Derating Nominal Equipment Speeds for Mixed Package Electronics Assembly Line Balancing
Derating nominal placement speeds based on package mass, feeder width, and vision complexity is required to establish accurate line balance and cost models.
Z-Axis Stroke Clearance
Travel Limit
A physical travel limit in pick and place machines defines the vertical distance between the tip of the nozzle at its highest point and the surface of the circuit board. This parameter is known as z-axis stroke clearance, and it determines the maximum height of components that the head can safely carry over the board. If the component height exceeds this travel distance, the nozzle cannot lift the component high enough to clear other mounted parts.
It is a fixed hardware constraint of the placement head design.
Assembly Sequence
High-density assemblies require careful planning of the vertical movement of the head during the placement cycle. When working with tall shields or connectors, the lack of z-axis stroke clearance can force the head to take longer routes to avoid collisions. This increases the travel path and adds to the cycle time of each board.
System Protection
Machine software uses this clearance value to plan safe movement paths and to generate collision warnings during programming. If a collision risk is detected, the software prompts the engineer to change the sequence of placement or use a different machine. This prevents damage to the delicate linear motors and encoders of the placement head.