Industrial Skills Fasteners & Hardware - PowerPoint Presentation

Slide1

Industrial Skills

Fasteners & HardwareSlide2

Fasteners are used in manufactured products for several basic purposes:

They simplify manufacture.

They simplify repairs.

They provide safety.Slide3

When selecting a fastener for a particular use, consider these factors:

Strength:

Will it hold the loads and pressures?Security:

Will it remain attached?

Cost:

Realistic?

Installation:

Appropriate for situation?

Skill:

Is specialized training needed?

Equipment:

Is specialized equipment needed and available?

Appearance:

If the fastener shows, which kind looks best?Slide4

Nails –

Most common method of fastening one wooden member to another.

Simple &

quick

May not result in the strongest of

joints

Variety of shapes and sizes

Each type designed for a particular purposeDrive nails at angles slanting toward or away from each other to get best holding powerSlide5

Screws

–

A large and important family of fasteners. The most common types of screws are:

Sheet-metal screws

Machine screws

Set screws

Wood screws

“Mechanical devices for fastening things together.

it

penetrates only by being turned, as with a screwdriver.”Slide6

Wood Screws

Serve much the same purpose as a nail, but:

greater

holding power

easily

removed and replaced.

neater

in appearance and offer more decorative possibilities.

In addition to fastening pieces of wood together – the most common use of wood screws would be to anchor objects (hardware) to a wood surface. Slide7

Sheet-Metal Screws

Also called “Tapping Screws” or “Self-Threading Screws”.

Used to fasten light pieces of metal together or to attach covers, panels and other light parts.

These screws have sharp threads that can cut their own grooves into metal.

Distinguishable

from wood screws in that they are threaded all the way from the point to the head.Slide8

Machine Screws

Used for the assembly of metal parts and usually are driven into “threaded” holes rather than drawn tight with nuts.

there

are many head designs to choose from.

Machine screw threads are also designated by the number of threads per inch, just like bolt threads:

A 6-32 machine screw has a #6 body diameter and 32 threads per inch of length.

Most machine screws are fully threaded to the head.Slide9

Set Screws

Frequently used to hold a knob, collar, pulley or gear to a rotating shaft.

There are a variety of “head” or “point” styles, each best suited for its job.

Not

an especially strong type of fastening – depend on friction and “shear” to hold parts together.Slide10

Once you have decided to use screws, in addition to the use category, you must consider four things before ordering.

Type of head

Material made of

The length

The diameterSlide11

The “type of head” should include both the

“shape”

and the

“style”.

Pan Head

Truss Head

Hex Head

Flanged Hex Head

Screw Head “Shapes”

Screw Head “Styles”Slide12

The most common material

screws are made

of

is steel.

When exposed to “weather”, coatings

offer more protection

.

Steel

BluedZinc CoatedChromiumGalvanizedNickel

Silver PlateGold Plate Marine

ApplicationsStainless SteelAluminumCopper

Brass

Bronze

Synthetic Materials (Plastic or Nylon)Slide13

Screw

Dimensions

Length

commonly range from ¼ inch to 4 inches.

Shorter or longer lengths are generally special order items.

Metric lengths are also availableSlide14

Screw

Dimensions

D

iameter

expressed by the “gauge” number or by the fraction of an inch.

m

etric diameters are expressed in mmSlide15

American Screw Gauge

Diameters

less than ¼ inch (6 mm) use gauge number.

Diameters greater than ¼ inch use fractions of an inch. Wood screws are an exception to this rule in that they generally go up to a #20 gauge (

21/64

”).Slide16

Bolts

Machine Bolts:

Square or hex head

U

sually used in plain holes drilled through the parts being fastened.

G

enerally held in place with a nut.

Carriage Bolt:

Round headed bolt

Commonly used for fastening wood partsSquare neck under head

Generally held in place with a nutSlide17
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Threads

Threads

–

External helical ribs on the body of a bolt. Usually a bolt “mates” with

internal

threads of a nut.

Threads

are measured by counting the

number per inch. (Metric threads are measured by the distance between threads – pitch – in mm)

Thread gauges are available that match threads against those on the gauge.Slide19
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Nuts and Washers

have

internal

threads so that a bolt may screw into it. The threads must match!

Threads

per inch or distance between threads can be determined with a thread gauge just like bolt threads.

Nuts have three important dimensions:

Thickness

Distance across the flatsInside diameter (same as that of the bolt with which it is to be used).Slide22
Slide23

Washers

They are paired with and matched to bolts and nuts