31 Screw Classifications Unified National Standard ISO (Metric) Thread Pitch UNC –coarse UNF –fine UNEF –extra fine coarse fine ¼-20 UNF –2A Class 2 20 threads/in. d=0.25” external threads fine M12 x 1.75 metric d=12mm p=1.75 mm/tread Tolerance Class 1 Class 2 Class 3 Class 1 Class 2 Class 3
51 Fasteners The Nuts and bolts we all use PHS Auto Salisbury
52 SYSTEMS OF THREAD MEASUREMENT ENGLISH SYSTEM System of thread measurement uses a fractional system to determine thread diameter when 1/4” or larger. Each diameter increases by 1/16” up to about 1/2” Thread diameters of 1/4”, 5/16”, 3/8”, 7/16” 1/2” are most commonly used
53 SYSTEMS OF THREAD MEASUREMENT TABLE OF BOLT SIZES/THREAD PITCH-UNIFIED NATIONAL COARSE (UNC) AND UNIFIED NATIONAL FINE (UNF) Size- Fractional (decimal) Threads UNC Threads (UNF) 1/4" (.250")2028 5/16" (.3125") 1824 3/8" (.375")1624 7/16" (.4375") 1420 1/2" (.500")1320 9/16" (.5625") 1218 5/8" (.625")1118 3/4" (.750")1016
54 SMALL FASTENERS THREAD DIAMETERS 1/4” And Smaller use a wire size number. –The smallest is Zero (0) and the largest is 14 –#4, #6, #8, #10 and #12 are common sizes –Each has a standard UNC/UNF thread specification. Sizes are in increments of two
55 HEAD SIZE Vs DIAMETER Head size of fastener is not size of fastener Size is diameter of threaded portion of fastener For Example Wrench sizeBolt diameter 7/16 - 1/4 ½ - 5/16 9/16 - 3/8 11/16 - 7/16 ¾ - ½ 7/8 - 9/16 15/16 - 5/8
56 BOLT LENGTH MEASURED FROM UNDER HEAD TO END OF THREADS USUALLY COME IN 1/4” INCREMENTS STARTING FROM 1/2” LENGTH LONGEST BOLTS USED IN THE AUTOMOTIVE FIELD ARE LESS THEN 6 INCHES LONG
57 FASTENER STRENGTH FOR ENGLISH FASTENERS STRENGTH OR HARDNESS IS DETERMINED BY COUNTING SLASHES OR POINTS ON IT’S HEAD NO POINTS UNGRADED SHOULD NOT BE USED ON AUTOMOTIVE APPLICATONS 3 POINTS GRADE 5 COMMONLY USED 6 POINTS GRADE 8 HIGH STRESSES
58 Bolt Strength On U.S. bolts add 2 to the # of lines to get the grade for exampl e 3 lines plus two equals a grade 5 Bolt
59 FASTENER STRENGTH FOR METRIC FASTENERS INDICATED BY NUMBER ON HEAD (PROPERTY CLASS) –4.6, 4.8, 5.8, 8.8, 9.8 AND 10.9 –Nuts will have a class of 4 or 6
60 FASTENER STRENGTH FOR NUTS –Dots are used to represent the strength of Nuts
61 FASTENER STRENGTH FOR NUTS –Numbers are stamped to represent the strength of Metric Nuts
63 THREAD TYPE TYPE OR PITCH REFERS TO CONSTRUCTION OF THREAD –NUMBER OF THREADS PER INCH NATIONAL COARSE (NC OR USS) NATIONAL FINE (NF OR SAE) ALL 1/4” AND LARGER WILL BE EITHER NC OR NF 1/4” AND SMALLER USES SPECIAL DESIGNATION
64 A. Pitch C. Diameter D. Thread length E. Screw length F. Threads per inch G. Head size How to measure a bolt
65 American Standard bolts come in two thread pitch’s NC National Coarse & NF National Fine NF NC Coarse & Fine Thread
66 THREAD PITCH From 0-1 shows that you have 7 TPI Threads per inch. (US standard) Metric you measure the pitch, from top of thread to top of thread like # A
67 Thread pitch gauge Used to find how many threads in an inch come in metric and standard
68 Thread pitch gauge This bolt has 13 threads per inch
69 Thread Designations US Threads To write out Thread designations for US bolts first you give the Diameter then the Thread Pitch then the Length D X TPI X L ½ X 13 X 2 Take a bolt and give me the Thread designations for it. You can always add the grade of the bolt. Such as grade 5
70 METRIC FASTENERS SIMILAR TO ENGLISH SYSTEM THREAD DIAMETER IS EXPRESSED IN MILLIMETERS (mm) THREAD TYPE IS DIFFERENT –THREAD SIZE IS DETERMINED BY MEASURING THE DISTANCE IN MILLIMETERS FROM CREST OF ONE THREAD TO CREST OF NEXT ONE. Example 1.00, 1.25, AND 1.50
71 Thread Designations for Metric To write out Thread designations for Metric bolts first you give the Diameter then the Thread Pitch then the Length. Only this time it should be in millimeters D X TPI X L M12 X 1.50 X 60 You can always add the Class (grade) of the bolt.
