thicknesscontrol

Thickness control refers to the methods and systems used to regulate the thickness of a material layer during manufacturing, coating, or deposition. It is critical across industries such as metal processing, optics, packaging, electronics, and textiles. The objective is to produce uniform thickness within specified tolerances to ensure product performance, appearance, and cost efficiency.

Thickness is monitored in real time using non-contact methods such as laser triangulation, optical interferometry, ellipsometry, reflectometry, or capacitance sensors; and, where appropriate, with contact gauges. In many processes, in situ sensors track parameters such as coating gap, deposition rate, or substrate speed to support closed-loop control.

Control approaches convert thickness measurements into adjustments of process variables. Proportional–integral–derivative control and model predictive control are common, sometimes aided by adaptive algorithms. Adjustments may include coating gap, spray pressure, extrusion rate, bath composition, or chamber temperature, depending on the process.

Applications include roll coating and slot-die coating for films, blade coating, and spray coating in large-area manufacturing; thin-film deposition in semiconductor and optical coatings; and thickness control of metal sheets or foams.

Challenges include measurement lag, substrate roughness, thermal drift, material variability, and edge effects. Quality programs rely on statistical process control to maintain tolerances and reduce waste.