Tips for Using Industrial Robotics in a CNC Machine Shop

08/24/2021 | Matt Oswald

CNC Robotics

At some point, we all need some help with the heavy lifting.

In the world of CNC machining, that can mean robots to lift, position, and pack metal castings, some weighing hundreds of pounds. It also means less physical and mental stress on employees, the most valued asset of any machine shop.

Working alongside a robot can improve operator productivity by taking on repetitive, physically demanding work. Smart manufacturers use robots to increase speed, enhance efficiency, and drive repeatability, which leads to better quality.

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Robots in a CNC machine shop can perform many tasks, reducing physical stress on shop workers.

Labor Shortage Challenges

Currently, U.S. manufacturing is in a well-publicized labor shortage. That’s forced the hands of many CNC machine shops to find new ways to automate processes. For example, a project that involves highly repeatable machining (lots of loading, lifting, and other tasks at which robots excel) is a candidate for robotics because of the labor crunch.

Is it easier for a CNC machine shop to add 8 people or 4 robots? It depends on the local labor market, of course, yet with some reengineering, processes can be changed to automate a project. These days, human labor is often supplemented with robots, especially for automating high-volume work.

Robots Perform A Variety of Functions

What can robots do? Well, with the right design and proper programming, they’re incredibly versatile. Industrial robotics in a CNC machine shop environment typically take on simple but important tasks.

Here’s an example of 9 tasks, all performed in this order by one robot:

  1. Locate and orient a casting in a dunnage using a vision system
  2. Grab it and pick it up
  3. Blow off fixture to remove any chips prior to loading
  4. Load it into a CNC machine for cutting
  5. After machining, blow off part and drain coolant back to machine
  6. Unload the machined part
  7. Deburr the part (remove sharp edges and burrs left from machining)
  8. Wash the part by loading and unloading in a washer
  9. Place the part on an outbound conveyor

Although these are 9 individual steps, it’s a very simple example. A robot can also apply a data matrix on a part for tracking; can sample parts for quality audits; and, if there are multiple parts, the robot keeps track of them without mixing them up.

Let’s explore the different functions of a robot:

  • Picking up parts — Parts can be picked from dunnages, conveyors, stands, and fixtures. When parts aren’t placed repeatedly, like in a dunnage or on a conveyor, vision systems are used to locate and orient parts before they are grabbed and lifted.
  • Flipping/manipulating/moving parts — A robot can flip a part around or set it on a stand and regrip it from the backside with another grip/tool.
  • Loading and unloading — Robots load and unload parts into/onto many places: fixtures within a CNC machine, queue stands, washers, pressure testers, conveyors, finished goods containers, operator stands, coordinate measuring machines (CMMs), etc.
  • Blowing off — Some robots blow metal chips and coolant off a part and fixture; chips are removed and recycled, coolant returns to the tank for re-use.
  • Deburring — Remove sharp edges that remain after machining.
  • Diverting parts — If two similar parts are being made, the robot keeps them separate and also samples Nth part for a quality check; defective parts (from a failed pressure test, for example) can be automatically segregated to be removed for analysis and quarantine.
  • Tracking parts — Robots hold a part to a direct part marker (DPM) to receive a data-matrix mark and hold it to a reader to verify the mark and track the part.
  • Packaging — Robots pack parts and manipulate packaging materials. Using air suction cups, robots pick up and place plastic layer pads between vertical layers of parts. For larger parts (engine covers, for example) a plywood divider is placed using a stronger air-foam grip.
  • Queuing — Robots queue input, in-process, and finished parts, keeping the machines running and removing the need for workers to pack one part at a time.

Programming a Robot is Straightforward

So, how do robots know how and when to perform all of these functions? Robots are “taught” motions and behavior as a sequence of points and functions. For instance, an operator jogs a robot’s arm throughout an operation, teaching the points, and then the robot repeats it over and over. Operations can update robots to adjust to changes and issues without relying on engineering.

The most challenging part is setting up an entirely new robotic manufacturing cell. It involves logic expertise, a bunch of functions and subfunctions, input and output, part tracking and manipulation, and a lot of engineering and expert programmer experience.

All of that work makes the initial implementation cost of using robotics quite high. The robot itself, front-end design, choosing the right grippers, programming the robot, determining how the robot is going to fit into established processes, etc. Making all of that happen takes a lot of upfront work.

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Industrial robotics programming requires upfront logic expertise and expert engineering experience.

