EOS Whitepaper - C & A Tool Quality

1. Quality Whitepaper
Ensuring repeatable quality
with Additive Manufacturing
Additive Manufacturing (AM) has
gained a foothold in a variety of
industries that require quality
and repeatability. The medical
and aerospace industries are
embracing AM, not only because
it enables highly complex,
lightweight and strong designs,
but also because the printed
parts meet the quality standards
delineated by regulatory agencies.
Even in healthcare, which values
AM’s ability to create completely
customized outputs – think
implants unique to your anatomy
– quality and repeatability are
critical for mainstream adoption.
As a global leader in contract
manufacturing for the highly
regulated medical and aerospace
industries, C&A Tool understood
a major acceptance hurdle for
a new industrial manufacturing
process was demonstrating
the new process produced
equivalent mechanical properties
to subtractive manufactured
Titanium product.
Introduction

2. The Challenge:
The lack of understanding regarding quality approach to additive manufacturing remains one
of the biggest investment hurdles today – the uncertainty outweighing any benefits of the
technology – especially in heavily regulated industries. Therefore, it is incumbent upon the AM
industry to highlight the true value of this technology, showing that the quality and repeatability
of parts can stand up to quality protocols met by traditional manufacturing standards. Using
metal additive manufacturing machines (EOS M290, Krailling, Germany) C&A Tool created a
protocol to demonstrate the direct metal laser sintering process could meet or exceed industry
standards for mechanical integrity.
Using Good Manufacturing
Practice (GMP) quality control
requirements and ASTM testing
methods, C&A Tool created a
protocol to challenge additive
manufacturing process using
critical to quality variables, such
as laser power. The goal was to
demonstrate the DMLS process
meets the appropriate ASTM
material acceptance criteria for
mechanical testing and part
density for Titanium ELI alloy
(ASTM F3001). The standard
procedures and C&A Tool work
instructions utilized in this study
are listed in Table 1 & 2.
Table 1
Doc. Control # Description
ASTM F3001 Additive Manufacturing Titanium-6 Aluminum-4 Vanadium ELI with Powder Bed
Fusion
ASTM E8/E8M Tension Testing of Metallic Materials
ISO 3369 Impermeable sintered metal materials and hardmetals - Determination of density
QP 7 Quality Procedure Product Realization
QP 8 Quality Procedure Measurement
Table 2
Operator Procedures
Powder Sieving and Cycle Reclamation
File Management
M290 Work Instruction
Powder Selection
Tear Out
Powder Removal
Validation References/
Applicable Procedures

3. Methods
Prior to beginning the quality test protocol, C&A Tool created
a cause and effect (C&E) study to determine the worst case
variables in the process using design of experiments. This initial
study considered laser power, heat treatment temperature, and
heat treatment time, orientation, position, exposure strategy, and
layer thickness as potential critical to quality (CtQ)variables.
CtQ Variables Matrix
Details:
EOS parameter sets include vari-
ables such as laser power, layer
thickness, and scan strategy. These
variables in an EOS parameter set
can be varied through program-
ing of the EOSPRINT software;
however, for production process
these parameters must be fixed.
Similarly, exposure strategies are
controlled by the program sent
to the machine. As a result, if the
exposure strategy, layer thickness,
or parameter set is changed a
requalification may be necessary.
Laser Power
Laser power is controlled by
the parameter sets within the
exposure strategy of each program
sent to the machine. In this study,
laser power was monitored during
the build and a warning was
triggered when the instantaneous
laser power went below 4 percent
(355 W) of the 370 watts nominal
setting. A warning is also triggered
if the monitoring device records
instantaneous laser power under
5.5 percent (350 W). In this quality
protocol, a laser measurement
device verified laser power before
and after a build.
In the cause and effect (C&E)
study, two programs were created
to produce worst case scenarios
in terms of laser power, a critical
to quality variable. One program
took into account the lowest laser
power anticipated (error message
at 5.5% laser power degradation)
plus the margin of error for the
laser measuring equipment.
The laser measuring equipment has
a margin of error of ± 4%.
Therefore, the lowest laser
power that the DMLS parts may
see is -9.5% (334.85 W).
The second program took into
account the highest laser power;
which accounting for the
measurement variation of the laser
measuring equipment would be
+4% or 384.8 W.
Layer Thickness
Layer thickness is controlled by
the program sent to the machine.
In all parameter sets the layer
thickness was set to 0.060mm. If
the thickness is changed from the
0.060mm setting in this protocol,
requalification or justification will
be required.
Heat Treat
The heat treatment will be set and
the extremes will be challenged
during this protocol. In this in-
stance, requalification or justifica-
tion will need made if
this is changed.
Position/Orientation
Position or orientation is
challenged on all areas of the
plate within this protocol as
pictured In Figure 1.
The results from the C&E study
were reviewed and worst case
variables were determined to be:
• Laser power
• Heat treat temperature
• Heat treat time
Four builds were produced on two different DMLS machines, in the build
configuration detailed in Figure 1. Each build comprised tensile test bars
and density cubes configured on the build platform to capture potential
sources of variation, including location and orientation of the coupon
during the build process (Figure 1). Worst case variables of laser power, heat
treatment temperature, and heat treatment time found in the C&E study
were varied in the four builds. Layer thickness, material (Ti6Al4V ELI, ASTM
3001), exposure strategies, and machining (ASTM E8) remained constant
throughout the protocol. Hot Isostatic Pressing (HIP) was not
considered in this study.
All builds were grown using a parameter matrix, which included:
Class A based on ASTM F3001, laser power, layer thickness, material,
position/orientation, exposure strategies, heat treat time, and heat
treat temperature.
A stress relieving heat treatment (Applied Thermal, Warsaw, IN) was
performed prior to parts being removed from the platform. Round tensile
bars were processed and tested according to ASTM E8 and density cubes
were processed and tested according to ISO 3369.
Acceptance Criteria
It’s important to note that the mechanical properties, chemical properties
and density listed in Table 4 are specific to these builds. All builds were
tested and evaluated per the following specifications:
• Mechanical Properties: Table 3 of ASTM F3001
• Chemical Properties: Table 1 and 2 of ASTM F3001
• Density: ISO3369
In addition to acceptance criteria, Table 3 details average results for
all builds showing they meet the standard acceptance criteria for each
mechanical property.
Quality Protocol
Figure 2. Build plate orientation
Table 3: Results with acceptance criteria.
Titanium 64V - ELI - GRADE 23
Standard Tensile
Strength
Yield
Strength
Reduction
of Area
Elongation Young’s
Modulus
Hardness Density
ASTM F3001-13 125 ksi
(860 MPa)
115 ksi
(795
MPa)
25% 10% x x x
ASTM F136-13 125 ksi
(860 MPa)
115 ksi
(795
MPa)
25% 10% x x x
ASTM B348-13 120 ksi
(828 MPa)
110 ksi
(759
MPa)
15% 10% x x x
C & A Tool
Tested
Mechanical
Properties
156 ksi
(1075 Map)
143 ksi
(986
Map)
52% 24% 16500 ksi
(113.7
Gap)
35 (HRC) 4.42 g/cm3
(99.8%)
Figure 1. Test coupon location and orientation on the build platform

