Thread rolling is a threading procedure and one of the metal threading services that includes rolling a metal stock through dies to distort it. This method creates external threads on the surface of the metal stock. Internal threads may also be generated using the same process known as thread formation.
Moreover, thread rolling, unlike some other regularly used threading techniques such as thread cutting, isn’t really a subtractive operation. This implies that no metal is removed from the stock. The benefits of rolled threaded fasteners include excellent surface quality, exact final dimensions, stronger threads, and a decreased coefficient of friction.
Screw machine goods include threaded machine components such as screws, nuts, and bolts. Threaded machine elements may be classified according to their purpose. Fasteners are structural components such as bolts, nuts, and screws. You may incorporate threaded fasteners into the component to create threaded fittings.
Specifically, threaded fasteners form non-permanent connections that may be loosened or removed mechanically. Power and lead screws are examples of mechanisms or mechanical drives. These machine elements direct movement and send electricity to other machine components.
Thread Rolling Advantages
There are several advantages to employing a rolled screw machine product. The primary benefits of thread rolling are improved product surface and dimensional accuracy. However, since this technique is based on metal deformation, it is confined to soft metals and necessitates more costly tooling.
Its advantages are:
Good Surface Finish
Thread rolling metal threading services produce smooth and burnished threads without further polishing operations. The intense compressive pressures that distort the metal erase any irregularities on the thread’s surface.
Additionally, the surface roughness of rolled surfaces spans from 8 to 24 microinches Ra, whereas cut threads vary from 64 to 125. Rolling threads are also free of cutting marks, chatter marks, rips, and burrs.
Lower Friction Coefficient
A smooth surface resulted in a reduced coefficient of friction. A lower coefficient of friction enables more uniform and consistent tightening of nuts and bolts, as well as better power transmission for lead screws.
High Thread Strength
Thread rolling is often done at low temperatures, resulting in a frigid working procedure. Cold working produces stronger components without requiring further heat treatment. As a result, rolling is appropriate for threading materials that do not react to heat treatment. Threads that have been rolled are 10 to 20% stronger than threads that have been chopped or ground.
In metal threading services, thread rolling can manufacture items with great precision and accuracy over lengthy runs since the dies used are mirror copies of the threads to be produced, and no material is taken from the stock. This is true as long as the dies are precise and of suitable hardness.
Reduced Production Lead Times
Thread rolling is often faster than thread cutting. Rolling speeds are determined by the kind of material, thread profile, machine size and capacity, and manner of feeding the metal stock. Thread rolling revolving dies with stock sizes ranging from 5/8 to 1 1/8 may produce 30 to 40 pieces per minute. 10 to 30 pieces per minute for cylindrical dies in diameters ranging from 1 to 12 inches.
Considering the Factors in Thread Rolling
As with any other machining process, numerous factors must be considered to achieve optimum working conditions and product quality. Some of the most critical factors influencing thread rolling are listed below.
- Stock Diameter. The proper stock diameter is almost identical to the screw or bolt pitch diameter. Above the pitch line, the thread volume is generally the same as the space or cavity between the threads. You may require certain tolerance changes to achieve the desired crest formation, particularly if secondary operations such as coating or plating are required.
- Feeding. The stock is fed into the dies using one of three methods: radial infeed, tangential feed, or through the feed. Tangential feed involves the pitch of the stock approaching the rollers from the side, resulting in a square, tangential contact. Finally, the cylindrical die mates against the stock through feed, forcing it to move axially.
- Lubricant and coolant. Thread cutting uses coolants or cutting fluids, which are also required for thread rolling. Deforming the metal also produces heat, which may damage both the dies and the stock. Furthermore, coolants may function as lubricants, reducing friction between the dies and the stock.
- Material requirements. Thread rolling can’t handle hard materials. Rolling materials can’t be harder than HRC 40. Low-carbon steel, copper alloys, stainless steel threading, mild steel, and aluminium are rollable. The material must be malleable. A 12-20% elongation factor is indicated.
Thread rolling improves the material’s resistance to stripping by forcing such defects to occur across the grain flow rather than with it. In order to have a deeper understanding of metal threading services like thread rolling, the benefits of thread rolling as well as the factors associated with thread rolling, have been outlined above.