APPL310 BME352 Junior Biomedical Design

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APPL310BME352Junior Biomedical Design
Manufacturing

• Prof. Bob Dennis
• bob_at_unc.edu

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LECTURE 8

• Questions? bob_at_unc.edu
• Modern Design Practice
• a,ß-prototypes, Documentation, ECN
• Manufacturing
• Water-jet, EDM, DMF
• Projects Reports

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Prototypes

• a-Prototype (Bench Test, used by developers)
• Basically proof-of-concept
• Demonstrate key features
• Prove principle of operation
• Identify problems and non-compliance w/ spec
• ß-Prototype (Beta Test, used by end users)
• Functional prototype
• Incorporate design changes and improvements
• Incorporate user feedback
• Consider manufacturability, maintenance, field use

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Documentation

• Engineering Notebook
• Receipts, concepts sketches, photos, test data,
  source contact information, ...
• BoM - (Bill of Materials)
• Detailed design
• Solid models
• 3-view drawings
• Process Materials notes
• Record of design evolution, ECN...

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ECN

• What is an ECN?
• A brief technical document (a technical memo)
  showing the details of a change to a design.
• SHORT GOOD

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Engineering Change Notice
IS
WAS
¼-20 x 1.5 Grade 2 Nut Bolt
¼-20 x 1.5 Grade 8 Nut, Bolt Washers
Notes Needed to replace Grade 2 bolt
with Grade 8 bolt hardware to prevent failure
while loading cattle into sling. Washers were
also added.
Bob-Co Engineering, Inc.
Project Trebuchet
Ref Drawing Sling Clamp
Engineer R.G. Dennis 3/4/2003
Proj. Mgr S. Skerlos 3/6/2003
Mgmt./Sponsor B. Gates 3/6/2003
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ECN

• ECN Content
• Sketch of what was changed
• What part or project does this impact
• Why was the change made?
• Who made the change (date)
• Who authorized the change (sponsor?)
• Each organization will have their own format

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ECN

• What can an ECN be used for
• Any changes to a mature design (usually after
  the final approval of the first complete design
  or prototype)
• Use the ECN for changes to
• Dimensions, materials, processes, components,
  specifications, test protocols,

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ECN

• Why use an ECN?
• To communicate (clear, concise, in writing)
• To formalize the Design Process
• (Who has authority to make changes?)
• To track the changes in a design, process
• (Corporate memory 20 years down the
  roadWhyd they do that?)
• To allow non-design engineers to formally
  request design changes
• (test engineers, sales, field engineers,
  customer reps, sponsors, )
• To accumulate many small changes before making
  a major design revision.
• To maintain a LIVING DESIGN

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Water-jet Cutting

• Currently the fastest growing machine tool
  process
• Water is pressurized to 60,000 psi
• Ultra-high pressure pump, UHP gt 30,000 psi
• Stream is directed through a small nozzle
• Pure water water-jet
• Can cut many soft materials
• Food, textiles, foam, rubber, paper
• Water abrasive abrasive water jet
• Abrasive is usually fine mesh garnet
• Can cut almost any hard material
• Steel, titanium, ceramics glass, bone, stone,
  concrete
• Advantages
• cold cutting, no noxious fumes, very fast, no
  residual stresses

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Trends in modern manufacturing processes

• Rapid planar geometry manufacturing
• Cut shapes quickly from plates sheets
• Laser machining
• Plasma cutting
• Water-jet cutting

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Electron Discharge Machining (EDM)

• Spark machining rapid series of electrical
  sparks are used to blast off metal surface
  nearest to the electrode
• Metal and electrode are immersed in an ionic
  fluid
• fluid conducts electricity, flushes away
  blasted-off metal, and provides coolant
• Only works with electrically-conductive materials
• Usually used for extremely hard metals

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Electron Discharge Machining (EDM)
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EDM depends on electrode

• Ram EDM
• A graphite negative mold of the desired piece is
  made into an electrode using traditional
  machining techniques
• The graphite electrode is then slowly rammed into
  the metal using EDM to create the final metal
  part
• Wire EDM
• A thin metal wire is slowly moved into and
  through the metal, cutting away the metal using
  EDM
• Extremely fine, complex, precise and arbitrary
  shapes can be machined by wire EDM

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Direct Metal Fabrication (DMF, EBM, FFF)
Arcam EBM S12 (www.arcam.com)
DMF Direct Metal Fabrication EBM
Electron-beam melting FFF Free Form
Fabrication Available at NCSU (research) Can be
used for Rapid Manufacturing Functional,
homogeneous components Component surface is
rough some finishing is generally
required Component geometry can be achieved that
is not possible using other manufacturing
technologies. Builds parts from successive
layers of metal powder, melted together by a
focused electron beam in a vacuum.
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EBM Biomedical Applications
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Arcam EBM Process

• Begin with an .STL file (same as our FDM)
• Arcam software slices the STL into layers
• Powdered metal is placed in EBM machine
• EBM puts down successive layers of powder
• EBM fuses powder in each layer to build part

CAD
EBM/FFF
Part
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EBM _at_ NCSU
Titanium Alloys Ti6Al4V (Grade 5) Pure Ti
(Grade 2)Steel Alloys Arcam Low Alloy 200
Arcam Tool SteelMaterials under development
include Cobalt-Chrome alloys Super Alloys
(Inconel 718, 625 620) Stainless Steel
Titanium Aluminide Beryllium. AlBeMet
NOTE post-EBM finishing is required
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EBM Practical considerations
support
support
support
support
FIXTURE
FIXTURE
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SUMMARY

• Questions? bob_at_unc.edu
• Modern Design Practice
• a,ß-prototypes, Documentation, ECN
• Manufacturing
• Water-jet, EDM, DMF
• Projects Reports
• Reverse Engineering
• Manufacturing Rotating Bioreactor
• Manufacturing Research 3-pages

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ASSIGNMENT

• Water jet cutting is a new and rapidly growing
  manufacturing technology. In its simplest
  embodiment it allows you to cut two-dimensional
  features into sheets or plates of material.
  Consider water jet cutting, and think of some
  sort of biomedical product where you might
  consider using this manufacturing process to
  custom-manufacture various shapes or features of
  a product line.
• What biomedical product line might you choose to
  employ water-jet cutting? Choose something very
  simple if possible.
• Use SolidWorks to draw up at least two samples of
  a line of biomedical products you could make
  using primarily a water-jet cutter as the
  manufacturing process.