4. The Figure 3 below detail results
for ultimate tensile strength,
yield strength, reduction of
area, and percent elongation for
Class A (ASTM F3001) additive
manufactured tensile bars as
compared to ASTM F136, standard
for surgical implants, ASTM F3001,
standard for powder bed fusion,
ASTM B348, standard for bars and
billets, and ASTM F1108, standard
for titanium casting materials.
This study clearly demonstrates
DMLS process exceeds the relevant
standards for all applicable
mechanical testing properties
as defined by industry accepted
standards in medical and aerospace.
Capability results can be seen
in the Appendix.
Test Results
and Discussion
Figure 3: Mechanical testing results for all group as compared
to relevant standards.
“These kinds of OQ tests have become an important part of our business. Our findings
show what we’ve known all along to be true: AM produced parts not only free engineers
from traditional manufacturing and design restraints, but also enable production of
high-quality, repeatable parts.” – John Halverson, General Manager of Medical Business Unit C&A Tool
Conceptual tibial tray design using Titanium additive manufacturing

5. Figure 4: Mechanical properties reported based on location of
specimen on build platform.
In recent years there has been a greater interest in build location in additive manufactured production. Build location was controlled in this
study and the results are shown in Figure 4 below. The data demonstrates that for the EOS M290 DMLS machine using 60 micron layer
thickness and the previously described laser power variation, the mechanical strength properties do not vary significantly based on build
location (quadrants top left, top right, bottom left, bottom right and middle).

6. Similar to the consistent mechanical testing results, density measurements did not vary per machine build location.
Another variable of interest is part orientation on the build platform. Figure 6 below demonstrate there is not a significant
difference in mechanical properties between horizontal and vertical built test specimens (ASTM E8)
Figure 5: Density measurements reported based on location
of specimen on build platform.
Figure 6: Mechanical properties reported based on build
orientation on the build platform.
Critical to quality variables of laser power, build location,
build orientation, and heat treatment temperatures were
challenged in this protocol. The results clearly demonstrate
direct metal laser sintering can meet or exceed industry
standards for mechanical integrity and part density does not
vary across the build platform.
Ensuring quality protocols will continue to be essential to
driving widespread adoption of additive manufacturing,
Conclusion
especially in the more heavily regulated industries like
medical, aerospace and automotive. As a result, the AM
industry must continue to prioritize this type of QP testing
as completed by C&A Tool. The outcomes embolden the AM
industry to take on quality skeptics with compliant data
demonstrating the value of EOS solutions to produce the
highest quality parts.

7. Think the impossible. You can get it.
EOS GmbH
Electro Optical Systems
Corporate Headquarters
Robert-Stirling-Ring 1
82152 Krailling/Munich
Germany
Phone +49 89 893 36-0
Fax +49 89 893 36-285
Further EOS Offices
EOS France
Phone +33 437 49 76 76
EOS India
Phone +91 44 39 64 80 00
EOS Italy
Phone +39 02 33 40 16 59
EOS Korea
Phone +82 32 552 82 31
EOS Nordic & Baltic
Phone +46 31 760 46 40
EOS of North America
Phone +1 248 306 01 43
EOS Singapore
Phone +65 6430 05 50
EOS Greater China
Phone + 86 21 602307 00
EOS UK
Phone +44 1926 62 31 07
www.eos.info • info@eos.info
Status 5/2017. Technical data subject to change without notice. EOS is certified according to ISO 9001.