1. Beginning Metal Repair

2. Introduction Herb Spenner  hspenner@gavilan.edu hspenner@gavilan.edu Background  Electrical Engineer – Purdue, A&P – Gavilan College  Gavilan Aviation Technology Instructor FAA Airframe and Power (A&P) mechanics program A&P with IA (Inspection Authorization) Teach General & Airframe classes Web based information  http://hhh.gavilan.edu/hspenner/BeginMetal/ http://hhh.gavilan.edu/hspenner/BeginMetal/

3. Class’s Starting Idea

4. Topics Rules & Safety Basic metal properties Cleaning Cutting Drilling & tapping holes Fasteners Welding Finishing

5. Projects Drilling and Tapping  Cutting bar stock  Drilling  Tapping  Bolt extraction  Thread repair (Heli-Coil®)

6. Projects Sheet Metal Welding  Cutting  Cleaning  Tack  Butt  Rosette  Flanging  Finishing

7. Projects Rolling Cart  Cutting  Cleaning  Fitting  Welding  Joint reinforcement  Finishing

8. Rules and Safety Safety First!  Get instruction on equipment  Eye protection and gloves required for all power tools  Welding only with a helmet, jacket and gloves Proper Attire  No loose fitting cloths  Natural fiber cloths Nylon and Polyester will burn  Long pants - blue jeans  Closed toed shoes  No loose jewelry

9. Rules and Safety Act Professional  Respect the facilities Don’t touch anything in a cabinet without asking Don’t touch any of the students tools Return all Gavilan tools to their proper place  Respect your colleagues No eating or smoking allowed in classroom or lab  Drinks are acceptable Cleanup after yourself

10. Ferrous Metals Ferrous metal is one that contains iron Pure iron is too soft for most uses  Add carbon to iron and you get steel SAE - Society of Automotive Engineers  SAE four-digit numbering system for identifying steel Hard steel, such as drill bits and taps, break very easily Heat treated, hardened & coated metals are not welded

11. CRES Corrosion Resistant steel Stainless steel 10+% of chromium 200 thru 400 series Usually not as strong as carbon steel Usually non-magnetic Difficult to weld

12. Aluminum Alloys Soft, lighter and more expensive than steel Aluminum alloy four-digit identification system:  First digit - Alloy type  Second digit - Modification of alloy Many of the stronger alloys corrode and can’t be welded Work hardens and fails dramatically Steel fasteners will cause aluminum to corrode  Paint aluminum or use “sacrificial” washer

13. Copper Alloys Alloys  Beryllium  Zinc – makes brass  Tin – makes bronze  Aluminum  Manganese Corrosion resistant Becomes brittle when work hardened Can’t be welded  Braze or solder

14. Cleaning Metal All corrosion must be removed before welding or paint Steel corrosion removal  Scotch-Brite  Sand paper  File  Grinder  Wire brush or wheel  Phosphoric acid e.g. Naval jelly

15. Cleaning Metal Aluminum corrosion removal  Scotch-Brite  Very fine sand paper  Stain steel wire brush – not used on steel  Phosphoric acid wash Copper  Scotch-Brite  Sand paper  File  Grinder  Wire brush or wheel

16. Cleaning Metal Oil must be removed before welding or painting  Denatured alcohol  Acetone – fingernail polish remover Water test – water will form a film on clean metal  If the water film “breaks”, the surface is not clean

17. Welding Puddle

18. Welding Welding – a process that joins metal by melting or hammering the work pieces until they are united together.  Base metal must be melted  Process must protect molten metal from atmosphere  Material (filler) is added to joint  Filler material must match base metal  Process must control the amount of heat and the rate that filler is added

19. Weld Joints

20. Bead

21. Welding Gas welding – The use of oxygen and acetylene (oxy-acetylene) to create a flame that melts the metal to be welded  Burning process protects metal  Uses filler rods  Medium hard to learn  Portable  Dirty  Easy to add heat treating and cutting options

22. Welding Shielded Metal Arc Welding (SMAW) –– “stick”  Arc welding process that uses a consumable flux- coated electrode  Flux melts and coats molten metal Forms a glass like cover – must be remove Helps remove impurities  Easy to learn  Simple equipment  Crude results  Can be used outside  Video Video

23. Welding Gas Tungsten Arc Welding (GTAW) – an arc welding process that uses a non-consumable tungsten electrode to produce the heat for the weld.  TIG – Tungsten Inert Gas  Shielding gas usually is argon or helium  Similar to Gas Welding, except uses a electric arc  Very clean/very sensitive to dirt  Can’t be used in windy conditions  Very hard to learn

24. Welding Puddle

25. Welding Gas Metal Arc Welding (GMAW) – MIG - a method of welding in which the filler metal wire supplies the electric current to maintain the arc, which is shielded from the surrounding air by an inert gas, usually argon or carbon dioxide (CO 2 )  Filler is automatically fed from reel of wire  Easy to learn - one handed application  Fast  Can’t be used in windy conditions  Dirty and splatters  Difficult to determine the quality of the weld

26. Welding Video

27. Welding Video 1Video 2

28. Welding Flux Core – Combination of “stick” and MIG welding  Uses a MIG welding machine  Welding wire is hollow with flux inside  No shielding gas  Easy to learn  Can be used outside  Dirty

29. Welding Spot welding – Uses electric current to fuse two pieces of sheet metal together  No filler material  Clean  Easy to use  Extensively used in the automotive industry  Video Video

30. Weld Joints

32. Tack Weld

34. Rosette Weld Video

35. Drill Bits Sizes available in fraction of an inch, metric and numbered Soft metals – high speed and light pressure Hard metals – low speed and higher pressure Reduce speed a bit size increases Use oil for cleaning chips and cooling

36. Tap and Die Tap Die

37. Tap and Die Threads  UNF – fine  UNC – course  National Taper Pipe (NTP) Tapered to seal fluids  Rolled and cut Rolled is stronger Use matching drill size Use cutting oil and/or grease (catch shavings) 1/2 turn forward and then backup Straight and slow

38. Tap

39. Plain Washers Provides a smooth bearing surface Protects surface from galling & corrosion  Must be used when using a locking washers Should be used under every bolt head and nut When using lock washer, the order should be:  Bolt  Plain washer  Mating surface  Plain washer  Lock washer  Nut

40. Metal Cutting Abrasive chop saw  Good for bar stock  Rough finish  Hard to get accurate  No oil Angle grinder  Cutting wheel – abrasive Wears quickly  Grinding disk - shaping  Sanding disk - shaping Belt sander - shaping

41. Metal Cutting Saws with teeth use oil Hack saw  More teeth per inch (TPI) the finer the cutter  If careful, can be very accurate  Invest in a ridge frame Saber saw Scrolling saw Band saw Shears

42. Home Welder Invest in a good helmet MIG best option Be care of “MIG” core flux welders Be care full of combo welders – inexpensive ones may have to many compromises  e.g. starter circuits  May need “optional” equipment Find one with infinite (smooth) adjustments Is 110 volt enough? – ¼” max welding Cart with good wheels

43. Longevity MIG 140