A Study on the Design and Effectiveness of Conformal Cooling

the Technology Interface Journal/Fall 2009
Meckley, Edwards
A Study on the Design and Effectiveness of
Conformal Cooling Channels in Rapid
Tooling Inserts
______________________________________________________________________________
by
Jonathan Meckley
Penn State Erie, The Behrend College
[email protected]
Robert Edwards
Penn State Erie, The Behrend College
[email protected]
Abstract: Reduction in plastic injection molding cycle time and increase in part quality are two
goals that are not usually thought of as being compatible. Conformal cooling channels are one of
the technologies that will help achieve both goals. Cooling time is the only phase of the injection
molding cycle that has significant time to reduce. Reduction in cooling time usually results in
parts with hotter temperatures. This could result in increased part shrinkage and warpage. The
key to cycle time reduction and better quality is to cool the parts uniformly and more quickly.
This study will show that conformal cooling channels provide better cooling than standard
conventional cooling lines. By designing cooling channels around the part’s geometry, more
uniform cooling can be achieved compared to standard conventional cooling lines. Rapid tooling
is the easiest and most inexpensive method to construct conformal cooling lines in mold inserts.
It is important to balance mold strength with cooling concerns. Cooling lines in the inserts
reduce the structural integrity of the inserts. Correct placement and design of the cooling
channels is needed to reduce the effect of the cooling lines on the structural integrity of the
inserts. Computer-Aided-Engineering tools are needed to optimize the mold inserts for cooling
and strength.
High Density Polyethylene and Polycarbonate were used in this study. The mold and melt
temperature differences between the two materials will help to illustrate the difference between
the mold materials and cooling line layouts.
I. Introduction
In today’s competitive global market, working smarter and more quickly will give a company an
edge. The amount of time in the injection and packing phases is low and cannot be reduced
much further. However, because cooling time can be more than two-thirds of the molding
cycle[1], it is the most common phase to remove time. But decreasing cooling time can result in
excessive shrinkage and warpage in parts. By using new rapid tooling techniques, it is possible
to reduce cycle time and increase part quality. If the part’s temperature can be reduced more
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Meckley, Edwards
quickly and uniformly, it will shorten the cooling time. Near uniform temperatures can be had in
mold inserts with conformal cooling. This study will show the differences between conventional
and conformal cooling channels. The differences between a rapid tooling material (S4) and P-20
steel will also be examined.
Designing conformal cooling channels in rapid tooling for plastics injection molding can pose
challenges to the mold designer. The balance between optimum cooling and insert strength
means there needs to be a compromise between both. Compared to P-20, rapid tooling materials
are not as strong. Another objective of this study was to determine how effective mold filling
and cooling analysis along with Finite Element Analysis (FEA) were to assist with designing
conformal cooling channels.
Two cooling times were used in this study. One cooling time was around the optimum cooling
time and one was at the lowest cooling time. Temperatures were captured with an infrared
camera. The simulation results were compared to actual mold and part temperatures.
A semi-crystalline and an amorphous plastic material was used in this study to show the
behavioral differences. The semi-crystalline material was High Density Polyethylene (HDPE).
The amorphous material was Polycarbonate (PC).
II. Background and Theory
Rapid prototyping processes can be broken down into two major categories, subtractive and
additive. Subtractive prototypes start with a block of material that is bigger than the final part.
The block has material removed until the final part is revealed. It is typically done on a mill or a
lathe. This is a traditional machining process that has been practiced for many years.
Numerically controlled machining centers and computers were combined in the 1970s, but
needed to be programmed manually[2]. Complex surfaces were difficult to construct. With the
marriage of Computer Numerical Control (CNC) machining centers and Computer-AidedDesign (CAD) software, complex geometry could easily be machined from the CAD solids
model.
Commercially available additive processes have only been in existence since 1986[3]. 3D
Systems was the first manufacturer to create a commercially available machine. These processes
create a part out of liquid, molten, or powdered polymer or metal. Parts are created by using
lasers or ink-jet technology. In the CAD software, solids models are represented by their outside
surfaces. In order for the CAD model to be used in an additive process, it has to be converted to
a format that the rapid prototyping machine can understand. Figure 1 shows the conversion of a
CAD model. The files that represent the outside surfaces are called STL files. In this format,
triangles represent the surfaces. To import the STL file into the rapid prototyping machine, it has
to be processed by converting the triangles, called slicing, into a set of 2D cross sections. This
slicing of the STL triangles creates the paths that a laser will travel or that ink-jet type machines
will use as a boundary for printing. The slicing thickness is determined by machine capability
and accuracy requirements for the parts. In most machines this is done from the bottom of the
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the Technology Interface Journal/Fall 2009
Meckley, Edwards
part to the top, because the equipment to manufacture the prototypes is mounted on the top of the
machine.
There are several manufacturers that make additive rapid prototyping machines.
Stereolithography is the most used process for additive prototypes[4]. 3D System is the oldest of
the manufacturers making Stereolithography machines. In this process an overhead laser traces
the 2D cross section on a vat of photopolymer. It uses the lines generated from the slicing as a
boundary. Once the boundary is traced on the liquid photopolymer, the laser traces a fill pattern
to fill inside the boundary. The part indexes down into the vat of photopolymer by the slicing
thickness and the next layer is traced. This process is repeated until the last layer is traced. The
part is only 96% cured when it is finished in the machine[5]. It needs to have a post cure to fully
cure the part. Other additive processes follow the same basic process, but the method to
construct each layer is different. Some processes use the laser to sinter a polymer powder.
Another will use ink-jet technology to bind together a plaster powder. There are more than a
dozen different types of processes.
In rapid tooling applications, the traditional processes that make polymer parts can be used to
make cavity and core inserts. However, the polymer tooling is not hard enough to resist wear
and the forces from the injection molding cycle. Depending on the geometry, only about 200
parts can be made[6]. These inserts are not used for production and are only good for
prototyping. Since polymers have a much lower thermal conductivity compared to metals, the
cooling time is very long and not economical for production.
Rapid tooling can be broken down into direct and indirect tooling. Direct tooling inserts are
made on subtractive or additive type prototyping machines. Today, when most companies
advertise rapid tooling, they are using high speed machining of aluminum for their inserts, which
is a subtractive process. For certain parts, this can be a quick way to get inserts. These inserts
will most likely have conventional cooling lines. While these inserts can be machined more
quickly than standard steel inserts, the aluminum inserts will wear more quickly and the forces
from injection molding will likely damage the inserts over time.
