Rapid Manufacturing: For Metalcasting

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Rapid ManufacturingFor Metalcasting

• Martin Koch, O.F.D.
• Industrial Manufacturing Engineering
• California Polytechnic University, San Luis
  Obispo, CA

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Rapid Manufacturing

• What does this mean? (for Metalcasters)
• To use Rapid Prototyping methodologies?
• To make the part/s?
• To make the tools?
• To get a product into production?

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Rapid Prototyping Methodologies
All methods currently take a solid cad model
represented by an STL file, slice it into layers
and perform a 2D process to build each
layer. The 2D process may be the writing with a
laser beam, extruding a material, exposing with
an image or jetting.
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Knee Implant STL Model
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Sliced into layers
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1 layer
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Layer with Roads (tool paths)
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Top view Sliced layer with Tool Paths
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Rapid Prototyping Systems
Stereolithography
Laminated Object Manufacturing
Fused Deposition Modeling
Selective Laser Sintering
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Stereolithography
Mirror System
LASER
Base
Elevator Platform
Liquid Photopolymer
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Laminated Object Manufacturing
Mirror System
LASER
Laminating Roller
Supply Roll
Take-Up Roll
Elevator Platform
Excess material cross-hatched for later removal
Part boundary
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Fused Deposition Modeling
Thermoplastic Filament
Extruder Head
Elevator Platform
Supply Roll
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Selective Laser Sintering
Mirror System
LASER
Laser Selectively Sinters Powder
Leveling Roller
Loose Powder
Powder Bed
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To make the part/s?You can use RP to make metal
parts

• There are RP Fabrication processes that can make
  metal parts.
• Some of these are
• ProMetal from Extrudehone
• SLS from 3D Systems
• EOSINT M from EOS

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ProMetal Extrudehone
Components are removed from the printing machine
and placed in a high temperature furnace where
they are either directly sintered to maximum
density, or are sintered and then infiltrated
with a lower melting temperature metal. (from
the Extrudehone web page)
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3D Systems SLS
The SLS Process 1. Start with an STL file of
your 3-D CAD data. 2. Enter the data into a
Vanguard HS SLS system. 3. Spread a layer of
powdered material. As the process begins, a
precision roller mechanism automatically spreads
a thin layer of powdered SLS material across the
build platform. 4. Sinter a cross-section of
the CAD file. Using data from the STL file, a CO2
laser selectively draws a cross section of the
object on the layer of powder. As the laser draws
the cross section, it selectively "sinters"
(heats and fuses) the powder creating a solid
mass that represents one cross section of the
part. 5. Repeat. The system spreads and sinters
layer after layer until the object is complete.
6. Remove the part. Once the part is complete,
remove it from the part build chamber and blow
away any loose powder. 7. Finish as desired.
Use the part as isor sand, anneal, coat, or
paint it before using it for its intended
application. 8. Sinter and infiltrate part
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EOSINT M Direct Metal Laser-Sintering (DMLS)
Applications

• DirectTool
• injection moulding tool inserts
• die casting mould inserts
• other tooling, e.g. sheet metal forming, blow
  moulding etc.
• tooling fixtures etc.
• DirectPart
• Prototypes for
• sintered products
• customized, one-off parts
• small-series production

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e-Manufacturing

• Fast, flexible and cost-effective production
  directly from electronic data

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Rapid Manufacturing Castings?

• No.
• These systems can not compete with sand casting.
• However the output from RP systems can be used
  for several casting methods for low volume work.
• A few examples
• The RP part as an expendable pattern for
  Investment Casting
• A tool to make expendable patterns/ molds
• Injection die
• Rubber Plaster molding
• A pattern to make molds
• For metalcasting
• For other materials

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Secondary Processes

• A few examples
• The RP part as an expendable pattern for
  Investment Casting
• A tool to make expendable patterns/ molds
• Injection die
• Rubber Plaster molding
• A pattern to make molds
• For metalcasting
• For other materials

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FDM ABS Pattern on Wax Tree
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Ceramic Shell I/C Mold
Normal procedures have to be modified somewhat to
facilitate the use of ABS patterns. Nothing new,
but not standard
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I/C Burn Out
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Casting the Ceramic Shell
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Metal Casting
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FDM ABS Injection Die
The injection die is Built hollow to save
Material and time. It will be filled with Epoxy
for strength.
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Wax Injection
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FDM Wax Injection Die
Produces waxes for Investment Casting The foundry
can use its normally procedures in producing
castings
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Rubber Plaster Molding

• An old process that has found new life with RP
• Used to produce fine details, such as those
  possible with die casting
• The RP pattern is used to make a flexible tool
  that is used to make a plaster mold set
• At one RPM foundry in California over 95 of
  their jobs are from SLA , or other, RP patterns

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Rubber Tool
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Rubber Tool
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Plaster Mold
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Our focus will be on Sand Casting

• We are Metalcasters and I would like to talk
  about how RP might be used to enhance our
  processes.
• Even though we have all heard the management
  focus phrase that We are not in business to make
  castings, we are in business to make money
• I would suggest that We are in business to make
  money by making castings
• Why? Because making castings is fun and Id
  rather die on the ride then listening to my CPA.
• So, what can Rapid Prototyping do for the process
  of making sand castings?

