Reference Target Placement for Flexible Plastic Parts
Position reference targets on flexible plastic parts at high-stiffness rib intersections using explicit 3-2-1 restraint forces to eliminate gravity sag and inspection disputes.
Reference Point System
Meaning
Industrial alignment and dimensioning of large, complex, or flexible molded parts requires a structured network of measurement points to define the part’s spatial position in three dimensions. Through a reference point system, designers establish a three-two-one coordinate frame on the drawing that corresponds to physical clamping points on the inspection fixture. This standardized alignment avoids the measurement errors caused by part deflection and ensures that all inspection data is gathered from a consistent coordinate system.
Fixturing Strategy
Holding a flexible plastic panel repeatably is essential for checking critical dimensions such as door seals or snap fits. Within the reference point system, the primary plane is established by three points, the secondary by two points, and the tertiary by one point, which restricts all six degrees of freedom. This fixturing prevents the part from twisting during coordinate measuring machine probing, giving a true representation of its geometry.
Tooling Application
Toolmakers rely on these coordinate frameworks to align the various inserts and sliders within a complex multi-cavity injection mold. Using a reference point system ensures that the cavity geometry is cut in the steel relative to the same datums that will be used to measure the molded parts. This alignment minimizes dimensional discrepancy and ensures that the mold-makers can quickly tune the cavities.
Assembly Alignment
Automotive and aerospace manufacturers use this dimensional scheme to analyze how various molded parts will fit together in the final product. By aligning all components to a shared reference point system, engineers can run tolerance stack-up analyses to prevent assembly interference.