Fault 1 — coating thickness varies across the batch
Cause is almost always that the bed is not turning over. In a coating pan the product must be continuously rolling so every kernel presents a fresh surface to the spray.
Our coating pan uses internal turning plates specifically to keep the bed rolling and the coating layer even. If the bed is stalling, check pan loading first — an overfilled pan will not tumble — then check pan speed, and only then look at the recipe.
Fault 2 — kernels stick together in clumps
Too much liquid at once, or powder added too late. The build-up has to alternate: a light syrup application, then powder, then time to dry before the next layer.
The vacuum powder feeder and the powder hopper with internal dosing screw exist so powder can be delivered in controlled amounts at the right moment. Dumping powder by hand is where clumping usually starts.
Fault 3 — the coating cracks after drying
- Layers applied too thick — many thin layers beat few thick ones, every time
- Drying too fast, so the outside sets while the inside is still shrinking
- Kernel too warm when coating started — let it cool properly after roasting
- Recipe too low in binder for the layer thickness you are attempting
Fault 4 — coating will not adhere at all
- Kernel surface too oily — common after frying without adequate de-oiling
- Kernel surface too dusty — fines from a previous process act as a release agent
- Kernel too cold and the syrup is setting before it spreads
- Syrup viscosity wrong for the spraying disc — this is the last thing to change, not the first
What the coating group consists of
A bucket elevator, weighing and dosing hopper, powder hopper with internal dosing screw, vacuum powder feeder, liquid additive tanks, spraying disc, coating pan with internal turning plates, pan bottom, discharge chute and control cabinet. Layout, pan diameter and number of stations are configured to the required output.
Knowing which component does what is half of fault-finding, which is why we walk your technician through the whole sequence during commissioning rather than just handing over a manual.