A screw is an externally threaded fastener capable of being inserted
into holes in assembled parts, of mating with a preformed internal
thread or forming its own thread, and of being tightened or released
by torquing the head. An externally threaded fastener which is
prevented from being turned during assembly and which can be tightened
or released only by torquing a nut is a bolt. (Example: round head
bolts, track bolts, plow bolts.) Additionally, any externally threaded
fastener that has thread form which prohibits assembly with a nut
having a straight thread of multiple pitch length is also defined as a
screw. (Example: wood screws, tapping screws.)
Screw Types
Some basic information regarding screws that Aspen Fasteners
offers from inventory.
Dowel screws
A double ended fastener with two tapered and threaded ends often
used in furniture manufacturing to create a hidden joint. Half the
length of the dowel screw is driven into each of the two pieces making
up the joint. Available in zinc plated
steel and
up to 6" in length.
Drywall/framing Screws
These screws are specialty drywall & framing screws and are
designed specifically for use in drywall applications. The bugle head
style, sharp point and threading of these screws are made to attach
drywall to wood or metal studs and provide the greatest holding power
in drywall. Available in hardened
steel
with a black phosphate finish and with either phillips or square
drives.
Eye Screws
Also known as screw eyes - a wire form with a looped head and
threaded end tapered to a point. Larger ones are often referred to as
lag eye screws. Designed to be used as attachment point, particularly
for something that is hung from it. Available in zinc plated
steel .
Hi-Lo Self Tapping Screws
These specially threaded screws designed to cut threads as they
are driven into untapped holes. Hi-Lo self tapping screws have a
double lead thread where one thread is high and the other low thread
for easier penetration into the substrate. The smaller minor diameter
thread increases contact with the substrate resulting in a stronger
grip and increased resistance to pull out. These screws are available
in
carbon
steel in a number of finishes (clear zinc, black zinc, black
oxide) and
stainless steel. Available in a variety of head styles (flat, hex
washer, pan and truss) and drives (phillips, slot, 6-lobe, hex)
Available in sizes from #2 to #14 diameters and lengths from 3/16" to
2".
Lag Screws/Bolts (US)/Coach Screws UK
similar to wood screws but usually much larger with lengths up to
12" and diameters from 1/4" to 3/4" Lag screws are designed to fasten
heavy lumber together, or wood to masonry/concrete. Hex head lag
screws are stocked in
steel with
zinc or
galvanized finishes.
Machine Screws
A full threaded screw with a blunt end and usually used with a
nut or driven into a pre-tapped hole. Always match your screws to the
job, considering both the finished result and the materials being
used. Available in
steel
with a variety of different head styles (binding, fillister, flat,
hex, hex washer, oval , pan, round and truss) and drives (phillips,
slot, 6-lobe, square, hex) and finishes (clear zinc, yellow zinc,
black zinc, green zinc, black oxide, nickel plated) and in
stainless steel and in
nylon. Steel machine screws also available with
metric threading. All machine screws feature standard 'machine'
points, and are available in sizes from #2-56 to 1/2" and lengths from
1/8" to 6".
Plastite 48-2 alternative screws
48-2 Plastite alternative screws are specially designed
trilobular™ thread-rolling screws for use in plastics.
Maximum holding power
48-2 Plastite alternative Trilobular™ screws have a twin
lead thread design offering quicker and more effective screw
penetration into the substrate. They also have a deep and narrow 48
degree thread profile with extra wide spacing between threads. This
thread profile improves thread-forming and thread engagement within
the plastic. In addition these screws have a Trilobular™ thread
configuration which improves displacement of material into relief
areas when driven into the plastic. This further increases the
resistance to vibrational loosening forces. The higher quality
internal threads produced by these specialized screws also reduces
material failure and improves holding power in plastic materials. It
also reduces stripping, pull-out and allows for repeated removal and
insertion into the same tapped hole.
Easier to drive
The three lobed design of the Trilobular™ thread with full
relief of the thread form takes advantage of the properties of
plastics by allowing recovery and filling-in between the lobes,
decreasing driving effort. 48-2 Plastite alternative screws are
available in
steel
with the following head styles: flat head, pan head , truss head and
hex indented washer head, drives: Phillips drive, 6-lobe drive and hex
head, and with either a clear zinc finish, or black zinc finish or
black oxide finish. 48-2 Plastite alternative screws are also
available in
stainless steel 18-8 and 410 with pan head, flat head and hex
indented washer head and either phillips or 6lobe drives. Because of
the variations in grades of plastics, depth of engagement and usage
requirements, it is highly recommended that tests be performed for
each application by a competent engineering laboratory to determine
the ideal pilot hole size.
