Hydraulic System
The hydraulic system is the core power source for HWAMDA hydraulic and two-platen machines. Proper care of the hydraulic fluid and components is essential.
Hydraulic Oil Selection
| Machine Type | Recommended Oil Grade | Viscosity at 40°C | Viscosity Index |
|---|---|---|---|
| Standard hydraulic (HMD100–1000) | ISO VG 46 anti-wear hydraulic oil | 46 cSt | ≥ 100 |
| Large machines (DU650–4000, M8SII 1200+) | ISO VG 68 anti-wear hydraulic oil | 68 cSt | ≥ 100 |
| All-electric machines | N/A (separate lubricants per gearbox) | — | — |
| Cold climate (< 5°C startup) | ISO VG 32 anti-wear | 32 cSt | ≥ 100 |
Approved brands: Mobil DTE 25 (VG 46), Shell Tellus S2 VX 46, Total Equivis ZS 46, or equivalent.
Oil Change Intervals
| Condition | Interval |
|---|---|
| First oil change (new machine) | After 500 hours |
| Normal operation (VG 46/68, mineral) | Every 2000 hours or 12 months |
| Biodegradable oil | Every 1000 hours or 6 months |
| When oil analysis shows: | |
| — Water > 0.1% | Change immediately |
| — Particle count > ISO 18/16/13 | Change immediately |
| — TAN increase > 0.3 mg KOH/g from baseline | Plan change within 500h |
Filter Element Replacement Schedule
| Filter Location | New Machine First Change | Routine Interval |
|---|---|---|
| Suction strainer (if serviceable) | 500h | Every 2000h or inspect quarterly |
| Return filter | 500h | Every 2000h |
| Off-line / kidney loop filter | 500h | Every 2000h |
| High-pressure filter (if equipped) | 500h | Every 2000h |
| Tank breather | 500h | Every 2000h or annually |
| Servo-proportional valve pilot filter | 500h | Every 1000h |
Hydraulic Component Maintenance
Hydraulic Pump
- Monitor case drain flow — an increase indicates wear
- Check coupling alignment yearly
- Replace shaft seal at first sign of leakage
- Typical pump overhaul interval: 15000–20000 hours
Proportional & Servo Valves
- Keep pilot oil clean (use 3μm or finer filtration)
- Perform null bias calibration yearly
- Replace pilot filter at every oil change
- Do not interchange valve cards between valves without recalibration
Cylinders (Clamp, Injection, Carriage, Ejector)
- Check rod surface for scoring or chrome flaking
- Replace rod seals when leakage appears (drips from rod wiper)
- Replace all seals preventatively at 5 years
- Check cushion adjustment screws annually
Accumulators
- Check nitrogen pre-charge monthly
- Standard pre-charge: 60–70% of system working pressure
- Replace bladder every 2 years
- Never weld or modify accumulator shells
⚠️
Accumulators store high-pressure nitrogen and hydraulic fluid. Always discharge both the gas pre-charge and hydraulic pressure before disconnecting any accumulator line. Severe injury can result from improper handling.