Additive processes can be used to create direct tooling. The rapid prototyping machines can
directly take the CAD model and create a set of inserts. Because the rapid prototyping machines
build the parts from scratch, any geometry can be created. Creating conformal cooling lines is
easy to do with the additive processes. They are simply constructed as another set of boundaries
as each layer is traced or printed. Since traditional prototyping machines that make polymer
parts are only good for prototyping, prototyping machines that make metal parts are the only
option for injection molding tooling. EOS’s Direct Metal Laser Sintering and 3D Systems’
Selective Laser Sintering use a laser to sinter a metal powder. Some newer processes deposit
drops of molten metal on top of the already formed layers. All of these processes create parts
that are near net shape. Because of shrinkages associated with the processes and the post
processing of some processes, the inserts need to be oversized. The inserts will need to be
squared and a finish machining operation needs to be done on the geometry and parting line.
Indirect tooling are molds that are cast around a prototype part. Usually the prototype parts are
constructed on rapid prototyping machines and are finished before the molds are cast. Silicone
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Meckley, Edwards
molds are not used for injection molding applications, but are a common way to get prototype
parts with some properties of injection molded plastic parts. The parts are cast from
polyurethane or silicone rubber. There are different grades of polyurethane or silicone to
simulate many common thermoplastic polymers. It is the simplest way to get prototype parts
with some of the properties of injection molded parts. However, these parts do not always
perform like injection molded parts, because there is no polymer orientation from the injection
molding process.
Another indirect tooling option that can be used in injection molding is aluminum-filled epoxy
molds. Epoxy molds are cast around a prototype part. It is a similar process to the silicone
molds. Because the molds are made of a polymer, the thermal conductivity is very low
compared to typical mold steels. The cooling times are very long to allow the parts to cool.
Typically there is a fan that blows air on the open mold to cool it before the next part is made.
Only a few hundred, to a couple thousand parts can be made from a set of inserts depending on
complexity of the part[7]. This is the least expensive option for true injection molded parts.
The ProMetal process is an ink-jet based process to make additive direct tooling for injection
molding inserts. This process was developed at MIT and commercialized in 1997[8]. The
process uses a print head to drop a liquid binder onto a bed of stainless steel powder (Figure 2).
Using the 2D layers generated by the slicing process as a boundary, the print head sprays
droplets of binder to fill in between the boundaries. The droplets not only bind with the adjacent
droplets, they bind to the layer below. There is a need for support of any downward facing
surfaces, such as overhangs, unconnected layers, and undercuts[9]. This is accomplished in this
process by the remaining powder that was not printed with binder. When the part is complete, it
is pulled from the powder bed and cleaned off. The powder that is in any internal passages is
evacuated by gravity or a spray of air[10]. Since the powder is spherical, it flows easily. When
the parts are completed, a high energy lamp is used to dry the part. It is then taken to an oven to
partially sinter the material. During this process, the binder is burned off. The part is only
partially sintered to reduce the amount of shrinkage. It then needs to be infiltrated with bronze to
reach full densification. This process is done under a vacuum which allows the bronze to wick
into the partially sintered part. Because of the drying and sintering process, there is some nonuniform shrinkage of the part. It is customary to size the geometry so the final part is oversized
by 1.5 mm to account for this shrinkage. This necessitates machining operations to take these
near net shape parts and make them to size[11].
The inserts used in this study could have been constructed for $7,500 in approximately three
weeks at a mold shop. A service bureau would have constructed the rapid tooling inserts and
performed the finish machining for $4,000 in two weeks. Most service bureaus that specialize in
rapid tooling have the capability to do machining. These prices do not reflect any mold design.
There would be additional time and cost to construct conformal cooling lines in the solids
modeling system.
The insert material used in this study was ProMetal’s S4. It is a composite material composed of
60% stainless steel and 40% bronze. Some newer materials from ProMetal are fully sintered and
provide better thermal and strength properties than S4; however, they experience excessive
shrinkage from the sintering process. The excessive shrinkage puts stresses in the parts and
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Meckley, Edwards
could lead to cracking. This limits the size of parts, because the larger parts will experience
more shrinkage. The partial sintering leaves a part with voids throughout the part. It can be
compared to a box of marbles. Even when packed into the box, there are open areas between the
marbles where they do not touch. When the sintering starts, the stainless steel powder starts to
melt where the powder particles touch each other. As this melting occurs, the part begins to
shrink as the particles start to bind to each other. The voids between the particles become
smaller as they melt more into each other. In full sintering, the particles bond all around each
other and leave no voids. At full sintering, the part shrinks as the voids are filled. Partial
sintering leaves some voids and therefore reduces the amount of shrinkage. The bronze is
infiltrated into the voids. This creates a composite structure where there are distinct regions of
stainless steel and bronze. The composite regions combined with the thermal conductivity of
stainless steel help slow the transfer of heat. The addition of bronze makes the structure softer.
P20 is a common pre-hardened mold insert material used in injection molding. It is a chromemoly alloy with a carbon content of 0.30% to 0.40%[12]. It is used in mold plates as well as many
mold components.
The properties for S4, P20, and stainless steel (SS) can be seen in Figure 3. The thermal
conductivity of S4 is 22.6 W/(m °K), P20 is 29.0 W/(m °K), and 420 stainless steel is 24.9 W/(m
°K). Heat transfer through composite materials encounters resistance at the boundaries between
the two materials. Even though the powder particles are bonded together and form a pathway for
the heat to flow, the heat will flow in the path of least resistance, as well as through those
pathways.
Some of the part’s performance and dimensions are determined by how it cools in the mold.
Mold temperature for each polymer material family is based on the processing needs of that
material. The thickness of the flow channel through a part can be affected by the mold
temperature. If the mold temperature is too low, the polymer that freezes against the mold walls
may become too thick and choke off the flow between the mold walls. Once flow has stopped, it
is the rate that the heat is removed that is important. When looking at the three materials, P20
should remove heat from the inserts better than the S4.
Because the heat transfer is important, a mold designer may look to Ampcolay or beryllium
copper for part or the entire insert. Better thermal conductivity is one approach to help reduce
cooling time. These materials are typically used in the core insert because the core has to absorb
the same amount of heat as the cavity, but the core has a much smaller volume to absorb that
heat. The higher thermal conductivity materials can help to remove the heat more quickly out of
the core.
