Time to look at tending your CNC Machining Centre with a Robot?

 PICTURE: The UR5 from Universal Robots with the Control Box and Teach Pendant.

Design Energy PIC

Design Energy, appearing on Stand 2075, says to remain competitive engineering companies are constantly looking for ways to reduce the cost of producing parts.

Some are spending significant amounts money on larger capacity machines, specialised tooling and CAM software which will optimise cycle times. In many cases shaving seconds off a cycle time is celebrated as a win. But three times a day, the machine stops for 15 to 30 minutes while the operator is at smoko or lunch.

Most engineering companies running CNC Machining Centres would ask themselves at some point; what is the cost/benefit in automating the loading of the machine?

A bar feed on a CNC Lathe is a cheap way to automate the machine loading process, and this has proved to be a ‘no-brainer’ for those application able to apply it. But what about all those other applications a bar cannot be applied to? A 6-axis robot is a great solution for these applications.

So why isn’t everyone doing it?

The short answer is that the technology is still catching up. Currently most robots are difficult to program and this programming time (up to 60 minutes for a simple loading operation) means the robot can only be economically applied to large runs of 1000 or more parts. In many New Zealand machine shops the batch sizes are more like 5 – 50 parts. Spending an hour programming a robot to load 5 parts does not make sense.

EMEX2014VLogoPosCMYK300dpiUniversal Robots, from Denmark focused on this issue when designing their latest robots, the UR5 and UR10. With this in mind they developed affordable, flexible robots which can be programmed to load a CNC Machine in 5 – 10 minutes. The programming time has been slashed by using a touch pad teach pendant, and being able to pull the robot around by hand, to show it where to go. They also removed the requirement for safety guarding, by building the world’s first ISO 10218-1:2006 compliant robots.

So what are the real benefits?

A typical CNC Machine is charged out at around $80 per hour. The real labour cost, with holidays / ACC / benefits included is usually around $40 per hour. So reducing the labour content has a significant effect on the cost of each part.

For example, a batch of 5 parts with a cycle time of 300 seconds and a loading time of 45 seconds. The standard labour content would be 0.48 hours, but for a robot the labour time is 0.18 hours (10 minutes programming and 50 seconds to load material into a magazine). So the reduction in the labour cost of each part is $2.43, which may not seem like a lot, but if your CNC machine runs 70% of the time for a month (just 5.6 hours a day, 21 days per month) this adds up to savings of around $3000 per month.

And the cost? A 6-Axis robot from Universal Robot’s Distributor in New Zealand, Design Energy, can be applied to a CNC Machine for as little as $1,500.00 per month on a lease to own plan.

The Universal Robots weigh as little as 18kg, so you can easily pull it off one CNC Machine and apply it to another machine. The robot and CNC Machine could be set to start a production run as you walk out the door at the end of the day. If you get the same contract again the program can be loaded and the robot up and running in less than 2 minutes, further reducing the labour costs.

 

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