WPP-Fasteners & Hardware T-DAP MAP 32 WPP-Fasteners & Hardware

Agenda Fastener terminology & application Metric, Imperial and non-standard hardware Physical properties of hardware Factors that affect torque Fastener chemicals

Fasteners & hardware Function: To hold things together Most common automotive type – threaded fastener

Fasteners & hardware Automotive hardware includes: bolts / nuts screws studs locking devices pins rivets keys washers retaining rings helicoils

Fasteners & hardware Threaded fasteners are available in many sizes, designs & threads Threads can be rolled - definition “Threads formed by tightly pressing or rolling the piece of stock between serrated dies. This is the most common method of creating threaded fasteners today.” Rolled threads = 30% stronger and better fatigue resistance

Fasteners & hardware Threads can be cut - definition “Threads formed by cutting into a piece of stock.”

Fasteners & hardware

Fasteners & hardware

Fasteners & hardware

Fasteners & hardware Fasteners are made to imperial or metric measurements 4 classifications of threads (imperial) Unified National Coarse (UNC) Unified National Fine (UNF) Unified National Extra fine (UNEF) Unified National Pipe Thread (NPT,UNPT) Metric fasteners available in standard, fine and superfine

Fasteners & hardware Cap screws (a.k.a. bolts) nomenclature S = shank diameter T = thread diameter R = root diameter

Fasteners & hardware When measuring fastener diameter, always use “T” thread diameter which measures at the crest of the thread Beware: hex head size is not bolt size

Fasteners & hardware

Fasteners & hardware When measuring fastener diameter, always use “T” thread diameter which measures at the crest of the thread Beware: hex head size is not bolt size

Fasteners & hardware Bolts are usually made from steel Different grades of steel give different strengths Property Class Imperial bolts (fractional) have lines in the head of the bolt Metric bolts have decimal number in the head of the bolt

Fasteners & hardware

Fasteners & hardware Head markings other than property class Manufacturer specific (warranty purposes)

Max pound force per square inch Fasteners & hardware Approximate yields strengths Imperial Metric Max pound force per square inch Grade 1 Grade 5 Grade 7 Grade 8 4.5 8.8 9.8 10.9 60,000 120,000 130,000 150,000

Fasteners & hardware Property class explained Metric bolts – numerical e.g. 10.9 10 represents the grade or tensile strength 9 represents the yield point as a percentage of tensile strength 10 = 145,000 lbs/inch tensile strength 9 = 130,500 lbs/inch yield strength

Fasteners & hardware Understanding bolt strength Tensile strength Yield strength Shear strength

Fasteners & hardware Tensile strength (grade) Sometimes called ultimate strength, is the maximum stress level a material can withstand without breaking Under how much pressure will the fastener break Factors Materials Diameter of bolt Accelerators?

Fasteners & hardware Yield strength Maximum strength a material can withstand and return to its original form without damage or deformation Identifying a bolt that has reached yield

Fasteners & hardware

Fasteners & hardware Shear strength The force required to shear or split the bolt into two parts Approx 60% of ultimate tension strength

Fasteners & hardware

Fasteners & hardware M8 X 1.5 X 24 ½ X 13 X 1 M = metric 8 = ? 1.5 = ? 24 = ? ½ X 13 X 1 Imperial ½ = ? 13 = ? 1 = ?

Fasteners & hardware Studs Rods with threads on both ends Can have different threads on each end Why a stud/nut vs. a bolt? Soft material where coarse threads are needed but requires clamping force of fine threads Remember the finer the thread the greater holding power & resistance to vibration Remember coarse threads for soft material Square, cross, circle

Fasteners & hardware

Fasteners & hardware Nuts Most common is hex nut Grade (tensile strength only) of nut must match bolt grade If a grade 8 bolt were used with a grade 5 nut – connection is max grade 5

Fasteners & hardware

Fasteners & hardware Types of nuts Hex nut Hex nut – nylon insert (lock nut) Hex jam nylon lock nuts Cap nuts Flanged serrated Wing nuts K-nuts Prevailing torque lock nuts Castellated

Fasteners & hardware Washers Different washers have defined purposes Flat washers spread load of tightening nut or bolt prevents digging Copper – sealing – crush Lock washers Lock head of bolt or nut to prevent loosening

Fasteners & hardware Types of washers available in metric & imperial Flat USS SAE Fender Lock washers Split Internal teeth External teeth

Fasteners & hardware Pins Push pins Cotter pins Bend once One time use only! Throw away! Use with castellated nuts/shafts Available in different sizes and lengths

Fasteners & hardware

Fasteners & hardware Rivets Used for attaching two pieces of material Rivet gun

Fasteners & hardware

Fasteners & hardware Keys Used for aligning shafts Used for preventing pulley rotation on shaft Key sits in keyway machined into respective parts Types Flat/squre woodruff

Fasteners & hardware

Fasteners & hardware

Fasteners & hardware

Fasteners & hardware

Fasteners & hardware Retaining rings and snap rings are fasteners used to axially position a component on a shaft or in a bore.  The primary retaining ring type can be internal or external.  Internal retaining rings fit into a housing or bore. Note diameter and thickness of fastener for proper application

Fasteners & hardware Use special pliers for retaining ring installation and removal Under tension – watch for launched rings

Fasteners & hardware

Fasteners & hardware

Fasteners & hardware

Fasteners & hardware Thread repair Tap/die set Helicoil ™

Fasteners & hardware Helicoil insert are made from high quality stainless steel wire, with a diamond shaped cross section, wound to the shape of a spring thread. The insert, which is larger in diameter than the tapped hole, is compressed during installation then allowed to spring back, permanently anchoring the insert in the tapped hole. Because of its larger diameter, the Helicoil Insert has a greater contact area and is normally stronger than the original threads. (toolsnextday UK)

Fasteners & hardware Step 1 – Drill to clear out bad threads **right size please Step 2 – tap with helicoil tap Step 3 – insert helicoil Step 4 – knock tab *if in combustion chamber break off and pull out with pliers

Fasteners & hardware Step 1

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Fasteners & hardware OEMs may recommend the use of sealant or lubricant per application Antiseize May recommend in aluminum Thread sealants Used on fasteners tightened in oil cavities or coolant passages Threadlocker Prevents bolts from loosening due to vibration

Fasteners & hardware Major manufacturer in sealants/lubricants/threadlockers is Loctite

Fasteners & hardware Factors that affect torque Thread condition Damaged/Burred Corrosion Lubrication Reduces friction (even water) – changes torque value Temperature Heat vs. cold – shrinkage vs. expansion Fastener composition Different materials have different torque values

Fasteners & hardware Factors that affect torque Torque Chart What do you do? Always follow manufacturer literature on fastener torque Apply lubrication when specified otherwise dry *wheel nuts Torque Chart

Fasteners & hardware