Glue Bead Inspection on a Smartphone
Assess glue adhesion volume dimensions and position using 3D laser profiling
Smartphones are made up of a wide range of materials, including glass, metal, rubber, and engineered plastics, all of which must be solidly connected to each other. The small form factor precludes most threaded fasteners. As a result, a number of parts on a smartphone, including cover glass, EMI shielding, speakers, battery compartment, and housing, are attached with several thin lines of adhesive glue.
Glue can be overapplied, underapplied, or applied in the wrong locations, leading to over glue, lack of glue, or wrong route situations. Since this glue must continue to adhere while exposed to cold, heat, UV, humidity, and spills of many kinds of liquid, correct application is crucial to device function and durability.
The most reliable method for measuring the position, size, and height of the glue bead, regardless of the color of the glue or the background, is through the use of a 3D laser displacement sensor such as the Cognex DSMax. The combination of the green laser and the telecentric lens delivers a 3D representation of the glue bead, to micron-level accuracy, for accurate measurements and inspections.
The DSMax 3D laser displacement sensor has a high scan rate up to 18 kHz, concentrates 2,000 profile points within a 31-mm field of view for maximum resolution, and uses high dynamic range (HDR) to reduce noise on bright and highly reflective surfaces. The user can set different tolerances, thresholds, and locations while outputting data to your PLC. From the measured dimension, glue bead volume can be accurately calculated.
In addition to ensuring that downstream operations receive only properly glued parts, this dimensional analysis provides early warning of developing upstream issues with the glue dispenser by detecting subtle trends in glue application. The quality engineer can receive warnings well before glue dispensing moves outside of defined tolerances, reducing rates of scrap.