1. BLACK&DECKER Jess Dibelka Mark Steimer Laura Traub Julianne Twomey 12/10/07

2. Introduction Lithium-ion battery pack Metal Oxide Semiconductor Field Effect Transistor (MOSFET) Electrical switch that controls the speed of the drill head Introduces an electrical resistance Continuous current loading raises MOSFET temperature

3. MOSFET Small Voltage applied to gate Creates electric field across +p substrate Conduction bands allow large currents to flow through MOSFET Trigger Motor

4. 75°C (OSHA) Objectives 98 °C (Plastic Deformation Temperature) 175°C Goal: Reduce the temperature of the MOSFET junction during use to avoid failure

5. Quantity of Energy Absorbed Circular Saw Current Profile Used to Over Constrain Design Heat Energy Trigger MOSFET Motor RjRj

6. Target Values

7. Heat Removal Concepts

8. Final Heat Sink Concept

9. Design Issues MOSFET Attachment/Orientation Geometric fit within handle Heat Absorbed Thermal – Thermal Gradient – Cp, K, ρ

10. Required Volume Volume Analysis Heat Sink Cast Aluminum 356 V = 9.37cm 3 Stamped Aluminum 6061 V = 9.99 cm 3 Using Law of Energy Conservation

11. Detailed Design Process 1) SolidWorks Modeling 2) Geometrically Fit in 3D Drill Handle 3) Thermal Model of Drill Handle Thermal Model Drill Handle Solid Works Design Fit Design in Drill Handle

12. Stamped Concepts Eliminated Maximum gage thickness of 3 mm Stamping designs occupy more space than cast Copper mass significantly higher MaterialMass (g) Al 606126.98 Cu62.78

13. 3 MOSFET Mounts = 3 Cast Designs Oval Flange D-Sink MOSFET wires bent 45 o MOSFET wires rotated 90 o MOSFET wires un-bent

14. Thermal Modeling Initial Solid Modeling Apply 1401 J of energy to heat sink Natural convection from heat sink Apply adiabatic wall on outer drill handle Heat Sink Temp ProfileHeat Sink in Drill Handle 97.4 o C 95.3 o C 1401 J

15. Thermal Modeling Results Heat Sink Temp Surface Plot Drill HandleTemp Surface Plot Design ConstraintsFlangeOvalD-Sink Max Heat Sink Temperature (Constraint < 98 o C) 81.275.581.4 Max MOSFET Temperature (Constraint < 175 o C) 85.376.383.4 Max Drill Handle Temperature (Constraint < 75 o C) 67.444.062.2

16. Testing Overview 1)Indicate Heat Sink temperatures with simplified Box Test 2)Test Heat Sink in Drill Handle a.Heat Sink Thermal Repeatability b.Test Procedure Repeatability

17. Testing Procedure 1)Attach thermocouples 2)Attach resistor and apply thermal grease 3)Place Heat Sink in Box 4)Apply 1401 J of energy over 732 s 5) Obtain temperature profiles Thermocouples Test 1: Box Test Testing Set-Up

18. Testing Procedure Test 2: Drill Handle Test 1)Identical procedure 2)Heat sink placed in drill handle 3)Thermal repeatability: Flange tested 3 times 4)Test procedure repeatability: Oval tested 2 times Thermocouples

19. Testing Data Collected For each trial collected thermocouple readings for: Heat Sink MOSFET Handle

20. Heat Sink Testing Conclusions Relatively No Thermal Change Between Heat Sinks Flange has Best MOSFET Attachment Therefore : Flange is Best Design Heat Sink Loading and Test Procedure Proved Repeatable

21. Design Process Conclusion Temperature difference due to Adiabatic wall condition in Modeling. Can re-design using FloWorks assuming 10 o C Temperature difference. FloWorks to Test Analysis Heat SinkFlangeOvalD-Sink Drill Handle10.42 ±.4511.55 ± 2.469.36 ±.72 Box15.10 ± 2.2615.31 ± 2.9313.10 ± 2.46 Average ∆T (FloWorks - Testing) ± Standard Deviation

22. Ultimate Re-Design 1)Incorporates 0° wire bend angle MOSFET attachment 2)Use FloWorks to yield max heat sink temperature of ~96 o C. 3)Expect testing to yield a temperature of ~86 o C 4)Leaving a Margin of Safety of ~10 o C V = 6.45 cc Ultimate FloWorks ( o C) Expected Test Results ( o C) Maximum MOSFET Temperature 40 o C Ambient102.292.2 Maximum Outer Handle Temperature 40 o C Ambient66.456.4 Maximum Heat Sink Temperature 40 o C Ambient95.9585.8

23. Cost Analysis Machinist 10 hrs at $70/hr Material $2/lb, 50% scrap Thermocouples Production cost $30,000 tooling cost 700,000 total parts

24. Path Forward- B&D Confirm Predicted Test Results of Ultimate Design Use Design Methodology to Develop Heat Sinks in Future Tools Receive Cost Quotes from Heat Sink Suppliers Test Reliability of Bolt and Nut Attachment Under Long Term Thermal Cycling Adapt If Needed To Fit Other Tools

25. Summary All constraints and target values are achieved in heat sink design!!! Heat sinks and testing procedure are repeatable Difference in heat sink performance between FloWorks and Testing is ~10 o C New “Ultimate” heat sink is lighter and incorporates positives of previous heat sinks Cost for Black and Decker to implement Ultimate is approximately 13 ¢ per heat sink

26. Questions Thank You: Black and Decker Daniel Brisach (Thermal Modeling Help) Roger Stahl (Rapid Prototypes) & Dr. Glancey

27. Test Data CV

28. Test Data Delta T

30. Testing Target Value Results Heat Sinks Satisfied the Constraints with ~ 20 o C Margin of Safety Constraint Maximum MOSFET Temperature @ 40 o C Ambient 175 o C79.581.479.1 Constraint Maximum Outer Handle Temperature @ 40 o C Ambient 75 o C49.047.054.0 Constraint Maximum Heat Sink Temperature @ 40 o C Ambient 98 o C70.269.770.6 1Quantity of Heat Absorbed 1401.9 JControlled 4 Qty Battery Cycles or Time before T j = 175 o C 2 or 732 sControlled 8 Max Temperature Change 1 o C 1.12.10.6 Testing Prototype MetricsTarget ValueRankingD-Sink ActualFlange ActualOval Actual

31. Testing Results Flange Repeatability Plain English Statement Example of C V  Poor controlC v =.2 Fair controlC v =.1 Tight controlC v =.05 Excellent controlC v =.025 World classC v =.0125 Seldom achievedC v =.000625 Courtesy of Dr. Glancey Oval Test Repeatability Thermocouple12345 Coefficient of Variability0.0830.0770.0040.0760.082 Thermocouple678910 Coefficient of Variability0.0090.0020.0470.0270.028

32. Energy Analysis MOSFET Total Energy Equation Actual MOSFET Junction Temperature

33. Energy Calculations

34. Energy Analysis Heat Sink Volume of Heat Sink Required

35. Thermal Analysis Handle TPTP

36. Thermal Analysis Constants Equation Constants

37. Material Properties

38. Testing Calculations