Fasteners Flashcards
Define American National thread
A general use V shape thread
Define left-hand thread
A thread that loosens and tightens in the opposite direction (e.g. on a bicycle pedal)
Define square thread
A thread in a square shape that is ideal for power transmission
Define acme thread
A trapezoidal thread that is stronger than a square thread (e.g. threads on a lead screw)
Define buttress thread
A thread that is sloped on one side and vertical on another. Ideal for handling heavy forces in one direction (e.g. lifting machinery up)
Define a slotted head
The most popular head designed to strip less
Define a Philips head
A head in the shape of a cross designed to cam-out at a certain torque limit
Define a Robertson head
A square shaped head with the highest torque tolerance. Commonly used in the automotive and furniture industry
Define a Torx head
A star shaped head designed to prevent cam-out and stripped heads
Define a set/grub screw
A screw without a head used to fix rotating parts on a shaft. Used only for light loads
Define a shoulder bolt
A bolt that has a shank with a very precise diameter and a threaded portion with a smaller diameter. Used to locate the bolt on a part precisely
Define a slotted/castle nut
A nut that is used with a split pin on a drilled bolt to permanently secure the nut in place
Define pitch
Pitch is the distance from crest to crest on a thread (inverse of threads per inch)
Define a wing nut
A nut with two wings that’s easy to adjust
What is the format of metric threads
M (major diameter in mm) X (pitch in mm). For example: M12 X 1.75
What is the format of imperial threads
(major diameter in inches) — (threads per inch) (course/fine series). For example: 5/8” — 18 UNF. Screws with diameter less than 1/4” are numbered with gauge sizes instead.
What does UNF and UNC mean and what are advantages of each and common uses
Unified fine and unified course threads. Course threads for rugged applications in softer applications and are faster to remove and replace. Fine threads are slightly stronger (due to larger minor diameter), are easier to tap on tougher materials and will not wear with vibrations as easily.
What angle are unified (imperial) threads
60 degrees
What is a rivet and how do they work
A rivet is a smooth cylindrical shaft with a head on one end that is deformed to make a permanent fixture. A rivet gun is typically used on the head to pull a ball in the rivet and deform the shaft.
Define anchor bolts
Bolts that dig into the side walls as it is fastened in (used to secure baseplates into concrete)
Define NPT thread
National Pipe Taper thread. Used for fastening pipes. Are tapered so that the tighter it is, the more water tight it is (like a cone pushing against a countersink)
