Tag Archives: sheet metal

3 Common Screw Types at a Glance – Machine, Sheet Metal, and Cap Screws

Machine ScrewsMachine Screws

  •  Fully threaded shank
  • Usually used with a nut

  • Typically smaller than the average screw

  • Designed to be fastened to an existing tapped hole

Machine screws, also sometimes referred to as machine bolts, are normally smaller than the average screw. They usually range in sizes up to ¾ of an inch (19.05 mm), but can still come in larger variations. Typically machine screws are designed to be fastened to an existing tapped hole on a metal surface, usually in conjunction with a corresponding nut. The main differentiating characteristics of machine screws are: overall size, shape of head, slot type, length, material, and thread type.

The two main drive types associated with machine screws are slotted (flat head) and Phillips. There are also a number of specialized drives that they can come in, these are typically associated with tamper-resistant screws. Some of these drive types include, torx – six pointed, spanner, and trident to name a few. The shape of the head will determine how the machine screw lies once it’s fastened in place. Round and Pan heads will protrude from a flat surface, while flat head machine screws are designed for holes that are countersunk so that they lay flush with the surface.

Machine screws are always threaded the entire length of its shank. Threading on a machine screw is very important because the corresponding holes that they are being fastened into are typically tapped for a specific size and type of screw thread. The two main characteristics of threads are size of the outer diameter of the threads and pitch, the distance between each thread. Machine screw can be made to have either clockwise (right-handed) or counter-clockwise (left-handed) thread.

Sheet Metal ScrewsSheet Metal Screws

  • Fully threaded shank

  • Very versatile fastener, can be used in metal, wood, and plastics

  • Most are self-tapping screws and only require a pre-drilled hole, some come with self-drilling tips

  • Specially hardened, sharp threads that allow it to cut into material and form its own internal thread

Sheet metal screws have a fully threaded shank with sharp threads and tip that allow them to cut through metal, wood, plastic, and various other materials. The size of sheet metal screws are commonly shown as a series of three numbers, these numbers represent the diameter, thread count, and length of fastener. A sheet metal screw listed as 4-32 x 1-½” has a diameter size of 4, 32 threads per inch, and a length of 1-½”.

There are two basic types of sheet metal screws, self-tapping screws and self-drilling screws. Self-tapping screws have a sharp tip that is designed to cut through metal, but the metal must be pre-drilled before these screws can be used. Self-drilling screws have a drill point tip that can easily cut through metal without a pre-drilled hole.

The head of sheet metal screws can come in a number of different styles. Pan or round head screw will have heads that extend above the surface of the material after being installed. Flat or oval countersunk screws will be flush with the top of the material after being installed. These screws can come with a Phillips, flat, or combo drive.

Sheet metal screws made out of carbon steel are the most common and typically the most economical. These screws are prone to rust and corrosion when exposed to moisture or chemicals, so they should typically only be used indoors. Galvanized or stainless steel screws are designed to resist rust and corrosion, but tend to cost more than the standard steel screws. Sheet metal screws may be coated with zinc or nickel to modify their appearance.

Cap ScrewsCap Screws

  • Normally used without a nut

  • Available in both English and metric sizes

  • Fasten machine parts – home appliances / consumer electronic devices

  • Large head, diameter is larger than threaded portion

Cap screws have a large head and a cylindrical shaft with external threads. The head has a larger diameter than the threaded portion, this provides a positive mechanical stop when tightening the screw. Cap screws are tightened directly into a threaded or tapped hole, usually without a nut. A cap screw can generate a high amount of clamping force when tightened.

Commonly used cap screw heads styles include: hex head, socket head, and button head. Cap screws are typically  manufactured out of carbon steel, stainless steel, and metal alloys. The choice of type and size of of cap screw for a particular application mostly depends on the forces required to adequately secure the mechanical connection.

Know Your Torx® Tamper-Resistant Screws

Torx® Tamper-Resistant Screws

Torx® Tamper-Resistant Screws are characterized by their unique, six point, star shaped pattern. The star design provides various benefits, including preventing cam-out and increased ease in maintaining a consistent torque. Torx® Tamper-Resistant Screws contain a solid post formed in the middle of the recess during the heading process. The solid post blocks the insertion of an ordinary Torx screwdriver or any other driver. This added security feature makes it nearly impossible to remove without a unique tamper-resistant tool. Torx® Tamper-Resistant Screws that are available at Tanner are: masonry screws, self-drilling screws, sheet metal screws, and cap screws. Continue to read below for more information about each type of Torx® Tamper-Resistant Screws offer at Tanner.

Torx® Tamper-Resistant UltraCon® Masonry Screws

Torx® Tamper-Resistant UltraCon® Masonry Screws

Torx® Tamper-Resistant UltraCon® Masonry Screws are the perfect combination of the security of a Torx® tamper-resistant drive and the superior quality and easy installation of an UltraCon® masonry screw. These screws are the optimal fastening solution for use in concrete, brick, or hollow block. The special Hi-Lo threads on the Torx® Tamper-Resistant UltraCon® Masonry Screws lead to a greater resistance to pullout and also creates stronger fastening in masonry materials. These tamper-resistant masonry screws are coated with Stalgard® finish to provide superior corrosion resistance. The Stalgard® finish helps prevent red rust and other base material corrosion on significant surfaces, even after 800 hours of 5% neutral salt spray exposure (ASTM B117).

Torx® Tamper-Resistant Self-Drilling Screws

Torx® Tamper-Resistant Self-Drilling Screws

Torx® Tamper-Resistant Self-Drilling Screws eliminate the separate drilling and tapping operations for a faster, more economical installation process. This is possible because the Torx® Tamper-Resistant Self-Drilling Screws have a sharp, clean and consistent drill point, excellent thread engagement and holding power. What makes the Torx® Tamper-Resistant Drive System one of the most efficient fastening systems available is its ability to transfer greater torque, reduce end load, and virtually eliminate tool slippage. These fasteners are nearly impossible to remove without the special tamper-resistant Torx® Drive tool. Torx® Tamper-Resistant Self-Drilling Screws offered at Tanner are: pan head screws made from hardened 410 stainless steel, button head and flat/oval head screws, which are both made from zinc plated case hardened steel.

Torx® Tamper-Resistant Sheet Metal Screws

Torx® Tamper-Resistant Sheet Metal Screws

Torx® Tamper-Resistant Sheet Metal Screws are a high strength, one-piece, one-side installation fasteners, with the unique ability to “tap” their own mating internal thread when driven into preformed holes in metallic and nonmetallic materials. These screws have the ability to form or cut their own mating thread, creating an unusually good thread fit, which enhances resistance to loosening in service. They also have the ability to be disassembled and are generally reusable. Torx® Tamper-Resistant Sheet Metal Screws offer at Tanner are: button and flat head screws. Each head style is made in zinc plated case hardened steel and 18.8 stainless steel.

Torx® Tamper-Resistant Cap Screws

Torx® Tamper-Resistant Cap Screws

Torx® Tamper-Resistant Cap Screws have many of the same security features as the Torx® Tamper-Resistant Sheet Metal Screws. These screws are used in facilities where tamper-proofing is essential to reduce vandalism, tampering, and theft. Tanner offers three head style of Torx® Tamper-Resistant Cap Screws: button head, flat head, and flat head undercut. Each head style is made in zinc plated case hardened steel and 18.8 stainless steel.