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CNC Machining & 3D Printing: A Hybrid Approach to Precision Manufacturing

With recent advancements in 3D printing capabilities, it is becoming easier for manufacturers to use additive manufacturing to create parts from a wide variety of materials, including polymers like ABS, TPE, and PLA as well as carbon fiber composites, nylon, and polycarbonates. Even pricey metals like Titanium, Stainless Steel, and Inconel are becoming increasingly common in the world of additive manufacturing as well.

There is no doubt that the additive manufacturing space will continue to develop and grow in the coming years, but will it render subtractive manufacturing methods like CNC Machining obsolete? Absolutely not. In fact, precision CNC machining is likely more important to the additive manufacturing process than you may think, as a new process called “hybrid manufacturing” is quickly taking hold in the industry.

3d printing metal
3D printing of metal parts is becoming more common, but subtractive manufacturing is an important part of manufacturing precision additive parts.

Additive Manufacturing vs. Subtractive Manufacturing

Before implementing a hybrid manufacturing approach, it is important to understand the pros and cons of each method. Here is a quick breakdown of both additive and subtractive manufacturing, and the benefits and drawbacks of each.

Additive ManufacturingSubtractive Manufacturing
Adds material layers to create partsRemoves material layers to create parts
Slower process, better for small production runsFaster process, better for large production runs
Better for smaller partsBetter for larger parts
Rough surface finish that requires significant post-operation finishingMore definied surface finish with minimal post-operation finishing required
Less precise part tolerancesAble to hold extremely precise part tolerances
Cheaper material costsMore expensive material costs
Less material wasteMore material waste
Intricate details easier to createIntricate details can require complex programs and additional capabilities (5 axis)

Using CNC Machining to Create Precise 3D Printed Parts

Looking at the chart above, you will notice that one of the key differences between additive manufacturing and subtractive manufacturing is the surface finish and tolerances that can be achieved with each method. This is where a hybrid approach to additive manufacturing can be extremely beneficial.

As parts come off the printer, they can be quickly moved into a CNC machine with a program designed for part completion. The CNC machine will be able to get 3D printed parts down to the tight tolerances required by many industries and reach the desired surface finish. Advanced finishing tools and long reach, tapered tools from brands like Harvey Tool can easily machine the tight geometries of 3D printed parts, while extremely sharp diamond-coated tooling and material-specific tools designed for plastics and composites can work to create a beautiful, in-tolerance finished part regardless of the material.

long reach end mill
Long reach tools can easily machine hard to reach, intricate part details on 3D printed parts.

By designing a workflow like this in your shop, you can spend less time worrying about the precision of printed parts by adding in subtractive operations to keep material costs low, create less waste, and keep parts in tight tolerances for precision machining excellence.

Using 3D Printing to Increase CNC Machining Efficiency

If your shop is focused completely on subtractive manufacturing methods, you are probably thinking that there is no need for an additive option in your shop. Can’t a CNC machine create everything a 3D printer can, and in less time? Not necessarily. Again, by using the two methods together and taking a hybrid approach, you may be able to lower your manufacturing and material costs.

For example, you could machine the bulk of a part with typical subtractive machines, which would likely take a very long time using additive methods. Then you can go back to that part with a 3D printer to add intricate features to the part that may take complex programming and hours of planning on a subtractive machine. An impeller is a great example, where the bulk of that part can be machined, but the tricky fins and blades could be printed onto the part, and then finished back on the CNC machine.

3d printed metal parts
3D printed impeller waiting for finishing operations

The ability of additive machines to literally “add-on” to a part can also make for a cheaper approach to part design. Instead of using expensive materials like Inconel or Titanium to machine an entire part, portions of the part that do not require extreme heat resistance could be machined out of cheaper steel, while the heat resistant portions using expensive materials can be added later through additive methods.

Hybrid Manufacturing Machines

As hybrid manufacturing workflows become more popular, so do new hybrid manufacturing machines. These hybrid machines are all-in-one machines where both additive and subtractive manufacturing can be performed in a single setup. Many of these machines offer metal 3D printing as well as multi-axis machining capabilities, ready for even the most complex parts thrown their way. With a bit of customization, large-scale 3D printing machines or CNC mills can be retrofit to allow for hybrid manufacturing with add-ons from companies like Hybrid Manufacuring Technologies.

hybrid manufacturing machines
Example of a hybrid machine add-on from Hybrid Manufacturing Technologies, featuring 3D printing spindles and milling tools in the same machine carousel.

As manufacturing and design techniques get progressively “smarter” with CAM/CAD programs offering generative design and artificial intelligence, these hybrid machines could become a new standard in high-end machine shops working in advanced manufacturing industries like aerospace, medical, defense, and the mold, tool & die market.

Overall, in 2021 we are still early on in this new revolution of hybrid machining and advanced design methods, but it is important to understand the role that adding a CNC machine could have in your additive-focused shop, and vice versa. By combining additive and subtractive together, shops can mitigate the cons of each method and take full advantage of the benefits of having both options available on the shop floor.

Hybrid Machining – Featured Customer

Featured Image Courtesy of Jeff Robinson, Hybrid Machining

Located in Holland, MI, Hybrid Machining uses machining skills combined with 3 different 3D printing technologies to manufacture complex projects. Hybrid Machining is a manufacturing company that can take the customer’s design from start to finish, allowing customers to dictate their path. Rather than focusing on a single product, Hybrid has listened to customer needs and presented solutions that, in many cases, customers didn’t know were possible. Jeff Robinson, the owner, took some time out of his day to answer some questions about Hybrid Machining.

