I am going to be honest here, I didn’t think I needed a 7th axis on a robot. I thought it was a marketing gimmick or an additional linkage to make the kinematics equations harder… I was wrong.
Disclaimer: There are two different options to get 7 different axis; 1) a 7 axis robot, 2) an additional 7th axis for a 6 axis robot. Two different things. I am going to be talking about 7 axis robots in this post rather than adding an elevator or a slide to a 6 axis arm.
Save time on the design stage
You don’t need to spend tons of time and money designing your machine around your robot. For example, let’s think of a machine tending application. With a 6 axis robot, you need to make sure you can clear the door of the CNC machine, and your reach is enough to get to all of the positions that you need to go. Even then, you might see some surprises where a joint is out of limit after you reach into the machine or when you are closing the door.
With a 7 axis robot, you can easily reach around the door and you don’t really need to think where the robot should go to be able to do the application. Just a couple of basic measurements and you should be good to go!
If you have ever worked with a 6 axis arm, you know that if you are packing a box or if you need to operate close to the base of your robot, you just can’t. To be able to get the rotation on a 6 axis arm, you have to rotate your 1st joint. Take a look at the picture below and see how the first joint of the robot is pointing at a different angle than the end-effector. This helps with distributing the load on each axis better since you can rotate joint 1 and actuate other joints to achieve the same rotation of the overall robot as a 6 axis robot, you end up not exhausting that Joint 1. This leads to longer lifetime of the robot and saving money in the long term. (Check out this link to see a video of a 7 axis robot going through motions that you wouldn't be able to do with a 6 axis robot.)
3. Save space on your factory floor
With a 7 axis robot, it is no problem to have a working area right near your robot base.. The 7th axis helps with bending the arm in such a different way so that you can easily work right in front of you.
But what does this mean? This means when you are building a machine, your machine can take way less space than if it would with a 6 axis robot. Everything can be compact. And you can also get away with purchasing a robot that has shorter reach for the same application compared to a 6 axis robot.
Maybe in the design stage, you didn’t think about the limitations of a 6 axis robot. And you put the place station a little too close to your robot. Now you need to spend time and money to change the layout of your application.
Or, if you know a 6 axis robot can definitely do this application, you might spend hours if not days more to program the robot. Usually robot programmer times are expensive, so this could be the factor that makes or breaks the project financially.
I don’t want to sound wrong. 6 axis robots definitely have their application. Every product has their place. But sometimes you have some details in the application specifications that makes getting a 7 axis robot more sense.
Now that you know where you can use a 6 axis or 7 axis robot, please reach out with your application details and we’ll be more than happy to discuss it with you at Gibson Engineering.