A disciplined inspection routine and hard‑faced screw flights are extending press life, protecting extraction efficiency, and delivering about 90% system reliability at ~Rp131.4 million a year — a 47.4% saving versus unscheduled fixes.
Industry: Palm_Oil | Process: Digestion_and_Pressing
In palm oil pressing, it’s not just throughput and torque that set margins — it’s maintenance. Industry surveys point to the obvious culprit behind most press failures: irregular upkeep. A Malaysian survey noted that “irregular maintenance schedule and poor handling topped the list of common cause for malfunction” of screw presses (eprints.utm.my: source). A failure analysis from an Indonesian mill found that most failures (seal leaks, worm‑screw damage, bearing failures) ultimately traced back to overload, lack of cleanliness, or operator error (etd.repository.ugm.ac.id: source).
That’s why operators lean on routine checks and strict housekeeping. In practice, plants run daily or shift‑based walkarounds (checking oil levels, leaks, unusual noise), then schedule weekly equipment shutdowns for tightening bolts and cleaning. At each stop, bearings are checked for play, coupling alignment is verified, and gearbox oil quality is logged. Many equipment vendors recommend monthly wear checks on the screw flights and cage to catch problems early (palmoilmachine.com).
Preventive maintenance economics
The cost case is strong. A recent Indonesian study using FMEA (failure mode and effects analysis, a structured way to prioritize risks) found that scheduling maintenance on the most critical components — including the worm screw press — delivered about 90% system reliability at an annual maintenance cost of ~Rp131.4 million; the proactive schedule “save[d] as much as 47.4%” in maintenance costs compared to ad hoc repairs (researchgate.net).
The efficiency penalty from wear is also real. Studies on single‑screw extruders (analogous to oil presses) show that as flight clearance grows, machines must run at higher speeds or lower throughput to hold output, which raises temperatures and energy use (gpsmarker.ru). In palm presses, increased clearance means poorer oil squeezing and higher residual oil in the cake. Regular inspection therefore protects both uptime and oil recovery.
Wear control via hard‑facing overlays
The highest‑wear items in a press — screw flights (worms) and the cage — see abrasive and impact service. Hard‑facing (a weld overlay with wear‑resistant alloy) is a common countermeasure applied during rebuilds or heavy maintenance. “Recargue duro” (hard welding) involves depositing a wear‑resistant alloy onto worn screw and cage surfaces (researchgate.net). Böhler‑Metallurg’s UTP DUR 600 electrode, for example, is designed for impact‑resistant abrasion and deposits a layer (~55–58 HRC on the Rockwell hardness scale) that resists crushing and gouging (researchgate.net). Other specialized alloys — for instance “Ledurit 65” — incorporate Mo–V–W–Nb carbides to withstand extreme abrasion and high temperatures (up to ~500°C) (researchgate.net).
Done right, the overlay’s effective hardness is 2–3× that of untreated cast steel, and proper TIG/MIG (gas‑shielded welding) hard‑facing with good fusion (few voids) yields “considerably longer screw life” than inferior methods (flitetech.com). Cast screws typically require preheating (≈250 °C) before welding to avoid cracking in the brittle base metal (researchgate.net). Heavy layers are built up in multiple passes, then machined back to the original flight geometry and ground to maintain uniform flight width and profile — precision that avoids stress concentrations and delamination (flitetech.com).
In service, hard‑facing slows flight wear dramatically. Deposited layers such as UTP DUR 600 even carry a reported “efficiency” rating of ~130% (researchgate.net). Properly executed, hard‑facing can reduce the annualized wear rate by tens of percent. Mills track hours on each screw and plan to hard‑face or replace flights once wear exceeds a threshold (e.g., 20–30% of original thickness), rather than waiting for failure.
Full press rebuild workflow
When wear is severe, mills schedule a full rebuild during seasonal slowdowns. The press is completely disassembled: the screw cage comes out, the worm shaft is pulled, and internals are separated. Bent cage frames are typically annealed and straightened, then precision line‑bored and planed on the side rails to restore geometry (industrialhardfacing.com). Shafts are checked for runout and re‑aligned using a hydraulic press (not hammering), preserving integrity (flitetech.com). Bearings, seals, chains, and lubrication fittings are replaced per OEM spec.
Heavily worn screw flights are ground away; the entire flight and root are re‑built with hard‑facing weld. After welding, the screw is machined or ground back to the original thread profile to tight tolerance, with custom grinding rigs used to ensure constant flight widths and correct root radii (flitetech.com). The perforated cage (basket) is inspected; worn holes or bars are rewelded and re‑profiled.
Comprehensive overhauls extend to the drivetrain. Gearboxes and motors are disassembled, cleaned, and overhauled or replaced as needed. One specialist shop puts it plainly: it can “take in your complete press and return it back to new, from the gearbox to the choke (screw)” (industrialhardfacing.com), with “every component – belts, gears, bearings, couplings – … restored or replaced” so the press meets “original factory specifications” (industrialhardfacing.com) (industrialhardfacing.com). After reassembly, clearances and pressures are reset, bolts are torqued to spec, bearings are aligned, and a dry‑run confirms smooth operation before returning to service.
Operational payoff in oil extraction
Following this regimen — frequent inspections and preventive service, hard‑facing wear components, periodic overhauls — maximizes uptime and protects oil yield. The numbers back it up: preventive scheduling can nearly halve maintenance costs (researchgate.net), and keeping flight clearance tight avoids higher residual oil in cake and unnecessary energy use (gpsmarker.ru). In short, regular maintenance prolongs equipment life and delivers measurable gains in efficiency and profitability — from the gearbox to the choke.
