The application scenarios of BOLYFA's air tightness testing fixture for mobile phone middle frames mainly focus on the manufacturing fields of electronic devices that require water resistance, dust prevention, or gas penetration prevention. In particular, it is applied to products with strict requirements for sealing performance, such as smartphones, wearable devices, and automotive electronics.
Smartphone manufacturing: Overall waterproof testing of the finished product, incoming inspection of the middle frame components, and re-inspection after repair.
Wearable devices and IoT products: Smartwatches/bracelets, true wireless stereo (TWS) earphones.
Automotive electronics: In-vehicle central control screens/instrument panels, advanced driver assistance system (ADAS) sensors.
The air tightness testing fixture for mobile phone middle frames is a specialized device dedicated to detecting the sealing performance of mobile phone middle frames (or the entire device). It is a crucial automated or semi-automated tool to ensure that products meet dustproof and waterproof standards (such as IP67/IP68 ratings).
Detection Objects: It is mainly used to verify the sealing performance at the assembly joints of the mobile phone middle frame with the screen and the rear cover (such as the sealing effects of glue and foam), as well as the waterproof performance of buttons and interfaces (such as the charging port and the speaker area).
Testing Criteria: Generally, it refers to the IP rating standards (for example, IP68 requires being kept at a water depth of 1.5 meters for 30 minutes), or the detection is carried out according to the pressure decay threshold set by the manufacturer.
Composition and Key Design Points of the Testing Fixture**
Mechanical Structure Part
Contoured Sealing Chamber: It is custom-made according to the 3D data of the mobile phone middle frame. Silicone or polyurethane sealing rings are selected to ensure a tight fit with the middle frame and achieve a good sealing effect.
Rapid Clamping Device: Pneumatic or electric fixtures (such as cylinders combined with linear guides) are used to uniformly apply pressure, effectively preventing the middle frame from deforming due to uneven pressure application, which could lead to missed detections.
Adaptation Components: A replaceable fixture head is designed to meet the detection needs of multiple models. However, the tolerance range of the middle frame dimensions needs to be fully considered during the design process.
Pneumatic System
Air Source Interface: Clean compressed air is connected, with a pressure range typically between 0.1 and 0.5MPa. A precision pressure regulator is also equipped to accurately adjust the air pressure.
Pressure Sensing Element: A high-precision (with an accuracy of up to ±0.1% FS) pressure sensor is selected to accurately detect pressure changes. Commonly used ones are differential pressure sensors.
Flow Control: Solenoid valves and throttle valves are used to adjust the inflation and deflation speeds to prevent instantaneous pressure surges from affecting the detection results.
Detection Logic Ideas
Direct Pressure Detection Method: First, carry out the inflation operation. After reaching the set pressure, enter the pressure holding stage, and then monitor the pressure decay situation (for example, under a pressure condition of 5kPa, the leakage amount within 3 seconds should be less than 0.05kPa).
Differential Pressure Comparison Method: Compare the pressure with that of a standard sealed chamber to eliminate the influence of environmental temperature fluctuations on the detection results.
Introduction to the Auxiliary System
Leakage Location Determination (Optional Function):
Ultrasonic Detection Method: High-frequency sound waves are used to capture tiny leakage points, but it requires scanning with a probe.
Bubble Detection Method: Immerse the tested part in water and determine the leakage point by observing the position where bubbles are generated. However, this method is a destructive test and is generally suitable for sampling inspections.
Automation Integration Function: It can communicate with the PLC (Programmable Logic Controller) or MES (Manufacturing Execution System) of the production line. When a non-conforming product is detected, it can automatically trigger the operation of removing the NG product.
Detailed Explanation of the Workflow
Loading and Positioning Step: The mobile phone middle frame is placed into the fixture by a manipulator or manually, triggering the positioning sensor to ensure the accurate position of the middle frame.
Sealing and Pressurizing Link: The fixture closes, and the detection chamber is inflated until it reaches the target pressure (such as 10kPa).
Pressure Holding and Detection Stage: Close the air circuit and monitor the pressure change situation in real-time. The pressure holding time is usually set between 2 and 5 seconds.
Judgment and Result Output: If the pressure decay exceeds the set threshold, an alarm signal will be issued and it will be marked as NG; qualified products will proceed to the next process.
Explanation of Key Performance Indicators
Accuracy Performance: The detection sensitivity can reach 0.01kPa, which can effectively detect tiny leakage holes (such as a leakage hole with a diameter of 0.1mm).
Detection Cycle: The single detection time does not exceed 10 seconds, which can meet the production line's demand of producing more than 60 pieces per hour.
Stability Index: It has good resistance to vibration and temperature interference, and the misjudgment rate is less than 0.1%.
