One advantage of the V-thread is that the same cutting tool may be used for all pitches, whereas, with the American Standard form, the width of the point or the flat varies according to the pitch.
Due to that, square thread is better in power transmition, but it is more difficult to manufacture because it needs a flat cutting tool. V thread is easier to manufacture but generally used for fastening and tighting rather than power transmition.
V Threads at Work
Sharp threads are also used as fastening screws for frictional connections such as screw connections with anti-fatigue shafts or tension anchors. Sharp V-threads are not well suited for linear motion applications or power transmission.
Explanation: In fastening, high frictional force is required and hence V threads are used whereas in power transmission, reduction in frictional forces is required.
The square threads are not so strong as V-threads but they offer less frictional resistance to motion than Whitworth threads.
With a high strength to weight ratio, nylon is one of the strongest threads available, making it a great choice for stitching upholstery, leather, and vinyl.
Size for size, a fine thread is stronger than a coarse thread. This is both in tension (because of the larger stress area) and shear (because of their larger minor diameter). Because of the smaller pitch, they allow finer adjustments in applications that need such a feature.
V-threads are less suitable for leadscrews than others such as Acme because they have more friction between the threads. Their threads are designed to induce this friction to keep the fastener from loosening.
The screw jack is intermittently used device and wear of thread is not an important consideration. Therefore instead of trapezoidal or V threads, the screw is provided with square threads. Square threads have higher efficiency and provision can be made for self-locking arrangement.
Explanation: Buttress thread is stronger than other threads because of greater thickness at the base of the thread.
4. V threads are highly recommended for fastening as well as power transmission purpose. Explanation: In fastening, high frictional force is required and hence V threads are used whereas in power transmission, reduction in frictional forces is required.
Most triangular threadforms are based on an isosceles triangle. These are usually called V-threads or vee-threads because of the shape of the letter V. For 60° V-threads, the isosceles triangle is, more specifically, equilateral.
V threads have some specific angle between 30–60 degrees. Square threads have an angle of 90° between two threads. Square threads are more efficient than V-threads. Square threads are used in power screws whereas V-threads are used to provide high frictional force!
Advantages of Thread
Threads minimize the context switching time. Use of threads provides concurrency within a process. Efficient communication. It is more economical to create and context switch threads.
A square thread is adapted for the transmission of power in either direction. This thread results in maximum efficiency and minimum radial or bursting pressure on the nut. It is difficult to cut with tap and dies. It is usually cut on a lathe with a single point tool and it cannot be easily compensated for wear.
All three varieties of acme threads use a 29-degree angle, which makes it broader, stronger and more square than standard V-shaped threads. They are often used for jack screws, lead screws, CNC systems and many other applications.
1) Square thread has the greatest efficiency as its profile angle is zero. 2) It produces minimum bursting pressure on the nut. 3) It has more transmission efficiency due to less friction.
Also known as dowel screws, double-ended screws are threaded fasteners that are used to create a hidden joint. Hidden joints, of course, are hidden areas where two surfaces meet and are connected. All double-ended screws are used for this purpose.
Generally, aircraft screws are manufactured with a Class 2 thread fit for ease of assembly. Bolts and nuts are also produced with right-hand and left-hand threads. A right-hand thread tightens when turned clockwise; a left-hand thread tightens when turned counterclockwise.
Power screws have large load carrying capacity, are compact, provide large mechanical advantage, provide very accurate and precise linear motion, have smooth and noiseless operation, are reliable and have lesser cost. Disadvantages are that power screws have poor efficiency and high rate of wear.
A very important property of a screw thread is that it can be used to amplify force: A small torque applied to a screw can exert a large axial force on a mass. Therefore, a threaded component is said to produce a Mechanical Advantage.
Because the minor diameter (root) of the threads is significantly less than the full-size diameter of the unthreaded shank on a headed bolt, the rod with nut often breaks at a much lower strength than a headed bolt.
There are three standard thread series in the Unified screw thread system that are highly important for fasteners: UNC (coarse), UNF (fine), and 8-UN (8 thread).
There are two common forms of threads: straight threads and tapered threads. Straight threads have a parallel profile that remains the same diameter throughout the part. Tapered threads taper along with the thread profile and become smaller in diameter as the part moves down.
Fine threads have greater resistance to unscrewing as a result of a lower helix angle.