A Perforation Primer: Fundamental Considerations of Metal Punching

With hole type, size and pattern established, it’s time to put the design under analysis to determine the reliable strength and stiffness. An analysis of equivalent solid material will determine the elastic properties or yield strength of the material. To calculate equivalent solid material, determine the ratio of equivalent yield strength of the perforated metal to the yield strength of the solid or unperforated metal.

This ratio will tell the designer important safety issues to take into account for bending and stretching; the designer then can decide the best thickness to use for a specific application where the strength of the perforated material is equal or close to the strength of the unperforated material.

WHY IT’S BEST TO LOOK TO AN EXPERT
To make holes with great accuracy and speed, a special process is required. A hefty investment in machinery and tools is needed, and specialized technology and expertise must accompany this equipment.

Punching without a press requires special cluster tooling that is not only expensive but can take time to make as well. In addition, the tool can only punch a small cluster of holes at once and thus the time to punch the metal can be lengthy. Even then, the tooling will be limited in use with a specific material and will be rendered obsolete if the material or thickness change.

Using the tool, as mentioned, can be time consuming and challenging in terms of accuracy. Modern high-speed and numerically controlled presses can punch holes as fast as 300,000 per minute with extreme accuracy. Expert perforators can accommodate hundreds of hole patterns and the subsequent manufacturing processes needed. After punching, for example, the material will need flattening. Without a roller leveler, you would need to send the part out to be put back into shape. In addition, an expert perforator can perform secondary operations such as bending, welding, painting and plating.

Therefore, before attempting a punching job, it’s important to consider and compare your costs:
• The cost of tooling
• The time it takes to make tools
• The set-up charges on your turret press
• The production cycle of your press
• Machining time
• Roller-leveling, de-burring and degreasing
• Quality considerations

As you see, metal punching is a versatile and valuable process, but it’s also a challenging one. To get the job done most cost effectively and at the highest quality, in many cases, you should consider an experienced perforating specialist.

The Industrial Perforators Association is the only North American organization devoted to the advancement of perforated material and continues to push the boundaries of what these materials can do. Through extensive research, knowledge sharing, standards setting and more, the IPA provides members with the tools to drive innovation and increase utilization in perforation. In the process, the IPA acts as an essential resource to anyone who may benefit from incorporating perforated materials into their design.

Discover more about the IPA and perforated materials at www.iperf.org.