Tile and sanitary ware makers: kiln drift, powder and slip swings

The roller kiln profile drifts, and tiles lose size and flatness

What happens. The roller kiln runs a temperature profile that was set for each product. Over hours and days it drifts: burners age, rollers wear, gaps in production change the load, the body arrives with a slightly different density. The first sign is at the sorting line, where tiles come out a calibre larger or smaller, or slightly bowed.

What it costs. Tiles sorted into more calibres or a lower grade, and more rejects for flatness. By the time someone corrects it, a batch is already fired on the wrong profile.

Why the usual fix fails. Operators correct zone setpoints after the sorting line reports a problem, too late for what is already in the kiln. Each zone has its own standard controller, so changing one shifts the others.

How a fixed-price remote diagnosis checks it. From zone temperatures, burner and fan data, line speed, load gaps and the sorting line’s size and flatness data, I check how early the drift shows in the kiln data. The fixed-price remote diagnosis tells you whether predictive control of the profile could hold size and flatness tighter, and what it would take.

Background: Predictive control of process plants

Spray-dried powder moisture swings, and the press pays for it

What happens. The spray dryer turns the slip into press powder. Its residual moisture moves with the solids content of the slip, the burner, the outlet temperature and the weather. Moisture is checked on samples now and then, and the press operators notice the swings first: tiles with different density, edges that crumble, lamination.

What it costs. Pressing defects, density differences that show up later as size differences after firing, and rejects. Running the dryer drier than needed to be safe costs gas.

Why the usual fix fails. Controlling the outlet temperature to a fixed value keeps the dryer steady but not the moisture, because the slip changes. A moisture analyser on the belt helps but needs calibration, and its reading arrives after the powder is made.

How a fixed-price remote diagnosis checks it. From your spray dryer data (slip density and flow, inlet and outlet temperatures, burner gas, nozzle pressure) and the moisture samples, I check whether powder moisture can be computed continuously. The fixed-price remote diagnosis tells you whether such a computed value could lead the dryer, and what it would need.

Background: Computed measurements

Casting times stay fixed while the slip keeps changing

What happens. Washbasins and toilets are cast in moulds with a casting time that was found for a normal slip. The slip changes in density, viscosity and temperature, and the moulds change with their moisture and age. The caster sees the result when the piece is demoulded: walls too thin, too thick, cracks or soft spots.

What it costs. Pieces that crack in drying or firing, after much value has been added, and rejects found only at the end of the line.

Why the usual fix fails. Casters adjust times by experience and by touch, which works for the people who have done it for years. Measuring slip properties more often gives numbers, but nobody turns them into casting times.

How a fixed-price remote diagnosis checks it. From your slip lab values (density, viscosity, thixotropy), casting times, mould records, room conditions and reject data, I check whether the state of the slip and the wall build-up can be estimated well enough to set the casting time. The fixed-price remote diagnosis tells you whether casting times could follow the slip, and what it would take.

Kiln burners change to hydrogen, and nobody knows what it does to the ware

What happens. Kiln makers offer burners that run on hydrogen or on natural gas mixed with hydrogen. The flame is hotter, radiates differently, and burning hydrogen produces more water vapour in the kiln atmosphere. How glaze, colour, size and strength respond is not yet known for most products.

What it costs. An investment decision taken with an open quality question, and trial firings that tie up the kiln and produce scrap. If the effect is found only after the switch, a lot of product is at risk.

Why the usual fix fails. Trial and error on the production kiln is slow and expensive. Tests in a lab kiln do not reproduce the atmosphere and heat transfer of the real kiln.

How a fixed-price remote diagnosis checks it. From your kiln data, product quality records and the burner maker’s data I check which product properties are most likely to react to the changed atmosphere and heat transfer. The fixed-price remote diagnosis gives you a model-based view of the risks and a trial plan that tests the critical cases with as few firings as possible.