Robot Grippers are available in all sizes and types from the small precision robot gripper, to the larger robotic hand for heavy duty material handling. They are all standard, off-the-shelf items.
Selection of a gripper, for an application, is determined primarily by the size, weight and shape of the part. The repeatability of the part position, when gripped, must also be considered, to ensure consistency of placement position
Schunk is a German company, that has been around for a long time and has a reputation for building first class equipment. I have used them many times and have always been very satisfied with the results.
The MPG-Plus is a new range of small precision robot grippers, that have 3 sizes in the range. The actuating air cylinder is available with a bore of 25mm (0.984 in), 32mm (1.259 in.) and 40mm (1.575 in.)
The clamping jaws move in a parallel motion and have strokes of 3mm (0.118 in) per finger, 4 mm (0.157 in.) and 6mm (0.236 in.), for the 3-bore sizes available.
The fingers are moved via a cam mechanism and slide on cross roller bearings.
The grip can be set-up for internal or external clamping and can be locked clamped when the air supply is lost. This can be important if parts are not to be dropped, in the case of air supply failure.
2D and 3D software is available and design the fingers such that the full stroke is not used to clamp. Leave say 0.5mm of stroke to go, before the full stroke position is reached. This ensures that the mechanism does not "bottom out" and clamping force is still available for part clamping.
Proximity switches are available to sense open and closed positions. Note that some designers do not use switches for this application. Reliability can be an issue, but the switch technology is constantly improving and maybe satisfactory.
Take a look at the Schunk USA web site for full details of the complete range available of many different sizes and types of robot grippers.
Barrington Automation is an American company, that makes a wide range of grippers as well as pick and place modules. The above photo shows the range of radial motion grippers that are available.
The radial motion of the grippers, generally gives more clearance in the open position. The longer stroke usually means that a slightly longer cycle time is required, when compared to parallel motion robot grippers.
As is usual, finger extensions are bolted and dowelled to the fingers and custom designed to suit the part.
Fest has a very large range of all types of grippers and the HGPL type gives an extra long stroke.
The strokes of each jaw can be from 40mm (1.574in.) to 300mm (11.811 in.) and clamping force can be up to 2742N (603.2lb)
Cylinder bore sizes vary from 14mm (0.551 in.) to 63mm (2.408 in.)
SMC has a wide range of different types of gripper and here we look at the MHS series.
This range has 2,3,and 4 jaw grippers that are ideal for gripping round parts. Bore sizes vary from 16mm (0.629in.) to 125mm (4.921 in.) and proximity switches, to sense open and closed positions are available as an option.