Before Adding a Robot, Consider These Tips

First: look at your goal for staying competitive. To accomplish that, do you need to lower production costs and/or increase productivity? Think about how adding a robot versus adding numerous employees can make that happen.

Second: think ahead. Do your upcoming projections include lots of repeatable, physically demanding projects (heavy lifting, such as loading and moving castings)?

Third: be patient and plan well. As of Q3 of 2021, lead time for a robot delivery could be 8 months or more. That’s not significantly longer than a CNC machine, but it still could bottleneck your plans.

A CNC machine shop with engineering expertise on staff is best suited for working with a robotics distributor and introducing robotics into the shop. Setting firm boundaries is key: the CNC machine shop handles engineering challenges, and the robotics supplier handles only issues directly related to the robot. Those expectations — having the scope very well defined — keep machine shop production moving.

Learn more about the importance of precision machined parts from our resource: CNC Machining Industry Guide.

CNC Machines vs. Robots

Let’s briefly compare CNC machines to robots.

CNC machines are highly automated, standardized cutting machines. They require programming (similar to a robot). Robots use 6-axis arms and are great for moving a part from point A to point B, while a CNC machine part and work tool geometry use 3, 4, 5, or even 6 axes.

CNC machines have spindles that spin up to 15,000 RPMs and are designed for precise machining: milling, drilling, boring, reaming, threading, etc. A robot doesn’t have a spindle and can’t nail the level of precision needed, but it definitely performs repeatable actions very quickly, efficiently, and reliably. Where a CNC machine uses multiple cutting tools, a robot will typically use grips, deburr tools, vision, and air. Plus, having a robot in a work cell provides some operator flexibility. The robot can work from a queue of parts keeping equipment running, for multiple machine cycles. When done right, robots simplify the operator’s job, which means operators get through the learning curve faster. In the end, this improves production team scheduling flexibility.

Speaking of labor, neither robots nor CNC machines are any good on their own; they require skilled operators and programmers. And, of course, they can’t think creatively or solve problems, are less flexible, and won’t add anything to a CNC machine shop’s culture. So, while robots are consistently productive and don’t require sick time, they can't do everything.

The Perks of Choosing a CNC Machine Shop that Uses Robots

Not all CNC machine shops use robots. Smaller shops and those that specialize in lower volume, highly customized parts don’t typically use robots. For CNC machine shops using robots, they can competitively quote projects of high volume in a long-term contract. Another advantage is how robots help eliminate staff burnout, both physically and mentally. It’s the difference between using a hoist to slowly move a 90-pound part or use a robot to lift it quickly and safely.

There is no doubt, a CNC machine shop has to get machining done right FIRST. That must be the focus. Only then can robots help make manufacturing faster, cheaper, and more consistent.

In general, CNC machine shop workers are becoming more robot friendly over time. With training and education, many operators have become industrial robotics experts. Some have become engineers and supervisors, helping to maintain, train, and improve robot systems.

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Robots perform many repeatable actions within a machine shop, but they can’t replace the precision of a CNC machine.

Final Thoughts on Costs, Implementation, and Stecker

For all manufacturers, robots are not expensive, but integration is, with the initial process often being long and expensive, which is the case for most CNC machine shops. Even tiny changes to a line require redesigning and repurposing robot work cells.

As an example, one project at Stecker shook out like this:

  • 4 CNC Machining Centers = 75% of outsourced costs
  • 2 Robots = 10% of outsourced costs
  • Automation (equipment, programming) = 15% of outsourced costs

Robots were actually the least expensive aspect of that project.

As beneficial as they are, robots are inflexible, with new system setup taking 3-6 months and technology not easily repurposed when needed. At Stecker, we’re working to improve how robots run “lights out,” with no operator for up to eight hours at a time. That requires rethinking our design to be both fast AND robust. Currently, we’re focused on making parts as fast as possible. We’ll get the machines up and running, make parts, prove out machining, and then automate.

If you’re interested in how robots’ efficiency can help you with the heavy lifting, review our guide: “Lean Manufacturing eBook.” It explores how a machine shop can be dedicated to lean manufacturing and the benefits that come with it.

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Matt Oswald

About the Author

Matt leads Stecker Machine's marketing and recruiting projects as well as managing and coordinating improvement initiatives. Matt's skills go beyond machining into other areas including robotics, web/marketing, and leadership. Matt has 14 years of electrical engineering R&D experience with wireless systems and continues to transition into CNC machining, inbound marketing, and everything else. Matt and his wife, Karen, are part owners of SMC.

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