3D printing is a process of making three dimensional solid objects from a digital model. 3D printing is achieved using additive processes, where an object is created by laying down successive layers of material. This work investigates surface finish improvement techniques used with 3D printed metal parts during the infiltration treatment. The goal is to produce an acceptable surface quality without performing a secondary machining process. Such a surface would be categorized as a D-series surface under the surface finish standards the injection molding process.

1. IJSRD - International Journal for Scientific Research & Development| Vol. 2, Issue 07, 2014 | ISSN (online): 2321-0613
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An Analysis of Surface Roughness Improvement of 3D Printed Material
Abhay Kumar Dubey1
M. Y. Ansari2
Anurag Shrivastava3
Mr. Vishnu Pratap Singh4
1
M.Tech Student 2
Assistant Professor 3
Faculty 4
Lecturer
1,2
Department of Mechanical Engineering
1,2
A.I.E.T Lucknow 3
M.M.M.U.T. Gorakhpur 4
I. T. M. Gida Gorakhpur
Abstract— 3D printing is a process of making three
dimensional solid objects from a digital model. 3D printing
is achieved using additive processes, where an object is
created by laying down successive layers of material. This
work investigates surface finish improvement techniques
used with 3D printed metal parts during the infiltration
treatment. The goal is to produce an acceptable surface
quality without performing a secondary machining process.
Such a surface would be categorized as a D-series surface
under the surface finish standards the injection molding
process.
Key words: 3D Printing, Surface Roughness, Additive
Manufacturing Process, Selective laser Sintering, Powder
Size.
I. INTRODUCTION
3D printing is a rapidly developing technology that allows
simple objects to be perfectly replicated. While still at an
early stage, the potential of the field is truly world-changing.
Three dimensional printing allowed manufacturers to
produce those prototypes much faster than before, often
within days or sometimes hours of conceiving the design. In
three dimensional printing, designers create models using
computer aided design (CAD) software, and then machines
follow that software model to determine how to construct
the object. The process of building that object by "printing"
its cross-sections layer by layer became known as 3-D
printing Today, some of the same 3-D printing technology
that contributed to three dimensional printing is now being
used to create finished products. The technology continues
to improve in various ways, from the fineness of detail a
machine can print to the amount of time required to clean
and finish the object when the printing is complete. The
processes are getting faster, the materials and equipment are
getting cheaper, and more materials are being used,
including metals and ceramics. Printing machines now range
from the size of a small car to the size of a microwave
oven.3-D printing and other forms of additive
manufacturing are still new players in the field of
manufacturing. Additive manufacturing is often compared
to, or even mistaken for, another common manufacturing
process called computer numerical controlled (CNC)
machining. However, CNC is subtractive, which is the
opposite of additive manufacturing 3D PRINTING. In CNC
machining, material is removed from some pre-existing
block until the finished product remains, much like a
carving a statue from stone.
II. EXPERIMENTAL WORK
A. Steps Involved In Three Dimensional Printing Processes
No matter which approach a 3-D printer uses, the overall
printing process is generally the same. So the basic and
accepted universal working steps for any of the three
dimensional process are as follows-
1) Step 1: CAD:
Produce a 3-D model using computer aided design (CAD)
software. The software may provide some hint as to the
structural integrity you can expect in the finished product,
too, using scientific data about certain materials to create
virtual simulations of how the object will behave under
certain conditions.
2) Step 2: Conversion to STL (steriolithography):
Convert the CAD drawing to the STL format. STL, which is
an acronym for standard tessellation language, is a file
format developed for 3D Systems in 1987 for use by its
steriolithography apparatus (SLA) machines. Most 3-D
printers can use STL files in addition to some proprietary
file types such as ZPR by Z Corporation and Obj DF by
Objet Geometries.
Fig: 1: The Three dimensional printing processes explained
from cad software application to final product (source-
courtesy of Z printer corporation Inc.)
3) Step 3: Transfer to 3d printing Machine and STL File
Manipulation:
A user copies the STL file to the computer that controls the
3-D printer. There, the user can designate the size and
orientation for printing. This is similar to the way you would
set up a 2-D printout to print 2-sided or in landscape versus
Portrait orientation.
4) Step 4: Machine Setup:
Each machine has its own requirements for how to prepare
for a new print job. This includes refilling the polymers,
binders and other consumables the printer will use. It also
covers adding a tray to serve as a foundation or adding the
material to build temporary water-soluble supports.

