How to achieve precise control during the grease filling process for switch products?

In the production of switch-type products, the grease application (or greasing) process—though seemingly minor—directly impacts the product's tactile feel, service life, and electrical performance. Insufficient grease can lead to accelerated wear or a dry, gritty feel; conversely, excessive grease may spread to the electrical contacts, resulting in poor electrical connectivity. Achieving precise control typically requires a synergistic approach involving three key dimensions: hardware systems, process parameters, and visual inspection.

1. Selection of the Core Dispensing System

Traditional pressure-based dispensing methods are highly susceptible to variations in fluid viscosity. Modern high-precision production lines, therefore, predominantly employ the following two technologies:

Piezoelectric Jet Valves: These utilize the high-frequency vibration of piezoelectric ceramics to achieve non-contact droplet dispensing. Their key advantages include extremely rapid response times (on the millisecond scale), precise control over the diameter of the dispensed "dot," and immunity to variations in the height of the workpiece surface.

Screw Pumps: Driven by high-precision servo motors, these pumps rotate a screw mechanism to dispense grease using a volumetric metering method. This approach is insensitive to fluctuations in grease viscosity, making it ideally suited for the precise, quantitative dispensing of high-viscosity lubricants.

2. Closed-Loop Management of Critical Process Parameters

To ensure true "precision," the system must possess capabilities for automatic compensation and real-time monitoring:

Temperature Control: Grease viscosity is extremely sensitive to temperature fluctuations. By integrating a heating and temperature control system to maintain the grease at a constant temperature (e.g., between 25°C and 35°C), the system ensures that the volume of grease dispensed remains consistent with every shot.

Automatic Pressure Compensation: As the fluid level within the grease reservoir drops, the system's back pressure changes. The system should be equipped with pressure sensors to automatically adjust the compressed air pressure, thereby maintaining a stable flow rate.

Vacuum Suck-Back Function: A slight vacuum suction is generated the instant dispensing concludes; this prevents stringing and dripping, ensuring that the edges of the dispensed grease spot remain clean and well-defined.

3. Visual Guidance and In-Line Inspection

No matter how precise the dispensing equipment itself may be, if the switch is misaligned, the grease will be applied off-target.

Visual Alignment: Utilizing industrial CCD cameras to identify key feature points on the switch, the system performs real-time compensation for any coordinate deviations (along the X and Y axes) of the robotic arm or platform, ensuring the grease is deposited precisely within the designated sliding track or groove.

AOI Volume Inspection: Employing 3D laser profilers or visual comparison algorithms, the system immediately inspects the dispensed grease after application to verify its coverage area, height, and presence/absence. If the volume deviates beyond the ±5% tolerance range, the system automatically triggers an alarm and rejects the defective unit.

4. Needle and Workstation Design

Multi-Head Simultaneous Operation: For switches arranged in a matrix configuration, a multi-head synchronized dispensing mechanism is employed. This approach not only boosts efficiency but also minimizes individual variations by utilizing a unified pressure source.

Needle Anti-Collision Compensation: The system incorporates needle fixtures equipped with spring-loaded compensation mechanisms to prevent equipment damage—which might otherwise occur during contact dispensing—caused by variations in workpiece height.

Achieving precise control over grease dispensing for switches is, fundamentally, the result of an integrated application of volumetric metering control, temperature stability, and vision-based deviation correction. With the widespread adoption of Industry 4.0, an increasing number of systems are now incorporating data acquisition capabilities to record the specific dispensing profile for each individual switch, thereby enabling comprehensive quality traceability.

About Us:

Ruide Automation Technology Co., Ltd. is a high-tech enterprise specializing in the development of non-standard automation and intelligent equipment. We are dedicated to providing comprehensive solutions—including automated production lines, MES (Manufacturing Execution Systems), vision-based positioning and inspection, and laser applications—for a diverse range of products such as switches and sockets, photovoltaic new energy components, contactors, circuit breakers, relays, micro-switches, and valves.