Can machining robots outperform CNC machines?

Can machining robots outperform CNC machines?
Date Submitted: 10/08/2020 11:56 AM

    Machining robots are challenging for cnc machines. but are robots really good enough for machining? if you haven't heard, robots are the new cnc machine! can traditional cnc machines go the way of dinosaurs? (i.e. go extinct, instead of turning into a multi-million dollar movie franchise).

    Over the past decade, robots have begun to be used instead of traditional machine tools for a wide range of tasks, including milling, polishing, via, cutting and more. but, can machining robots really outperform specialized machine tools?


    Let's find out together.

    Is robot machining real?

    If the idea of ​​robotic machining is new to you, you might be a little skeptical. robots are not known for their rigidity, which is often considered the most important asset of a cnc machine. however, machining with robots has some great benefits that can outweigh this disadvantage.

    Imagine you've got a giant block of ice.

    You want to sculpt a funny ice statue. however, you don't have the skills – nor the time – to learn ice sculpting by hand. you have the right to go to a workshop full of cnc machines, but they are all too small to fit on the ice cube.

    But you have a robot.

    This is the kind of complete application for machining with robots. it involves a great deal of machine communication, generated by material interaction and machining journals that cannot be achieved with most cnc machines. this is why robotic machining is especially popular for rapid prototyping tasks.

    However, you're probably thinking: all is well, but i don't want to carve a block of ice. i want to precisely machine our products. can machining robots work for me?

    Robots vs cnc machines: how they compete with each other

    Let's break down the difference between the two technologies by comparing 5 important properties:

    Accuracy

    Machining accuracy is probably the top attribute that people use to determine the performance of a cnc machine. if your machine is not accurate, how can you hope to make a quality product?

    The accuracy of machine tools is always improving. high-end machines can achieve an accuracy of 20-50 microns. the most precise lathe in the world, called the lathe (created in 2001 and apparently can't be beat) has an accuracy of 0.2 microns.

    Robot accuracy has improved over the past few years. industrial robots can be calibrated close to their repeatability. for example, the kuka kr210 robot with a repeatability of 100 microns can be calibrated to an accuracy of up to 200 microns.

    However, it is important to remember that the accuracy of the robot depends on good calibration because the calibration depends on the end user.

    Winner: cnc machine

    Working environment

    When it comes to working environment, there are some impressive cnc machines out there. some machines are as big as an elephant. however, most have much smaller workspaces.

    Industrial robots often have large workspaces. a medium-sized industrial robot will have a workspace of 7 to 8 cubic meters. what's more, you can easily add an external axis to the robot and expand its workspace even further.

    Winner: machining robot

    Versatility

    Perhaps the biggest benefit of robots is their versatility. you can easily move them from one task to another. cnc machines are great at a particular task, whether it's milling, turning, drilling… a robot can do all this and more.

    The robot can also move along more complex paths than most cnc machines. cnc machines tend to use 3 or 4 degrees of freedom. this is sufficient for many machining tasks, but it can be limited. almost all industrial robots have 6 degrees of freedom. that means you can make pretty much any machine in any shape you want.

    Winner: machining robot

    Stiffness

    the rigidity of the machine tool strongly affects its accuracy. a machine toolwith low stiffness will shift when it encounters hard material. this will cause an incorrect cut. robots generally have much lower rigidity than traditional machine tools. robotic stiffness is usually less than 1 newton per micrometer, while cnc machines are typically more than 50 newtons per micrometer.

    tools with low stiffness also tend to have lower natural frequencies, which means the tool will vibrate when it comes into contact with the material. robots have a natural frequency of 10 to 20 hz, compared to a few hundred or thousand hz for machine tools.

    Robotic machining can easily handle soft materials such as foam, wood, plastic, etc. however, harder materials such as steel or titanium can cause backlash in the robot motor, reducing accuracy.

    Winner: cnc machine

    Affordable prize

    Both machine tools and robots can be expensive. however, robots have two distinct advantages over traditional cnc machines: their large workspace and versatility. the ability to machine objects of (practically) any size, shape and complexity means robots can bring more value to the business at a lower cost.

    Winner: machining robot

    Conclusion

    The answer to the question “can a robot outperform a cnc machine?”, is exactly
    yes!

    But, with a word of caution: it depends on what the word “out of the box” means for your application. if your machining task requires high precision and rigidity, cnc machines can't be  beat. however, if you need flexibility, large workspaces, and affordability, robotics outsourcing is the way to go.

    How do robots work for you?

    Machining robots is easy, but only if you have the right programming software. robodk comes with a built-in robot machining tool that will convert your cam or gcode-produced asm file into a path for your robot. you can find demo videos of this tool on many websites. it also supports robots specifically designed for robotic machining applications (with improved rigidity and accuracy.

    Source: internet

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