How to use multiple leakage prone suction cups for picking up an object?
This How-To will inform you about how to use multiple leakage prone suction cups for picking up an object.
Suction cups are used for picking up objects. If you want to pick up a simple object with a flat surface it’s easy.
For example you can use a low flow ejector to create suction and attach the right tube to it. Then once the suction cup comes in contact with the flat surface of the object it creates a suction force, whereafter the ejector doesn’t need to put in that much effort to keep the suction active. Make sure that all tubes have the same diameter. If you want to use a pneumatic tube longer than 2 meters you need to take that into account when calculating the needed ejector for your use case.
If you want to pick up an object that doesn’t have a consistent surface that might even be prone to leakage, it’s way more difficult to pick it up. Let’s say you have a 1kg (flimsy) plastic bag of 300 small ceramic parts that’s prone to getting small holes in it. In this case a normal suction cup wouldn’t work, a good enough seal to create negative pressure just wouldn’t be possible.
You’d want a suction cup that forms around the plastic a bit to ensure a good seal.
And if the object is prone to getting holes you want multiple suction cups to make sure at least one gets the desired seal.
Choosing the right suction cup
So first you want to choose the right suction cup to make sure you can actually create enough force to lift up the object.
If you know your object is prone to leakage you might want to consider a high flow ejector to over compensate or use multiple suction cups to ensure at least one picks up the object. In that case one of the suctions cups should be able to hold to object entirely by itself.
Tips to ensure you get the right suction cup for the job.
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Test with your hand.
- Simply attach a suction cup to an ejector, hold them in your hand and try to pick up the object.
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Know that using a robot to pick up the object with a suction cup isn’t the same as you using the exact some suction cup to pick up an object.
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Try and test with the robot mount to find the sweet spot.
- Using the robot suction cup mount with your hand simulates the movement the robot needs to make to ensure the necessary seal.
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Less is more.
- Sometimes multiple suction cups can work against each other. Especially when using a flimsy bag where all air gets sucked out of it because of small leaking holes.
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Use a calculator
- If you don’t have suction cups available to test you should use a calculator, for example https://calculator.schmalz.com/. This way you can ensure you got the right suction cup for the job without test material.
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Ask around
- Their are numerous experts in the suction cup field you could ask for advice. Just to list a few, you can go to: the minor supervisors, a school teacher, suction cup companies (Schmalz, Festo) or the company you do the minor at. Just give them a call if visiting their website isn’t enough.
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Sample testing.
- Most companies have local sale personnel that would just love to help you get right what you need, as long as it’s from their respective company :).
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Ask around: minor supervisors, school teacher, Expert companies (Schmalz, Festo), The company you do the minor at
Choosing the right ejector
When choosing the right ejector for the job you need to know what you want. Do you want a high flow or high vacuum one and what about the venturi diameter? In this case you want a high flow one, since to little flow won’t hold the seal, and you want a decentlty sized diameter.
All these decisions make sure you need little time to create the required seal and keep the vacuum alive.
Connecting the suction cup and ejector
When using multiple leakage prone suction cups to pick up an object you need to make sure that each suction cup has it’s own ejector. Sharing one ejector for multiple suctions cups won’t work well since you then need both suction cups to have a good seal before both suction cups will actually pick up the object.
One suction cup that looses it’s seal will make all the suctions cups not work since you basically created a big leak. So when using multiple suction cups for one ejector they will work as leaks for eachother.