A Race Car in a World of Tractor Trailers
Why Building Machines for Speed and Efficiency Means Doing Things Differently.
I’ve heard it hundreds of times. At trade shows, during demonstrations, in online forums, on social media… It usually goes like this:
Person asks: “How much does this machine weigh?”
I respond: “This DATRON weighs (____) thousand pounds”
Person replies: “That’s it?! My (CNC Brand Here) weighs twice as much!” Or something to that effect.
Honestly, it’s not an unfair question to ask. One of the predominant principals of an accurate CNC machine is having a lot of mass in the assembly. The reasoning behind this is quite simple – the heavier the machine, the more stable it is. As well, the additional mass serves to absorb any vibration created from milling. That is why it is not uncommon to see large CNC machines with cast iron frames, with weight so immense that it’s necessary to pour a special foundation just to support the heft.
A lot of attention is also paid to the fact that DATRON machines are gantry/bridge style machines, as opposed to the typical “C frame” style so commonly used on Vertical Machining Centers (VMC). This draws comparisons to CNC routers, which are typically lightweight and somewhat flimsy machines that are built for basic wood and soft material machining. So how can a machine that’s similar to a router possibly stack up to the competition? The answer is simple: a DATRON is designed with a purpose.
Confused? Please, allow me to explain. Your typical VMC is designed to do a little bit of everything, from cutting small plastic parts, to milling aerospace alloys like Inconel, to machining large molds made from tool steel. While this is a great in terms of broad capability, it is not terribly efficient. A machine tool that can cut everything, small or large, soft or hard, is usually not going to be the best at anything. That is where DATRON is different: we design machines intended to make DATRON Parts (for examples of good DATRON parts, check out our CNC Milling Applications page).
It’s about having the right tools for the job. I always like to make analogies to get this point across: If you’re a brain surgeon, you need a scalpel, not a machete. A carpenter needs a claw hammer, not a sledgehammer. If you are a racing driver, you need a Porsche, not a Peterbilt. That last one’s my favorite, personally. A semi-truck is fantastic at hauling heavy loads, but miserable at handling hairpin turns. If you’ve got the right parts, using a normal VMC instead of a DATRON is like driving a tractor trailer truck on a race track: You can finish the race, but you’re not taking home the gold.
“Let’s get back to our Porsche analogy. If Porsche were to build machining centers, what would they be like? For starters, they’d be German Engineered, just like Datron. Natch. But I think they’d also adhere to Datron’s focus on being unconventional.” – Bob Warfield, CNCCookbook.com
So, lets break down what makes DATRON a race car in the CNC world.
It’s As Heavy As It Needs To Be
First and foremost – it is worth stating that a DATRON is not a lightweight machine, it’s just not as heavy as a comparable machine from your typical VMC manufacturer. For instance, despite its petite size, a neo weighs over 1,500 lbs. An M8Cube is around 3,000 lbs, an MLCube is nearly 3 tons, and an MXCube weighs as much as both of them, combined. Few can argue that a 4 ton machine is “lightweight”. Most of the machine’s weight is in the primary casting. For the Cube series, that is the machine table, while in the neo, it is the portal. Supporting that is high-strength, rigid steel frame.
On Cubes, the gantry is critically designed to be as light as possible, while still maintaining high torsional rigidity and stiffness. This emphasis on keeping components as heavy as necessary pays off big when it comes time to machine.
“Nothing moves like a DATRON”.
Thanks to the weight and rigidity of the components, a DATRON has excellent acceleration capabilities that often out-perform the competition. While not impossible for a large, heavy VMC to achieve similar speeds, it subsequently requires much larger motors, more frequent maintenance, and much higher amounts of electrical energy. In the end, a DATRON is designed around the sort of parts it mills best, and thus, does not need to be so vastly over-built.
It’s Made From The Right Materials
Another key design decision that helps make our machines as rigid as possible is the use of polymer concrete for the table/portal casting. In the VMC industry, the use of cast iron for the frame material is common. It makes sense, after all, since cast iron is heavy and relatively thermally stable. However, cast iron has a bit of a disadvantage when it comes to vibration damping. Vibration damping is essentially the materials ability to absorb vibration energy instead of transferring the oscillation throughout the structure. Polymer concrete (sometimes referred to as epoxy granite) is far better at absorbing vibration than cast iron or other common base materials.
A good analogy for this is to think of a cymbal on a drum set. The reason it is made from bronze alloys is because of their poor ability to absorb vibrations – thus, they resonate when you hit them. On a drum set, that’s great, but on a CNC machine, it’s terrible. Excessive vibration can lead to poor surface finish, inaccuracy of the part, and diminished lifetime of machine components. To overcome this issue on a traditional VMC using a cast iron frame, you must rely on adding more mass to counteract the vibration. However, with DATRON, the core structure is reinforced with polymer concrete – adding considerable weight while also having superior vibration damping properties.
Using High Speed Machining Strategies
One of the important reasons why a DATRON can be built this way comes down to how you use it. On a traditional machine, low RPM, high torque spindles are commonplace, and the immense cutting forces that are created require a hefty machine to handle the vibration and stresses. DATRON is inherently different from the start – since the machines are focused on specific parts and materials, the spindle choice can be tailored far more suitably, and that changes everything.
The slowest DATRON spindle has a maximum speed of 30,000 RPM, with others going as high as 60,000 RPM. The reasoning behind this is clear – a focus on small cutting tools. Since tools never exceed 1 inch in diameter, the need for low speed and high torque is just not necessary. The smaller a cutting tool gets, the faster you will need to spin it to be efficient. This is another place where a DATRON will make considerable strides over a traditional VMC: when tools are under 1/4”, efficiency starts to taper off quickly. That is also why DATRON develops our own line of cutting tools – to be even more efficient and productive with a high speed spindle.
Along with efficiency using small tools, a DATRON can leverage its quick acceleration to utilize high speed machining (HSM) strategies that have become quite popular with modern CAM software (for example – Dynamic Motion from MasterCAM, Adaptive Milling from Autodesk). These milling strategies do a great job at reducing the cutting forces generated from pocket milling (especially in tight corners) which can be especially useful for maintaining tool life for small cutters. All machines can benefit from these strategies, but the benefits are even greater on a machine that is purpose built for high speed machining.
So, long story short, there are lots of typical VMCs on the market, but a DATRON is not one of them. This is very intentional as we design them from their initial concept for a narrowed scope of work so that they can truly excel in the right applications. Like I said, it’s like having a race car in a world of semi-trucks. Are you ready to race?
High-Speed CNC machining is more than 60,000 RPM spindle-speed. When you’re making small or complex parts, you need speed and precision at every stage. DATRON AG engineers didn’t just invent a faster, more precise CNC machine. They re-interpreted and optimized your entire machining workflow from start to finish.
About the Author
Dann Demazure is the Technology Evangelist for DATRON Dynamics. He has worked with a wide variety of customers to solve challenging manufacturing issues. With over 7 years of experience in Applications, his technical knowledge is now used to educate the manufacturing community about DATRON technology.