Shutdowns and Long Idle Periods: How to Store and Restart a Machine

When Long-Term Storage Is Needed

Many food plants make seasonal products: mooncake fillings, Mid-Autumn gift boxes, nian gao (年糕), zongzi (粽子), and tangyuan (湯圓). They run flat out for a few months of peak season, and the rest of the time the machines sit idle. Other plants rest their machines for a while because of a product change, a retrofit, or a move.

Being idle doesn't hurt a machine in itself; being idled "without proper preparation" does. Leftover dough going moldy, moisture rusting parts, rubber deforming under pressure, and rats and cockroaches hiding inside the machine are all common results.

Before Shutdown

1. Clean thoroughly: More carefully than the daily cleaning. Remove and wash all removable parts, and clean the hard-to-reach areas of the machine body, the underside of conveyor belts, and beneath the machine, leaving no food residue at all.
2. Dry completely: Moisture is the main cause of rust and mold. Dry the parts and machine body thoroughly; gaps can be blown dry with clean compressed air (the air should be filtered).
3. Rust protection: Stainless steel resists corrosion on its own, but machines often have carbon steel shafts, screws, chains, and similar parts. These can be coated with rust preventive oil; for areas that may contact food, choose products suitable for food plants, such as those in the NSF H1 or H3 category, and remove them before restarting. In the US, 21 CFR 178.3570 also includes, among the uses of lubricants with incidental food contact, "as a rust preventive film on food processing equipment," with the amount kept to the minimum necessary.
4. Lubricate: Lubricate according to the manufacturer's lubrication chart so the oil film protects bearings and drive components.
5. Release tension: Moderately loosen conveyor belts and drive belts to prevent deformation from long-term stretching; also release springs, pressure plates, and similar mechanisms if possible.
6. Seals: Remove detachable rubber seals, clean and dry them, and store them separately to prevent deformation from prolonged compression.
7. Disconnect power: Switch off the power and unplug the machine; lock out and tag out if necessary, and hang a "Out of service, in storage" sign.
8. Record: Photograph where removed parts came from, and list the removed parts and where they are stored.

During Storage

• Moisture: Keep the machine in a dry, ventilated place that won't flood. In humid areas, consider dehumidifiers.
• Dust: Cover with a breathable dust cover. Don't use fully sealed plastic sheeting, which can cause condensation inside.
• Pests: Food plants must already practice pest control, and idle machines should be included in inspections. Annex 1 of the Regulations on Good Hygiene Practice for Food (食品良好衛生規範準則) requires effective pest control measures.
• Periodic checks: Every so often, check for rust, standing water, and signs of pests; some manufacturers recommend briefly powering up and running the equipment periodically, so follow their instructions.
• Electronics: Control panels, inverters, and other electronic components may absorb moisture if left unpowered for a long time, so the storage environment should be dry.

What to Watch for When Restarting

1. Visual inspection: Rust spots, signs of pests, chewed wires, and whether all parts are present.
2. Remove rust preventive: On areas that may contact food, remove the rust preventive oil completely.
3. Full cleaning and sanitizing: Even if the machine was washed before shutdown, dust and environmental contamination during storage must be dealt with; treat it as if it were the first use.
4. Reinstall parts and replace aged ones: Replace seals that have hardened or cracked.
5. Restore tension and lubricate: Return conveyor belts and drive belts to the correct tension and top up lubrication.
6. Electrical check: Power cords, plugs, grounding, and emergency stop switches.
7. No-load test run: Listen to the sound, watch the motion, and confirm the safety devices work; see the pre-start checklist.
8. Small trial run: Confirm weight, shape, and quality before starting full production.

If the machine has been idle for a very long time, or anything is abnormal during the test run, have the equipment maker inspect it before production.

FAQ

Q: How should a machine be stored if it won't be used for a long time?
A: Clean and dry it thoroughly, protect it from rust, lubricate it, release conveyor and drive belt tension, remove and store seals separately, disconnect the power, and keep it somewhere dry and protected from dust and pests.

Q: Can ordinary machine oil be used as rust preventive?
A: For areas that may contact food, use products suitable for food plants (such as the NSF H1 or H3 category), and remove them before restarting.

Q: Can a machine that's been idle for a long time go straight into production?
A: Not recommended. First inspect it, remove the rust preventive, clean and sanitize, lubricate, run it empty, and then do a small trial run.

Q: Is it better to wrap it tightly in plastic sheeting during storage?
A: Fully sealing it isn't recommended, as condensation forms easily. Use a breathable dust cover and keep the environment dry.