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Bending Tooling

Bending Tooling

Bossray offers rotary draw tube bending die sets with the best fit and finish in the industry.
We use proprietary metallurgy for shock resistance and long die life, as well as the most durable mandrel linkage available with the toughest “snap-back” system for production tube bending.
We are also proud to sell the only wipers with fully machined precision feathered edges.
Bossray has a long history of innovation in both the design and manufacturing of rotary draw tube bending die sets.
Bossray CNC Tube bender toolings
  • Design and Installation
  • Correction
  • Features and Options
  • Related Products
  • Wipers
  • Tool System

The Design And Set Up Of Tooling For Rotary Draw Bending

Bossray Pipe Bending Machine toolings
Hardened tool steel or alloy steel, heat treated and nitrided
Clamp insert is secured with cap screws and dowel pins
Drive key must be parallel to clamp insert
Bore should have a slip fit over centering ring or spindle
Note:  Bend dies may have special tube grooves with captive lip or Empty Bending
Hardened tool steel or alloy steel, heat treated and nitrided
Preferable length is 3 x tube O.D.
Tube groove is grit blasted or may be serrated if less than preferred length
With tube held in bend die, advance clamp die and adjust for vertical alignment.
Adjust for parallel contact with entire length of clamp
Adjust for pressure
Alloy steel and nitrided
Tube groove must be parallel to back of die
If follower type pressure die is used, length equals 180 degrees + 2 O.D.
If a boosted system is used, groove should be grit blasted
With tube clamped to bend die, advance pressure die and adjust for vertical alignment
Start with minimal pressure and increase as required in small increments
Type of mandrel and number of balls indicated by Tooling Selection Guide
Aluminum/Bronze, chrome, or Kro-Lon mandrels for ferrous tubing. Only chrome mandrels for non-ferrous
Gain best results with most mandrels when shank projects a small amount past tangent (bend and try)
Lube I.D. of each tube
The Tooling Selection Guide indicates when a wiper may be required
Push tube over properly located mandrel and bring clamp and pressure dies up to bending position
Slide wiper along tube as far as possible into bend die then secure to holder
Unclamp pressure and clamp dies, tip of wiper should be “very close” to tangent

Corrections For Poorly Bent Tubes

After the initial tooling set-up has been made, study the bent part to determine what tools to adjust to make a better bend. Keep in mind the basic bending principle of stretching the material on the outside radius of bend and compressing the material on the inside of the bend. Make only one adjustment for each trial bend unless the second adjustment is very obviously needed. Avoid the tendency to first increase the pressure die force rather than adjust the wiper die or mandrel location. Start with a clean, deburred and lubed tube with the elongation properties sufficient to produce the bend. Note: There are certainly other corrections that could be made for the following problems. These illustrations are a few examples of how to “read” a bend and improve the tooling set-up.
Hump at end of bend adjust
Tool marks on centerline of bend adjust
Tool marks on centerline of bend in clamp and pressure die area adjust
Wrinkling throughout bend adjust
Bad marks at start of bend and over bend for 90 degree adjust
Wrinkling occurring for only a portion of the bend adjust
Wrinkles throughout bend area with wiper and mandrel in known proper position adjust
Excessive collapse with or without wrinkling throughout entire bend adjust
Mandrel ball humps adjust
Excessive collapse after tubing is pulled off mandrel balls adjust
Deep scratches throughout the bend and in wiper die area adjust
Heavy wrinkles through bend area adjust

Tube Bending Die Set Features & Options

We offer standard dies and die sets for most tube- and pipe-bending machines:

Bend die with precision-machined inserted clamp
Reversible for left-hand and right-hand mounting
Single keyway
Lifting holes for bend dies larger than 8 inches (203mm) in diameter
Reversible clamp die with T-key or hanger bracket
Reversible pressure die with hanger brackets
Zero-lip die cavities
Smooth or V-Type (fine) serrated clamp cavities
Proprietary metallurgy and case-hardening for shock-resistance and durability

