BasicMechanical Fasteners TED126
mechanical fasteners…Choosing • The choice of a fastener is dependent • on the design requirements and the • environment in which the fastener will be used.
mechanical fasteners…Choosing • Attention to various aspects of the fastener must be considered. Some of these are listed below: • Function of the fastener • Operating environment of the fastener • Type of loading on the fastener in service • Thickness of materials to be joined • Type of materials to be joined • Configuration of the joint to be fastened
mechanical fasteners…Choosing • The choice of the correct fastener may simply entail fulfilling a requirement for strength (static or fatigue) or for corrosion resistance. • Conversely, the choice may be constrained by a complex set of requirements. • The scope and complexity of the fastener system required is frequently determined by the consequences of fastener failure.
mechanical fasteners…Choosing • One method of guarding against failure of a new fastener in a critical application is to sufficiently test the fastener system prior to use. • A designer must be careful when extrapolate existing data to an increased size of the same fastener, • because larger-diameter fasteners can have considerably lower fatigue endurance limits than smaller-diameter fasteners.
mechanical fasteners • Is the Zipper a fastener? ….hmm • What two simple tools make up the zipper? • Wedge • door stop and a plow • Simple machine - incline • Hook • The zipper was patented on August 29, 1893 • by Whitcomb Judson, a Chicago mechanical engineer. • The paper clip is considered a fastener. • 1867
mechanical fasteners… Functions • To hold parts together. • To hold a completed product to a • wall, floor or other parts of a building or object.
mechanical fasteners… Types • Non-threaded • Threaded
mechanical fasteners… Non-threaded • Four Major Types • Nails • Rivets • Staples • Special fasteners • Cotter pin • Corrugated fasteners • Glazing pins • Skotch fasteners
Four Major Typesmechanical fasteners… Non-threaded Nails • Hand made nail • 18th century • Cut nail • 1790 to 1900 • Wire nail Nails provide one of the best clues to the age of historic buildings, especially those constructed during the nineteenth century, when nail-making technology advanced rapidly.
Four Major Typesmechanical fasteners… Non-threaded • Nails • What simple machine is associated to the nail? • Wedge • Other examples: knives, axes and forks • How many incline planes does a nail have? • Two • When a hammer pulls a nail out of the object… • What are the two simple machines at work? • Wedge and lever
Four Major Typesmechanical fasteners… Non-threaded Nails • Nails go back at least to the Roman period. • Nails are usually sold by weight (either in bulk or in boxes). • In the US, the length of a nail is designated by its penny size (d) from the head to the point. • It is commonly believed that the origin of the term "penny" in relation to nail size is based on the old custom in England of selling nails by the hundred. • A hundred nails that sold for six pence were "six penny" nails.
Four Major Typesmechanical fasteners… Non-threaded Nails • Nails go back at least to the Roman period. • Nails are usually sold by weight (either in bulk or in boxes). • In the US, the length of a nail is designated by its penny size (d) from the head to the point. • Ranges from 2d to 60d. • Anything larger than 10d is referred to as a spike. • It is commonly believed that the origin of the term "penny" in relation to nail size is based on the old custom in England of selling nails by the hundred. • A hundred nails that sold for six pence were "six penny" nails.
Four Major Typesmechanical fasteners… special Nails • HurriQuake Nail (2005-2006) • The features of the nail are designed primarily to provide more • structural integrity, • especially against the forces of hurricanes and earthquakes. • Special high-carbon alloy
Four Major Typesmechanical fasteners…special Nails • HurriQuake Nail (2006) • Tests at the Clemson Wind Load Test Facility confirmed what had already been stated. • With equipment to simulate the force of winds, roofs attached with traditional nails were pulled apart at around 13,500 pounds of force. • At forces up to 16,000 pounds, walls built with the HurriQuake environment nail showed minimal wall movement. • As the test rig pushed 20,000 pounds, the maximum it was capable of testing, showing that the HurriQuake environment nail sustained 20,000 pounds of force and still was not sheared or completely pulled out.
