L., Physicotechnical Institute named after A. F. Joffe, [Russian]1984,
p.69-70.
8. Kremen Z.I., Massarskiy M.L., Turbo-Abrasive Grinding of Parts is a New Method of Finishing. -
"Vestnik mashinostroyenia",[Russian] 1977, #8, p.68-71.
9. Davidson, D. A., “Mass Finishing Processes”, 1999 METAL FINISHING Guidebook and Directory,
White Plains, NY: Elsevier Science, 1999
10. Davidson, D. A. "Current Developments in Dry Process Mass Finishing, Finisher's
Management, Vol 33., No. 7, September, 1988, p.43-46
11. Davidson, D. A., "Refining Plastic Surfaces by Mass Finishing Methods", Plastics
Engineering, April, 1986
12. Davidson, D. A., High Energy Dry Process Finishing, SME Technical Paper MR90-389,
International Manufacturing Technology Conference, Sept 6-10, 1990, Dearborn, MI:
Society of Manufacturing Engineers
13. Davidson, D. A., “Developments in Dry Process Mass Finishing", SME Technical Paper
MR89-147, SME - DSC'89 Conference, San Diego, CA., Feb. 13- 16, 1989,

13. APPENDIX 1.1 – Typical Surface Profilometer Readings for TAM and Turbo-
Polish Surfaces
PROFILOMETER TAPE 1 – TURBINE DISK BEFORE TAM PROCESSING [Ra =
57.0 micro-inch]
Part: Nickel Alloy Turbine disk. As broached and rotary ground, prior to TAM
processing.
Profilometer reading was taken prior to processing to determine initial surface
roughness and condition. Stylus was tracked on ground surface on part tooth
prior to TAM processing. Although TAM is looked at as primarily a deburring
and edge contour method in this application, considerable refinement and
improvement of surfaces are generated also, as subsequent profilometer
tapes will show.
12

14. APPENDIX 1.2 - PROFILOMETER READINGS [Profilometer Tape 2] TURBINE DISK
AFTER FOUR-MINUTE TAM PROCESSING WITH GRINDING MEDIA [Ra = 22.4
micro-inch]
As can be seen, Turbo-Abrasive Machining has removed burrs and developed edge
contour in the broach area of the disk in an accelerated automatic process (3-5
minute cycles typically). But as an additional corollary effect, substantial surface
improvements are generated as can be easily discerned by a comparison of this
profilometer tape of a reading taken of tooth surfaces after TAM with ZA grinding
media. Further surface refinement is possible with the use of finer abrasive materials
in a secondary process (SEE Profilometer Tape 3)
13

15. APPENDIX 1.3 - PROFILOMETER TAPE 3 TURBINE DISK AFTER (1) TAM
GRINDING (2) TAM POLISHING [Ra = 11.8 micro-inch]
Part: Nickel Alloy Turbine disk, (1) TAM w/Grinding abrasives to deburr and
edge contour (2) TAM with polish granules to enhance low Ra surfaces in both
edge and surface areas
This part shows even further surface enhancement, it has been processed in a two
step TAM method, utilizing first a grinding media for burr removal and edge
contour, and then a secondary process in which softer granular materials coated
with micro-fine polishing materials to incrementally clear surfaces of peaks and
develop the neutral or negative skew surface finishes desirable on this type of
critical hardware.
14

16. APPENDIX 2.0 – PICTORIAL BEFORE AND AFTER COMPARISON OF TURBINE DISK EDGE AND SURFACE
CONDITION (1) BEFORE TAM PROCESSING (2) AFTER TAM PROCESSING
15
(1) Nickel
Alloy Turbine
disk, prior to
TAM
processing.
Note feature
sharp edges
and rough
rotary ground
surfaces with
linear.
(2) The same disk after TAM, burrs removed, sharp
edges replaced with uniform edge contour, and
machining/grinding lines on the surface have been
blended into a negative or neutral skewed surface
profile with a more randomly oriented and finely
defined surface pattern.

17. 16
APPENDIX 3.0 –
Before and after
comparison of
turbine blade
surfaces. The first
tape (L) shows
initial “as cast”
surface condition.
The second tape
(R) shows
readings on the
same blade
segment after
super-polishing or
turbo-polishing
using recipro-pressure
finishing
methods with
successively finer
free abrasive
materials.

18. 17
APPENDIX
4.0 – Even
very coarse
surfaces can
be improved
by TAM
methods. These
tapes are a
before and
after
comparison of
very coarsely
machined cast-iron
bull gears.
A short 4-
minute process
was sufficient
to reduce
surfaces from
approximately
140 Ra micro-inch
down into
the 40’s (Ra
micro-inch)