The bend die determines the radius of the part being bent. The groove in the die conforms to the configuration of the part: round, square, rectangular, extrusions and more. Prior to bending, the clamp block secures the part to be bent to the straight section of the bend die, During the bending, the groove in the bend die supports the inner section of the part to be formed and as the die rotates the part , contained by the pressure die is drawn past a stationary wiper die and over a mandrel if required. The wiper die and mandrel are required when the ratio of the tube diameter to wall thickness gets larger and when the center line radius gets smaller. Mandrels prevent wrinkling in the bent section and wipers inhibit wrinkling behind the bend.


Originally designed for use on numerically controlled tube bending machines, self- aligning tooling has proven equally advantageous on conventional machines, especially those with worn tool mountings. Self-aligning tooling is distinctive because of its self0aligning rail design. Since clamp and pressure dies interlock with the bend die tool misalignment is eliminated. Pressure die weight is self-supporting at the bend tangent. Setup time and scrap tube can be reduced up to 50%. The constant alignment during bending helps compensate for machine wear, material inconsistencies, or the tendency for pressure dies to raise when a pressure die booster is employed. Self-aligning clamp, pressure and bending dies are made from various type of tool steel and various heat treating methods. Some tooling is made reversible to fit both a Left Hand (Counter Clockwise) and Right Hand (Clockwise) rotation machines. You will find that the mountings vary between manufactures and models.


Mandrels are used when it is necessary to provide internal support in a tube or other hollow section. The primary function of the mandrel is to prevent excessive flattening of the material in the bend by supporting the outside wall of the tube. Hard chrome mandrels are used for mild steel, aluminum, 304 stainless, 321 stainless, copper and bronze tubing. Ampco bronze mandrels are used for Inconel, 21-6-9 stainless, titanium, and titanium alloys. There are different types of mandrel pitches, standard, close and ultra close. When ordering a mandrel a few items are required.

1. Tube OD

2. Tube Wall Thickness

3. Bend Centerline Radius (CLR)

4. Material to be bent

5. Maximum angle of bend

6. Number of Balls

7. Mandrel rod thread size


In many instances draw bends are required in material that is too hard, too thin, or shaped in such a manner that the metal on the inside radius of the bend forms a hump or series of wrinkles. The function of a wiper die is to fill the gap behind the bending form and confine the metal into a smooth, wrinkle-free compression on the inside radius. The wiper die is a stationary tool requiring a mounting base on the bending machine nose behind the bending die boss. The die itself is fitted to ride against the tube groove of the bending form, tapering to feather edge tip behind the tangent point. The wiper dies are cut to match the centerline radius of the bend die. When ordering a wiper a few items are required:

1. Material to be bent

2. Bend Centerline Radius (CLR)

3. Tube OD

4. Mounting information

5. Any Lubrication

6. Type – Square Back or Tip to mount to a holder