Sensitivity analysis and calibration of a high-viscosity dispensing prototype for advanced manufacturing applications

Abstract

Abstract High-viscosity dispensing is widely used in advanced manufacturing, but reliable open-loop delivery remains difficult because viscous resistance, hydraulic loading, and actuator limitations can make the relationship between pump command and delivered amount dependent on the operating point. This study addresses the scientific problem of determining when conventional proportional command to delivery scaling becomes unreliable in an encoder driven dispensing system representative of an industrial fibre-rolling process. Experimental calibration tests were conducted for resin and hardener by varying encoder speed and shot duration, with delivered mass measured under a fixed hydraulic configuration. A compact analytical formulation with an operating point dependent effective gain was used to calculate normalised sensitivities and interpret the calibration behaviour. The results show that the hardener maintains an approximately proportional speed to delivery response, whereas the resin presents a concave-down nonlinear relationship and a progressively decreasing speed sensitivity at higher encoder speeds. This reduced effective delivery gain indicates that additional speed commands become less effective under increased high-viscosity loading. In contrast, delivered mass remains approximately proportional to shot duration for both liquids at a fixed operating speed, which gives a normalised duration sensitivity close to unity. The primary contribution is the experimental identification and quantitative characterisation of this operating point dependent delivery behaviour, together with practical guidance to select a responsive speed range and use shot duration as the preferred fine adjustment variable.