From Handbook of Machining and Metalworking Calculations


Screw thread systems are shown with their basic geometries and dimensions in Sec. 5.2.

Engagement of Threads. The length of engagement of a stud end or bolt end E can be stated in terms of the major diameter D of the thread. In general,

  • For a steel stud in cast iron or steel, E = 1.50 D.

  • For a steel stud in hardened steel or high-strength bronze, E = D.

  • For a steel stud in aluminum or magnesium alloys subjected to shock loads, E = 2.00 D + 0.062.

  • For a steel stud as described, subjected to normal loads, E = 1.50 D + 0.062.

Load to Break a Threaded Section. For screws or bolts,

where P b = load to break the screw or bolt, lbf

S = ultimate tensile strength of screw or bolt material, lb/in 2

A ts = tensile stress area of screw or bolt thread, in 2

NOTE. UNJ round-root threads will develop higher loads and have higher endurance limits.

Tensile Stress Area Calculation. The tensile stress area A ts of screws and bolts is derived from

where A ts = tensile stress area, in 2

D = basic major diameter of thread, in

n = number of threads per inch

NOTE. You may select the stress areas...

Products & Services
A bolt is a type of threaded hardware fastener that is used to position two workpieces in specific relation to each other. A bolt is specifically designed to be used with a mating, internally threaded hole or nut, which will maintain the bolt's alignment as well as the material's position on the bolt. While used synonymously, screws and bolts are not mechanical clones.

A screw is a wide-encompassing type of hardware fastener that attributes its mechanical capabilities to the helical groove that extends around the circumference of the device's shank. These threads provide the friction and traction that serves a screw's purpose: to assemble or position two workpieces in relation to each other. While used synonymously, screws and bolts are not mechanical clones.

Thread Rolling Machines
Thread rolling machines generate threads by displacing and flowing metal into a thread shape.

Nuts are a type of hardware fastener with a tapped inner diameter. They are used with a mating threaded bolt or rod to secure components. There are many sizes and varieties of nuts; each with a particular fastening purpose. Some nuts can be applied without tools, and others may have special designs to prevent the nut from loosening.

Anchors are mechanical fasteners that attach an object to a support structure. Product categories include concrete anchors, expansion anchors, lag screw anchors, machine anchors, screw anchors, spring anchors, wall anchors, and wedge anchors. Toggle bolts are also available.

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