Grippers

Grippers.

You can, and many companies do, make their own compressed air grippers, using a collection of air actuators to provide the gripping motion.

Custom built grippers can work well enough, but they've got penalties to their use. They are usually large and weigh a lot. For large pick and place applications, a large gripper is fine. For smaller, high speed pick and place, you need a gripper built for that use.

Of course, the heavier the end tooling is, the less load capability of the pick and place apparatus, and the slower the cycle of the system. If high speed is what you need you'll do better buying a gripper that's ready to use.

Compressed air equipment manufacturers have risen to the occasion, churning out "standard" air grippers to suit many applications that are compact in size, light in weight, lightning fast, and able to handle extraordinary loads when you consider the size of them.


What's inside a gripper?

Almost all air gripper contain a double acting air cylinder, and an internal mechanism that produces movement in the gripper fingers when the piston on the internal cylinder cycles. Air in one in port and the fingers open; air in the other, fingers close.

The fingers of the gripper are designed to attach tooling to them. Tooling might be a simple as rubber nubs or some such, to enable the gripper fingers to better clamp and hold a part.


Using the gripper

The obvious first thing to be concerned about is if the gripper has the load carrying capacity for what is to be gripped and lifted.

Or, if the gripper is to be used to position something, it must be strong enough to hold the part.

The strength of the gripper is predicated on how big the piston is inside it, and the available air pressure. Force equals pressure times area, after all.

Grippers will normally self-center the part to be held. All the commercially available grippers move their fingers together or apart at the same time. If moving together, the fingers will tend to move a part to the center point, at which the fingers grip the item.

You will want to add tooling to the gripper fingers, if nothing more than rubber bumpers to add better gripping.

Don't forget, grippers do work by opening as well as closing. You can insert the gripper fingers into an opening on a part, and have that part gripped by having the fingers open against the part.

Standard Gripper Formats

The manufacturers of air grippers have standardized on the following gripper styles:

~ Parallel
~ Angled
~ Radial
~ 3 Point

Parallel Grippers

As the name suggests, the parallel gripper's fingers move parallel to the gripper's orientation.

In the graphic below....

1. Depicts the gripper body
2. Shows the supply line is charged
3. The gripper fingers are opened to their widest
4. The supply line is now opened to exhaust
5. The fingers have moved in a parallel fashion to their closed position