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Nibbling large holes with a small punch is one of the most inefficient, frequently overlooked fabrication techniques. While nibbling works, this process causes problems that affect both the machine and the workpiece, such as:

• Punching debris that damages turret bores
• Increased production time from the numerous hits
• Excessive tool wear that requires more frequent maintenance and replacement
• Machine wear and tear
• Rough or scalloped edges on the workpiece that need secondary operations.

This last problem—post-punch rework—is typical in sheet metal fabrication shops, but it doesn’t have to be this way. You can eliminate the rework caused by nibbling with a simple punching process change and a minor tool investment. Mate’s Sales Engineers can identify these opportunities to bring significant savings to your manufacturing process. Let’s take a look at the following example.

Tri-Radius Tool to the Rescue in Mexico

A manufacturer in central Mexico used a nibbling process to punch three large circles, each with a different diameter. The edges of the parts had a rough finish that required manual grinding after completing the punching process. Two workers dedicated their entire work shifts to correcting these defects. During a visit to this customer’s plant, David Inzunza, Mate Sales Engineer for central Mexico, spoke to the engineer in charge of this operation.

Most turret presses include an auto-index station that rotates a punch and die to any designated angle dictated by the machine program. David recommended using Mate’s tri-radius tool, a punch with three different radii. The tri-radius can create three different diameters using a D Auto-Index station in a thick turret machine (or Size 2 tooling in a Trumpf punch press). Mate designs and manufactures this tooling with the three radii the customer specifies.

The result is a surprisingly clean circle, eliminating the need for secondary grinding operations and allowing the personnel dedicated to this activity to perform other functions. In addition, there are significant savings in grinding supplies. The company, in this example, saved over $40,000 through lower labor and grinding consumables costs. Download the case study. Watch an animation of how a tri-radius tool works in a thick turret punch press.