Maintenance & Reliability · SOP

Hydraulic Press Brake Die Changeover and Tonnage Setting

Standardized procedure for safely changing dies on hydraulic press brakes and setting the correct tonnage. Ensures repeatable bend quality and reduces setup time while preventing hydraulic overload and operator injury.

Estimated Time

45 min

Difficulty

Advanced

Regulation

CSA Z142

Version

1.0

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Purpose

This SOP ensures that die changeover and tonnage setting on hydraulic press brakes are performed consistently, safely, and without damage to tooling or the machine. Following this procedure reduces setup time, prevents improper tonnage that could overload the press, and guarantees bend accuracy to print tolerances.

Scope

Applies to all operators, setup technicians, and maintenance personnel working with hydraulic press brakes in the metal fabrication department. Covers V‑die, urethane, and precision tooling changeover. Does not cover die sharpening or hydraulic system service – those are separate PM procedures.

Safety Precautions

LOTOLockout/tagout the press brake at the main disconnect and verify zero energy before opening guards or handling dies.
PPEWear steel‑toe boots, cut‑resistant gloves, safety glasses, and hearing protection. Remove all loose jewelry and tie back long hair.
HYDCheck for oil leaks around rams, hoses, and fittings. Do not work on a machine with active hydraulic leaks – report to maintenance immediately.
LIFTUse an overhead crane, die cart, or hoist rated for the die weight. Never manually handle dies heavier than 25 kg.

Required Tools & Materials

Die cart or hoist (capacity ≥ die weight)
Overhead crane with lifting slings (if required)
Die set (punch and die) per work order
Feeler gauges or shim set
Torque wrench with appropriate socket
Press brake controller key / access code
Hydraulic oil (ISO VG 46 or as specified)
Cleaning solvent and lint‑free rags
Bend angle gauge or protractor
Scrap material for test bends

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Procedure: Step-by-Step

1 Lockout/tagout: Isolate hydraulic and electrical power at the main disconnect. Attach personal LOTO device and verify zero energy by attempting to cycle the ram. Release hydraulic pressure through the bleed valve if fitted.

2 Remove existing die: Loosen top and bottom clamp bolts (back off 2–3 turns). Lift die vertically using die cart or overhead crane – keep it level to avoid binding. Set die aside in a designated rack.

3 Clean mounting surfaces: Wipe the ram bed and die holder area with solvent and a lint‑free rag. Remove all oil, debris, and metal shavings. Inspect for burrs or damage; use a stone if needed.

4 Inspect new die set: Check punch and die for cracks, wear, or deformation. Confirm dimensions (width, opening, height) match the work order. Measure the die height with a calliper if necessary.

5 Install new die: Position the lower die on the bed and align centreline marks. Lower the ram gently until the punch contacts the die’s V‑opening. Tighten clamps to manufacturer torque specification (typically 50–80 Nm). Re‑torque after one cycle.

6 Set tonnage: From the bend calculator or chart, determine required tonnage. Input value into controller using access key. Perform a dry cycle to verify gauge clearance. Then run a test bend with scrap of the same material thickness.

7 Verify bend angle: Measure the test bend angle with a protractor or digital angle gauge. If outside ±1°, adjust tonnage in 1‑ton increments (increase to sharpen angle, decrease to open). Re‑test until within tolerance.

8 Record settings: Log die ID, tonnage, pressure reading, bend angle achieved, and any adjustments in the press brake maintenance log (digitally or paper). Sign off the LOTO removal and return machine to service.

Hydraulic Press Brake Die Changeover and Tonnage Setting

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