Selection of the right screws from your sheet metal application will ensure a strong, permanent connection. Review these handy tips to ensure your work is meets the project demand.

There are basically two types of screws -- wood and sheet metal. The main difference between them is the thread in the screw. Sheet metal screws have sharper and more pronounced threads to enable them to better penetrate metal surfaces. Both types of screws are measured in the same manner and are identical in all other aspects. Screws usually come in lengths ranging from ¼ inch to 3 inches. Diameters are indicated by gauge numbers. Many length and gauge combinations are available. When buying screws, state the length and gauge number you want.

Use stainless steel or aluminum screws for a project that will be exposed to moisture and brass or bronze ones to match hardware. Otherwise, you will save by using plain, plated, or galvanized screws.

Sheet Metal Screws

Phillips Flat-Head

These are countersunk into the material for a smooth surface area.

Applications and uses

• Mounting plywood in Telco closets so that screw heads won’t interfere with mounting of hardware.
• Areas where a smooth surface is wanted

Phillips Oval Head

Oval head screws are similar top flat head but have a slightly rounded top for more of a finished look.

Applications and use

• Connecting of metal-to-metal products where appearance and esthetics are important .
• Mounting of rack supports and hardware in shelters

Phillips Truss Head

The truss head protrudes above the surface to be fastened but with a larger surface area under the head.

Applications and uses

• Areas where it is necessary to have a larger head on the screw to achieve strength in mounting, but not to have the head of the screw so big that it interferes with other mounting hardware.
• Used to mount racks in enclosures.

Phillips Pan Head

A pan head screw protrudes above the surfaces to be fastened.

Applications and uses

• When attaching to metal where the appearance of the head does not interfere with the function of the screw.
• Attaching mounting hardware to metal surfaces

Phillips Pan Head Self-Drilling

This is a sheet metal screw with a drill point which creates it’s own hole and a Phillips pan head.

Applications and uses

• Attachment of hardware where there is a pilot hole started and no need for a bolt on the other end of the screw
• Mounting of items in vehicles

Hex Washer Head

This is a sheet metal screw with a hex head and washer attached. Has a slotted head also.

Application and uses

• Attachment of metal where there is a pilot hole started.
• Provides flexibility of tools where a screwdriver or wrench can be used

Mystified about Other Fasteners?

Review a white paper on screws, bolts, washers and nuts:  "Take the Mystery Out of Fasteners" (PDF).