Mechanical Fastening

1
Mechanical Fastening

• Hold the parts without the use of outside
  assembly devices. Internal mechanical forces of
  the material position and hold parts in place.

2
Physical Structures

• Parts can be designed to interlock. These
  physical structures include
• 1. Seams
• 2. Tabs and slots
• Beads, dimples, and flanges
• Seams use assembly of interlocking edges of
  materials. These include single lock, double lock
  , and Pittsburg.

3
Physical Structures cont.

• Tabs and slots-Used to temporarily or permanently
  assemble sheet metal or plastic parts. Tabs
  protrude from the parts, often fitting in a hole
  or a slot. A common shelf bracket uses a tab and
  slot assembly.
• Beads- is a recessed groove around a cylinder.
• Dimples are recesses formed on a part often lock
  parts together with a punch or chisel mark.
• Flanges- shaped edges often used for temporarily
  assembly of plastic parts mating pieces. A
  Zip-Lock bag uses a double flange to grip the
  beaded strip.

4
Physical Structures cont.

• Interference fit- when friction between the two
  surfaces is used to hold the parts together.
• Three major types
• Running or sliding fit
• Location Fit
• Interference fit

5
Fastener Assembly

• Fasteners are devices that are added to the parts
  being joined. They grip and hold the parts into
  position.
• Common fasteners are
• 1. Threaded fasteners.
• 2. Rivets.
• 3. Pins and nails.
• 4. Retaining rings.
• 5. Stitches.
• 6. Quick-operating devices.

6
Bibliography

• Wright, R. T. (1999). Processes of manufacturing
  pp. 371-381. Tinley Park, IL Goodheart-Wilcox.