When it comes to bending metal, there are two main techniques that we rely on at Franklin Sheet Metal: air bending and bottom bending. Each method has its own strengths, and understanding the difference can be helpful before requesting a quote. While most of our work involves bottom bending, air bending comes into play for special cases and thicker materials. Let's dive into the details of each method so you know which one suits your project best.
Bottom Bending: Precision and Sharp Inside Radius
Bottom bending is our go-to forming method. Why? Because it's reliable, precise, and provides a sharp inside radius that works well for a majority of applications. With our standard tooling, we achieve an inside bend radius of around .005", which is quite sharp. This is a great choice for applications that need a crisp, precise bend. Many of our clients' drawings indicate a radius of .03"—a typical CAD software standard—but at Franklin Sheet Metal, we're always transparent about the sharp corners produced by our tooling and forming methods. For most applications, this sharp radius does the job, but we can also accommodate special radii (like 1/4", 3/8", or 1/2" etc.) if a project demands it.
Air Bending: Flexibility for Thicker Materials
Air bending, on the other hand, is a more flexible technique and is often used when working with thicker materials over 1/4". Unlike bottom bending, air bending doesn't push the material all the way into the die, which leaves some "air" between the metal and the tooling. This means the angle and radius can be adjusted based on the depth of the punch. While it doesn't provide the same tight inside radius as bottom bending, it offers the advantage of adjusting bend angles more flexibly without swapping out tooling.
When working with thicker sheets, air bending becomes necessary to avoid putting excessive stress on both the material and the tooling. It also gives us more control over larger radii that may be required for thicker metals, which wouldn't be achievable with the sharp-radius bottom bending approach.
Choosing the Right Method for Your Project
So, what's the best bending technique for your project? Here's a quick breakdown:
If you need a sharp, precise bend and are working with standard sheet metal thicknesses, bottom bending is usually the best fit.
For thicker materials or if specific radii are required, air bending is the go-to, allowing for a wider range of bend angles and larger radii without straining the material.
Forming Tolerances: Precision that Adapts to Your Project's Needs
Our general sheet metal forming tolerances range from ±1/64" to ±1/32", giving reasonable wiggle room for most project requirements. However, these tolerances are based on project complexity (size, material, thickness, etc.).
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