Brake Press Set-up Aids: Notes of Interest

Press Brake Deflection

Mecon Deflection-Compensating Die Holder.

• Multi point calibrating adjustment.
• Crown read-out indicators.
• Patent#1234039

Offset Dies

The relation between depth of offset and metal thickness affects the accuracy of the 90° bends. Good results in material up to 18 gauge can generally be obtained by bottoming, if the depth of the offset is six to eight times the metal thickness. The press brake tonnage requirements are approximately five times that needed for a single 90° air bend. When forming heavy gauge sheets, the depth of offset should be greater than eight times metal thickness.

Tonnage requirements can be reduced by air bending rather than bottoming (compromising on accuracy), and also by using larger radii on the forming points.

Radius Dies

When the radius exceeds four times material thickness, spring-back must be compensated for in the dies. The large radius used to prevent fracturing may also create problems such as material pre-bending, causing fluting and pulling away from the punch radius. Such pre-bending may require coining the radius at the bottom of the press stroke and adding to the tonnage. When forming exceptionally large radii, a bumping die will often prove more practical than a large deep die.

Fracturing

When bending mild steel plate 1/2″ thick and heavier or high strength materials, fracturing can be reduced by increasing die opening to 10 to 12 times material thickness. Increasing the punch radius also reduces fracturing. Tonnage Increase: When making 90^° bends the pressure to form the material rises rapidly to reach 85% of maximum when the material is bent up only 20^°, and a maximum when the material is bent up 40^°.

Channel Dies

The corner sharpness requirements and the flatness of the bottom of the channel have a direct bearing on the tonnage applied. Increasing corner radii reduces tonnage and helps in achieving a flatter bottom. Results depend on material which is uniform in thickness, temper, and yield point.

Brake Press Set-up Aids

PressBrake Features

Common Types of Brake Punch Tongues – Others on Request

Box Forming

Brake Press Tonnage Chart

Tons Required Per Linear Foot to Bend Mild Steel Plate Having 60,000 PSI Tensile Strength

For other metals as compared to 60,000 PSI tensile strength mild steel adjust as follows:

Brake Press Bending Allowance Chart

Bend Allowances for 90° Bends in Low‑Carbon Steel and Aluminum (Al)

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w = a + b + c + d + e –
(4 x bend allowance)

w = a + b –
(single bend allowance)

w = a + b + c –
(2 x bend allowance)

w = a + b + c + d –
(3 x bend allowance)

Note: w = developed width of blank, t = metal thickness, r = inside radius of bend

Thinking Safety

• Require that dies be set only by a qualified, safety-conscious die-setter.
• Insist that the die-setter be fully familiar with the press or machine’s manual.
• Provide all point-of-operation guards or devices necessary to avoid exposing any part of the operator’s body to the closing of the machine or press.
• Provide hand tools to insert, hold, and remove material, and to keep hands at a safe distance from the point of operation.
• Insist on safety practices and procedures and enforce them daily.
• Follow the instructions provided in the manual for the machine in which dies are being installed and operated.
• Ascertain that operators are trained in safety procedures, and arrange for periodic inspections to ensure that those procedures are being followed.
• Make available such safety-standard approved devices as pull-backs, fences, and infrared light curtain and controls for all press equipment. Two-button operation may also be necessary in some instances.