There is no question that electronics are getting smaller and smaller. As a result, electro-mechanical parts like Printed Circuit Boards (PCB), must be produced in smaller sizes. Therefore, the demand for step stencils (for stencil printing) is increasing, as well as the requirement for precision and accuracy in order to produce them with intricate detail. This Blog is about Step Stencil Milling and the advantages of this process over both Laser Cutting and Chemical Etching.
If you are not familiar with step stencils, they are metal sheets that help to control the volume of solder paste applied to specific components or features of a printed circuit board during the solder paste printing process. Because PCB’s are getting smaller and smaller, the components that populate the board have to be positioned closer and closer together. So, you can probably see the challenge here – smaller components and tighter spaces demand accuracy.
Milling vs. Laser for Step Stencil Production
Here’s where milling comes in … and more specifically the demand for very precise high-speed milling machines. Step stencil material such as stainless steel sheets can be milled with slots and other features to reduce the thickness in desired locations. The depth of these slots (known as “steps”) need to be very precise as does their location. This is where high-speed milling has a significant advantage over laser cutting – because laser has less accuracy as well as restrictions in depth in terms of accuracy. With laser cutting, as you go deeper in the material, the laser (an intense beam of monochromatic light) tends to bend or walk. Whereas with a high-speed milling machine very precise and even depths can be maintained. As an example, the DATRON M10 Pro has a +/- 5 micron position accuracy with <3 micron runout when using HSK-25E tool holders. If you have a need for a very large work area to produce a large step stencil or many step stencils from one sheet of material, the DATRON MLCube LS (with linear scales) delivers the same kind of accuracy and provides a 60″ x 40″ work envelope.
Milling vs. Chemical Etching for Step Stencil Production
The other process used to produce step stencils Chemical Etching. In this process, stencil material such as stainless steel is made thinner in selected areas with chemical etching. All areas that will not be made thinner (or etched) are covered with a protective film. Chemical etching is a less accurate process but is very fast. The problem is the cost and quite frankly the mess. By nature (and law), chemicals have to be managed carefully and disposed of properly, which can be very costly for the manufacturer.
High-Speed Milling Advantages for Step Stencil Production
So, getting back to the high-speed milling process, the focus should be on achieving the best production quality while saving time and obtaining a damage and residue-free stencil underside. Our customers have found that the combination of integrated probing and vacuum table workholding yield a perfectly reproducible quality, despite any material tolerances … and result in a residue-free stencil underside.
The integrated vacuum table is ideal for holding flat substrates like stainless steel sheets during the milling process. Plus, job setup is incredibly fast. The integrated probing adds to the speed of setup because the probe is used for automated part location. Additionally, the probe is used for surface scanning which records any variance in material thickness so that variance can be automatically compensated for in the milling program. This means that the depth of milled features (or steps) on the stencil will be deadly accurate!
Time Savings: faster than laser
No thermal degradation of the material structure
Absolute and constant accuracy in rapid removal of material
No costly chemicals, or chemical disposal
Download DATRON M10 Pro for Step Stencil Production Brochure
DATRON neo was specifically designed and purpose-built to provide an easy and affordable introduction to high-speed milling. It’s a Plug-and-Play system that features the new DATRON next software which gives you full control of 3-axis milling without requiring years of experience as a machinist. That said, customers ask me all the time about the CNC workflow for this machine and whether it is actually as easy to use as we say it is. Well, I’m not a machinist, I’m a salesman, but in detailing the CNC workflow below, I operated the machine myself (as evidenced by my reflection in the touchscreen). Keep in mind, that I’ve included instruction on many optional functions and features and the actual CNC workflow for DATRON neo can be as short as 4 simple steps. Anyway, here goes:
CNC Workflow for DATRON neo
Once the CAM’d part or “G” code is done, simply load onto a flash drive or send to DATRON neo if networked.
Once loaded, DATRON neo will take the operator through the steps to run the part.
