How to choose a suction pad
For this reason we feel it would be helpful to explain all the parameters to be taken into consideration, in order to choose the right suction pad.
· Flat suction pads without cleats
Used for handling flat or slightly rounded, rigid, smooth objects. They withstand lateral forces and can be used for vertical handling.
· Flat suction pads with cleats
Used for handling thin, flexible, deformable objects. They increase resistance to lateral forces and horizontal handling.
· Suction pads with bellows
Used to handle spherical, cylindrical or egg-shaped objects. The effect of the technical characteristics increases with the number of bellows. They can be used for gripping objects with height differences, for a ball-joint effect, to lift and to grip corners or edges.
The force of a suction pad is proportional to its surface under vacuum and also depends on its shape, flexibility, material and especially on the level of vacuum attained inside the suction pad.
. F(N) = Surface of the suction pad (cm2) x Percentage of vacuum (%) x 0.01013
The force given in the COVAL suction pad tables is the force of the suction pad measured in practice at 65% vacuum. This figure also includes a safety factor of 2.
As its name implies, this force represents the actual force of the suction pad when in use. In general this is 50% less than the calculated theoretical force.
This difference is explained by the distortion of the suction pad during handling (which reduces the gripping surface), and by the condition of the surface of the object being handled.
The safety factor
All the forces are given in the tables for the various ranges of suction pad. These are actual values at 65% vacuum, calculated with a safety factor of:
. 2 for horizontal gripping,
.4 for vertical gripping,
For applications involving high acceleration, the safety factor will be calculated accordingly.
The force of the suction pad and the product's available gripping surface depend on this parameter. COVAL offers standard suction pads of 1 to 600mm in diameter over all its ranges.
You will find the most comprehensive list possible of parameters to be taken into consideration when choosing a suction pad, on the following page.
To meet the constraints of industrial applications, COVAL has a wide range of both standard and specific materials. COVAL can also study new materials based on specific requirements of your applications.
The COVAL laboratory has developed a new material: SITON®.
SITON® is a silicone-free material which therefore does not leave a mark and was specially developed for handling hot objects that are waiting to be painted.
Example of an application: Unmolding paintable plastic parts.