Cooling is affected by several material and geometry considerations and it is important to
balance these to get the most performance out of the inserts[13]. As the coolant flows through the
cooling lines, it picks up heat. In general, it is best to keep the temperature increase to less than
5.0°C. In long cooling channels, areas towards the end of the cooling channels will not have as
much heat removed. The flow of the coolant is important because more heat can be removed if
the flow is turbulent. Reynolds Number is a measure of laminar or turbulent flow. Reynolds
Numbers below 2000 show laminar flow. Above 4600 it is turbulent flow. Between those two
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numbers is a transition from laminar to turbulent flow. An optimum Reynolds Number is
10,000. Above this number, there is little gain in heat transfer[14]. Polymer materials have poor
thermal conductivity compared to metals. Each polymer family has a unique thermal
conductivity. This affects how quickly a part can give up its heat. Because of the different
structure of each polymer family, the temperature to melt is distinctive to that family.
The goal of cooling is to remove heat quickly and cooling lines should be economical to
construct. At times these two attributes can conflict with each other. It is cheaper and quicker to
machine straight drilled cooling lines. In complicated part geometries, these straight drilled lines
may not always follow the part geometry evenly. This may create cool spots in the mold and
change how the part shrinks. To achieve proper cooling, several levels of cooling lines should be
used. The spacing between the cooling lines should be 2.5 to 3.5 times the diameter of the
cooling line. Figure 4 shows a cross section of a cooling line layout. The thin green, yellow,
purple, and red lines are isotherms representing the temperature distribution from the cooling
lines to the mold wall. The lines should be spaced to keep the temperature as uniform as
possible. The spacing from the mold wall should be 0.8 to 1.5 times the spacing between the
cooling lines[15].
Designing of the cooling lines is usually done after most other mold details are finished.
Placement of gates, venting, core pins, and ejection are considered first because their placement
in the mold is essential to making a good part. In some cases, cooling is put in quickly without
regard to how it will affect the part. However, because of its importance to part quality, cooling
should be considered earlier in the design and concurrently with the other mold features. Mold
cooling analysis should be run to optimize the cooling design. There are few of these analysis
performed on new molds. Without this type of analyses, it is guesswork as to whether the
cooling layout will be effective.
Mold temperature is controlled by the use of a thermolator. The temperate setting on the
thermolator is usually around 7°C below the temperature of the mold surface. The regulation of
the temperature is important because it impacts the filling of the part and the surface finish. A
colder mold will pull more heat out and increase the frozen layer thickness. This reduces the
flow channel of the polymer during filling and packing. A warmer mold will allow the polymer
to pick up more mold details and have a glossier finish.
Conformal cooling lines follow the part geometry in the mold. Optimum placement will make
for uniform mold temperatures. The use of mold cooling analysis and FEA is essential to
designing these types of cooling lines. It would be easy to put in too many cooling lines to
increase cooling. During the filling and packing phases there could be as much as 150 MPa
pressure inside the mold cavity. The force from this pressure needs to get past the cooling lines
without busting through. In the injection molding process the pressure is cyclical and it is
generally recommended that the stresses in the mold are less than 10% of the tensile yield stress.
As the part starts to cool, the pressure is reduced. This cyclical force will fatigue the insert if it is
not designed correctly. In order to have the best cooling line placement that will have the best
structural integrity, the use of both mold cooling analysis and FEA is essential.
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Conformal cooling lines can be machined, but that will increase the build time and the cost.
Figure 5 shows a two piece conformal cooling machined insert. The amount of machining to
make the two pieces could be more than double of a conventional insert depending on the
complexity of the geometry. Molds with conformal cooling could not be used with geometry
that would require thin cores or some complex geometry.
Today, global competition and the need for better quality parts more quickly drives how
companies proceed through the design process. It was common in the past to make a mold,
sample the parts, and make changes to the mold to increase part quality. This cannot be done as
easily when competing with countries that have a lower cost of operation. It now means that
engineers must do a better job of designing parts and molds that need minimum reworking. The
use of CAE tools is essential to making this happen. Ten or more years ago, the computing
power and software demanded expensive computing platforms and expert analysts to run CAE
analyses. That has changed over the last few years. The software has become easier to use and
computing power has drastically increased from ten years ago. Although the software is easy to
use, the analysts need training to understand how to set up an analysis and interpret the results.
This software allows the designer to experiment with different strategies on the computer to
optimize the design before any “steel” is cut[16]. Although this creates more time in the design
cycle, it reduces the time from when the first trials are run on a mold to when the actual
production starts.
The polymer material properties can be seen in Figure 6. HDPE is a semi-crystalline material.
The polymer chains start folding on themselves, forming crystals, when the temperature drops to
the melt temperature (Tm). This happens because the intermolecular forces begin to dominate the
forces between the molecules[17]. When the polymer becomes solid, almost all crystal formation
stops. Full crystallinity cannot be achieved because of polymer chain entanglement. The speed
of cooling determines the amount of crystallinity. When the mold is colder, the polymer is
solidified quickly and does not allow the maximum amount of crystal growth. With a warmer
mold, the polymer has more time to form crystals.
Because PC is an amorphous polymer material, there are no crystals formed when the polymer
starts to cool. The polymer’s structure determines if it will be semi-crystalline or amorphous.
Amorphous polymers have no distinct melt temperature. There is a general softening around the
Glass Transition Temperature (Tg). Semi-crystalline polymers do have a Tg, but it is the point
where the behavior changes from glassy and brittle to leathery.
III. Equipment and Method
The basic dimensions on the parting line for the part used in this study are 57.15 mm long and
38.10 mm wide. It is 29.97 mm high on the top step and slopes down from the back to the front.
It also slopes up from the left to the right. The wall thickness was set at 2.54 mm. The part can
be seen in Figure 7. Using the orientation of the picture, several areas of the part will be defined.
The top surfaces are defined as the surfaces at the top of the picture. There are two steps for
those top surfaces. The top step on the top surfaces is seen in the upper left of the picture. The
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Meckley, Edwards
lower step is seen in the upper right of the picture. The bottom of the part is towards the bottom
of the picture.
The mold was designed to allow for a quick change of inserts. Each core and cavity insert slides
into the main insert body (Figure 8). Two screws hold each insert into the main insert body. The
cooling lines interface on the bottom of the pocket on the main insert body. O-rings around the
holes for the cooling lines are used to seal the interface.
There were three sets of inserts used in this study. A P-20 insert with conventional cooling lines
was used as a base line to compare cooling efficiency with the S4 inserts (Figure 9, Figure 10,
Figure 11, and Figure 12). One of the S4 inserts was constructed with the same cooling line
layout as the P20. The other S4 insert was constructed with conformal cooling lines (Figure 13,
Figure 14, Figure 15, and Figure 16). All three sets of inserts were treated to remove the shine
from the surface to help eliminate the light reflecting off the inserts, which can change the
temperatures recorded on the infrared camera.
