TL;DR
Oil overheating on a press brake is usually a clogged cooler or low fluid level. Check the oil cooler heat exchanger and top up fluid before resuming production.
What you might see
- oil temperature alarm on the controller
- sluggish or slow ram movement
- system pressure drops at high cycle rate
- visible discoloration or burnt smell from hydraulic fluid
Likely causes
Blocked or fouled hydraulic oil cooler fins
Low fluid level reducing the thermal mass of the system
Relief valve stuck open causing continuous bypass flow heat
Hydraulic pump internal wear generating excess heat
Required tools
- Compressed air blowgun
- Hydraulic oil per machine specification
- Replacement filter element (as required)
- IR thermometer
- LOTO kit
Safety first
- Never open hydraulic fittings while the circuit is under pressure or the fluid is hot.
- Lock out the main disconnect before accessing any hydraulic components.
- Wear splash goggles when working near hydraulic connections.
Procedure
- 1
Stop production and allow the machine to idle until the oil temperature alarm clears or drops below 55 C.
- 2
Lock out and tag out the main power disconnect.
Warning: Hydraulic fluid at operating temperature is hot. Allow the system to cool before opening any hydraulic connections. - 3
Inspect the oil cooler fins for dust, metal chips, or blockage. Blow out with compressed air from the clean side.
- 4
Check the hydraulic fluid level against the sight glass on the reservoir. Add the grade specified on the nameplate if below the low mark.[1]
- 5
Inspect the system return filter indicator. If the filter indicator shows bypass, replace the return filter element.
- 6
Check the coolant water supply (if water-cooled) for flow rate and inlet temperature.
- 7
After maintenance, restart the machine and monitor oil temperature over 20 cycles to confirm it stabilizes below the alarm threshold.[1]
Sources
Amada Amada HG / HFE 3i Press Brake general technical documentation, Amada
Amada HG / HFE 3i press brake hydraulic system maintenance documentation (general)
More guides for Amada Amada HG / HFE 3i
How to correct back-gauge drift on an Amada HG / HFE 3i press brake
Back-gauge drift is usually a worn ball screw, loose timing belt, or lost home reference. Check belt tension and re-home the axis before bending production parts.
How to fix ram positioning error on an Amada HG / HFE 3i press brake
Ram positioning errors usually trace to dirty or damaged linear encoders or worn hydraulic seals. Clean the encoder strip and check hydraulic pressure before adjusting parameters.
Stop fixing the same fault twice.
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