The principle of flat thread rolling dies is the oldest process of cold forming threads, which are used to produce fasteners such as bolts, nuts, and screws in various external thread forms.

Definition

Thread-rolling in a flat die process is constituted by two dies: one is kept fixed, called stationary dies, while the other is operated with an alternative work feed, called moving dies. The process is performed in one pass, starting from one end of the fixed die, the work-piece is rolled and deformed as it moves towards the opposite end and ejected. The dies are grooved with a geometry corresponding to the development of the desired thread and inclined by an angle characterizing the thread helix. Thus, the tools represent the mirrored geometries of the pieces that will be obtained. The two dies are arranged such that the crests of one are aligned with the grooves of the other. 

Material

Flat thread rolling dies are usually made of 9SiCr, Cr12MoV and other tool steel. The hardness of the working part is kept 59-62HRC. When higher than HRC62 the dies are easy to chip, or lower HRC59 they are easy to wear. According to the working conditions of flat thread rolling dies, the selected materials should have the following properties:

• Good hardenability, high matrix hardness and good wear resistance
• Good dimensional stability
• Good impact toughness and appropriate strength
• Good machinability and hot workabilityAdvantages

Advantages

Flat thread rolling die has many advantages over machining processes, such as low manufacturing cost, high material utilisation without chipping, superior mechanical properties due to plastic forming, low forming load owing to the incremental process, and high production speed. Hence, it is widely used by the automotive industry.

Classification

There are two types of flat thread rolling dies.

Single face thread rolling dies, with single setting application. Recommended for lap-free rolling, hard rolling and special thread and form rolling applications on all types of reciprocating machines

Duplex (double-faced) thread rolling dies, threads on both sides, with two- or four-way setting. Recommended for commercial machine screw threads.

UKO are manufacturers of Flat Thread Rolling Dies for production of all types of Automotive, Industrial, Structural and General Purpose Fasteners. It can offer standard and customized flat dies according to customers’ requirements.UKO flat thread rolling dies features as below:

• Various kinds of raw materials are available including Cr12MoV, DC53, D55, H5, H9 and high-speed tool steel.
• Thread forms in different standards, ISO, ANSI, BS, DIN and other, can be made by rolling, grinding or milling.
• With excellent heat treatment, hardness of the die can reach HRC62.
• Surface treatment make a higher production of one set of flat dies, exceeds 2 million pieces.

For more details, please feel free to contact our professionals.