1. R·I·T Kate Gleason College of Engineering Design of a Tensile Load Frame for a Scanning Electron Microscope Senior Design Project 04004 Project Manager - Robert Rinefierd Faculty Mentor - Dr. Elizabeth Debartolo

2. R·I·T – Senior Design 04-004 Kate Gleason College of Engineering Team Members Project Manager – Robert Rinefierd Lead Engineer – Evan Kastner Mechanical Engineers –Nicholas Currier, Evan Kastner, Robert Rinefierd, Blaine Stuart Industrial Engineer –Kennedy Mogwai Computer Engineer –Evan Brunner

3. R·I·T – Senior Design 04-004 Kate Gleason College of Engineering Agenda Introduction Concept Development Feasibility Assessment Objectives and Specifications Design Analysis Preliminary Design Production Schedule

4. R·I·T – Senior Design 04-004 Kate Gleason College of Engineering Project Overview Design and construct a load frame to apply tensile loads to specimens inside the Scanning Electron Microscope (SEM) in the CIMS Materials Science Lab The load frame should be lightweight, modular, and easy to carry between buildings Developed for Mechanical Engineering Department faculty and students performing metallographic research Funded by the Mechanical Engineering department

5. R·I·T – Senior Design 04-004 Kate Gleason College of Engineering What is a Scanning Electron Microscope? High powered microscope for analysis of surfaces or near- surface areas (up to 25,000X) Has a good depth of field, so images remain in focus Good tool for evaluating fracture surfaces Capable of producing chemical analysis of surfaces

6. R·I·T – Senior Design 04-004 Kate Gleason College of Engineering How does it work? Electrons from an electron gun are reflected off of the surface Image is produced from the energy and electrons reflected by the surface Image is displayed on a monitor screen Magnification controlled by reducing the scanned area Electron Microscopy and Analysis, Goodhew, 1992

7. R·I·T – Senior Design 04-004 Kate Gleason College of Engineering The Position Fixture Dials control motors to adjust the position. The frame has xyz and tilt controls. Available space is roughly 9”wide, 3” high, and 11” deep. Doors and ports can be replaced to allow for tensile controls or a window to monitor tensile display on frame.

8. R·I·T – Senior Design 04-004 Kate Gleason College of Engineering Design Constraints Spatial constraints Vacuum compatibility CIMS Materials Lab owns the SEM; Mechanical Engineering department will own the load frame –Load frame to mount to existing position fixture –Limited to existing ports for vacuum feedthrough Budget

9. R·I·T – Senior Design 04-004 Kate Gleason College of Engineering Concept 1 – Internal Motor, 2 Screws Internal components 2 power screws Motor driven Advantages: reliable Disadvantages: slightly over budget limit

10. R·I·T – Senior Design 04-004 Kate Gleason College of Engineering Concept 2 – Internal Motor, 1 Screw Motor –Stepper motor Drive Train –Single screw Mounting Frame –Fixed base Grips –Self locking Interface –Vacuum Control/ Display –Automatic –Closed loop

11. R·I·T – Senior Design 04-004 Kate Gleason College of Engineering Concept 3 – Manually Powered Uses a removable hand- driven crank to apply load Advantages: –Cheap –Reliable –Easily within scope of team’s knowledge Disadvantages: –Down time to change loads –Eliminates ability to analyze load dynamically

12. R·I·T – Senior Design 04-004 Kate Gleason College of Engineering Concept 4 – External Motor Advantages –additional internal space –air cooled heat dissipation Disadvantages –complex gearing –lack of mobility –cost

13. R·I·T – Senior Design 04-004 Kate Gleason College of Engineering Feasibility Assessment Introduction –Major part of design activity –Decision making activity –Qualitative or quantitative –Attributes Resources Economical Schedule Technical feasibility

14. R·I·T – Senior Design 04-004 Kate Gleason College of Engineering Feasibility Assessment Evaluation of Design Concepts Pugh Evaluation –Similar to “paired comparison” –Qualitative evaluation –Reference concept –Eliminate weak concepts Weighted Concept Evaluation –Systematic quantitative –Performed in Six step –Relative weight importance –Value judgment

