Gripping with Air – Vacuum Tweezers

Here’s a riddle: Without touching them, how do you pick up small, delicate parts, such as those with ultrafine finishes or tiny, electronic components sensitive to electrostatic discharge? Answer: With vacuum tweezers.

These devices don’t have much in common with that old Hoover in the front hall closet. Although vacuum tweezers share some of the same characteristics as that clunky dinosaur, many VTs are precise, scientific instruments that no laboratory or cleanroom can do without.

Why not use mechanical tweezers? For starters, it’s pretty easy to drop something with mechanical tweezers, especially a micropart, which is one of the areas where VTs shine. And because of the mechanical forces involved, you can easily damage fragile surfaces or shapes with mechanical tweezers.

Vacuum tweezers excel at picking up things that shouldn’t be touched: temperature- or moisture-sensitive biological specimens, micromachined parts requiring inspection or assembly, surface-mount electronics, computer chips and optics. (They’re also good for stamps and coins, and even dead moths and butterflies!)

They can’t pick up everything, though. Because they operate via suction, they’re not much good at lifting heavy things. And the size of the part is limited by the diameter of the nozzle tube—pick too large a nozzle and you might spend the afternoon disassembling the vacuum pump to look for your parts. In general, however, VTs can handle parts as small as 100µm across.

VTs come in a variety of shapes and sizes. They function by creating a difference in atmospheric pressure—the same phenomenon that drives windy days and hurricanes.

Read the rest: http://www.micromanufacturing.com/content/vacuum-assist

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