Options for standard die sets:

Double-inserted bend die
Double keyway and closed-end keyway
Precision posthole shoulders for mounting to tie-bar
Captive-lip die cavities
Carbide grip coating, or aggressive serrated clamp cavitie

Stackable die sets (for multi-bend operations):

Includes all features and options of our standard tube and pipe-bending die sets
Inter-die locating keys and hubs

Basic Mandrels And More

Tube bending has come a long way since wet-packed sand cerrobend or cable mandrels. 
In addition to the basic mandrels described below, Bossray has designed these and many other specialty hybrid materials: hydroforming, waveguide, tube-within-a-tube, bend-on-a-bend, sizing, bullet-nosed, plastic, and sheathed materials.
Bossray copper ball mandrels
Among the many factors which influence the type of mandrel selection and number of balls, these are the most important considerations:“D” of Bend (center line radius ÷ tube O.D.)

Wall Factor (tube O.D. ÷ wall)
Ovality and wall thinning requirements
Tubing materials
Cosmetic considerations
Size and location of weld flash

3 products found

Bender Tooling Systems


Bossray full sets bending dies
The Bend Die…Rotates with the tube forming it to the correct radius.
The Clamp Die…Grips the tube against the bend die to prevent slipping.
The Pressure Die…Moves forward with the tube forcing it to conform to the radius of the bend die.
The Mandrel…Internal to the tube supports the tube at tangent prevents collapse of the tube.
The Wiper Die…Rides between the tube and the bend die controls the compression side on the bend.
Bossray straight clamp dies
Bossray compound clamp die
Bossray gusseted spool bend dies
Bossray added compound clamp dies


Bossray leading inserted wiper die is our most popular product. 
Over the past twenty years, we have perfected the design and manufacture of our inserted wiper dies for tube bending, and no one else comes close to our quality, price, and speed of delivery.
We also manufacture traditional “aircraft-quality” square-back solid-body wiper dies plus we have a resharpening service for these tools (including those made by our competitors). 
Square-back solid-body wiper dies are excellent for high-pressure tube-bending jobs that require the wiper to be set at zero-rake. 
However, they are relatively costly to purchase and then recondition as they wear.
Whether inserted or solid, our wiper dies for tube bending have a fully machined feathered edge. 
Unlike our competitors, there is no manual honing or sanding of the feathered edge. 
Bossray precision machines this essential attribute of the wiper die. 
With tube bending equipment, do not settle for less.
Understanding Wiper Set-up with Standard-Style Inserts
Bossray standard-cut wiper proper positioning
Standard-Cut Wiper Proper Positioning
Wiper tip raked slightly to ensure tip will not become pinched between tube and bend die. Full contact with bend die for maximum support.
Bossray standard-cut wiper zero rake angle
Standard-Cut Wiper Zero Rake Angle
Wiper tip may become pinched between tube and bend die. This may damage the tip or lead to imprint on tube.
Bossray standard-cut wiper zero rake angle pulled back
Standard-Cut Wiper Zero Rake Angle Pulled back
No support to the heal of the wiper insert will allow the wiper tip to flex during bending. Wrinkles may form.
Understanding Wiper Set-up with “Aerospace” (Aero) Inserts

Bossray Aero-cut wiper proper positioning
Aero-Cut Wiper Proper Positioning
Very little or no rake angle. Full contact with bend die for maximum support.
Bossray Aero-cut wiper negative rack to bring tip closer to tangent
Aero-Cut Wiper Negative Rake to bring tip closer to tangent
Back of wiper insert may drag against tube causing marking. This may also lead to clamp slippage and wrinkles.
Bossray Aero-cut wiper too much rake angle too close to tangent
Aero-Cut Wiper Too much Rake Angle Too close to tangent
No support to feathered edge of wiper insert will lead to wiper tip failure.

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Bossray provides professional services throughout the pre-sales, sales and after-sales processes to solve various problems for you.

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Bossray bending tooling adjust service
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