Question about weighing product.

Is it possible to weigh parts during the pick and place process? The part I am interested in weighing are between 100g and 400g.
Is there a scale or load cell that could be connected to the gripper, that would weight the part while in the process of unloading the machine? Not sure if this is the right kind of question for this forum, but any informmation anyone has would be greatly appreciated.

jon511 said:

Is it possible to weigh parts during the pick and place process? The part I am interested in weighing are between 100g and 400g.
Is there a scale or load cell that could be connected to the gripper, that would weight the part while in the process of unloading the machine? Not sure if this is the right kind of question for this forum, but any informmation anyone has would be greatly appreciated.

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From my scale company background of many years ago, the accuracy you are looking for could probably not be obtained. In order for a load cell to work properly, the force of gravity on the object should be perpendicular with the load cell. If the load cell is suspended, the force should be hanging straight down. Where the load cell is suspended from a level beam and flexible connections are used such as chain links to suspended the load cell.

If the load cell is mounted to a base or platform the load should be applied perpinducular to the top, and again the base should be level and the force of the load applied perpendicular to the load cell.

In order for a pick n place to work, a suspended type load cell would be needed to measure the differnce in weight of the pick and place clamp or suction head. That would mean the load cell would need to cut into the middle of the pick n place arm, and any electonics or pneumatics must have flexible connections around the load cell.

I cannot seeing this being done practically.

If it can't be added to the arm, perhaps it could be added as a station. The arm could unload the part from the machine and place it on the scale. After it is weighed, it could place it in the container or whatever it is unloading it into. It would add time; you might be able to use two scales to speed up the process (one scale settles while the robot unloads the other.) But it will still take more time than it takes now.

Brian

I think this is possible, I purchased from a company called Transducer Techniques, Load cell "MDB-2.5" http://www.transducertechniques.com/mdb-load-cell.cfm
and signal conditioner,
http://www.transducertechniques.com/tmo-1.cfm

This was connected to analog input of PLC.

The load cell has a suction cup mounted to it to weigh metal parts.

Got side tracked and didn't finish the job, my memory was that I was getting accurate weights from the system as I tested it.

Nothing is like actually trying it out, never say never!