Emerging trend: combining cobots with CNC machining | Robotics
The global market for CNC machines is expected to grow to $93 billion US by 2024, highlighting a 6.3% CAGR. (Source)
The reasons for this growth are easy to understand: a tight labor market, economic growth, and competition mean manufacturers around the world want to improve processes wherever they can, according to Modern Machine Shop’s 2016 Capital Spending Survey report.
CNC machining reduces human error while allowing companies to produce parts more efficiently. When first introduced, these machines required highly skilled labor to program the machines as well as attend to the machine.
Technology innovations, however, are moving toward unattended operation. Although workers may tend multiple machines, the job is still repetitive and mundane – leading to quality or safety errors, inefficiencies, and job turnover.
For this reason and others, manufacturers are combining collaborative robots with CNC machining.
“CNC integration is a hot area for us,” said Adam Welch, Automation Robotics Product Manager for SunSource Automation, a Rethink Robotics distributor.
“We’re seeing high interest from two market segments: manufacturers that specialize in small batch runs and manufacturers with high volume opportunities.
“For the former, it’s about performing a set process with smaller, lighter parts – and then moving the robot to a new task when needed. For the bigger manufacturers, it’s about filling a dedicated task. A robot can perform the same task 24/7.”
According to Welch and Russ Miller, SunSource’s Automation Manager, manufacturers are looking for a turnkey solution – meaning, the cobots perform all the actions associated with tending a CNC machine.
“A cobot like Sawyer is easily set up to perform a set task, such as placing parts in a bin,” said Miller. “The challenge, however, is when you want the robot to control the process. To integrate the robot, you have to take into consideration machine orientation, cycle time, tasks to be performed, etc. The more complex the operation, the more you need to think things through.”
For example, in a recent Sawyer-CNC machine deployment, the customer wanted the robot to open and close the machine door, but faced some challenges.
“Sawyer’s force sensing technology is a very positive benefit, especially when placing parts into a CNC machine correctly,” said Miller. “For the safety aspects of a collaborative robot, it can also mean that the robot lacks the ‘strength’ to handle some tasks, such as closing a heavy machine door.”
To solve this challenge, SunSource added a pneumatic cylinder and multiple sensors to the machine door to perform the open-close function.
In addition, the SunSource team worked with the manufacturer to configure the work cell and position the CNC machine in order to optimize Sawyer’s reach.
According to Miller, having Sawyer place the part into the chuck is where the robot’s full force sensing technology came into play. “The integral camera and force sensing feedback meant the robot could sense when the part was fully loaded into the chuck.”
As you can see in the video, Sawyer takes the raw part from the rack, removes the worked part from the chuck and installs the raw part, and then adds the worked part to the bin.
“The other benefits of using Sawyer for this operation include the custom quick-change end-of-arm tooling and the adjustable pedestal – which is also mobile,” said Welch.
“As far as trends go, no one is producing parts to put on a shelf,” said Welch. “Today, plants do two hours of this part and two hours of that part, then the cobot is moved. Sawyer can be programmed to perform one task and then moved to perform another.
“With Rethink’s Robot Positioning System, you simply hit a switch for the camera to check the process using the landmarks, and the cobot is now up and running smoothly. It’s one of those ‘must-have’ features for a just-in-time facility.”