Press brake punch and die are the two basic parts of press brake tooling. The tool’s punch is used to exert force on the metal, and the die is used to mold the metal into the appropriate shape. The intended function of the punch and die is to cooperate to shape the metal into the required shape.
Types of Press Brake Punches:
Punches come in a variety of forms for a range of applications. Only after becoming familiar with the fundamentals of each sort of press brake punch should one choose a punch. These various blows include:
Acute Angle Punch
Very short angles can be bent with an acute angle punch. Punches with an acute angle are sometimes shortened to acute punches. These punches are typically used when a bend angle of no more than 30° is needed. Larger angles, such as 60°, can also be bent with ease by these punches. These punches feature a thick body and a pointy tip.
Sash Punch
A sash punch is a kind of tool that is bent inside a press brake and has an extremely tiny body and an angled tip. The angled tip makes it possible to bend and work around curves. Making door jambs and sashes is a typical use for a sash punch.
Standard Punch
The press brake tooling that is most frequently used is standard punch. It can bend the thickest material because of its greater tonnage, which is exerted by its narrower punch tip and larger body. The outside of the inward side is flat, with a small concave curve. This makes it possible to fold a shorter flange.
However, there is currently no unified definition of standard tools, and the commonly used types are standard tools.
Joggle Punch（Z-tool）
A press brake specialized tool called a joggle punch is used to create bends around corners. Because the joggle punch has a thinner profile, it’s quite helpful for bending S shapes. These are uncommon punches that are frequently employed in specialized punch selection tasks.
Radius Top Punch
As opposed to other punches’ sharp tips, the radius top punch has a rounded tip. Instead of a severe V-shaped curve, this produces a U-shaped bend. Usually, a U-shaped die is used in conjunction with this punch to create a suitably rounded corner.
Narrow Punch
A low-thickness punch that is homogeneous along its length is narrow. These punches are employed in situations where there is some clearance and other punches might not fit securely. Another name for it is a sword punch. Using a narrow punch to close off a square or box-shaped profile is a popular use.
Swan Neck Punch
For marking purposes, a swan neck punch is employed. They are employed in the workpiece to produce specialized U profiles. The swan neck punch’s unique shape was designed to prevent the bent workpiece’s legs from slamming into the tooling. The gooseneck punch is a variant of this technique that is also utilized for U profiling. An unsupported line of force is produced by the swan neck’s and the gooseneck punch’s niche shape. As a result, these punches are not as strong as other options. They have a smaller tonnage capacity.
Components of Press Brake Dies
A die is a hollowed-out piece of equipment that is positioned beneath a workpiece to support and guide the bending process. All of the punch’s force is absorbed by the dies. That’s why high-strength materials are also used to make these. Die sizes and shapes vary widely to accommodate a wide range of operations. Typical die forms are:
Two-Way Self-Centring V Dies
Two parallel V-shaped cavities make up two-way self-centering V dies. With this, the workflow is quicker than with a single V die. Retooling is not necessary if a different bend angle is needed.
Single V Die
A “V”-shaped cavity is hollowed out of the tooling of a single V die. They also have a single “Vee” die stylization. Because of their extensive adaptability, they are the most widely used press brake die. The rule of eight is used to determine a single V die. It specifies that the material thickness should be eight times the length of the V die aperture.
Multi V Die
Multiple V cavities are positioned all around the die in multi-V die arrangements. Three is the maximum number of V-cavities that can be present. The number of bending choices that can be added to a single tooling set by using a multi-V die. A straightforward die rotation can be used to adjust the bend angle or material thickness.
Channel Forming Dies
A ‘U’ shaped channel is made on a flat sheet of metal using a channel-forming die. Traditional V dies must be passed through twice to create a U-shaped channel. On the other hand, the task can be completed in one pass by a channel-forming die.
Hemming & Flattening Dies
The entire flange length is folded into an acute angle bend and flattened using a flattening and hemming die. There are two types of bottom tools: the U-section bottom tool and the sprung-loaded bottom tool.
Materials Used in Press brake punch and die:
Special grade steel, such as Yasuki Steel or Type 4 Molybdenum Steel, is typically used to make punch and die. The majority of the force produced by the press brake is handled by the die and the punch.
Thus, to maintain this tonnage, high-strength hardened steel is essential. T10 grade, T8 grade, 42CrMo grade, and Cr12MoV are further popular steel grades used to make the proper press brake tooling.
For press brake tooling, Chromoly, or Chromium-Molybdenum Steel is thought to be the ideal material. Chromoly steel is incredibly strong and resistant to corrosion.
As such, it offers a long service life and the capacity to handle all press brake requirements. Another excellent choice for press brake tooling is tungsten carbide, which offers excellent quality at a fair price.
