Material handling in industries is increasingly relying on grippers. Industries, ranging from automotive assembly to electronics manufacturing, all handle their materials with grippers. The increasing requirement for grippers is evident from the market being worth $100 million in North America alone today, with the number expectedly growing by 5% annually.
The sudden spurt in growth in the use of grippers can be attributed to the rise in robotics. This includes industrial robots taking on special tasks like handling increasingly complex workpieces. Designers now can take their pick from more types of grippers than before. However, even with the latest developments in robotics and gripper technology, picking the most suitable gripper for a specific application can be a daunting task.
The market today has a plethora of grippers including mechanical, adaptive, soft, magnetic, and vacuum types, with each type offering key design features and benefits. For instance, adaptive and soft grippers adapt themselves to the contours of the workpiece and are useful in various handling applications.
Mechanical grippers, both electric and pneumatic types, are popular for handling applications. Of these, the pneumatic types make up about 90% of the demand, as these tend to be lighter and more cost-effective compared to the electrical types. Being more suitable for harsh environments, pneumatic grippers have faster cycle rates and higher grip forces.
On the other hand, electric grippers offer their users better travel and force control along with greater precision. However, the presence of motors and other internal components in these grippers tends to make them heavier and increases their upfront costs.
Irrespective of being pneumatically or electrically operated, there are several design classes of mechanical grippers. For instance, parallel grippers have fingers that can pull directly apart. The most common among these is the two-finger parallel gripper. These make up more than 85% of the market for mechanical grippers. Another version is the three-finger gripper, and it can perform centering functions and handle round objects.
Other classes of mechanical grippers include the angular and radial versions. These typically have fingers that open at an angle. For instance, angular grippers open their fingers only to 30-degrees, while radial grippers can open their fingers up to 180-degrees, allowing them to handle workpieces of varying dimensions while being slower than angular grippers.
Selecting grippers for a specific application requires considering important factors. Depending on the nature of the workpiece, the designer must consider the gripping force required, the guiding strength of the jaw, and the type of the gripper itself. For instance, long gripper fingers require a long lever arm to exert greater torque on the jaws. There are flat finger designs that offer a friction-based grip for durable and bulky parts. On the other hand, handling slippery parts that require precision placement must use encapsulated designs.
Encapsulated designs have fingers with a profile shape matching the object they will handle. Usually, the fingers will be curved to hold a round object. This helps to retain the object in a specific position while preventing that part from dropping if the pressure is lost.