Enrober Troubleshooting: Causes & Fixes

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Problems on this page:

Coating too thick or too thin Dull finish or bloom Feet or tails on the product Bare spots on the product Coating temperature unstable Air bubbles in the coating Wire belt tracking or damage Long changeovers and cleaning Coating thickening in the machine

Coating too thick or too thin

Hits OEE: Quality

Symptoms: Product weights after coating are high or low, or the coating looks uneven.

Coating temperature or viscosity off

Check the coating temperature and viscosity against the recipe.

Blower setting changed

Set the air blower for the product and record it.

Shaker setting changed

Check the shaker setting.

Belt speed changed

Check the belt speed against the recipe.

Prevention: Coated weight checked on samples each hour.

Dull finish or bloom

Hits OEE: Quality

Symptoms: The coating looks dull or grey, or white streaks appear after a few days.

Chocolate not tempered correctly

Check the temper with a temper meter and the tempering machine settings.

Cooling tunnel too cold or too warm

Check the tunnel zone temperatures against the recipe.

Product centres too warm or too cold

Check the centre temperature at the enrober infeed.

Humid room

Check the room humidity.

Prevention: Temper measured each shift.

Feet or tails on the product

Hits OEE: Quality

Symptoms: A foot of coating spreads under the product or a tail forms at the back.

Too much coating left on the bottom

Adjust the licking roller and the shaker.

Detailer roller not working

Check the detailer roller speed and position.

Blower too weak

Adjust the air blower.

Transfer to the tunnel belt too slow

Check the transfer and belt speeds.

Prevention: Product shape checked at the tunnel outfeed.

Bare spots on the product

Hits OEE: Quality

Symptoms: Parts of the product are not covered.

Curtain broken by blocked holes

Clean the curtain plate or trough.

Products too close together

Space products on the belt.

Bottom coating level too low

Check the bottom bath level.

Centres dusty or too cold

Check centres for dust and temperature.

Prevention: Coverage checked on samples each hour.

Coating temperature unstable

Hits OEE: Quality

Symptoms: The coating temperature drifts and the finish changes through the shift.

Water jacket temperature not controlled

Check the jacket water heater and its controller.

Temperature probe faulty

Check the probe against a calibrated thermometer.

Tempering machine output varying

Check the tempering machine settings and flow.

Room temperature changing

Keep the room temperature steady.

Prevention: Coating temperature logged continuously.

Air bubbles in the coating

Hits OEE: Quality

Symptoms: Small holes or bubbles appear in the coating surface.

Pump drawing air

Check the coating level and pump suction.

Coating level too low in the tank

Keep the tank at its working level.

Over-stirring the coating

Check the agitator speed.

Return flow falling from a height

Check the return flow path.

Prevention: Coating level kept within marks on the tank.

Wire belt tracking or damage

Hits OEE: Availability

Symptoms: The wire belt runs to one side, catches or has broken wires.

Belt tension uneven

Adjust the tension evenly.

Rollers out of alignment

Align the rollers.

Hardened coating on rollers

Clean the rollers.

Belt worn

Replace damaged belt sections.

Prevention: Belt condition checked at each clean.

Long changeovers and cleaning

Hits OEE: Performance

Symptoms: Product or coating changes take much longer than planned.

Coating not drained before cleaning

Drain the enrober fully before cleaning starts.

Parts not prepared

Prepare parts and tools before the run ends.

Cleaning steps not standardised

Write the sequence and time each step.

Hardened coating in hard to reach places

Keep the enrober warm while draining.

Prevention: Changeover time recorded per product pair.

Coating thickening in the machine

Hits OEE: Quality

Symptoms: The coating gets thicker during the run, the curtain becomes uneven and the coated weight rises.

Water or steam getting into the chocolate

Check the water jacket for leaks and keep steam and wash water away from the open coating.

Coating overheated

Check the heater controls, since overheated chocolate thickens and loses its temper.

Crumbs and centre fragments building up in the coating

Sieve the coating on the return line and clean crumbs from the infeed.

Coating recirculated too long without fresh supply

Keep a steady top-up of freshly tempered coating.

Prevention: Coating viscosity checked at set times during the run.

Guidance only. Always follow lockout/tagout and your site's safe-work procedures, and verify against OEM manuals before acting.

Related equipment guides: cooling tunnel · depositor · spiral conveyor · flow wrapper · chiller · chocolate tempering machine

Stop the same fault coming back

Recurring enrober stops usually trace to a cause you cannot see by hand. The partner we recommend is Fabrico: it tracks OEE and downtime live from PLCs, IoT sensors or AI cameras; where cameras are fitted, the video of a stop sits next to its machine data so the cause can be reviewed; and a technician opens the work order from the stop in the same system. Data is hosted in the AWS EU region, and Fabrico and the company behind it hold ISO/IEC 27001, ISO/IEC 20000-1 and ISO 9001.

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Methods that cut recurring stops: the six big losses · root cause analysis · preventive vs predictive maintenance · TPM · SMED & changeover