Factors Affecting Punch and Die Selection
V Opening and Material Radius
There are multiple V-die opening sizes when bending sheet metal if the thickness and metal type are the same. When bending, the sheet metal must not be lost. The workpiece will deform if the internal radius of the metal plate is less than its thickness because the plate will be stretched.
A radius larger than the sheet’s thickness won’t lead to distortion. It is important to select a lower radius in addition to avoiding radius distortion when selecting the ideal V-die opening.
Bending Material
The kind of metal you wish to bend is a crucial consideration. The die opening, bending angle, and bending radius are all dependent on the metal’s thickness. For instance, the tensile strength (UTS) of steel refers to its ability to withstand stress better than that of other steels.
Different strength molds are needed for different metals due to their varying tensile strengths. Furthermore, the number of toolings needed is determined by the length of the metal plate.
The metal’s thickness is an additional factor. Press brakes and other equipment may suffer premature wear and tear if sheet metal-specific tools are used on thicker materials.
The Rule Of 8
The rule of eight is a general guideline that can be used to press brake dies with V-openings. The rule of eight states that the V-opening die must be eight times the thickness of the bending material and is based on 60,000 PSI tensile cold-rolled steel.
This rule of eight holds true for most bending operations. One can create an internal radius that is roughly equal to the material’s thickness within the given tonnage range.
This law, however, is not ideal because the factor will change as the thickness of the material does. Consequently, some V-die apertures have a width that is six, ten, or even twelve times the material thickness.
Because of their decreased ductility, thicker plates sometimes need a V-opening ten times larger than their thickness in order to disperse the load over a greater area and prevent cracks.
Choose the thickest and thinnest metal sheet that needs to be bent before figuring out the press brake dies. Then, use the rule of eight to figure out the right size for the V dies.
To get the next V die, take the smallest V die and double its size, continuing until the maximum mold is achieved. The dimensions should be rounded to the closest mold if an exact match cannot be found.
Length Minimum of the Leg or Flange
Consideration should be given to the flange length or leg that the workpiece requires when choosing V-shaped dies. The sheet metal must always come into direct contact with the die’s shoulder when bending.
Inaccurate bending results will result from the flange falling into the V-shaped opening if its length is less than that stated. As a result, the minimum flange or leg needed on the metal plate increases with the size of the V-shaped aperture.
An acute angle die can reach 110% or more of the V-die opening, whereas a V-die’s minimum flange is approximately 70% of the conventional V-die’s aperture. The sheet metal should be put on the die such that the material contacts the die shoulder at a location equal to 20% of the V-die opening before establishing the minimum flange length.
V Opening Affects the Radius of The Bending Material
The radius of the bending material is influenced by the V opening of the press brake dies. The internal radius of a material should ideally match its thickness in general. The material removed from the radius vanishes if the inner radius is less than one thickness.
In the case of plate bending, a “side bulge” may develop at the bend if the inner radius is smaller than one thickness. The metal plate’s radius increases with the size of the V-die aperture.
But the radius will also depend on the material’s tensile strength. The stronger the material, the larger the radius on a particular V-die opening. The formula for bending radius (R) on mild steel is R = V/8, where R is typically equal to 1/8 of the V-die opening. This guideline, however, will change depending on the kind of metal.
Maintenance and Care:
Press brake tooling that receives the proper maintenance and tooling program can live much beyond its anticipated service life. In this context, some pointers are:
Sharpening
For press brake functioning, tool sharpness is crucial. But after a while, this sharpness may become less noticeable. Observe appropriate reconditioning and resharpening procedures on schedule. Poor precision and higher wear are caused by dull tooling edges.
Rated Limits
It’s critical to use the equipment within its rated limit capacity. Excessive use might quickly cause the machine and its tools to malfunction.
Tool Cabinet
It is recommended that your press brake toolings be kept in a special tooling cabinet. To facilitate efficient workflow, this cabinet can be positioned close to the machine.
Cleaning
The first and most important rule for Press brake punch and die is cleaning. A lot of people keep their press brakes without cleaning out any dirt, grease, or other impurities. This can even lead to corrosion and increased tool wear. Consequently, after each workday, wipe the press brake tooling. Utilize the cleaning agents advised by the tools manufacturer.
Tool Replacement
Examine the tooling for signs of wear, cracks, or corrosion. When needed, replace the tools. When tooling is destroyed, the bends won’t be up to par.
Storage Environment
Make sure that there is no moisture or chemical contamination present in the tooling’s storage environment.
Lubrication
To lessen friction between parts, lubricate the tool before beginning the operation. The tooling manufacturer’s handbook will recommend the appropriate lubricant.
Now that you have the information above, you may select the appropriate tooling type for any given work requirement. It will expedite the entire bending process and enhance the quality of your bends.
