TL;DR
Hydraulic overheating on the Roboshot points to a blocked or failed oil cooler, or an internal valve that is bypassing flow and generating heat. Check the cooler first, it is the most common cause.
What you might see
- oil temperature warning or alarm on controller
- hydraulic performance degraded during long run
- oil cooler fan running continuously
- hydraulic fluid discolored or smells burnt
Likely causes
Blocked or fouled oil cooler reducing heat rejection
Internal valve leakage causing continuous fluid bypass and heat generation
Low hydraulic fluid level reducing the thermal mass of the reservoir
Cooling water supply to the hydraulic cooler insufficient or too warm
Required tools
- Hydraulic oil temperature gauge or controller readout
- Low-pressure compressed air for cooler cleaning
- Oil sample collection kit
- Hydraulic filter differential pressure indicator check
- LOTO kit
Safety first
- Hot hydraulic fluid above 60 degrees C causes burns on skin contact. Wear heat-resistant gloves when taking oil samples or working on warm hydraulic components.
- Bleed hydraulic pressure to zero before opening any hydraulic fitting. Pressurized fluid causes severe injection injuries.
- Lock out the main disconnect before performing any internal hydraulic component replacement.
Procedure
- 1
Check the hydraulic oil temperature reading on the Roboshot controller against the specified normal operating range.[1]
- 2
Inspect the oil cooler exterior for contamination, blocked fins, or debris. Clean the cooler exterior with low-pressure compressed air.
- 3
Check the cooling water supply to the hydraulic cooler: verify flow rate, inlet temperature, and that the supply valve is fully open.[1]
- 4
Check the hydraulic reservoir fluid level. Low fluid reduces heat capacity and raises temperature faster.
- 5
Pull an oil sample and check color and smell. Dark or burnt-smelling fluid has exceeded its service life and must be replaced.
- 6
Check the hydraulic filter differential pressure indicator. A blocked filter forces fluid over the bypass valve, adding heat.
- 7
If all external checks pass, suspect an internal valve passing fluid under no-flow conditions. Monitor which circuit stays warm at idle; a circuit that remains warm when commanded off has an internal bypass.
- 8
Replace any failed internal valves with Milacron-specified components. Replace hydraulic fluid and filter after valve replacement.
Sources
Milacron Roboshot All-Electric Injection Molding Machine Operator Manual, Milacron
Milacron Roboshot Injection Molding Machine Operation and Maintenance Manual, hydraulic system maintenance and fluid specifications (general)
View source
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