Lead Screw Assembly and Types

Figure 1 Lead Screw Assembly

A lead screw may be a threaded bar or bar that interprets rotational movement into straight movement. When it comes to interpreting the revolving movement of a engine to straight movement, there are numerous diverse ways of finishing this errand. Frequently times within the world of movement control, the fight between the distinctive strategies and innovations can get very disagreeable. Be that as it may, as a run the show, it’s best to keep in mind that particular application are superior for a few innovations than others, and as continuously, taken a toll and item life time are too basic components in deciding which innovation to utilize in a given application. Lead screws use the helix angle of the thread to convert rotary motion to linear motion. The performance of a lead screw is heavily dependent on the coefficient of friction between the nut and the screw, which in turn depends upon the material used for the nut and screw. Lead screws typically use nuts made of internally lubricated plastic or bearinggrade bronze. Plastic nuts usually travel on stainless steel screws while bronze nuts often run on carbon steel screws. When bearing-grade bronze nuts are used, stainless steel screws are an option. Leadscrews are manufactured in the same way as other thread forms (they may be rolled, cut, or ground). Sometimes used with a split nut also called half nut which allows the nut to be disengaged from the threads and moved axially, independently of the screw’s rotation, when needed (such as in single-point threading on a manual lathe).

Types of Lead Screw

Classified by the geometry of their thread. 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. Leadscrews, on the other hand, are designed to minimize friction. Therefore, in most commercial and industrial use, V-threads are avoided for leadscrew use. Nevertheless, Vthreads are sometimes successfully used as leadscrews, for example on micro lathes and micro mills.

Square head

Square threads are named after their square geometry. They are the most efficient, having the least friction, so they are often used for screws that carry high power. But they are also the most difficult to machine and are thus the most expensive.

Acme thread

Acme threads have a 29° thread angle, which is easier to machine than square threads. They are not as efficient as square threads, due to the increased friction induced by the thread angle. ACME Threads are generally also stronger than square threads due to their trapezoidal thread profile, which provides greater load-bearing capabilities.

Buttress thread

Buttress threads are of a triangular shape. These are used where the load force on the screw is only applied in one direction. They are as efficient as square threads in these applications but are easier to manufacture.