Posts Tagged ‘cold forming dies’

Cold Forming Die

Cold Forming Die

Cold Forming Die (Cold Heading Dies) Tungsten Carbide Cold Forming Dies Cold forming, or cold heading, starts with a cold metal slug placed into a die that is hit with a heavy strike to shape it into its desired form. The force from the strike causes the metal to flow into the desired shape inside the carbide die by exceeding the metal’s yield strength. Modern cold forming is commonly used for rapidly forming metal parts such as screws, bolts and many other fasteners.

Draw Ding Die

Carbide Drawing Die

Carbide Drawing Dies (Draw Dies) Drawing dies are typically used to shape wire, rod, bar, and tube. Commonly drawn materials include steel, aluminum, and copper. Tungsten carbide has a high compressive strength allowing it to handle extreme pressure; this makes the material ideal for use in drawing dies. Most major manufacturers use carbide dies in the drawing process. Drawn materials include mild steel, stainless steel and high carbon steel as well as other steel alloys. Softer materials, like aluminum and copper alloys, are frequently drawn as well.

The wire drawing process involves drawing wire through a die to reduce the diameter of the wire to the desired size and tolerance, while the volume remains the same. Wires are sized by drawing them through a series of drawing dies, with each die having slightly smaller bore diameter than the one preceding it to gradually reduce the width of the wire. The final die in the series forms the wire to its target size. Tube, or pipe, drawing dies are commonly round, hex or square, but can be made into any shape desired by the manufacturer. The process of drawing tubing is similar to the wire drawing process; however, a mandrel is used to form the inner dimensions of the tubing. The mandrel is inside the tube, or pipe, and situated inside the die. As the tube is drawn through the die it is being shaped on the inside by the mandrel, which establishes the wall thickness and inner diameter. A properly formed mandrel will provide for a smooth surface on the inside of the tube or pipe. Bars and rods are drawn in a similar fashion to wire; only they tend to be much thicker. A wide variety of metals are used in this application, including many steel and copper alloys. A cut-off knife is used to size the rods and bars to length.

Carbide Extrusion Die

Extrusion Die

Extrusion Dies Extrusion dies are typically used in a process where a slug is pushed through the die, forming the desired cross sectional area. A mandrel is used in the process if the application is for tubing, or pipes. Extrusion can be performed on a wide variety of materials and at various temperatures to obtain the desired properties of the extruded product. Materials that can be formed with extrusion dies include steel, copper, aluminum, tin, lead, nickel and even plastic. Products formed through extrusion operations include pipe, wire, rods, bars, tubes, and welding electrodes.

Carbide Shaving Dies Shaving dies are typically used to remove surface defects that are produced during the drawing process. The shaving process can be used on steel alloys, aluminum alloys, and copper alloys. Carbide Swaging Dies Swaging dies are generally used in a manufacturing process called rotary swaging. The rotary swaging process is usually a cold working process, used to reduce the diameter, add a taper, or make a point to a round work piece. It can also provide internal shapes in hollow work pieces with the help of a mandrel.

Thanks to Raven Carbide Die for the Images.

Carbide Dies

Carbide Dies 

Cold Forming Dies

Figure 1: Cold Forming Dies

Cold forming is a metal working technique used for rapidly forming steel parts such as screws, bolts and many other fasteners. Cold forming, also referred to as cold heading, uses a heavy strike against a cold metal slug to shape it into the shape of a Cold Forming Die. The force of the strike exceeds the metal’s yield strength, causing the metal to flow into the desired shape inside the carbide die.

The first step in colds forming is cutting the slug, also called a blank. Round wire from a coil is cut to the exact size needed. It is critical that the volume of the metal slug matches the volume of the finished product since cold forming process doesn’t add or take away any materiel.

After a metal slug is prepared the slug is then placed into the carbide die by the cold forming machine (or header) using “fingers”. The slug is then hit by one or more strikes (see figure 1). The carbide die and punch work together to create the new form. The force of the strike is great enough to cause the metal to momentarily become a fluid. This actually creates a stronger part than if the grain of the metal was cut into in order to form the desired shape. Often a progression of dies is used to achieve the final form desired. Each of these strikes are done at a different station and they progressively change the product into its final form. Most cold forming machines utilize either one or two strikes.

After the part is formed an ejector pin is then employed to pop it out of the machine. This, like the rest of the operations completed by a cold heading machine is completed at a rapid pace. Cold heading machines work at such a high rate of speed that the operations are invisible to the naked eye. Additional processes can be completed by these machines as well, for example, trimming, piercing and sharpening.

Obviously, this is a very brief description of cold heading and cold forming. We will continue with more in depth articles in the future.