Punch and Die Maintenance: The Formula for Success and Productivity

September 27, 2022

Many fabricators have high-volume, active punches and die that must be properly maintained to function effectively. Regular maintenance increases the equipment’s capacity to deliver clean, sheared, straight-cut edges and ensures that the tooling will keep very tight dimensional part tolerances, reducing the likelihood of quality concerns.

Fabricators can save significant time and money by doing this type of maintenance appropriately and consistently. Many firms refurbish their tooling in-house for products such as rooftop punches, turret press tooling, ironworker tooling, progressive dies, die sets, carbide tooling, and stripper plates because this is so crucial.

The Tooling Design

The design of a tool consists of four crucial components: the punch, the stripper, the die, and the tool holder system. The tooling manufacturer’s elements in these components are the foundation of the punching operation’s successful execution. The punch is subjected to compressive and tensile forces while used in the punching operation. When the punch makes contact with the material’s surface being punched, the tip of the punch exerts pressure on the workpiece until it can overcome the material’s tensile strength. The workpiece’s material breaks apart, resulting in the creation of the hole and the release of the compressive stresses on the punch. As the punch continues to pierce the die to assure that slug discharge will occur, the workpiece material begins to scrape against the flanks of the punch.

Elements to Successful Punching

Punching successfully depends on certain elements designed into the tooling to limit the consequences of certain forces that cannot be avoided. One example of a solid initial step is using high-quality tool steels with metallurgical qualities designed to withstand chipping, cracking, and edge wears even under extreme conditions. These steels can be found in a variety of grades. Another illustration of this concept is the utilisation of a slight back taper, which lowers the pressure exerted on the punch flank during the stripping stage of the punching cycle when the punch is retracted. Another illustration of this concept is the use of a surface finish close to being polished on the punch flanks. This reduces the amount of friction that occurs during stripping, which in turn reduces the amount of heat that is generated.

Perfect Punch-Die Fit

The punch and the die need to have a very exact fit for it to be possible to punch a hole effectively. When the punch and die are concentric to one another and have good angular alignment, the punch can enter the die without coming into contact with it. Die clearance, also known as the dimension difference between the punch and the die, is another factor to consider. It is essential to have a uniform die clearance around the punch’s edge. This is especially true for tools with sharp corners, such as squares and rectangles. A uniform clearance can be maintained by including a tiny radius in the corners of the die. The radius size grows proportionally with the increase of material thickness across the die clearance. Die strength can be improved along with part quality by using the appropriate radius.

Basic Maintenance Requirements

Proper tool maintenance involves timely lubrication following the tooling manufacturer’s instructions, sharpening with job-specific grinding equipment, and regular punch press maintenance to ensure turret alignment. Tool manufacturers can design tooling to last as long as possible. Compared to equipment that does not have these properties, tooling designed to minimise punching forces has a longer interval between sharpenings. Increasing the period between regrinds using high-quality tool steels, near-polished punch flanks, and a back taper improves machine uptime and component quality. Furthermore, when the tool requires grinding, the quality of the tool steel is vital to success. Grinding is reasonably simple and rapid when sharpening high-quality tool steel parts created using a specific heat treatment method. Furthermore, simple tools to disassemble, grind, and tune encourage machine operators to do routine maintenance rather than waiting until the part quality is poor before sharpening the tooling.

For anything and everything punch and die, contact Gunna Engineering today!

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