The molding was performed on a Husky Hylectric 90 injection molding machine. A thermolator
was used to control the temperature of the mold inserts. The mold and part temperatures were
recorded with a FLIR A20. The flow of water through each insert was measured with a Burger
& Brown – Smartflow Tracer.
The HDPE is LG Chemical’s Lutene ME9180. The PC is GE Plastics’ Lexan 124R.
Moldflow Plastics Insight 6.1 Version 2 was used for the mold filling and cooling simulations.
The part and cooling lines were modeled and imported from Pro/Engineer Wildfire 3.0. ANSYS
11.0 was used for the stress analysis.
Before running the experiment, a hand-held pyrometer was placed on a mold surface to measure
the temperature. The infrared camera was aimed at that same location to verify the temperatures.
It was within 0.5°C. The flow of water through each insert was measured and recorded.
The process was optimized on the P20 conventional inserts for both materials and can be seen in
Figure 17. It was used as a baseline for the other inserts. The mold was run for fifteen minutes
to bring it to temperature equilibrium at the 18 s cooling time. The infrared camera was set up to
record the temperatures of the cavity insert. Three cycles were recorded and the infrared camera
was changed to record the core insert. After three more cycles were recorded, the infrared
camera was moved to record the part. Three parts were used to record the outside and three for
the inside. Only one infrared camera angle was used for each insert. It was selected for each
view to show the top surface and a side of the part geometry.
The cycle was then set to the lowest achievable cooling time. The HDPE was set at 4 s and the
PC was set at 10 s. The infrared pictures were taken again.
The process parameters and coolant flow rates were entered into Moldflow and the analyses were
run. The pressures from Moldflow were used in ANSYS to determine the maximum pressure in
the mold cavity.
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Presentation of Data
Plot Name
Plot
Number
Low
Temperature Range
High
Difference
°C
HDPE
P‐20 Cavity Insert Results
18 s Actual
18 s Moldflow
4 s Actual
4 s Moldflow
°C
°C
Uniform
Temperature
Y/N
Moldflow Temperature
Difference
Low
High
°C
°C
Moldflow
Trend
Y/N
Top Surfaces
Temperature Moldflow
Difference
Trend
°C
Y/N
18
S4 Conventional Cavity Insert Results
18 s Actual
18 s Moldflow
4 s Actual
4 s Moldflow
19
S4 Conformal Cavity Insert Results
18 s Actual
18 s Moldflow
4 s Actual
4 s Moldflow
20
32.0
35.0
33.0
38.5
33.0
38.0
36.5
41.0
1.0
3.0
3.5
2.5
N
N
N
N
31.0
37.5
33.0
38.8
34.0
39.0
37.0
40.0
3.0
1.5
4.0
1.3
N
N
N
N
31.0
37.0
32.0
35.0
31.0
38.0
34.0
39.0
0.0
1.0
2.0
4.0
Y
N
N
N
3.0
5.0
Y
5.5
4.5
Y
6.5
5.0
Y
5.8
3.0
Y
6.0
7.0
Y
3.0
5.0
Y
0.5
Y
0.5
Y
1.0
Close
Table 1 - HDPE Cavity Results
Plot Name
Plot
Number
Low
Temperature Range
High
Difference
°C
HDPE
P‐20 Core Insert Results
18 s Actual
18 s Moldflow
4 s Actual
4 s Moldflow
°C
°C
Uniform
Temperature
Y/N
Moldflow Temperature
Difference
Low
High
°C
°C
Moldflow
Trend
Y/N
Top Surfaces
Temperature Moldflow
Difference
Trend
°C
Y/N
21
S4 Conventional Core Insert Results
18 s Actual
18 s Moldflow
4 s Actual
4 s Moldflow
22
S4 Conformal Core Insert Results
18 s Actual
18 s Moldflow
4 s Actual
4 s Moldflow
23
31.5
40.0
34.0
41.0
34.0
45.0
39.0
55.0
2.5
5.0
5.0
14.0
N
N
N
N
32.0
40.0
34.0
42.0
38.0
51.0
45.0
59.0
6.0
11.0
11.0
17.0
N
N
N
N
30.0
34.0
31.5
40.0
32.0
36.0
37.0
47.0
2.0
2.0
5.5
7.0
N
N
N
N
8.5
11.0
Y
7.0
16.0
Y
8.0
13.0
Y
8.0
14.0
Y
4.0
4.0
Y
8.5
10.0
Y
1.0
Y
4.0
Y
0.5
Y
Table 2 - HDPE Core Results
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Plot Name
Plot
Number
Low
Temperature Range
High
Difference
°C
HDPE
P‐20 Part Interior Results
18 s Actual
18 s Moldflow
4 s Actual
4 s Moldflow
Meckley, Edwards
°C
°C
Uniform
Temperature
Y/N
Moldflow Temperature
Difference
Low
High
°C
°C
Moldflow
Trend
Y/N
Top Surfaces
Temperature Moldflow
Difference
Trend
°C
Y/N
24
S4 Conventional Part Interior Results
18 s Actual
18 s Moldflow
4 s Actual
4 s Moldflow
25
S4 Conformal Part Interior Results
18 s Actual
18 s Moldflow
4 s Actual
4 s Moldflow
26
42.0
42.0
49.0
60.0
44.0
42.0
71.0
63.0
2.0
0.0
22.0
3.0
N
Y
N
N
41.0
44.0
49.0
63.0
45.0
45.0
75.0
66.0
4.0
1.0
26.0
3.0
N
N
N
N
38.0
40.0
50.0
56.0
38.0
40.0
64.0
57.0
0.0
0.0
14.0
1.0
Y
Y
N
N
0.0
‐2.0
Y
11.0
‐8.0
Y
3.0
0.0
Y
14.0
‐9.0
Y
2.0
2.0
Y
6.0
‐7.0
Y
1.0
N
4.0
N
0.0
Y
Table 3 - HDPE Part Interior Results
Plot Name
Plot
Number
Low
Temperature Range
High
Difference
°C
HDPE
P‐20 Part Exterior Results
18 s Actual
18 s Moldflow
4 s Actual
4 s Moldflow
°C
°C
Uniform
Temperature
Y/N
Moldflow Temperature
Difference
Low
High
°C
°C
Moldflow
Trend
Y/N
Top Surfaces
Temperature Moldflow
Difference
Trend
°C
Y/N
27
S4 Conventional Part Exterior Results
18 s Actual
18 s Moldflow
4 s Actual
4 s Moldflow
28
S4 Conformal Part Exterior Results
18 s Actual
18 s Moldflow
4 s Actual
4 s Moldflow
29
42.0
41.0
