Refractories and ceramics: long firing cycles and shrinkage

Refractories are fired with long, conservative cycles

What happens. Refractory products are large and thick, and a crack in the kiln is expensive. The firing cycle is long, with slow ramps and long holds that cover the largest, most difficult piece in the load.

What it costs. Gas for hours that the smaller pieces did not need, and kiln time that blocks the next load. A long cycle holds the whole plant’s output down.

Why the usual fix fails. Shortening the cycle by hand leads to a crack once, after which the old cycle returns. A thermocouple in the kiln reads the gas, not the core of the piece.

How a fixed-price remote diagnosis checks it. From kiln logs (zone temperatures, gas flows, load data) and the quality records, I check how much the cycle could be shortened per load without raising reject rates. The fixed-price remote diagnosis tells you what an optimised cycle could save.

Background: Optimal paths and setpoint plans

Sintering shrinkage varies and parts miss their dimensions

What happens. Technical ceramic parts shrink as they sinter, and the shrinkage is not always the same. Powder lot, pressing, temperature profile and atmosphere all play a role. Parts leave the kiln too large or too small.

What it costs. Dimension rejects, grinding of oversize parts and rework for parts that would be right with the proper firing. Customers measure the dimensions and reject the lot.

Why the usual fix fails. Making the mould a little larger and grinding the rest costs extra work on hard material. Tighter kiln control is helpful only when the cause is the kiln.

How a fixed-price remote diagnosis checks it. From kiln profiles, lot data of the powder and measured dimensions, I check how the shrinkage depends on the inputs and whether the sintering state can be estimated and the profile adjusted per load. The fixed-price remote diagnosis tells you if that is promising.

Background: Computed measurements

Electric kiln trials bring new dynamics

What happens. Firms try electric heating in place of gas, to cut emissions. An electric kiln heats and cools in a different way: no flame, other heat distribution, fast changes in power. The control that worked for gas does not fit.

What it costs. Trial runs that spoil loads, uncertainty about the firing quality and a risk to expensive trial charges.

Why the usual fix fails. Using the gas kiln’s programme in the electric kiln gives parts of different quality. Tuning by trial costs charges.

How a fixed-price remote diagnosis checks it. From the kiln design, heating element data and test firings, I check what a heat model says about the temperature distribution and which control concept suits it. The fixed-price remote diagnosis tells you what to clarify before a larger conversion.

Background: Predictive control of process plants