SLIDE 1
F A S T E N E R S A F E T Y S E M I N A R
Fastener Facts
70% 80% 50%
OF ALL CONNECTIONS OR JOINTS ARE HELD TOGETHER WITH FASTENERS OF PRODUCTION TIME IS SPENT ON ASSEMBLY OF FASTENERS REPRESENTS IN PLACE FASTENER ASSEMBLED COSTS
Fastener SAFETY Seminar F A S T E N E R Fastener Facts S A F E T - - PowerPoint PPT Presentation
Fastener SAFETY Seminar F A S T E N E R Fastener Facts S A F E T - - PowerPoint PPT Presentation
Fastener SAFETY Seminar F A S T E N E R Fastener Facts S A F E T Y S E M I N A R OF ALL CONNECTIONS OR 70% JOINTS ARE HELD TOGETHER WITH FASTENERS OF PRODUCTION TIME IS 80% SPENT ON ASSEMBLY OF FASTENERS REPRESENTS IN PLACE 50%
SLIDE 2
SLIDE 3
F A S T E N E R S A F E T Y S E M I N A R
Common Fastener Failures
Stripped Threads Cracked, Bent, Broken Mushrooming of Nut Dishing of Washer Permanently Stretched
Page 2
SLIDE 4
F A S T E N E R S A F E T Y S E M I N A R
NASA Study of Fastener Failures
Percent of Failure
Assembly 24% Parts Damaged 23% Pre-load 14% Design 29% Defects 10%
SLIDE 5
F A S T E N E R S A F E T Y S E M I N A R
Fasteners In The News
Reprinted from AUTOMOTIVE NEWS
COMPUTERIZED TESTING SOLVES GM’S V-6 PROBLEM
Dale Jewett
Engineering Editor
Ann Arbor, Mich.—General Motors had a problem with a V-6
- engine. Many times the engine was
being wrecked because a connecting rod cap would break off and be thrown around the crankcase. Beefing up the cap and the mating area on the connecting rod didn’t help, and more times than not, throwing more metal and money at the problem is the wrong answer. The automaker sent the engine and its computerized design information to an Ann Arbor firm to see if it could help. In three weeks the problem was found: Bolts holding the cap on the connecting rod were not being tightened enough. GM’s machines were set to measure the bolt torque, but not the torque angle. Additional tightening of the bolts prevented them from working loose and fixed the problem. The testing firm’s main tool is finite element analysis: computerized, testing
- f parts and systems to simulate s
tress and temperature loads. Automakers are now adding such computerized testing capabilities.
SLIDE 6
F A S T E N E R S A F E T Y S E M I N A R
SLIDE 7
F A S T E N E R S A F E T Y S E M I N A R
Commercial Grade Capscrews
Page 4 & 5
SLIDE 8
F A S T E N E R S A F E T Y S E M I N A R
Maintenance Engineered Capscrews
Page 4 & 5
SLIDE 9
F A S T E N E R S A F E T Y S E M I N A R
Hex Nut Grade Markings
Page 6 & 7
60°
SLIDE 10
F A S T E N E R S A F E T Y S E M I N A R
Common Washer Markings
Page 8 & 9
SLIDE 11
F A S T E N E R S A F E T Y S E M I N A R
Stress - Strain Diagram
Failure (Tensile Break) Ultimate Tensile Strength
AXIAL ELONGATION
Elastic Range Plastic Range
AXIAL TENSILE LOAD, lbs.
Proof Load Yield Point Clamp Load Page 10
SLIDE 12
F A S T E N E R S A F E T Y S E M I N A R
Fatigue Failure in Common Bolted Joints
15% 20% 65%
2 Key Reasons:
- 1. Insufficient torque at installation
- 2. Loss of Clamp Load in service
SLIDE 13
F A S T E N E R S A F E T Y S E M I N A R
Fatigue Failure in Common Bolted Joints UNJ UN UNR
SLIDE 14
F A S T E N E R S A F E T Y S E M I N A R
Common Fastener Failures
Burnishing Straight Break Flattened/ Worn Threads No Stretch
Page 20
SLIDE 15
F A S T E N E R S A F E T Y S E M I N A R
Lockwashers
SLIDE 16
F A S T E N E R S A F E T Y S E M I N A R
Locknuts
Grade of Nut ….. Grade A Grade B and F Grade C …………. Grade G Tensile Strength of Bolt (ksi) Not greater than 90 Not greater than 120 Not less than 105, nor greater than 150 Not less than 120, nor greater than 150
SLIDE 17
F A S T E N E R S A F E T Y S E M I N A R
Wedge-locking action uses tension instead of friction (Shur-Loc)
When a bolt attempts to
- loosen. the pair of washers
expand more than the corresponding pitch of the thread. The tension created helps to positively lock the fastener in a joint which is subjected to any kind of vibration or dynamic loads The teeth seat into the mating surfaces allowing movement only across the face
- f the cams.
SLIDE 18
F A S T E N E R S A F E T Y S E M I N A R
Where are Shur-Loc Washers Used?
Rammer – rock hammer On the connection between the adapter plate and the machine body
SLIDE 19
F A S T E N E R S A F E T Y S E M I N A R
Where are Shur-Loc Washers Used?
The Screen Machine – topsoil shredder
SLIDE 20
F A S T E N E R S A F E T Y S E M I N A R
Where are Shur-Loc Washers Used?
Tidaplast AB – fastener for flag staff
SLIDE 21
Fastener SAFETY Seminar
SLIDE 22
F A S T E N E R S A F E T Y S E M I N A R
Coarse Threads vs. Fine Threads
SLIDE 23
F A S T E N E R S A F E T Y S E M I N A R
Metric Mechanical Properties
MPa: Megapascal (1 MPa = 145 psi) Page 16 & 17
SLIDE 24
F A S T E N E R S A F E T Y S E M I N A R
Metric Head Markings
Page 16 & 17
SLIDE 25
F A S T E N E R S A F E T Y S E M I N A R
Thread Identification
Fractional Measured in number
- f threads per inch
Metric Measured in distance between peaks of thread
Thread Pitch
Page 13