54.0
59.0
46.0
48.0
69.0
62.0
4.0
7.0
15.0
3.0
N
N
N
N
42.0
43.0
52.0
62.0
45.0
48.0
72.0
66.0
3.0
5.0
20.0
4.0
N
N
N
N
39.0
44.0
50.0
61.0
39.0
45.0
69.0
63.0
0.0
1.0
19.0
2.0
Y
N
N
N
‐1.0
2.0
Y
5.0
‐7.0
Close
1.0
3.0
Y
10.0
‐6.0
Y
5.0
6.0
Y
11.0
‐6.0
N
4.0
N
3.0
N
0.0
Y
Table 4 - HDPE Part Exterior Results
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Plot Name
Plot
Number
Low
Temperature Range
High
Difference
°C
PC
P‐20 Cavity Insert Results
18 s Actual
18 s Moldflow
4 s Actual
4 s Moldflow
Meckley, Edwards
°C
°C
Uniform
Temperature
Y/N
Moldflow Temperature
Difference
Low
High
°C
°C
Moldflow
Trend
Y/N
Top Surfaces
Temperature Moldflow
Difference
Trend
°C
Y/N
30
S4 Conventional Cavity Insert Results
18 s Actual
18 s Moldflow
4 s Actual
4 s Moldflow
31
S4 Conformal Cavity Insert Results
18 s Actual
18 s Moldflow
4 s Actual
4 s Moldflow
32
48.0
60.0
49.0
61.0
52.5
62.0
55.0
66.0
4.5
2.0
6.0
5.0
N
N
N
N
50.0
62.0
51.0
62.0
53.0
64.0
57.0
66.0
3.0
2.0
6.0
4.0
N
N
N
N
49.0
55.0
48.0
56.0
52.5
60.0
52.5
61.0
3.5
5.0
4.5
5.0
Y
N
N
N
12.0
9.5
Y
12.0
11.0
Y
12.0
11.0
Y
11.0
9.0
Y
6.0
7.5
Y
8.0
8.5
Y
3.0
N
3.0
N
2.0
Y
Table 5 - PC Cavity Results
Plot Name
Plot
Number
Low
Temperature Range
High
Difference
°C
PC
P‐20 Core Insert Results
18 s Actual
18 s Moldflow
4 s Actual
4 s Moldflow
°C
°C
Uniform
Temperature
Y/N
Moldflow Temperature
Difference
Low
High
°C
°C
Moldflow
Trend
Y/N
Top Surfaces
Temperature Moldflow
Difference
Trend
°C
Y/N
33
S4 Conventional Core Insert Results
18 s Actual
18 s Moldflow
4 s Actual
4 s Moldflow
34
S4 Conformal Core Insert Results
18 s Actual
18 s Moldflow
4 s Actual
4 s Moldflow
35
47.5
59.0
49.0
66.0
52.5
78.0
56.0
84.0
5.0
19.0
7.0
18.0
N
N
N
N
45.0
60.0
50.0
63.0
52.5
83.0
64.0
91.0
7.5
23.0
14.0
28.0
N
N
N
N
42.5
53.0
45.0
55.0
47.0
66.0
52.0
73.0
4.5
13.0
7.0
18.0
N
N
N
N
11.5
25.5
Y
17.0
28.0
Y
15.0
30.5
Y
13.0
27.0
Y
10.5
19.0
Y
10.0
21.0
Y
4.0
Y
7.5
Y
4.0
Y
Table 6 - PC Core Results
Plot Name
Plot
Number
Low
Temperature Range
High
Difference
°C
PC
P‐20 Part Exterior Results
18 s Actual
18 s Moldflow
4 s Actual
4 s Moldflow
S4 Conformal Part Exterior Results
18 s Actual
18 s Moldflow
4 s Actual
4 s Moldflow
°C
°C
Uniform
Temperature
Y/N
Moldflow Temperature
Difference
Low
High
°C
°C
Moldflow
Trend
Y/N
Top Surfaces
Temperature Moldflow
Difference
Trend
°C
Y/N
36
55.0
72.0
65.0
90.0
65.0
81.0
84.0
90.0
10.0
9.0
19.0
0.0
N
N
N
Y
54.0
68.0
58.0
87.0
58.0
80.0
74.0
91.0
4.0
12.0
16.0
4.0
N
N
N
N
17.0
16.0
Y
25.0
6.0
N
14.0
22.0
Y
29.0
17.0
N
4.0
Y
2.0
Y
37
Table 7 - PC Part Exterior Results
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In each picture, the part and mold outline have been added for a reference. Because of distortion
from the infrared camera and having the perspective added to the Moldflow models, the part
mold insert boundaries are not exact. The part geometry was sized and placed to give an
accurate representation of the part geometry in the mold.
The results for the P20, S4 Conventional, and S4 Conformal cooling line inserts with HDPE and
PC can be seen in Figure 18 through Figure 37. The results on the left are at 18 s and the results
on the right are at 4 s (10 s for PC). The top results are from the infrared camera and were taken
just after the mold opened to its final position. It was generally 1 s from the time the mold
started to open until it was fully open. The bottom results are from Moldflow.
The cavity, core, part interior and exterior results (Table 1, Table 2, Table 3, and Table 4) for
HDPE show that the S4 Conformal has the lowest temperature. It consistently is lowest of the
three inserts. The S4 Conventional has the highest temperature of the three inserts.
The temperatures are generally higher on the side walls and slightly cooler on the top surfaces. It
is hotter on the side walls closer to the back wall near the top step. The temperature is lower on
the part geometry in the mold close to the parting line for the Conventional cavity inserts. In the
Conformal cavity inserts, it is warmer towards the parting line.
The core inserts have a warmer temperature on the top surface, except at the regions close to the
top of the baffles. The temperature decreases towards the parting line of the insert.
The interior and exterior part plots show that the temperature is hotter on the top surfaces. The
temperature of the side walls decreases towards the parting line. The same trend can be seen in
the Conformal parts at 4 s. The temperature is very uniform at 18 s.
Moldflow does a good job of predicting the trends with the Insert Temperature (top) result. It
over-predicts the mold temperatures for the core and cavity inserts. The cavity insert
temperature prediction is higher than the core. For the part temperatures the Bulk Temperature
plot is used. There is a mix of over- and under-predicting the part temperatures. In most cases,
the prediction is above the actual minimum and below the actual maximum temperatures.
