Working Principle of the SMT Board Unloading Machine (NGOK Board Collector)

The SMT board unloading machine (also known as a board collector or unloading machine) is a critical piece of equipment at the end of the SMT production line, responsible for automatically unloading, sorting, and transferring PCBs (printed circuit boards) after assembly and soldering. Its core working principle can be summarised as follows:

‌Detailed Explanation of the Working Principle‌

PCB Reception and Positioning

PCBs that have completed reflow soldering enter the unloading machine via a conveyor track. Guide devices or positioning pins along the track edges ensure the PCBs are precisely positioned at the designated workstations. Sensors continuously monitor the PCB positioning signals, triggering subsequent operations.

NG/OK Sorting System

Based on the results from online inspection equipment (such as AOI or X-RAY):

‌Passing Boards (OK Boards)‌: These are smoothly transferred by robotic arms or push rods to the board collection rack or outfeed track, proceeding to the packaging stage.

‌Failing Boards (NG Boards)‌: These are directed to rework stations or isolation areas via cylinder-driven sorting mechanisms (such as flipping arms or slides), enabling automatic diversion.

‌Double-speed chain transmission technology‌

Mainstream equipment adopts a double-chain differential double-speed chain system:

The transmission chain consists of a drive chain (fast chain) and a load-bearing chain (slow chain) nested together, achieving smooth PCB transfer through speed differences to prevent surface components from being damaged by sudden stops or starts.

Synchronous belts or rollers assist in positioning to ensure PCB transmission without deviation.

‌Intelligent control centre‌

The PLC (Programmable Logic Controller) receives sensor signals (such as photoelectric switches and pressure sensors) to coordinate the联动 of robotic arms, sorting modules, and alarm devices.

The human-machine interface supports setting sorting rules, storage capacity, and fault diagnosis parameters.

‌Key Component Functions

Application Value

Efficiency Improvement: Replaces manual sorting, with single-board processing speeds of 3–5 seconds, increasing production capacity by over 30%.

Quality Assurance: Avoids static damage and contamination caused by human contact, reducing secondary defect rates.

Production Line Integration: Integrates with MES systems to connect production data, enabling full-process digital management.

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