Troubleshooting & Overhaul

TECH SPECS

Technical points & process standards

The key control points and acceptance criteria we hold to on site for this kind of work: standards first, data speaks, and clients can supervise against the list.

1
Evidence at key overhaul steps: fit clearances, bolt torque and alignment data are recorded item by item and confirmed by both sides — no record, no next step.
2
The three-step diagnostic method: reproduce the symptom, eliminate systematically, verify the root cause. For intermittent faults, fit data capture before concluding — never guess by swapping parts.
3
Dual test runs at acceptance: the no-load run checks noise, temperature rise and vibration; the loaded run checks output and the temperature-rise curve. Both must pass for acceptance.
4
Closed loop against recurrence: the fault analysis report carries the root-cause conclusion and a preventive-measures list, followed by three months of verification to confirm no recurrence.

CROSS SUPPORT

How this module supports the others

A one-off job fixes a one-off problem; systemic problems need the modules working together. This module works directly with:

Module 02 Maintenance and preventive care — after overhaul the machine goes onto the preventive plan so performance cannot decay again Module 05 Refurbishment and upgrade of ageing equipment — for machines where retrofit beats repair, we provide a refurbishment assessment

WHEN YOU NEED THIS

When to call us for troubleshooting and overhaul

Not every fault needs outside support, but for the categories below, handling them yourself usually costs more.

Situation 1

The machine is down and the line has stopped

Orders are pressing, delivery dates are watching, and every hour down is money. What this situation needs is fast restoration of production: same-day attendance, get the machine turning first, then go back for the root cause. Repair-or-replace conclusions are given on the spot - you are not left burning time in waiting.

Situation 2

Long investigation, no root cause found

Parts have been swapped several rounds, parameters tuned several times, and the fault persists. Problems like this are usually compound - two or three factors stacked together, so treating only one gives 'fixed and back again'. What is needed is systematic screening and data capture, not more parts swapping.

Situation 3

An intermittent fault that clears on reset

It stops once or twice a day at random, resets and runs again, and half a month of investigation has produced nothing. For an intermittent, unrecorded fault, let it leave its own evidence first: fit data capture to log error counts, voltage fluctuation and scan cycle, then wait for it to strike again. These problems cannot be rushed, but once the data is in hand the fault is usually located quickly.

Situation 4

A planned overhaul needing a professional team

Annual overhaul, complete machine strip-down, key component replacement - these need manpower, tooling and workmanship standards. We schedule to your shutdown window, stage spares and tools in advance, record data for every key operation, and finish with dual trial runs and accuracy re-measurement.

Situation 5

Old equipment with no drawings that nobody dares touch

A machine of fifteen years, its documentation long lost, its circuits modified many times over. We first survey the circuits on site, verify terminals and components and fill in the mechanical reference data - then decide repair, upgrade or replace. The survey is itself an inspection, and many hidden defects are found at this step.

Situation 6

Equipment assessment after an accident

After a crash, flooding, an overload burnout or a burnt-out neutral, whether the machine can continue in service, which parts are damaged and how far repair must go to be safe all require professional assessment. We issue a written assessment conclusion and a repair plan, including the safety-critical mandatory items.

DIAGNOSIS PATH

How we investigate difficult faults

Diagnosis follows a path; it is not left to luck. The method below is one we use on site again and again, and it is the part most written about in the case reports on this site.

1
Reproduce first, then intervene: a fault you can reproduce is half solved. If it cannot be reproduced, create the conditions for reproduction - run it again with the same load, temperature, speed and action sequence. Rushing to strip the machine usually ends with the fault gone after reassembly, returning two days later, plus a fresh crop of assembly hazards.
2
Split mechanical from electrical, and classify first: sudden jumps in accuracy or condition are mostly electrical (poor contact, interference, parameter drift), while slow drift is mostly mechanical connection (looseness, wear, deformation). Classifying before investigating cuts out half the wasted effort.
3
Measure the data, do not guess: current, temperature, vibration, insulation, clearance, alignment - nothing that should be measured is skipped. Vibration is read from a spectrum rather than listened to - bearing characteristic frequencies do not lie; for temperature control problems a step response is used first to identify the process characteristics, and only then are parameters tuned.
4
Systematic screening: never stop at one finding: after confirming one cause, still ask 'is there a second one'. Most difficult faults are compound: dust plus poor cooling, wear plus misalignment, parameter drift plus mechanical looseness. Treat only one and the fault comes back in another form.
5
Verify the root cause: do not stop at the symptom: a worn bearing is an effect, not a cause. Chase the trigger - misalignment, improper lubrication, seal failure, a sudden load change, one tool crash - and only at that level have you found the root. Do this step properly and only then can you speak of 'one repair that lasts'.
6
Handling and prevention delivered together: once the repair is done, 'how do we stop it recurring' must be answered: which item to add to the inspection sheet, whether the lubrication interval changes, what to add to spare parts stock, what to add to the operating procedure. Repair without prevention is just waiting for the next repair.

MODULE FAQ

Common questions about fault elimination and overhaul

In an emergency shutdown, how fast can you get here?

Across Nanchong city, its Shunqing, Gaoping and Jialing districts and the six counties of Langzhong, Nanbu, Yingshan, Yilong, Peng'an and Xichong, our resident Yilong team is dispatched the same day and normally on site within one to two hours; Chengdu, Chongqing and other prefecture-level cities in Sichuan are reached the next day; jurisdictions in Yunnan and Guizhou are normally scheduled within 48 hours. A sudden stoppage triggers the emergency mechanism with priority dispatch. The phone line is direct, 24 hours a day, seven days a week.

How do you advise between repair, upgrade and replacement?

We work out the economics: residual value, failure downtime losses, retrofit investment and replacement investment reduced to one table, with three options and their payback periods. We do not push the most expensive one - only the one whose arithmetic works. On a ten-year-old line we once used the cost comparison table to persuade the client to repair; on others we advised replacement. The criteria are payback period and reliability requirement.

What if the same problem comes back after the repair?

Fault services are tracked and verified for three months. If the same root cause recurs within the tracking period, that means we did not repair it properly, and it is handled on the original scope at no additional charge. Where the recurrence relates to new duty conditions, misoperation or spare part quality, we explain that and provide improvement recommendations.

How long does an overhaul take the machine down? Will the schedule slip?

Duration depends on the strip scope and the spare parts position. Our method is to put the effort in before the shutdown: survey, diagnosis, planning, spares and tooling preparation all brought forward, so only work that truly requires the machine down happens inside the window. The plan states the duration and the key milestones, and a tight schedule is never a reason to omit records or trial runs.

Can you guarantee it is fixed the first time?

For faults whose root cause has been located, we work to workmanship standards and complete dual trial runs with accuracy re-measurement - acceptance rests on the data. For difficult problems not yet fully located, we will not thump our chests and guarantee anything; instead we set out the investigation path, the conditions required (data capture period, trial run time) and our stage-by-stage judgement. That honesty is more useful than an empty guarantee.

Difficult and recurrent fault handling → Major overhaul of all types of mechanical equipment → Diagnostic methodology and acceptance criteria → Case study: three-level diagnosis of a noisy spindle → Case study: seven days of hunting an intermittent PLC stoppage →

Module 03 · Fault elimination and overhaul