Hardware, Fasteners, Drills, and Thread Repair M.C.V.T.S.

Characteristics For the basic theory of threaded fasteners, see the Threaded Fastener Theory Section (http://www.srl.gatech.edu/education/ME3110/primer/ftypes.html#bolts 7/13/04)

Fastener Grades SAE: Society of Automotive Engineers ISO: International Standards Organization

Fastener Grades SAE Grade Capscrews: are evaluated by the American National Standards Institute (ANSI) SAE Grade Capscrews: have markings to identify their strength. (Count the lines and add two.) Example: five lines is a grade eight bolt

Fastener Grades ISO: Classifies bolt quality in terms of tensile and yield strength. ISO: Graded bolts have grading numbers on the head or cap. ISO: Grades are given as two numbers (8.9,10.9, etc) ISO:The first number is tensile strength ISO:The second number is yield strength

Fastener Grades Tensile Strength: is the maximum stress the material can withstand without breaking Yield Point: is the maximum stress a material can withstand and still be able to return to its original form without damage Ultimate Strength: is about 10 percent higher than the yield point. That is the point where the fastener breaks.

Fastener Grades SAE Grade Property Class 5.8 Grade 5 8.8 Grade 7 9.8 Grade 8 10.9

Bolt Stretch Clamping Force: Bolts are stretched to provide a clamping force Elastic Limit: is reached when it will no longer return to its original shape Normally bolts are stretched to 70 percent of their elastic limit.

Nuts Must be matched to the bolt grade May have grade markings on the top or sides Grade five may not be marked Are softer than bolts

Flat Washers Case Hardened: only hardened on the outside Through-Hardened: are hardened throughout

Types of Washers Flat Lock Shaker-Proof

Taps & Threads Types Taper Plug Tap Bottom Used to start the tap into the hole Plug Tap Is a standard tap Bottom Makes threads all the way to the bottom

Taps & Threads SAE USS Metric Pipe Society of Automotive Engineers (fine thread) USS United States Standard (coarse thread) Metric Several Thread Types Pipe Uses Tapered threads

Dies Are used to make external threads Can be used to repair damaged threads

More Information

Barnhill Bolt Co., Inc.  Fastener Vendor with FAQ sheet for general info. The Nutty Company, Inc.  Fastener Vendor with Extensive Online Catalog (and a sense of Humor) Hayes Bolt & Supply Company Alloy Fasteners, Inc.  A manufacturer, distributor, and importer of stainless steel fasteners. AROW Components and Fasteners, Inc.  Fastener Vender with lots of nifty technical information on general Fasteners

Assignments Chap. 6 Automotive Service Review Questions Pg 66 Chap. 6 Automotive Service Workbook Using the google search engine find information on SAE and ISO