Development of a UV Cured Acrylic Resin Glue Viscosity Measurement for Lens and Barrel Assembly Process using a HC-SR04 Ultrasonic Sensor

Acrylic resin glue is one of the most often used glues for the lens and barrel assembly process for camera production. This glue type must be cured by ultraviolet (UV) radiation before use which somehow encounters problems related to improper viscosity and thus leads to high waste and losses. Therefore, to prevent the problems, full viscosity measurement and control should be implemented but, in fact, has some difficulties due to high measuring cost, long measuring time and unsuitable measuring methods. This paper proposes an alternative non-destructive viscosity measurement by using a simple, low-cost HC-SR04 ultrasonic sensor. The experimental test results showed that with the suitable installation distance and position, the ultrasonic device could measure and classify the viscosity of the glue as uncured, low viscosity, good viscosity, and overcured with high accuracy when testing 20 glue samples per curing type. This proposed measurement technique spent short measuring time with only 5.2–8.5 seconds per test in average while have sensor’s cost less than 6.39 USD and consume power less than 0.075W, which could possibly be used for 100% cure inspection for massive assembly production.