Problems on this page:
Chocolate under-tempered
Hits OEE: Quality
Symptoms: Products bloom, stay soft or stick in the moulds, and the temper meter shows a low reading.
Cooling zone not cold enough
Check the cooling water temperature and flow to the cooling zone.
Reheating zone too warm, melting the seed crystals
Check the reheating zone temperature against the recipe for the chocolate.
Throughput higher than the tempering capacity
Check the flow through the machine against its rated capacity.
Recipe or chocolate type changed
Check the temperature settings for the chocolate type in use.
Prevention: Temper measured with a temper meter at each start and every few hours.
Chocolate over-tempered and thick
Hits OEE: Quality
Symptoms: The chocolate thickens, flows badly and gives dull products.
Cooling zone too cold
Raise the cooling zone temperature as the recipe allows.
Reheating zone too cool
Check the reheating zone temperature.
Chocolate circulating too long at the depositor
Check the return flow and the time chocolate spends in the circuit.
Viscosity of the chocolate batch higher than usual
Check the batch specification with the chocolate supplier.
Prevention: Viscosity and temper checked each shift.
Temperatures drifting
Hits OEE: Quality
Symptoms: Zone temperatures move away from their setpoints.
Water circuit pump weak
Check the circulation pump and the water flow in each zone.
Heat exchanger fouled with scale
Descale the water circuit and check the water treatment.
Temperature sensor drifting
Check each zone sensor against a reference thermometer.
Mixing valve sticking
Service the mixing valve and its actuator.
Prevention: Zone temperatures logged per shift.
Chocolate pump or screw blocking
Hits OEE: Availability
Symptoms: Flow stops or the pump trips.
Chocolate solidified in the line after a stop
Keep the jacketed lines warm during stops and follow the restart sequence.
Foreign material in the chocolate
Check the sieve on the chocolate supply.
Over-tempered chocolate too thick
See the over-tempered causes.
Pump worn
Check the pump clearances.
Prevention: Pump stops recorded.
Fat bloom on finished products
Hits OEE: Quality
Symptoms: Products develop a white or grey film after days or weeks in storage.
Temper not correct when the product was made
Check the temper meter records for the batch.
Cooling tunnel too cold or cooling too fast
Check the cooling tunnel temperature profile against the product.
Storage temperature going up and down
Check the warehouse and transport temperatures.
Fat migrating from a nut or praline filling
Review the recipe and the barrier between filling and shell with the development team.
Prevention: Bloom checked on stored samples at set intervals.
Long start-up after weekends
Hits OEE: Performance
Symptoms: The machine takes hours to reach temper after a weekend stop.
Chocolate fully solid in the tank and lines
Start melting early enough with a timed heating program.
Water circuit cold at the start
Pre-heat the water circuit before the chocolate starts circulating.
No written start-up procedure
Write the start-up sequence with the target temperatures for each step.
Settings reset after power loss
Check the settings against the recipe at every start.
Prevention: Start-up time recorded per week.
Water leaking into the chocolate
Hits OEE: Quality
Symptoms: The chocolate thickens suddenly and becomes grainy.
Heat exchanger or jacket leaking water
Have the water side pressure tested for leaks.
Shaft seal letting water in
Replace the seal.
Condensation dripping from cold surfaces
Check the room humidity and the insulation of cold pipes.
Cleaning water left in the circuit
Dry the chocolate circuit fully before refilling.
Prevention: Water side leak test on the maintenance plan.
Changeovers between chocolate types
Hits OEE: Performance
Symptoms: Changing from dark to milk or white chocolate takes long and wastes chocolate.
Purging done without a planned sequence
Plan runs from light to dark so less purging is needed.
Settings not stored per chocolate type
Store the zone temperatures per chocolate as a recipe.
Allergen cleaning needed between products
Plan the production order to reduce allergen cleans.
No written changeover procedure
Write the changeover sequence and record the time each one takes.
Prevention: Changeover time and purge quantity recorded.
Guidance only. Always follow lockout/tagout and your site's safe-work procedures, and verify against OEM manuals before acting.
Related equipment guides: enrober · depositor · cooling tunnel · heat exchanger · chiller
Stop the same fault coming back
Recurring chocolate tempering machine 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.
Book a Fabrico demo
The directory stays free.
Related tools: full troubleshooting directory · OEE calculator · downtime cost · MTBF / MTTR · glossary
Methods that cut recurring stops: the six big losses · root cause analysis · preventive vs predictive maintenance · TPM · SMED & changeover