The most common causes of manufacturing downtime, and how to fix them
Unplanned manufacturing downtime is the most expensive line item that never appears on a budget. Industry research, including Siemens’ True Cost of Downtime study, says the cost of just one lost production hour in FMCG’s can be up to €39,000, and in pharmaceutical manufacturing, a single lost batch can run far higher than that. These headline figures understate the real damage in food, dairy and pharma plants including missed dispatch windows, product written off mid-run, cleaning cycles restarted from zero, and audit questions that follow any deviation in a GMP environment.
After 35 years designing, building, installing and maintaining production equipment across food, dairy, pharmaceutical and advanced manufacturing sites, we see the same handful of problems behind most unplanned stoppages. This guide covers the five we encounter most often, and the practical engineering steps that fix each one.
What counts as manufacturing downtime e
Before fixing downtime, it is worth defining it, because the definition determines what gets measured and what gets ignored. Unplanned manufacturing downtime any period where a line was scheduled to produce and could not: breakdowns, faults, jams and emergency stops. Planned downtime covers scheduled maintenance, changeovers and cleaning cycles. The distinction matters because plants tend to track the first category closely and the second rarely. Yet, a changeover that routinely overruns its allocation is costing production hours just as much as a failed part. The five problems below span both categories, and the plants that reduce downtime most effectively are the ones that track and proactively account for these.
1. Reactive Maintenance on Wear Components
The most common cause of unplanned manufacturing downtime is also the most preventable: running wear components to failure. Bearings, belts, gearboxes, drive chains and seals all have predictable service lives. When they are replaced on a schedule, the plant chooses when the line stops. When they are run to failure, that choice is taken away.
The pattern we often see is; a bearing starts to run hot on a Friday and with no condition monitoring in place, nobody knows. It seizes mid-shift the following Tuesday, taking-out the drive shaft with it, and a 20-minute scheduled swap becomes a six-hour stoppage with product on the line.
The Fix: a preventive maintenance schedule built from the equipment’s actual duty cycle, not the generic intervals in the manual. For example, high-duty lines in washdown environments wear faster than the datasheet assumes. Where the equipment is critical to output, add condition monitoring, vibration and temperature sensing on drives and bearings is now inexpensive relative to a single avoided stoppage, and gives maintenance teams days of warning. A structured service level agreement puts defined response times behind all of this, so a developing fault is regularly handled inside a planned window instead of it being an emergency.
2. Conveyor and Product-handling Failures
Conveyors are the arteries of a production facility, and they stop lines in ways that rarely show up as major failures. Belt mistracking that gradually shreds an edge. Product build-up on rollers in a washdown area. Transfers that jam intermittently at full line speed but never during commissioning. Accumulation zones that back product up into upstream equipment.
In hygienic environments the problem compounds, because conveyors that are difficult to clean are cleaned less thoroughly and less often, which accelerates mechanical wear, and adds contamination risk on top of the downtime risk.
The Fix: First, specify hygienic design at the outset: open-frame stainless construction, tool-free belt removal and CIP-enabled designs cut cleaning time per cycle and remove the places where build-up causes mechanical faults. Second, audit existing conveyors for the known failure points, tracking, tensioning, transfer geometry and drive condition, before they become stoppages. Third, standardise components across lines where possible, so one spares holding covers multiple conveyors and a failed part is a swap instead of a procurement exercise.
3. Obsolete Control Systems & Unavailable Spares
A large share of the plants we walk are running production on PLC’s, drives and HMI’s that their manufacturers no longer support. The equipment works, until it does not, and then the stoppage is measured in weeks rather than hours because the replacement part no longer exists. A control platform that is ten years past end-of-life turns every electrical fault into a sourcing problem.
The same applies to mechanical spares. Single-sourced gearboxes, custom fabrications with no drawings on file, and imported components with long lead times all convert minor failures into extended outages.
The Fix: an obsolescence audit: list every control component on critical lines against its manufacturer support status, and plan phased upgrades for anything unsupported, starting with the lines where a failure costs most. Upgrades done in planned shutdown windows cost a fraction of the same work done in an emergency. For mechanical spares; a criticality-ranked spares holding, with drawings and specifications on file for every custom part means the plant is not waiting on a supply lead time to restart production.
4. Changeover & Cleaning Cycles that run over
In food, dairy and pharma production, a substantial share of lost hours is planned manufacturing downtime that overruns: product changeovers that take 90 minutes against a 45-minute allocation, cleaning cycles that have to be repeated because a swab fails, strip-downs that require tools and three operators when they should require none.
This is the manufacturing downtime that hides in plain sight, because it happens every day and nobody logs it as a loss. Over a year, 30 minutes of overrun per changeover on a single line adds up to weeks of lost production.
The Fix: engineer the overruns out with tool-free strip-down on product-contact equipment, CIP-enabled conveyors and vessels that clean in place instead of being dismantled. Changeover parts can be stored at the line on shadow boards rather than in a store. Where recipes and formats change often, automation of format adjustments removes both the time and the variability of manual settings. The gains are permanent: a changeover engineered down from 90 minutes to 40 delivers 50 minutes back on every changeover, every week, for the lifetime of the line.
5. Knowledge Gaps & Undocumented Systems
The fifth problem is organisational rather than mechanical, and it compounds all the others. On many sites, the knowledge of how a line actually runs, its quirks, its fault history, its undocumented modifications, lives with one or two people. When they are unavailable, fault-finding takes hours longer. If that employee leaves the company, the knowledge goes with them.
The signature of this problem is a stoppage where the first 90 minutes is diagnosis rather than repair. This could happen because the fault is intermittent, the drawings do not match the installation, or even something as simple as the one person who fixed it last time is on holidays.
The Fix: documentation and structure. As-built drawings and control system backups kept up-to-date after every modification. Fault logs that record cause and remedy, as well as duration, so patterns emerge and repeat faults get engineered out rather than repeatedly repaired. And a maintenance partner under SLA who knows the installation, holds the documentation, and answers inside a defined response time, so the plant’s uptime does not depend on any single person’s availability.
Measuring What it Costs You
Most plants underestimate their downtime because they only count the breakdowns. A useful measure counts every hour the line was scheduled to produce but did not including; breakdowns, overrun changeovers, failed cleans and slow restarts. This is then priced at the line’s contribution per hour. That figure, tracked monthly makes the case for the preventive work above, and it shows whether that work is paying back.
For example: a line contributing €4,000 per production hour that loses two hours a week to breakdowns and one hour a week to changeover overruns, equates to a €12,000 a week loss, or over €600,000 a year. Most of this lost production value will never appear in a downtime report. Against that figure, condition monitoring on the critical drives, a spares audit and one changeover engineering exercise are not costs. They are the highest-return investments available to the plant. In our experience the payback question answers itself. The cost of a structured maintenance programme is almost always a fraction of the downtime it removes, a point we cover in more depth in our guide to Understanding Total Cost of Ownership in Food & Pharma Automation.
Where to Start
If unplanned manufacturing downtime is a recurring cost in your plant, the practical first step is an audit: wear-component condition, conveyor failure points, control system obsolescence, changeover losses and documentation gaps, assessed in one pass, ranked by cost and risk.
Noreside Engineering has designed, manufactured, installed and maintained production equipment for the food, dairy, pharmaceutical and advanced manufacturing sectors since 1990. Our Site Services and Maintenance division delivers planned maintenance, SLA-backed response and obsolescence upgrades across Ireland and Europe.
Book a consultation to arrange a downtime audit of your production lines.
Call: +353 (0)56 77 639 66
Email: info@noresideengineering.com
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