How did you get into manufacturing?  

I started working in an architectural shop during my high school years.  I quickly realized that there was a more advanced part of the industry that I was missing out on. Therefore, I started researching CNC Routing.  I fell in love with the technology and have been studying it ever since. 

What sort of machines and materials do you use in your shop?

We currently run a Datron Neo, Fanuc Robodrill, and a CR Onsrud 5-axis Router. We work primarily with wood, plastic, and non-ferrous materials. We currently use Autodesk Fusion 360, FeatureCAM, Powermill, Vectric Aspire, and AlphaCAM for CAM.  For CAD, we run Fusion 360, Inventor, and Solidworks.

hybrid machining datron neo
Photo Courtesy of: Jeff Robinson, Hybrid Machining

When did you start using 3D printing and how has it benefitted you?

I have been 3D printing for just over a year.  It was the first technology that we initiated here at Hybrid Machining, and it has allowed us to provide the best solution to the customer no matter what the requirements are. By expanding into 3D printing, we can help the customer decide which technology will work the best for their part. Many times, we take the “Hybrid” approach and use both additive and subtractive technologies together.

How have you adapted during the Covid-19 outbreak and how has it changed your business?

We started by stopping normal production to form a non-profit called 3DC19 with other local, small business owners with the sole purpose of 3D printing and assembling plastic face shields.  Hybrid Machining became the distribution center for the efforts.  Collectively, we produced and donated 75K articles of PPE to local hospitals, nursing homes, doctor offices, and first responders.  You can learn more about the efforts at www.3DC19.com. We have also been machining a lot of acrylic face guards for customers so that we can help them to get their office staff back to work safely. 

fanuc robodrill machine
Photo Courtesy of: Jeff Robinson, Hybrid Machining

What sets Hybrid Machining apart from the rest of the manufacturing community? 

We have a serious passion for educating our youth and local businesses on the rapid changes currently happening in the manufacturing industry and preparing them for the impact that Industry 4.0 will have on our lives in the future.  We want to produce knowledgeable people just as much as we produce products, and we do this in our unique Learning Lab.  We team up with local schools, vocational schools, and community colleges to help them spread the word about manufacturing.  We also intend to do ‘Lunch and Learns’ with local businesses to help them understand what other manufacturing methods and advanced materials are available on the market today.

What is the coolest project you have had come through the shop?

Many years ago, at my previous shop, we worked on the presidential handrail that the last three presidents stood behind during the inauguration.

hybrid machining metal business card
Photo Courtesy of: Jeff Robinson, Hybrid Machining

Are you using HEM techniques to improve cycle times? 

Yes, we use a couple of the fastest and most nimble machines on the market: the Datron NEO and the Fanuc Robodrill.  We leverage the machine’s tools’ high accelerations and deceleration rates, along with HEM, to drastically reduce cycle times for our customers.  This allows us to be competitive against over-seas importers.

What do you have to lose other than cycle time? You purchased the entire tool, not just the tip, so use it!  You will be surprised how the different the machine will sound and you can get parts done faster with less tool wear.

Why is high quality tool performance important to you?

The tooling is super important to the success of a project because the tool is what is doing the work.  I like to tell people, “Why would you buy a high-end sports car with all bells and whistles and then put crappy tires on it?  All that power and handling is worthless unless you have good tires.”  The same goes for tooling.  You can have a half-million-dollar machine that is super-fast and accurate and yet still produce a terrible part with cheap tooling. 

When was a time that Harvey Tool, Helical Solutions, or Micro 100 saved the day?

Harvey Tool helped me get through some tough composite projects in the past.  Their technical support team was extremely knowledgeable on the subject matter and helped me pick the right tool and parameters to get the job done. 

machined metal part from hybrid machining
Photo Courtesy of: Jeff Robinson, Hybrid Machining

If you could give one piece of advice to a new machinist ready to take the #PlungeIntoMachining, what would it be?

NEVER STOP LEARNING.  Things may be going great at first and you think you have it all figured out, but then a new technology comes and swipes you off your feet.  Spend your spare time studying industry trends, talking to other business leaders, new and old, and preparing for the future.

 Is there anything else you would like to share with the “In The Loupe” community?

We are extremely thankful that Harvey Tool spends a lot of time developing ‘material-specific’ tooling.  We spend 90% of our time in that section of the catalog.  We recently tested out the new wood cutters and are extremely happy. We pushed these tools at speeds and feeds that are unbelievable.  We also use the Harvey Tool plastic cutters on a regular basis. 

Here at Hybrid Machining, we are blending the lines between routing and milling.  For many decades, the line had been fairly clear. There were certain types of jobs you ran on certain types of machines.  We are blurring those lines and are using the best tools for the jobs.  For instance, we use the 24K RPM spindle on the Robodrill to run it more like a router than a mill.  Therefore, we call it the “RoboRouter”.  We can produce wood and plastic parts at unbelievable speeds while achieving surface finishes that are off the charts.  This is not conventional practice, but the team at Hybrid Machining is willing to blaze the path forward for others to follow.

To check out more about Hybrid Machining go to their website or follow them on social media!