Holemaking in sheet metal: Laser cutting or punching machines?

A lot has changed in metal fabricating over the last 30 years, particularly when it comes to holemaking in sheet metal. In the 1990s the punching machine was the only way to go, until the emergence of the CO2 laser cutting machine changed the nature of the conversation.

By the 2000s, laser cutting technology was ready to take off. During the early years of the 21st century, punching machines still remained a competitive option for fab shops, particularly if they were delivering a multitude of holes to a sheet metal blank and forms that could be duplicated only in a press or press brake.

It wasn’t until the advent of fiber laser cutting technology in the 2010s that longtime fabricators had to rethink their approach to holemaking again. These solid-state lasers could rip through thin sheet metal at a speed that made the CO2 lasers look antiquated.

Now fiber lasers have reached 20 kW in power, and they are cutting thicker materials at speeds few would have expected when the technology first made its debut. Laser sales are expected to grow at an accelerated pace in the coming years as metal fabricating companies try to keep up with the technology advances. But where does that leave the punching machine when it comes to making holes?

Of course, punching still has its place. It’s versatile. Shops can create forms like louvers and embosses without having to move them to another machine. A punching machine also is generally less expensive than a fiber laser cutting machine.

But punching machines still stand out as holemaking workhorses for those applications where small holes need to be created consistently and quickly (see Figure 1). For these types of applications, punching might be the most economical way to produce holes.

Making Many Holes
Consider the production of perforated screens, for example. Cluster tools typically are used for punching these hole patterns as multiple punches can be used in one tool, maximizing the number of holes created in a single hit (see Figure 2). Imagine one punch having as many as 234 pins and creating that many holes with just one stroke! It’s been done.

Many different punch designs and cluster areas also are available, providing many punching choices. For instance, you can use a tool with a hexagon shape to create hole patterns with angles and add visual interest to the screen.

Keep in mind that for cluster punching, the punching machine has to be able to deliver the required amount of punching force for the application. The maximum recommended punching force should not exceed 75% of the press capacity. The following formula can be used to estimate the required punching force:

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