Technology and our changing world high Technology

Review questions.

1. 
   What are the four ways in which files are classified?
   
2. 
   Why should a file be cleaned before being used?
   
3. 
   What type of cut do the teeth on a mill file have?
   
4. 
   List some safely rules to follow when grinding, polishing, and bugging.
   
5. 
   List and describe threekindsof abrasives.
   

RIVETING
Riveting is placing a metal pin into a hole and clinching it so there is a head at each end. These metal pins, or rivets, are permanent fasteners. They areused to fasten together two or more sheets or pieces of metal.
A head is formed on one end when toe rivet is manufactured. To joint two metal pieces, the shank (body) of toe rivet placed in a hole that extends through both pieces. Then toe tip is pounded to form toe second head.
In automobile manufacturing, riveting has been largely replaced by wielding, special glues, and sheet metal screws. However, rivets are still commonly used in many industries, such as building construction. Heavy metal beams that make up toe skeletons of office buildings, bridges, and similar structures are riveted. It is a cheap and quick assembly method. Aircraft and space industries use rivets in assembly because such materials as aluminum and magnesium are hard to weld. In a jet airliner thousands of rivets hold toe parts together.


Kinds of Rivets
Rivets vary as to the kind of metal, kind of head, diameter (or shank size), and length. In ordering rivets, it is necessary to give this information completely. The following order is complete: black iron rivets, rounded,¹4”, ’Л” long.
Rivets are made of aluminum, copper, brass, and mild steel (blackiron). The three common head shapes are round, flat, and countersunk.
Tinner’s rivets are made for use on sheet metal. They are mild steel rivets with a flat head. They are coated with black oxide, tin, copper, or zinc. The customary size of the rivet is indicated by its weight per thousand. (A thousand of the smallest size weighs 6 ounces.) Common sizes are 10 ounce, 1 pound,2 pound, and 2 'A pound. For No26-gauge metal, for example, use a 1-pound rivet.


Equipment
The riveting equipment needed includes a ball-peen or riveting hammer, a rivet set, and a punch or drill. For all types of riveting expect for tinner’s rivets, select a ball-peen hammer heavy enough to form a head. The rivet set has a clearance hole on one side and a concave opening next to it. The rivet set is used to squeeze two pieces of metal together before riveting. It also forms the rivet head. Select a rivet set with a hole large enough for the rivet shank to slip into easily.
The hand pundr is used in joining lighter gauges of metal. Its punch should have the same diameter as lhe shank of the rivet. Use a drill on heavier gauges of metal.