Technology and our changing world high Technology

USING THE POP RIVETER
Drill a hole in the two parts to be joined using the correct size drill. Insert the pointed end of the rivet mandrel into the rivet tool. Place the rivet in the drilled hole. As you operate the tool, the mandrel head is pulled into the rivet body. This expands it into a blind rivet and securely clamps the materials to be joined. The mandrel is separated from the body and ejected. The tool is now ready for thenextrivet.


Review questions.

1. 
   What metals are commonly used to makerivets?
   
2. 
   How do you protect the round heads of rivets when riveting?
   
3. 
   Make a sketch of the three common rivet head shapes.
   

THREADS AND FASTENERS
If you look closely at a piece of machinery, you will find that many of its parts are joined by bolts, nuts, and other threaded fasteners. Industry uses threaded fasteners for thefollowing Ihreereasons:

1. 
   With threaded fasteners, the machinery can be taken apart for repairs, and reassembled without damaging any of theparts.
   
2. 
   Threaded parts can be used for fine adjustments such as controlling the lens of a camera.
   
3. 
   Threads can exert force through movement. The screw on a clamp is a good example of this.
   

Common Threaded Fasteners
Threaded fasteners are made in hundreds of different shapes and in inch and metric sizes. The most common head styles are shown in. Threaded fasteners are made of many different metals and plating (metal coatings). For example, fasteners used in home appliances often are chrome plated for appearance.
For assembling with many types of bolts and screw, washer and nuts are needed. Nuts come in many sizes and shapes. Washers are plain, which protects the surfaces of metal pieces. They also are of the lock type, with prevents a fastener from becoming loose.
You will be using many fasteners in your metalworking classes. Let’s look at a few of the more common ones.

• 
  Machine bolts and nuts are made in diameters from !4” to 1” and in lengths from ’Л” to ova^- 30”. They are used to fasten metal parts together. The bo It head can be held with a wrench as the nut is tightened.
  
• 
  Cap screws are not used with nuts. They are used to hold together two pieces of machinery. The screw is passed through an unthreaded hole in onepiece. It is screwed into a tapped hole in the second piece.
  
• 
  Machine screws are smaller than nuts and bolts. They are used to assemble small mechanical and electrical parts.
  
• 
  Setscrews hold two parts together to prevent one part from moving or turning. For example, they are used to hold apulley on a shaft. They come in avariety ofhead and pointshapes.
  
• 
  A stud is a headless fastener that is threaded on both ends. The threaded parts may have different diameters. The wheel on an automobile is held on by nuts tightened into studs.
  

• Self-tapping screws are made of hard steel. They are designed to cut their own threads in softer metals, such as galvanized sheet and aluminum or in plastics. They have many styles of heads and points.