The results for PC (Table 5, Table 6, and Table 7) show the same trends as HDPE, but with
higher temperatures. The S4 Conformal has the lowest temperature of the three inserts. The S4
Conventional has the highest of the three inserts.
For part temperature, only the exterior results are presented to reduce the number of plots. They
also follow the same trend as the HDPE.
Moldflow over-predictions of mold temperatures on the core and cavity inserts are a little higher
than for HDPE. The part temperature predictions are also higher than for HDPE.
The ANSYS results can be seen in Figure 38 and Figure 39. They show that the maximum stress
in the cavity was 19.727 MPa. It was seen at the reservoirs at either end of the cavity insert. The
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maximum stress in the core was 57.21 MPa. It was seen inside the core where the main manifold
on the upper step intersects with the top side cooling lines.
The Moldflow Temperature Difference results between the core and cavity insert temperatures
can be seen in Figure 40, Figure 41, and Figure 42. These plots are useful to determine if the
temperatures from core to cavity side are uniform. In general, it is recommended that the
temperature difference is less than 10°C. A positive temperature means that the cavity side is
hotter and a negative temperature means that the core is hotter. The P-20 has a maximum
temperature difference of -10.96°C. The core is hotter in the upper step of the top surfaces. The
S4 Conventional has the same trend, but has a maximum temperature difference of 18.86°C. The
S4 Conformal has a maximum temperature difference of -5.5°C. There is a spot where the
temperature is 5.76°C on the front wall, but it is an anomaly of how the cooling channels were
modeled in Moldflow. It is hotter on the high point of the lower step.
IV. Discussion of Results
HDPE Results
The P20 cavity inserts saw a temperature difference of 1°C at a cooling time of 18 s throughout
the part geometry in the insert. The cooling line layout, seen in Figure 10, is a two level circuit
that surrounds the part geometry in the mold. On the lower step, a cooling circuit crosses over
the lower step and lowers the temperature in that region. There is also a cooler region around the
parting line. The proximity of the bottom cooling circuits to part geometry and parting line help
to cool this region. At a cooling time of 4 s, the cooling circuits and the mold insert do not have
enough time to remove the heat from the plastic part. This was common for all of the results,
except for some S4 Conformal results. Moldflow predicted a higher temperature than what was
actually seen. Moldflow’s cooling results are cycle averaged. This provides an insight as to
what is happening during the entire cycle. Since the polymer enters the mold at its melt
temperature and cools to its temperature at ejection, the cycle averaged-results will always be
higher than the actual temperatures recorded when the mold opens. Moldflow did predict the
temperature trends in the mold.
The results for the S4 Conventional cavity inserts have the same trends as the P20 cavity inserts.
Since the cooling line layout is exactly the same, the temperature patterns should be the same.
The thermal conductivity of the S4 reduces the amount of heat that can be transferred out of the
mold during a given cycle time. The S4 Conventional cavity inserts were hotter by 1°C.
The S4 Conformal cavity inserts were 2°C lower than the P20 cavity inserts. The temperature
distribution was more uniform than the P20. There was no temperature difference at 18 s. The
placement of the cooling circuits was better than the conventional layout because they followed
the shape of the geometry. Moldflow predicted the temperature trends correctly, but was higher
than the actual temperatures.
The P20 core had a 2.5°C difference. It was hotter on the edges of the top surfaces. It was
cooler on the top surface above the baffles. Because of the turbulence of the coolant as it makes
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the 180° turn at the top of the baffle, there is more heat transferred. The temperature decreased
towards the parting line of the insert. The main body of the insert acted like a heat sink to cool
the bottom of the part geometry in the mold. There are three hot spots on the top surface. Two
of those spots are on the surface’s edge between the two baffles. The third hot spot is on the
high spot of the lower step. They are hotter because they are further away from the baffle.
Moldflow over-predicted the temperature more than with the cavity inserts. The core has to
absorb almost the same amount of heat as the cavity, but with a much smaller volume.
Moldflow’s results may have been affected by this calculation.
The S4 Conventional core inserts showed the same trends as the P20 core inserts. They were
hotter by 4°C.
The S4 Conformal core inserts were 2°C lower than the P20 core inserts and showed a more
uniform temperature distribution. There was a hot spot on the high spot of the lower step. The
cooling line was slightly further away from the mold walls in this area. There is no cooling line
that goes across the top surface. The center ejector pin location and the size of the part prevented
any cooling lines from going across the top surface.
The P20 part temperatures, interior and exterior, showed a nearly uniform temperature
distribution. The interior was within 2°C and the exterior was within 4°C at 18 s. The ejector
pin was recessed into the mold by 2 mm. This created a short solid boss in the part. Because
there was a lot of surface area around the boss, it allowed more heat to be pulled out of the part.
The opposite was seen on the exterior of the part. Where the boss intersects the main part body,
there is a hot spot because there is a localized thicker region. It takes longer to cool this region
and shows up on the surface opposite the boss. Moldflow showed a more uniform trend that was
actually recorded.
The S4 Conventional parts showed the same trend and were 1°C warmer at 18 s.
The S4 Conformal parts were 6°C less on the interior and 7°C on the exterior than the P20 parts.
The temperature was uniform in both the interior and exterior. The exterior was 1°C hotter than
the interior. Moldflow showed the trend, except at 4 s.
PC Results
The PC was run with a higher melt and mold temperature. It showed in the results with higher
temperature distributions. The P20 cavity and core inserts showed the same trends as the HDPE.
Moldflow over-predicted at a higher value than HDPE. The S4 Conventional cavity and core
temperatures were slightly hotter and followed the same trends as the P20
The S4 Conformal cavity insert temperatures were similar to the P20. With the higher coolant
temperature, it is possible that the second it took for the mold to open gave the coolant time to
cool both the P20 and S4 Conformal to the same temperature. The S4 Conformal core insert
temperatures were 5.5°C lower than the P20 core insert. Moldflow showed the same trends, but
at a higher temperature.
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The exterior of the P20 parts had a hotter temperature on the upper step of the top surfaces. The
cooling lines are a little further away at the back of the upper step. The ejector pin can be seen as
a hotter section on the exterior. The S4 Conformal has a more uniform temperature than the P20
part. The S4 Conformal parts are 7°C cooler than the P20 parts.
General Discussion
The hotter mold and part temperatures are a result of the S4 material’s poorer thermal
conductivity. The composite structure and stainless steel base material create more resistance to
the flow of heat compared to P20. S4 would not be a reasonable choice for a machined mold
insert. Moldflow showed the difference between the two materials.
