Safety notice: Before opening any pump housing, removing filters, touching line fittings or reaching into the feeder and delivery suction areas, stop the press normally, switch off power to the press and auxiliary equipment, apply lockout and tagout, shut off the air supply and release residual pressure. Electrical measurement may only be carried out by trained and authorised personnel. High-pressure air, rotating impellers and suddenly moving drive parts can cause injury: never block a leak with your hand, and never bypass a protective device to keep running.
1. Why a small air fault becomes a long stop
Feeder pick-up, sheet separation and delivery on a ROLAND 700 are highly sensitive to continuity of airflow. With a lightly clogged filter the press may still start, but vacuum build-up takes longer and nozzle movement becomes sluggish. Once sheet weight, coating or press speed changes, the previously hidden shortfall shows up as double sheets, missed sheets, skewed sheets and sheets hitting the front lays.
If the high-pressure pump runs with moisture, emulsified oil, corroded valves and contaminated lines further reduce stability. Pump noise, high temperature rise, fluctuating gauges and rising filter differential pressure are usually not four separate faults but signals at different points on the same maintenance chain. Keep alarm, pressure and sheet-condition records during repair, and avoid replacing a single element only to see the problem return.
2. Build the checklist by interval first
| Interval | Focus | What to check | Symptoms |
|---|---|---|---|
| Every shift | High-pressure pump and gauges | Listen for noise, check temperature rise, confirm stable pressure, drain condensate as specified | Noise, overheating, slow pressure build-up |
| Weekly | Lines and fittings | Look for hardened hose, loose fittings, leaks at seals and oil traces | Weak suction, frequent pressure compensation |
| Monthly | Vacuum and pressure filters | Clean or replace elements, inspect seals, filter seats and indicators | Dropping vacuum, insufficient airflow, rising differential pressure |
| By running hours | Pump oil and oil filter | Check level, condition and replacement interval against the maintenance schedule | Darkened or emulsified oil, abnormal temperature rise |
2.1 Daily draining and visual checks
Daily condensate draining is a basic task. Confirm the press is in the specified safe state, operate the drain slowly and avoid a sudden burst of water and air. Afterwards check whether the discharge carries oil, rust colour or emulsion, and record anything unusual on the check sheet. If water volume grows for several consecutive days, investigate ambient humidity, condensate discharge and pump condition rather than simply draining more often.
Visual checks also cover fan intakes, cooling fins, silencers and surrounding paper dust. Dust on cooling surfaces raises temperature, while oil on silencers or filter bodies increases flow resistance. Use tools suited to the machine and avoid blowing dust into motors, terminal boxes and bearing seals.
2.2 Filters: watch differential pressure and sealing
Filters cannot be judged on appearance alone. An element may look clean while the gauge fluctuates, feeder pick-up time lengthens or delivery suction weakens; in that case check for internal blockage, deformed seals and bypass at the filter seat. When a pressure filter shows a red indicator or clearly rising differential pressure, replace it to specification rather than tapping the element and reusing it.
Confirm the circuit is depressurised before dismantling filters. When fitting a new element, check orientation, seal lubrication and seat cleanliness, and tighten only as specified rather than over-tightening with an extension bar. After reassembly, check fittings at low pressure first, then build to working pressure and confirm there is no continuing leak.
3. Step-by-step diagnosis after isolation
3.1 Separate supply shortage from demand-side leakage
After safe isolation, record the pressure before the pump stopped, the alarm information and the location of the fault. Check the pump outlet, main filter, distribution valves and the branches to feeder and delivery. If total pressure builds slowly and every branch reads low, check the pump, main filter and header sealing first. If total pressure is normal but one function misbehaves, focus on branch valves, hoses, nozzles and local seals.
3.2 Check nozzles and the vacuum circuit
When the feeder produces double or missed sheets, clean nozzle tips and surrounding paper dust and confirm nozzles return consistently. Never enlarge the bore with a hard pin and never wipe nozzles with an oily rag. If suction is still weak after cleaning, inspect the vacuum line for cracks, kinks, loose fittings and blocked filters, then have a specialist test the pump body, vanes and valves.
3.3 Check airflow changes on the delivery side
If the delivery stack is untidy, sheet drop increases or suction noise becomes shrill, inspect the delivery suction line, filters and impeller. Do not confuse the issue with powder quantity or jogger position. Verify airflow at low speed with stable stock first, then adjust delivery parameters one at a time; if airflow falls as running time increases, focus on pump temperature rise and clogged filter media.
4. Four confirmations before restart
- Confirm filters, fittings, drain parts and housings are refitted and that tools, rags and old elements are removed from the machine.
- Confirm cables, earth leads, hoses and guards are back in position and that all access doors and interlocks are normal.
- Before removing lockout and tagout, the person who applied it must verify personnel position and machine state on site; nobody else may energise the press.
- Build air pressure without load first, then run a small number of sheets at low speed, checking separation, double-sheet detection, front-lay registration, delivery suction and pressure trend in sequence.
Acceptance after restart is not just the disappearance of an alarm. Watch at least one continuous low-speed production run and record whether pressure is stable, nozzle action is consistent, sheets enter the front lays flat, the delivery stack is tidy and pump temperature rise is normal. Only then step speed and sheet load back up.
5. Common maintenance mistakes
- Replacing elements without checking for leaks: leaks defeat a new element quickly and keep the pump under continuous heavy load.
- Watching the gauge but not the airflow: normal static pressure does not mean nozzles and delivery have enough flow under dynamic demand.
- Blasting filter media with compressed air: this can damage the media and carry contaminants into precision valves downstream.
- Running on after hearing noise: pump temperature rise and bearing noise accumulate and can escalate into motor or pump damage.
Conclusion
The core of ROLAND 700 air-system maintenance is keeping draining, filtration, sealing, pump condition and demand-side behaviour on one check sheet. Drain daily and watch the trend, inspect lines weekly, service filters monthly and maintain pump oil and related parts to schedule: that reduces double sheets, weak delivery suction and repeat alarms. All mechanical, electrical and pressure work must start from stopping the press, isolating energy and restoring guards, and only a restart validated at low speed counts as a completed repair.