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Casting Development

• Product into production
• Standard steps
• A) Design Part
• B) Design manufacturing process
• Are these separate, sequential steps?
• No!
• Both can benefit from prototyping
• For Rapid Manufacturing
• The goal is to develop both as concurrently as
  possible.

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What is a Prototype?

• What is a Prototype used for?
• To test Form, Fit, Function
• Two uses
• Conceptual
• Functional

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Conceptual Prototype

• Used to convey / communicate concepts
• It can be tested for form

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Conceptual Prototype

• Used to communicate concepts across the divides
  of culture, language, and discipline.

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Functional Prototype

• A prototype is functional if it is made in the
  desired material via the desired process.
• It can be tested for fit and function
• In other words the MEs can break it.

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Can the RP Prototype be functional?

• Normally not.
• The materials are still predominately
  non-structural materials wax, plastics, powder
  green bodies.
• Plus, surface finishes are still layered.

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FDM ABS Tensile Bar
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FDM ABS Pattern With Supports
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Producing Functional Prototypes

• It is the next goal to have the RP machines
  produce functional prototypes.
• This means that we have to make sand molds.

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How do we make sand molds from RP patterns?

• An email exchange illustrates a typical casting
  need
• We looking for some resource/advise for making
  sand cores for Aluminum castings. We have tried
  SLS sintered sand cores but process seems to be
  very expensive. We need at least 30-50 pieces.
  Has someone tried Zcorp machine to make the sand
  moulds? I'm keen for getting few ideas and
  technologies available, because it will be an
  ongoing process for us.
• Thanks in advance.

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A foundrymans reply

• Larry Blasch
• Design Engineer/CAE Systems Administrator
• OPW Fueling Components

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• If you are making 30-50 of the same sand core
  part, than just build the
• core prints with any accurate RP process and make
  high temperature
• epoxy core boxes to form the sand cores in.
• I do aluminum sand casting pre-production
  patterns often with SLA for
• quantities like that. I've also made tools for
  casting bronze, iron, steel
• and stainless the same way. It also works well
  for "Green Sand"
• molding when no cores are required.
• Just build the patterns for sand casting -split
  at the parting line with
• dowel pin holes already in the parts. Use the pin
  holes to match drill
• the plate and this will guarantee that the
  pattern halves get mounted to
• the mold plate accurately. Unless you plan on
  making more than 100
• parts, you can run SLA patterns in the sand
  without duplicating the
• plate. Glue the pattern halves to the plate, and
  rig gates and runners
• as necessary. A final coat of epoxy spray paint
  will help the sand pull
• clean.

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• I've run SLA "Master Patterns" with double shrink
  and used
• them to cast the production tooling plate. That
  was in the distant
• past, now we just NC machine the production plate
  if we need 100
• quantities.
• The same goes for core prints. Depending on the
  core sand
• process you are using, you may be able to just
  build the core box
• with RP and make the cores directly. I never
  tried it with the newer
• "High Temperature" SLA resins, but you may even
  be able to make
• shell cores in SLA core boxes.
• I've found that most pattern makers won't have
  any problem
• working with "accurate" RP masters. Typically, I
  just add a single
• shrink to the pattern and no shrink to the core.

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Sand Molds

• So, we can use RP patterns to make sand molds and
  core boxes.
• And, there are some new methods for making the
  sand molds directly on the RP machines
• Some of these systems are
• ZCAST from Zcorp
• EOSINT S from EOS
• Prometal RCT from Extrudehone

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Z CastDirect Metal Casting

• Sand Casting Process
• 3D printed sand mold and cores
• Dimensional accuracy
• good
• Maximum mold size 20 x 24 x 16
• Time frame, casting 3 days after after receipt
  of CAD file possible

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ZCAST

• A sand mold is printed directly via a binder
  being printed onto a sand bed, layer by layer.

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Cast Mold built in 4 sections
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Casting
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EOSINT S Laser-Sintering of Foundry Sand
Applications

• DirectCast - sand moulds and cores for metal
  castings
• motor blocks
• pumps
• hydraulic devices
• housings
• special castings

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EXTRUDEHONE S15
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Sand Molds and Cores
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Sand Mold
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The Clinkenbeard ProcessA patented process
tool-less cores molds
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CNC Tool
Sand Block
CNC Table
Very good process for producing one or two pieces
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Some concluding thoughts

• For a period of years the idea was to try to use
  RP to make the foundry tools.
• However, high speed machining has reduced the
  need for this.
• It is now common that one would machine the
  matchplates and core boxes.
• Or, one would machine the matchplates and RP the
  cores.
• With the direct production of sand molds it
  sometimes makes sense to RP the molds directly
  for small volume prototype needs of complicated
  castings. ie blocks and heads.

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Thank You

• Please come visit!
• Cal Poly
• San Luis Obispo, CA
• On the coast ½ way between SF and LA