2. An Analysis of Surface Roughness Improvement of 3D Printed Material
(IJSRD/Vol. 2/Issue 07/2014/070)
All rights reserved by www.ijsrd.com 313
5) Step 5: Build:
Let the machine do its thing: the build process is mostly
automatic. Each layer is usually about 0.1 mm thick, though
it can be much thinner or thicker Depending on the object's
size, the machine and the materials used, this process could
take hours or even days to complete. Be sure to check on the
machine periodically to make sure there are no errors.
6) Step 6: Removal:
Remove the printed object (or multiple objects in some
cases) from the machine. Be sure to take any safety
precautions to avoid injury such as wearing gloves to protect
you from hot surfaces or toxic chemicals.
7) Step 7: Post processing:
Many 3-D printers will require some amount of post-
processing for the printed object. This could include
brushing off any remaining powder or bathing the printed
object to remove water-soluble supports. The new print may
be weak during this step since some materials require time
to cure, so caution might be necessary to ensure that it
doesn't break or fall apart.
8) Step 8: Application:
Make use of the newly printed object or objects
B. Selective Laser Sintering (SLS)
Selective laser sintering (SLS) is an manufacturing
technique that uses a high power laser (for example,
a carbon dioxide laser) to fuse small particles of plastic,
metal (direct metal laser sintering), ceramic, or glass
powders into a mass that has a desired shape. The laser
selectively fuses powdered material by scanning cross-
sections generated from a 3-D digital description of the
part (for example from a CAD file or scan data) on the
surface of a powder bed. After each cross-section is
scanned, the powder bed is lowered by one layer thickness,
a new layer of material is applied on top, and the process is
repeated until the part is completed. Because finished part
density depends on peak laser power, rather than laser
duration, a SLS machine typically uses a pulsed laser. The
SLS machine preheats the bulk powder material in the
powder bed somewhat below its melting point, to make it
easier for the laser to raise the temperature of the selected
regions the rest of the way to the melting point.
Compared with other methods of additive
manufacturing, SLS can produce parts from a relatively
wide range of commercially available powder materials.
These include polymers such as nylon (glass-filled or with
other fillers) or polystyrene, metals including steel, titanium,
alloy mixtures, and composites and green sand. The physical
process can be full melting, partial melting, or liquid-
phase sintering. Depending on the material, up to 100%
density can be achieved with material properties comparable
to those from conventional manufacturing methods.
Fig. 2: selective laser sintering apparatus (SLS)( source-
courtesy of additive 3D Mfg Inc.)
III. RESULTS AND DISCUSSION
S.No.
Powder Size
(Micron)
Surface Roughness
(Nm)
1 19.00 13130
2 20.00 14479
3 19.50 13350
4 22.00 15202
5 21.00 11207
6 21.00 13251
7 18.00 15950
8 23.00 13252
9 23.50 16650
10 19.50 14250
11 22.50 13300
12 21.00 12540
13 21.00 14510
14 22.50 16350
15 21.00 13650
16 22.50 16520
17 22.50 17005
18 21.00 12500
19 21.00 11314
Table 1: Table for Surface Roughness
A. Effect Of Powder Size On Surface Roughness
The relationships between controllable parameters and the
responses have been plotted using Equations. Figure 3
shows that surface roughness (Ra) increases with increase in
powder size for a given set of parameters.
Fig. 3: variations of surface roughness to powder size
IV. CONCLUSION
The focus of present work is to investigate surface quality
improvements on 3D printed metal components.. Of
particular interest are the uses of contact infiltration
treatments cycle. In this study, the specimens and contact
blanks were designed. Then the parts were printed using
specific parameters and sintered under normal conditions.
During the post-processing stage of infiltration, several
variables were tested including the infiltration cycle
duration. Samples were then measured successfully
infiltrated parts were then analyzed qualitatively using a
scanning electron microscope and quantitatively using a
non-contact profilometer. This research concludes that:
When performing contact infiltration, the greatest
impact results when non-reactive highly polished surfaces
are used. The smooth contact surface aids the wetting action
occurring at the contact interface between the part and the
contact blank. For example, a sample face printed

3. An Analysis of Surface Roughness Improvement of 3D Printed Material
(IJSRD/Vol. 2/Issue 07/2014/070)
All rights reserved by www.ijsrd.com 314
horizontally, placed in contact with quartz, and infiltrated
with an extended cycle has an average roughness 78% less
than an untreated free surface after a standard infiltration
cycle
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