72 SPECIAL FASTENERS LEFT HAND FASTENERS –WILL HAVE NOTCHES CUT AT CORNERS OR WILL HAVE A “M” or a “L” STAMPED ON THEM
80 Name the different clips Internal snap ring Pal nut External snap ring Grease Zerk Blind Rivets Wing Nut E-Clip Split or Roll Pin
81 Name the clips Internal clip for a drive line (U-Joint Cross) External clip for a drive line
82 THREAD REPAIR One reason why we break off bolts is that we use to long of bolts in blind holes and it jams against the bottom of the hole this bolt is then very hard to remove If a Bolt is broken off the first thing you want to do is soak it with penetrating oil. If it is broken off flush use a hammer and punch to see if it will turn out for you. Center punch in the center of the fastener and use a left hand drill bit to try to remove it.
83 THREAD REPAIR Use a screw extractor sometimes called a easy out to remove it. First drill a hole in the center, all the way through the fastener. Lightly tap the extractor with a hammer and then remove with a wrench
84 THREAD REPAIR If it does not come out drill out and retap the hole. Do not break off the extractor or tap in the hole You may also try using heat and water to heat the area around the bolt and cool the fastener.
85 THREAD REPAIR Use locking pliers Reshape head or weld on nut CBC AUTOMOTIVE RK
86 THREAD REPAIR Drill out and use a easy out CBC AUTOMOTIVE RK
87 Heli Coil EZ- LOK Make sure you use the right drill & tap size THREAD REPAIR
88 Thread lockers Anaerobic cures after the components are put together Three basic colors Blue, Red, Green Clean and dry all parts removing dirt, oil, grease and/or any foreign material
89 Blue Thread lockers Medium Strength for all bolts ¼ or larger Able to Remove with hand tools Prevents parts from loosening from vibration Protects threads from corrosion Recommend for valve cover bolts,rocker arm nuts, carburetor studs, motorcycle, jet skis snowmobiles etc.
90 Red Thread lockers High Strength Hard to Remove Works well for studs and press fit Locks against heavy vibration Requires extra effort to remove or special tools like heat OEM specified as 271
91 Green Thread lockers Wicking Grade for Pre-assembled Parts Use on Calibration and adjustment screws OEM specified as 290 There is also a Green High Strength for sleeves
92 Purple Thread lockers Low strength Use on screws up to ¼ Not used a lot in Automotive applications that I am aware of.
93 Thread / Pipe Sealant Thread Sealant for metal tapered pipe threads and fittings replaces teflon tape Suggested applications Stainless steel fittings, head bolts into through holes, oil PSI sending units/sensors, oil and coolant lines, intake manifold switches, rear axle fill plug, fuel fittings
94 Teflon Tape Prevents leaks Just wrap tape around threads Use on stainless, aluminum, plastic, iron, copper, or brass.
95 The end for now most of these pictures were borrowed off of the web site Go check it out And the Permatex web site a big Thank you goes to both sites