Tech Briefs Magazine - April 2021 - MD-5

Figure 3. The Festo HGPT mechanical gripper.

plain, and rough workpieces; viton is
suitable for oily, plain, and hot workpieces; and antistatic buna is ideal for
electronics.
Cup shape is also an important factor,
especially when it comes to gripping
objects that are flat versus round, slim
versus large, and sturdy versus delicate:
* Standard cups - for flat or slightly
undulating surfaces.
* Bellows type - for pliable workpieces
as well as surfaces that are bevelled,
domed, or round. This type is also suitable for glass bottles, lightbulbs, and
other delicate objects.
* Oval type - for slim or oblong workpieces.
* Extra deep - for round and domed
workpieces.

Vacuum sources fall into two categories: electro-mechanical vacuum pumps/
blowers as well as compressed air-driven
vacuum generators/ejectors. In general, electro-mechanical pumps and blowers can achieve high vacuum and suction rates - up to 99.99 percent and
1,200 cubic meters per hour, respectively. At the same time, however, these
machines tend to be heavy and large,
requiring a reservoir with a complex
piping system. Because they run continuously, they also consume a lot of current, which generates heat.
Compressed-air-driven generators, especially single-stage units, overcome
many of these challenges. Compared to
electro-mechanical pumps and blowers,
they are more compact, lightweight, and
easier to install. They include simpler
piping systems, require lower upfront
costs, and incorporate no electrical connections, eliminating harmful heat
buildup. Although these units can run
up your air consumption rates, many
machines now come with energy-saving
functions, minimizing these effects.
In general, vacuum grippers are ideal
for material handling applications such
as steel fabricators, conveyors, electronic assembly, and industrial robotics;
food and packaging tasks including canning, bottling, capping, tray making,
filling, bagging and sealing, conveying,
box-making and labeling; and printing
applications such as sheet feeding and
handling.

Standard Cup

For flat, slightly undulating and
domed surfaces

Magnetic Grippers Offer
Unique Benefits
Lastly, magnetic grippers can handle
metallic objects like sheets of metal and
are ideal for tasks like de-stacking, fixture
tooling, and bin picking. Although these
grippers are limited to applications involving ferrous metals, they require minimal air consumption to actuate, achieving energy savings up to 90 percent compared to suction cup grippers. Other
benefits include:
* Strong gripping. Magnetic grippers use
a shallow magnetic field that enables
material de-stacking.
* True ON/OFF. Magnets can be switched
completely off and stay clean; any
metal fillings left behind from production processes instantly fall away.
* Fast. Magnetic grippers can actuate in
250 milliseconds, saving valuable cycle
time.
* Safe. They provide fail-safe performance
and will not drop parts in the event of a
power or air loss.

Summary
No matter your application, there's an
ideal gripper for you - the right choice
depends on a number of variables such
as workpiece size and shape, operating
conditions, industry, energy requirements,
and cost. Unique handling applications
could require a custom gripping device.
This article was contributed by Festo Corp.
(Islandia, NY). For more information, visit
http://info.hotims.com/79412-280.

Extra Deep

Oval Type

For round and domed
workpieces

For slim and oblong workpieces
such as profiles and pipes

Bellows Type

For bevelled, domed, round and large surfaces
and pliable workpieces

For delicate workpieces such as glass bottles or
lightbulbs (inexpensive height compensator)

Figure 4. Suction cup shapes and surfaces for vacuum grippers.

Motion Design, April 2021

Cov

ToC

http://info.hotims.com/79412-280 http://www.abpi.net/ntbpdfclicks/l.php?202104TBNAV

Tech Briefs Magazine - April 2021

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