Self Drilling Screws
Also referred to as TEK screws, self drilling screws are
specially designed to drill, tap and seal all at the same time with
one driving operation. They are similar to a self tapping screw, but
it has a drill-shaped point to cut through the substrate eliminating
the need for drilling a pilot hole. The points are numbered from 1
through 5, the larger the number, the thicker metal it can go through
without a pilot hole. Stocked in
steel
in a variety of head styles (flat, hex, hex washer, oval , pan, round,
trim, truss and wafer head) and drives (hex head, phillips, slot,
square, 6-lobe,) and also in
stainless steel in sizes from #2 to 5/16" and lengths from 3/8" to
6".
Self piercing screws
Self-piercing tapping screws are externally threaded screws with
designed to self-pierce A metallic material and tap their own mating
threads . Self-piercing screws are high-strength, with sharp point
angles of 25 to 30 degrees. Available with a hex slotted drive in zinc
plated hardened
steel.
Also available with a
bonded washer to self seal once driven into the material.
Self tapping/Sheet Metal Screws
These specially threaded screws designed to cut threads as they
are driven into untapped holes. A self-tapping screw requires a
pre-drilled pilot hole from the correct size drill. Recommended drill
bit sizes vary, depending on the diameter of screw to be used, type of
screw (points A, B, AB, and High-Low), and structural thickness of the
substrate. These screws are available in
carbon
steel in a number of finishes (clear zinc, yellow zinc, black
zinc, black oxide) and
stainless steel. Available in a variety of head styles (flat, hex,
hex washer, oval ,pan round and truss) and drives (phillips, slot,
6-lobe, square, hex) Available in sizes from #2 to 3/8" diameters and
lengths from 1/8" to 4".
Sems Screws
SEMS Screws is a machine screw pre-assembled with a free-spinning
lockwasher. The washer is held in place by the major diameter of the
screw being larger than the hole of the washer. Available in
steel with
an
external tooth lock washer,
internal tooth lock washer,
split lock washer or
square cone lock washer. Also available in
stainless steel.
Thread Cutting Screws
Another type of tapping screw with specialized tips (type 1, type
23, type 25, type F) that physically remove material from the
substrate to form the tapped thread path. They are available in
carbon
steel. this screw is designed to tap its own threads as it
penetrates the substrate but requires a pre-drilled pilot hole.
Available in points 'F', '1', '23' and '25' with a variety of head
styles (flat, hex, hex washer, oval , pan and truss) and drives (hex
head, phillips, slot, 6-lobe,), in sizes from #2 to 1/4" and lengths
from 3/16" to 3".
Thumb Screws
Thumb screws are specially designed fastener with machine screw
threads to be turned into a tapped hole by hand without the use of any
tool. Available in
steel and
in
stainless steel with either a knurled (with or without a washer
face) or regular head (with or without a shoulder).
Set Screws
A set screw is a headless screw driven into a pre-tapped hole. It
is often used as a compression device to hold a sleeve, collar or gear
on a shaft in order to prevent slipping to facilitate relative
rotation. Various drive types are available to rotate the set screw.
These types include hexagon socket, fluted socket, screwdriver slot
and square head. Aspen Fasteners stock set screws made of heat treated
alloy steel with a hex socket drive in coarse and fine thread.
Various point designs are available (the part of the set screw that
rotates against the shaft being secured) and include: Cup - Hollowed
end, is the most commonly used point style. Used when the digging in
of the point is not undesirable. Cone - Pointed end, this type
generates the highest torsional holding power and is typically used
for a permanent connection. Oval - Rounded end that is typically used
when frequent adjustment is required. The oval end prevents/reduces
indentation. Flat - Cause little damage to the shaft and are used when
frequent adjustment is required. Dog - Flat end with the threads
stopping short of the end with the end fitting into a hole. Sizes
range from #2 to ½" and lengths from 1/16" to 1-1/2".
U-Drive Screws
A thread forming screw with a high helical thread to be driven or
hammered into a substrate (e.g. plastics, sheet metals, or castings)
for a quick permanent assembly. Requires a pre-drilled or punched
hole. Available in
zinc or
black oxide coated steel in sizes ranging from #00 - #8 and
lengths between 1/8" and 3/4"
