Step By Step Guide To Sheet Metal Bending

Four sheet metal bending examples in four different materials
Table of Contents

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From concept to finished product, sheet metal bending requires a deliberate, thought-out design and intentional manufacturing. There are a few major steps to successful bending:

Step 1: Initial Design

Step 2: Preparing Your File 

Step 3: The Bending Process

Step 4: Finishing Processes

We have a variety of helpful resources on bending, but let’s walk through these key steps so you can achieve the best results from SendCutSend. 

Basic Sheet Metal Bending Terms

Before we jump into our step-by-step guide, there are a few basic bending terms that you should know. The video below goes through all those definitions and will help you prepare for creating a successful bent sheet metal product.

Step 1: Initial Design

We’re going to go over some general design principles for bending, but be sure to check out our software tutorials to see specific examples.

Bend deduction

One of the most important things to take into consideration when designing bent sheet metal is bend deduction. Bend deduction is used to account for the “stretching” that happens in a material when it’s being bent. Bend deduction changes based on the material, thickness, and angle of the bend being created, but essentially it’s just making your part slightly smaller to make room for the stretched material around the bend.

The best way to see what dimensions you should be using on your bent parts is to use our online bending calculator.

A laptop showing SendCutSend's sheet metal bending calculator which helps you calculate bend deduction

Flange length

You will also need to know what flange length you’ll need and if that length will work in your chosen material. (The flange is the edge of the part that’s bent from the stationary base.) For sheet metal bending with SendCutSend, the flange length must be at least 0.500″ or 4x the material thickness, whichever is greater (some materials and bend angles will require longer flange minimums). The maximum flange length we offer is 24”.

Flange and base of a metal bend

To see the full list of minimums and maximums for SendCutSend’s bending service, check out our Bending Min/Max Chart.

Bend relief notches

To reduce bulging in the corners of your bent parts and prevent tearing, you can incorporate bend relief notches into your design. Bend relief notches are just narrow notches or circles put into the corners of your design. These notches should be at least 50% of the material’s thickness in width and the depth should equal Bend radius + Material thickness +.020”. These notches allow for less stress on the inner radii of the flanges, and will help keep the corners of the bends from interfering with the base material.

A part with two flanges nearly meeting at a corner, with a bend relief notch laser cut between them

Features spaced away from die line

Finally, make sure that all holes and features are adequately spaced away from the die line. All cut out features should be 0.255”-1.150” from the center of the die line. Each material and thickness has its own recommended distance between features and the die line, so check in with our support team to make sure your bent part will not experience any feature warping. 

A bent sheet metal part with an oblong hole crossing the bend line. The hole is warped because it's too close to the bend

Step 2: Preparing Your File for Bending

To prepare a file for sheet metal bending, first make sure it’s laid out flat. CAD programs like Fusion 360 make this easy using the sheet metal feature. The part needs to be laid out flat because we require 2D files for bending here at SendCutSend, although we encourage you to also attach an image of the part in 3D when you’re checking out so we can see exactly how your part is meant to function.

Bend line indicators

Before uploading your file for quoting, make sure that you are using the correct lines to indicate bends. The bend line indicator we prefer changes depending on what program you are using to design your parts, and we’ve laid it all out in this chart:

SOFTWAREFORMATBEND LINE
Fusion360.dxfSolid line (default)
Adobe Illustrator.aiSolid, separate color from cut lines
Solidworks.dxfDashed line (default)
AutoCAD.dxfDashed line
CorelDraw.epsSolid, separate color from cut lines
Inkscape.epsSolid, separate color from cut lines

While we accept .AI and .EPS files, it’s critical that your bend lines are parallel when uploaded from these softwares or the file will delay processing. 

If you design your parts in Adobe Illustrator, please send us the original (native) ai file. We’ll take care of the conversion on our end. For the fastest turnaround on your order, we recommend designing your parts in a CAD software.

Pre-flight checklist

Finally, just make sure to follow our pre-flight checklist for file preparation and you’ll be ready to go:

  • File is a two-dimensional vector format file.
  • All holes and cutouts are at least 50% material thickness and adequately spaced away from the die line (no less than .063″ for waterjet cut parts)
  • Bend lines are shown using the correct indicator for your program
  • File is built at a 1:1 scale, preferably in inch-units
  • All objects are on the same layer
  • All stray points, duplicate lines, empty objects and text areas have been removed
  • No shapes have open contours
  • All shapes have been united, combined or merged
  • All text has been converted to outlines or paths
  • Cut-out text (reversed text) has bridges or has been stencilized

Step 3: The Bending Process

Sheet metal bending is capable of forming many difficult parts and products, but tooling does have its limitations. There are a few bends that we don’t currently offer: 

  • No acute angles greater than 130°
  • No joggle/offset bends
  • No curl, bump, or roll forming
  • No coining
  • No window bends
  • No hemming
Illustration showing the limitations of SendCutSend's online sheet metal bending service

The tooling bend radius is adjusted depending on the material and its thickness, but you can check what the bend radius will be by once again using our bending calculator. And check out our full bending guidelines to see all the capabilities and limitations of CNC bending.

Bending will also add a little bit of time to your order, so allow for an additional 3-5 business days for processing and shipping. 

Step 4: Finishing Bent Sheet Metal

Bending may leave die marks on your parts, but these marks are purely cosmetic and will not affect your part in any way. While we don’t offer any protection to prevent die marks, they’re easy to remove with a DA orbital sander after you receive your parts.

Close-up view of die marks leftover on a bent sheet metal part

You can also powder coat bent sheet metal parts, and it’s simple to add powder coating to your SendCutSend order. It’s important to note die marks can show through the powder coating, so while it won’t completely cover up machining imperfections, powder coating will give your parts a protective and aesthetic finish. Our online powder coating service currently requires a custom quote, so our support team will work with you to make sure your powder coated bent parts are manufactured to your specifications.

Making Sheet Metal Bending Simple

Our goal here at SendCutSend is to make bending a simple, understandable process, and we are continually growing our resource library to make that reality. Check out our bending FAQs and reach out to our support team with any additional questions.

After you have finished your design and prepared your file, upload it to our instant quote tool and get your custom bent sheet metal project started!

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