The advantage of conformal cooling lines overcomes the poorer thermal conductivity of S4. By
cooling the parts faster, the cooling time could be reduced. If rapid tooling materials with better
thermal conductivity exist, there would be more opportunity to reduce cooling time. This
material would also allow for more uniform temperature of the parts which could increase part
quality. Moldflow shows that the conformal cooling lines provide a much more uniform
temperature than the conventional cooling line layout.
During the injection phase of the molding cycle, high pressure is present in the mold inserts. The
force from this pressure is transmitted to the mold inserts and must be successfully resisted by
the mold inserts. The presence of cooling lines weakens the inserts. They must be placed and
shaped to minimize the weakening of the inserts. Using FEA stress analysis software like
ANSYS, the optimized placement and shape of the cooling lines can be made. The general rule
is to keep the stress below 10% of the tensile yield stress. The maximum stress in the cavity was
19.727 MPa and is well below the recommended stress of 42 MPa. The maximum stress in the
core was 57.21 MPa. It occurred at the intersection of a manifold and two cooling circuit
intersections. The corners are sharp and a round could be placed there to reduce the stress.
Even with the small part size, there was room to put conformal cooling lines into the mold inserts
and have an impact on the part’s cooling. The differences in actual temperatures do not reduce
the effectiveness of Moldflow to design cooling lines. The trends were very close and allow the
designer to optimize the cooling lines.
A possible source of error when using infrared photography to take pictures of metal parts is
stray light may change the temperatures recorded by the camera. To reduce this possibility, a
blanket was used to cover the mold during photography. The inserts were also treated with a
bluing agent to take off the shine.
Another potential source of error was the timing from when the molds were opened and the part
temperatures were taken. The parts were collected by hand and placed in a fixture. There could
have been a variance of a second from when the pictures were started. Several pictures were
taken and the picture with the lowest start time was used.
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V. Future Work
Another set of inserts is being designed to study the effects of warpage between conformal and
conventional cooling lines. The current part is too thick and too small to result in any change in
warpage between the insert materials and cooling line layout. The new part has been modeled in
Moldflow to make sure there is sufficient warpage between insert materials and cooling time.
The use of pulse cooling is another study in the planning stages. Pulse cooling works by
controlling the flow of coolant in the inserts. This keeps the inserts at a more uniform
temperature during the injection molding cycle. It is suspected that the conformal cooling
channels may do a better job at being more uniform compared to conventional cooling.
Monitoring of the coolant temperature increase from inlet to outlet is also planned for the future.
Although the conformal and conventional cooling lines remove approximately the same heat
over the cycle, it is suspected that the conformal will remove this heat more quickly.
Mold sections for blow molding may be investigated after the work has been completed on
injection molding. Neck inserts and complicated geometry may benefit from conformal cooling
lines.
VI. Conclusion
Using the phrases “increased part quality” and “cooling time reduction” in the same sentence has
been an elusive goal of many designers and molders. Many molders are already at the limits of
what conventional cooling lines can provide. Improvement in cooling line design is needed to
get further reductions in cooling time. Conformal cooling channels are the improvement needed
to get an additional reduction in cooling time. Because these cooling lines are optimized to
follow the part geometry in the mold, they provide near uniform cooling of the parts.
This study has shown that conformal cooling lines can overcome the poorer thermal conductivity
of the S4 material and provide better cooling than the standard P20 inserts. In HDPE the
reduction in part temperature was 6°C to 7°C and 7°C temperature reduction for PC. By getting
the cooling lines closer to the part, more heat can be removed from the parts. This reduction in
part temperature has the potential for cooling time reduction.
It would be impossible to get an optimized cooling line layout without the use of CAE tools such
as Moldflow and ANSYS. Even though Moldflow’s temperature predictions of the mold were
higher than actual, it did a good job of predicting the trends. It showed where potential hot spots
occurred in the mold and allowed the designer to modify the layout until they could be
minimized. FEA stress analysis was used to make sure the cooling lines did not reduce the
structural integrity of the inserts.
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VII. Acknowledgments
Thanks go to John Arlotti and ExOne for providing the rapid tooling inserts. Many thanks go to
my wife, Kim, Lucy Lenhardt and Shelley Readel for their constant revisions.
Special thanks go to Rick Coon for machining the inserts and helping plug leaks in the inserts.
Thanks also go to Glen Craig and Matt Baker for helping to plug leaks in one set of inserts.
VIII. References
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
17.
Shoemaker, Jay, Moldflow Design Guide, 1st Ed, 2006, Hanser, p 153
Groover, Mikell, Automation, Productions Systems, and Computer-Integrated Manufacturing, Rev Ed,
Prentice–Hall, 1987, p 284
Gebhardt, Andreas, Rapid Prototyping, 1st Ed, 2003, Hanser, p 90
“Stereolithography," Castle Island’s Worldwide Guide to Rapid Prototyping”, Rev 4a, 1 September 2006, 10
August 2007, http://home.att.net/~castleisland/sla_int.htm
Gebhardt, Andreas, Rapid Prototyping, 1st Ed, 2003, Hanser, p 87
Gebhardt, Andreas, Rapid Prototyping, 1st Ed, 2003, Hanser, p 222
“INDIRECT Tooling and Manufacturing Processes - Mature and/or More Common Technologies," Castle
Island’s Worldwide Guide to Rapid Prototyping”, Rev 2, 27 April 2005, 15 August 2007,
http://home.att.net/~castleisland/tl_tab1.htm
Gebhardt, Andreas, Rapid Prototyping, 1st Ed, 2003, Hanser, p 181
Sachs, Emanuel, Wylonis, Allen, Cima, Guo, Production of Injection Molding Tooling with conformal Cooling
channels using the Three Dimensional Printing Process, Polymer Engineering and Science, 40 5 (2000), p 1233
Sachs, Emanuel, Wylonis, Allen, Cima, Guo, Production of Injection Molding Tooling with conformal Cooling
channels using the Three Dimensional Printing Process, Polymer Engineering and Science, 40 5 (2000), p 1234
Gebhardt, Andreas, Rapid Prototyping, 1st Ed, Hanser, pp 181-183
Britton, Paul W. ,” What You Should Consider When Purchasing P20 Steel”, Moldmaking Technology, Nov.