15. R·I·T – Senior Design 04-004 Kate Gleason College of Engineering Objectives and Specifications Performance –200 lbs Compression, 1000 lbs Tension (2000 lbs Target) –Position and Load Control –Live Displays Implementation –Cylindrical Threaded Specimen –Remove Part of Position Frame Evaluation –Pass Fatigue and Stress Calculations Safety –Vacuum –Grounding

16. R·I·T – Senior Design 04-004 Kate Gleason College of Engineering Motor and Gearbox Selection Determining Factors in Motor Selection: –Vacuum Rating – Vapor Pressure –Space Constraints –Cost Determining Factors in Gearbox Selection: –Those Listed Above + –Reduction Ratio –Continuous Output Torque Ceiling

17. R·I·T – Senior Design 04-004 Kate Gleason College of Engineering Advantages of Design Overall Reduction Offers Near Continuous Resolution From a Stepper Motor Impossible for Motor To Damage Gearbox Largest Output Torque Possible with Size Constraint Large Torque Produced to Handle Dry Friction Problem Likely to Create a Large Factor of Safety

18. R·I·T – Senior Design 04-004 Kate Gleason College of Engineering Vacuum Compliance Obstacles With Vacuum Compliance –Cost –Time Budget Investigation of Component Materials Cleansing of Machined Parts & Pretreatments –Rare Properties (Friction Coefficients) –Lack of Substitutes (Scarcity  Price) –Heat Dissipation (No Convection Medium)

19. R·I·T – Senior Design 04-004 Kate Gleason College of Engineering Vacuum Compliance 300 Series Stainless Steel When Possible –High Corrosion Resistance –Outgassing Unproblematic All Materials of All Non-Vacuum Rated Components Evaluated or Will Be Evaluated For Vacuum Compatibility

20. R·I·T – Senior Design 04-004 Kate Gleason College of Engineering Power screws ACME ¾-10 - Self Locking Capability COTS Product: Nook Industries, Keystone –Exact tooth geometry unknown (pitch angle) –Bronze nut rated to 9000lbf force and 2250lbf dynamic force –Bronze nut must be replaced with stainless steel nut (cost under investigation) –Likelihood of need for custom flange mount for stainless steel replacement nut

21. R·I·T – Senior Design 04-004 Kate Gleason College of Engineering Gear linkage Consists of two 2 ½ inch diameter gears and one 1 inch diameter gear. All gears are connected inline. –Achieves a final gearing reduction of 2 ½. 1 inch diameter gear attached to shaft of gearbox. –Drives one 2 ½ inch diameter gear which drives the other. 2 ½ diameter gears drive the two power screws.

22. R·I·T – Senior Design 04-004 Kate Gleason College of Engineering Gear Specifications Gears are to be purchased –Custom Manufacture Type: Cylindrical Pitch: 16 Face Width: 0.75 inch Material: 8620 Case Hardened Steel or 17-4 (0.2% Yield  200KSI) 20° pressure angle

23. R·I·T – Senior Design 04-004 Kate Gleason College of Engineering Stress Analysis Key Design Issue: Transfer of a Torque To Create a Linear Force Concepts Investigated –Interference Pin Connection –Generation of clamping force with shoulder screw – using friction to transfer torque Steel on steel bearing contact surface –Needle bearing with cap to secure axial load; stepped ACME shaft with keyway Lowers torque dramatically

24. R·I·T – Senior Design 04-004 Kate Gleason College of Engineering Needle Bearing Option Shoulder screw option requires frequent lubrication to avoid metal transfer –Vacuum lubricant: $300/oz, 10 -6 torr vacuum Bearing allows continuation of ACME shaft to transfer lesser torque while withstanding high radial load from cylindrical gears –Details in flux due to late discovery of affordable vacuum compatible bearings

25. R·I·T – Senior Design 04-004 Kate Gleason College of Engineering Grip Design 1 inch diameter cylinder 1 inch long 3/8 – 24 female threads bored through center Material: 303 Stainless Steel Knurling around surface –Reduces stress concentrations –Improves grip ability Added Bonus: Also functions as a fastener within tensile stage.

