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Choosing the Right Gripper for your Universal Robots

Mathieu Bélanger-Barrette
by Mathieu Bélanger-Barrette. Last updated on Mar 12, 2015 3:24 PM
Posted on Nov 27, 2014 9:46 AM. 6 min read time

Once you have chosen a Universal Robots, you want to have a gripper that will fit well, has proven its efficiency and has good specs that match your applications. Proven products and easy to install devices are the best thing as you want to eliminate very complicated integration processes. The following post is about what you should look for when searching for a good gripper for your Universal Robots. 

Like Many Traditional Robots

The choice of a gripper is all about finding the right tool for your applications. Even if the end-effector has nice specs and unreal accuracy... do you really need all this. Can you introduce a pneumatic gripper into your workshop or would an electric one suit better? Like most industrial robot applications you need to look at the following points in your gripper choice. 

Parts

electric gripper machine tendingEach category of: dimensions, weight, material, shape of your parts has to be considered in the choice of your gripper. You also have to think about the variety of parts that the gripper will grasp. If the end-effector is grasping a wide variety of parts, it may be worth it to go with a more flexible gripper. You probably should also be thinking about the future; in fact if you think that your production will change in time, you don't want to have to completely change your gripper equipment in a year. Read the following article for more details. 

Process

Machine tending, assembly, pick-and-place are all process that requires different gripper specifications. In fact, often the machine tending applications will handle dirty parts, sometimes involving metal chips, while the assembly applications will work in a clean environment. Cycle time, required repeatability, motions/accelerations are really important to consider in the choice of the gripper. Most gripper manufacturers will rate their gripper according to these different aspects. To get more information, check out the following article

Inbound

Basically, this relates to how the part is fed to the robot. There are a very wide variety of pick and drop layers possible. Make sure the gripper (and the robot) can suit your layout. If you take it to a next level, what is the degree of flexibility your robotic cell needs in order to work with all your parts? To read more about this subject, take a look at the following article.

Environment

This aspect goes along with your process, the environment is where the robot will be working. Is this a clean room, a machine shop, a lab, etc. Make sure to talk with your application engineer or your vendor to get more information on the ability of the gripper to fit into your environment

The choice of your gripper should also consider flexibility. Indeed, does the robot always remain on the same task, does this create a bottleneck in the shop? Are there going to be future productions on this machine that will require a different end-effector? Why not use a robot and gripper combination that can be flexible and still be able to complete the operations flawlessly. 

A Plus for Universal Robots

Flexibility - If you need to repurpose the robot to a different task the 3 following points should be considered:

  • Easy programming
  • Be able to pick many different parts
  • Easy to customize if needed

If you are buying a collaborative robot such as UR, you don't want to spent a day reprogramming news paths every time you change tasks. In fact, the programming should be able to be done quickly and easily. With hand guiding capability and the easy to use interface, the UR is easy to move from one work station to another in a minimum amount of time. 

Picking different parts is also part of flexibility. For example, for assembly tasks, your parts will definitively be different from each other. As you don't want to have to change the gripper each time you pick a part, you should consider going for a flexible gripper. Payload is also important. We often think that only the shape is important, but you definitively want to use the whole range of the payload for both the robot and the gripper. With a 5kg payload for the gripper and 5 or 10 kg payload for the UR, a wide variety of parts can be handled. 

flexible robot gripperCustomized fingertips might be part of the process. If the fingertips provided with the gripper don't fit your applications, the best recommendation might be to build your own fingertips to insure a proper grip on your object. 

Safety - With the introduction of collaborative robots and the elimination of fencing, this doesn't mean security and safety worries have disappeared too. You still have to considered the safety factors. You are introducing robots to help your workers by helping them do their job right and with more ease. The last thing you want to is to injure your workers. 

  • Gripper itself 

The gripper used has to be designed in order to be safe for workers. A gripper with round shapes, limited pinch points and programmable speed and force would provide great specifications to ensure safety. 

  • Gripper on robot 

The interface between the robot and the gripper should be as uniform as possible. Some grippers have geometries that create a space between the gripper and the robot. This means that if an impact occurs, there will be two regions that will apply pressure on the impact site. If the interface between the robot and gripper is nice and sleek, the pressure of an impact will be spread over a larger surface and thus reduce the force of the impact. This point counts when its time to do a risk assessment for the robotic cell. 

  • Gripper on robot with part (how secure is the grip during normal operations, upon e-stop, upon power loss)

You want to use a gripper that is safe for your workers. Some gripper manufacturers out there are building grippers with auto-blocking systems. The principle, basically, is to keep the part in the gripper fingers once it is grasp. This results in a very efficient grip since it doesn't require any energy. It is also safer to use these types of grippers since the part is secure when a power outage occurs. This is really important in cases of electricity or air failure.  

electrical gripper on universal robots

New Gripper for Universal Robots

Easy to Install - Both Universal Robots and Robotiq 2-Finger 85 Adaptive Gripper are easy to integrate into a workshop. Both are user-friendly and require minimum installation time. When they are joined together they create a fast integration, flexible, low cost (fast payback) robotic cell. 

The new version of the 2-Finger 85 has been designed around the Universal Robots platform and has accessories that help you to integrate it easily. If you want to order a gripper for a Universal Robots, Robotiq will provide a complete kit including all you need for the installation. From the mechanical coupling to screws, wiring and software, everything has been taken into account in order to make life easier for end users. 

The Robotiq 2-Finger 85 Adaptive Gripper paired with a Universal Robots answers a lot of end user issues. This gripper can result in a fast and easy installation and integration. We are currently working on videos and customer examples for the new 2-Finger 85 Gripper. News and updates will be posted soon on this blog. Stay tuned.

 

eBook ON PROGRAMMING TIPS AND TOP APPLICATIONS FOR UR

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Mathieu Bélanger-Barrette
Mathieu is a production engineer at Robotiq, where he constantly strives to optimize the production line for Robotiq Grippers. He enjoys discovering new robotic applications and sharing what he learns on Robotiq's blog.
Connect with the writer:
http://robotiq.com

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