2004, July 2007, http://www.moldmakingtechnology.com/articles/110401.html
Rees, Herbert, Mold Engineering, 1st Ed, Hanser, p 260
Shoemaker, Jay, Moldflow Design Guide, 1st Ed, Hanser, p 167
Rees, Herbert, Mold Engineering, 1st Ed, Hanser, p 273
Murrell, Fred, Lange, Tom, The Democratization of Engineering Analysis, ANSYS Advantage, 1 2 (2007), pp
28-30
Osswald, A, Baur, Brinkmann, Oberbach, Schmachtenberg, International Plastics Handbook, 4th Ed, Hanser, pp
35-36
Jonathan Meckley
Mr. Jonathan Meckley holds associate and bachelor's degrees in
Mechanical Engineering Technology and a B.S. in Plastics
Engineering Technology from Penn State Erie in 1990. Jon has a
master's degree in Plastics Engineering from the University of
Massachusetts at Lowell. After graduation, Jonathan worked at
Penn State Erie’s Plastic Technical Center doing solids modeling
and running a Stereolithography machine. From 1992 to 1994,
Jonathan was a design engineer and co-owner of Innovation
Design Services, Inc., a computer-aided engineering consulting
firm for the plastics industry. From 1994 to 1998 Jonathan has
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Meckley, Edwards
worked for Penn State Erie’s Plastic Technology Deployment Center as a project engineer.
Since 1999, Jonathan has taught at Penn State Erie in the Plastics Engineering Technology as an
Associate Professor. He is the Past-Chair of the Blow Molding Division of SPE and President of
the Northwest Pennsylvania SPE Section.
Robert Edwards
Mr. Robert Edwards is a lecturer in engineering at Penn State Erie,
The Behrend College. He has been a faculty member in the
Mechanical Engineering Technology program since 1991 when he
was first hired as an adjunct. Mr. Edwards received his A.E. in
Mechanical Technology from Broome Community College in 1970,
his B.S.M.E. in Mechanical Engineering from the Rochester Institute
of Technology in 1973, and the M.S. in Engineering from Gannon
University in 1989. He came to Penn State Behrend with over 20
years of industrial experience. He was employed by General Electric,
Smith Meter Systems, American Sterilizer Company, Lord
Corporation and Finish Thompson.
Mr. Edwards is a member of the American Society of Mechanical
Engineers (ASME), the American Society of Electrical Engineers (ASEE), the Institute of
Electrical and Electronics Engineers (IEEE), the American Society for Testing and Materials
(ASTM), and its D09 Committee, and the International Microelectronics and Packaging Society
(IMAPS)
Figure 1 - STL File
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Conformal Cooling
Lines
O-Ring
Groove
Figure 2 - ProMetal Process
Courtesy of ProMetal
Insert Material Properties
Material
Powder
Infiltrator
Ultimate Tensile Strength
Yield Strength
Modulus
Elongation
Hardness
Thermal Conductivity
Mean CTE (at 300°C)
Specific Heat
P20
SS
Bronze
682
420
147
2.3
26
22.6
1.34E-05
478
SS
Figure 5 - Machined Conformal Cooling Lines
971
850
205
16
32
29
1.28E-05
460
Figure 3 - Insert Material Properties
655
345
200
25
12
24.9
1.03E-05
460
Mpa
Mpa
Gpa
%
HRC
W/m °K
1/°C
J/Kg °K
General Polymer Properties
Material
Density
Tensile Strength
Flex Modulus
Thermal Conductivity
HDPE
0.958
28.4
98.7
0.26
PC
1.19
63
2300
0.21
g/cm 3
Mpa
Mpa
W/(m °K)
Tm
133
°C
Tg
-125
150 °C
Figure 6 - Polymer Properties
Figure 4 - Cooling Line Spacing
Figure 7 - Part Geometry
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Figure 8 - Mold Inserts
Figure 10 - Conventional Cavity Cooling Lines
Figure 9 - Conventional Cavity Insert
Figure 11 - Conventional Core Insert
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Figure 14 - Conformal Cavity Cooling Lines
Figure 12 - Conventional Core Cooling Lines
Figure 15 - Conformal Core Insert
Figure 13 - Conformal Cavity Insert
Figure 16 - Conformal Core Cooling Lines
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Processing Conditions
Material
Melt Temperature
Mold Temperature
HDPE
176.67
32.22
PC
304.44 °C
54.44 °C
Figure 17 - Processing Conditions
Figure 20 - S4 Conformal Cavity Results (HDPE)
Figure 18 - P20 Cavity Results (HDPE)
Figure 21 - P20 Core Results (HDPE)
Figure 19 - S4 Conventional Cavity Results (HDPE)
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Figure 22 - S4 Conventional Core Results (HDPE)
Figure 24 - P20 Part Interior Results (HDPE)
Figure 23 - S4 Conformal Core Results (HDPE)
Figure 25 - S4 Conventional Part Interior Results (HDPE)
Volume 10 No. 1
ISSN# 1523-9926
http://technologyinterface.nmsu.edu/Fall09/
the Technology Interface Journal/Fall 2009
Meckley, Edwards
Figure 28 - S4 Conventional Part Exterior Results (HDPE)
Figure 26 - S4 Conformal Part Interior Results (HDPE)
Figure 29 - S4 Conformal Part Exterior Results (HDPE)
Figure 27 - P20 Part Exterior Results (HDPE)
Volume 10 No. 1
ISSN# 1523-9926
http://technologyinterface.nmsu.edu/Fall09/
the Technology Interface Journal/Fall 2009
Meckley, Edwards
Figure 30 - P20 Cavity Results (PC)
Figure 32 - S4 Conformal Cavity Results (PC)
Figure 31 - S4 Conventional Cavity Results (PC)
Figure 33 - P20 Core Results (PC)
Volume 10 No. 1
ISSN# 1523-9926
http://technologyinterface.nmsu.edu/Fall09/
the Technology Interface Journal/Fall 2009
Figure 34 - S4 Conventional Core Results (PC)
Figure 35 - S4 Conformal Core Results (PC)
Meckley, Edwards
Figure 36 - P20 Part Exterior Results (PC)
Figure 37 - S4 Conformal Exterior Results (PC)
Volume 10 No. 1
ISSN# 1523-9926
http://technologyinterface.nmsu.edu/Fall09/
the Technology Interface Journal/Fall 2009
Meckley, Edwards
Figure 40 - P20 Temperature Difference Results
Figure 38 - Cavity ANSYS Results
Figure 41 - S4 Conventional Temperature Difference
Results
Figure 39 - Core ANSYS Results
Volume 10 No. 1
ISSN# 1523-9926
http://technologyinterface.nmsu.edu/Fall09/
the Technology Interface Journal/Fall 2009
Meckley, Edwards
Figure 42 - S4 Conformal Temperature Difference Results
Volume 10 No. 1
ISSN# 1523-9926
http://technologyinterface.nmsu.edu/Fall09/