26. R·I·T – Senior Design 04-004 Kate Gleason College of Engineering Test Specimens Round “dog-bone” shape Both ends of specimen cut to 3/8 – 24 male threads –Screw into female threads of grips Viewable Area –Gage length of 1 inch –Diameter of ¼ inch

27. R·I·T – Senior Design 04-004 Kate Gleason College of Engineering Mounting to Position Fixture Purpose –Interface between stage and SEM –Mounting surface for stage –Hold SEM position resolution device How? –Match bolt holes –Calculate stresses in mating screws from base to the rest of load frame in worst case scenario

28. R·I·T – Senior Design 04-004 Kate Gleason College of Engineering

29. R·I·T – Senior Design 04-004 Kate Gleason College of Engineering Controls Control through LabView End user definable Serial port link Stock or freeware libraries Hard emergency stop

30. R·I·T – Senior Design 04-004 Kate Gleason College of Engineering Control Software User defines boundaries of operation previous to entry into chamber Interrupt driven communication between user interface and MCU

31. R·I·T – Senior Design 04-004 Kate Gleason College of Engineering Vacuum Interface Available port on the chamber door - 2 ¾ “ Flange - Vacuum chamber Tight seals around all electrical connections and plates Controls and digital monitor may be located outside the chamber

32. R·I·T – Senior Design 04-004 Kate Gleason College of Engineering Vacuum Chamber Feed through What is needed –8 wires through chamber wall 4 for stepper 2 for thermocouple 2 for load cell Places looked –Nor Cal (www.n-c.com)www.n-c.com –MDC (www.mdc-vacuum.com)www.mdc-vacuum.com –Varian Inc (www.varian-inc.com)www.varian-inc.com –Veeco (www.veeco.com)www.veeco.com

33. R·I·T – Senior Design 04-004 Kate Gleason College of Engineering Test Plan New scientific function – that of test and evaluation engineering Autonomous activity – product development cycle Integrated Test plan –Objectives & requirement –Detailed test plan & procedure –Test report requirement –Project scheduling SEM Integrated Test Plan – Development Test & Evaluation –Components or Parts Testing –Subassemblies Testing –Deployment Testing

34. R·I·T – Senior Design 04-004 Kate Gleason College of Engineering Production Schedule February: –Submit purchase order for motor, gearbox, vacuum lubricant, load cell, electrical feedthrough and components, and steel Mid-March: –Completion of all aspects of mechanical design –Submit order for all remaining components –Completion of detailed design including FEA analysis –Design for assembly analysis April: –Hand fabrication of steel components –Integration of control system May: –Testing and troubleshooting

35. R·I·T – Senior Design 04-004 Kate Gleason College of Engineering Cost Estimate ComponentManufacturerQtyUnit CostTotal Cost Stainless SteelAllegheny Ludlum1$1,000.00 GearboxEmpire Magnetics1$2,156.00 Gearbox-Motor Custom Adaptation CostEmpire Magnetics1$150.00 Stepper MotorEmpire Magnetics1$834.00 Motor Thermal SensorEmpire Magnetics1$157.00 Stepper Motor KeyEmpire Magnetics1$146.00 Load CellFutek1$475.00 Spur Gear - PinionMcMaster-Carr1$58.08 Spur GearMcMaster-Carr2$58.08$116.16 Shoulder ScrewsMcMaster-Carr2$15.13$30.26 CollarAllegheny Ludlum2$50.00$100.00 ACME Thread Stock and StudsNook Industries1$136.72 ACME Thread Stock and StudsNook Industries1$102.58 Vacuum LubricantMany Candidates1$0.00 Free End BoltMany Candidates1$10.00 Fixed End BoltMany Candidates1$10.00 ScrewsMany; Some Already in Possession20$0.25$5.00 Other Machining CostsN/A1$0.00 Vacuum Sealed Electrical InterfaceN-C1$150.00 Adapter Connection Set: Vacuum Electrical InterfaceN-C1$50.00 Teflon Jacketed, Silver Coated Copper Wires & Teflon/ Silver Wire Nuts Empire Magnetics, N-C, MDC-Vacuum, Varian1$100.00 Stepper DriveMany Candidates1$100.00 MicroprocessorMany Candidates1$200.00 Control Box - User InterfaceN/A1$0.00 TOTAL COST$6,086.80

36. R·I·T – Senior Design 04-004 Kate Gleason College of Engineering Questions and Discussion