When automating the sorting and packaging of polished gemstones, selecting the right End-of-Arm Tooling (EoAT) is critical. The wrong choice can lead to micro-scratching on polished surfaces or dropped items during high-speed movements.
Mechanical Pneumatic Grippers
Pneumatic grippers use compressed air to actuate fingers or jaws that physically grasp the stone. While they offer excellent security and can handle heavy or irregular objects, they require soft pad inserts (usually polyurethane or silicone) to prevent scratching. Additionally, the gripping force must be carefully controlled via pressure regulators to avoid cracking valuable stones.
Vacuum Suction Grippers
Vacuum systems use a suction cup or nozzle to pick up the gemstone by its flat table facet. Because there is no physical squeezing force, vacuum grippers have a near-zero risk of crushing or scratching. However, they rely on clean, dust-free environments to maintain seal integrity, and any oil or dust on the facet can cause suction failure.
"For raw or rough stones with irregular surfaces, mechanical grippers offer the best security. For polished stones with flat facets, vacuum grippers are the industry standard for safe handling."
The Hybrid Solution: Tactile-Sensing Micro-Claws
For high-end applications, hybrid tooling combining vacuum cups with light mechanical support claws is emerging. These systems provide the scratch-free benefits of vacuum picking with the physical security of mechanical guards, ensuring complete safety during high-acceleration movements.