Four Major Typesmechanical fasteners… special Nails • HurriQuake Nail (2006) • …..sustained 20,000 pounds of force and still was not sheared or completely pulled out.
Four Major Typesmechanical fasteners… Non-threaded Common Nails • Common nails have • larger nail shank diameters than other nails. • Common nails are • thicker than box, cooler or sinker nails and are therefore strongest and stiffest. • Common nails are • always specified for shear wall panels.
Four Major Typesmechanical fasteners… Non-threaded Common Nails • Used for most medium to heavy construction work, this type of nail has a thick head and can be driven into tough materials. • Common nails are made from wire and cut to the proper length and are available in sizes 2d through 60d.
Four Major Typesmechanical fasteners… Non-threaded Finish Nails • Finishing nails have rounded heads that can be driven flush with the surface of the wood (3d to 10d). • Although they are often countersunk like casing nails, they can be used without countersinking. • Brads are recommended for light assembly work where the head should be concealed (.5” to1.5”). Brads look like miniature finishing nails. • They are thinner, shorter, and smaller than finish nails. • Escutcheon pins - 3/16” to 2.0”- Round smooth shank, a diamond point and an oval head. Made in both brass and steel.
Four Major Typesmechanical fasteners… Non-threaded Casing Nails • These nails are used where the nailhead must be hidden. • They have small heads and smaller diameters than common nails. • Casing nails have a conical head, sometimes cupped, and are somewhat thicker than a finishing nail. A body of a common nail and head like a finish nail. • They are sometimes sold already painted and are used to attach trim.
Four Major Typesmechanical fasteners… Non-threaded Box Nails • …a nail having a long shank, smooth or barbed, with a sharp point and a flat head. • Box nails are designed for light construction and household use. • Sometimes coated with cement, rosin or galvanize to hold better.
Four Major Typesmechanical fasteners… Non-threaded Rivets To secure two or more pieces of material together, a rivet is placed into a hole cut just a bit larger in diameter than the rivet itself. Materials - steel, plastic, aluminum, nickel-copper, copper and stainless. • Steel- Use steel rivets for very heavy duty jobs and when riveting steel to steel. • Tinners- are solid steel rivets with either a tin or zinc finish. They are typically used in sheet metal fabrication. • Pop Rivet - A type of rivet that is installed with a tool that pulls a mandrel through the rivet body performing the riveting function and then snaps off giving a "popping sound". Sometimes referred as a “blind” rivet
Four Major Typesmechanical fasteners… Non-threaded Staples • Staples are U-shaped metal fasteners that are driven into a surface to hold or secure an object in place. • Staples include flat crown and rounded crown styles. • Flat crown staples have flat top or crown and are used for general fastening. • Rounded crown staples have a curved top and are used to secure wire, tubing, and other rounded items to flat surfaces. • Staples are available in different sizes, lengths, styles, and materials. • Fastest growing non-threaded fastener.
Four Major Typesmechanical fasteners… Non-threaded Special • Cotter pin (cotter key) - Typically made of wire with a half-circular cross section. • Once inserted, the two ends of the pin are bent apart, locking it in place. • In order to facilitate the initial separation of the tines, one tine of the cotter pin is often noticeably longer than the other.
Four Major Typesmechanical fasteners… Non-threaded Special • Corrugated fasteners - a small strip of corrugated steel with sharp points on one side; hammered across wood joints in rough carpentry.
Four Major Typesmechanical fasteners… Non-threaded Special • Glazing pins - an old method of holding glass in a sash prior to glazing the window. • Skotch fastener - wood fastener
Four Major Typesmechanical fasteners… Non-threaded Three ways to install a Nail • Pound with a hammer • Powder actuated tools - means a device for making instantaneous forced entry into materials by use of a tool, a fastener and an explosive load. • .22 caliber shot • .27 caliber shot • .38 caliber shot • Power • Electric • Gas • Pneumatic Air Different types of power nailers • roof, framing, finish, brad, stapler GO TO PART II