View
219
Download
0
Category
Tags:
Preview:
Citation preview
T-DAP MAP 32
WPP-Fasteners & Hardware
Agenda
Fastener terminology & applicationMetric, Imperial and non-standard
hardwarePhysical properties of hardwareFactors that affect torqueFastener chemicals
Fasteners & hardware
Function: To hold things togetherMost 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)1. Unified National Coarse (UNC)2. Unified National Fine (UNF)3. Unified National Extra fine (UNEF)4. Unified National Pipe Thread (NPT,UNPT)
Metric fasteners available in standard, fine and superfine
Fasteners & hardware
Cap screws (a.k.a. bolts) nomenclatureS = shank diameterT = thread diameterR = 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 steelDifferent grades of steel give different
strengthsProperty 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 classManufacturer specific (warranty purposes)
Fasteners & hardware
Approximate yields strengths
Grade 1 Grade 5 Grade 7 Grade 8
4.5 8.8 9.8 10.9
60,000 120,000 130,000 150,000
Imperial
Metric
Max pound force per
square inch
Fasteners & hardware
Property class explainedMetric bolts – numerical e.g. 10.9
10 represents the grade or tensile strength9 represents the yield point as a percentage
of tensile strength 10 = 145,000 lbs/inch tensile strength9 = 130,500 lbs/inch yield strength
Fasteners & hardware
Understanding bolt strengthTensile strength Yield strengthShear 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
FactorsMaterialsDiameter of bolt
Accelerators?
Fasteners & hardware
Yield strengthMaximum 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 strengthThe 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 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 Rivets
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
Fasteners & hardware
Step 2
Fasteners & hardware
Step 3
Fasteners & hardware
Step 4
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 What do you do? Always follow manufacturer literature on
fastener torque Apply lubrication when specified otherwise dry *wheel nuts
Torque Chart
Fasteners & hardware
Recommended