After loading the “G” code into the DATRON neo, the operator can pick the saved file to run.
As the operator moves through the process, DATRON neo will check the tools already loaded vs tools the file calls for. If a is tool is missing, DATRON neo can suggest a tool that is already loaded.
Next, the operator can drag their finger across the screen and use the integrated camera system to locate the part for probing.
Once the part is visually located, the operator can simply draw on the screen to start probing with the integrated probe on the DATRON neo.
DATRON neo will automatically place probing points based on the operator’s drawing. These points can be easily moved as the operator sees fit.
Another option that the DATRON neo operator has, is to move the probe points individually and manually set the parameters to avoid any special features, all by touch.
Once the probe points are to the operators liking, they just hit go.
The next screen will bring the part into a simulation so the operator can see the tool paths they created and make sure the part is ready to run correctly.
The DATRON neo operator has options on how to view the part to ensure the correct machining file was chosen.
After the simulation, the DATRON neo is ready to execute the program.
Other options can be done on DATRON neo for quick and simple milling. Macros are pre-set on DATRON neo to run pockets, drilling, face milling, and contours. For quick prototyping, these operations can be done right on the machine without the need to CAM a part.
With DATRON neo tools can be hand loaded into the machine very easily.
After the tool is placed, the operator can simply tell DATRON neo which space and tool were used.
DATRON neo can track tools inside the tool changer, as well as tools in the shop inventory. DATRON neo also has DATRON’s full tool library installed. This makes it a breeze to load tool information.
DATRON neo can accommodate two vacuum tables and each can be operated independently. Also, DATRON can provide a sacrificial card that is air-permeable. This allows for parts to be cookie cut without milling into the table.
DATRON neo has vacuum port controls at the front of the machine to easily turn the vacuum tables on and off. This type of workholding is a great option for flat parts. When using the vacuum table, parts do not need to be perfectly aligned because you can use the probe to locate parts and their rotation will be compensated for automatically.
There are a host of other accessories available for DATRON neo including a dust extraction head and pneumatic clamping. Please let Datron know if you would like further information on these items.
In 1985, Danny Strippelhoff became a partner in the business that his grandfather established in Georgetown, KY in 1943. Now, he oversees the day-to-day operations of the Carbide Products, Inc. as President/CEO. In 1987, another of the founder’s grandsons, Paul Strippelhoff, joined the business and now oversees all manufacturing operations as Vice President.
Today, Carbide Products, Inc. owns and maintains a 15,600 sq. ft. climate-controlled facility and serves more than 200 diversified industrial customers in 26 countries each year. They employ highly-skilled personnel using the most advanced equipment to manufacture made-to-order parts, tools, and gauges, using a wide variety of materials and material combinations. This includes solid tungsten carbide, carbide tipped, silicon carbide, silicon nitride, high-speed and tool steel, stainless steel, super alloys, samarium-cobalt rare-earth, cast iron, other ferrous and non-ferrous alloys, heavy metals, PCD (polycrystalline diamond), PCBN (polycrystalline cubic boron nitride), and plastics. All of Carbide Products machining processes, as well as heat treating, brazing, assembly, inspection, and documentation, are performed in-house for total quality control.
In particular, the company is adept at producing small runs of very small parts to exacting tolerances with requirements for superior surface finishes. According to Paul Strippelhoff, “Most of our jobs are 2- to 50-piece runs and in terms of size, in many cases, you can hold a dozen parts in the palm of your hand.” Often their customers provide them with prints and the job is quoted based on that print. But, Strippelhoff explains, “Sometimes we ask the customer if we can change the print a little bit to make it easier to manufacture. We work closely with all of our customers to save them money and save us time.”
In 2016, a unique job came in that the company hadn’t seen or heard of before. An equine podiatrist asked them to manufacture special aluminum horseshoes including corrective horseshoes for horses with hoof or gait problems and horseshoes for yearlings in the thoroughbred racing industry. According to Strippelhoff, “We were getting some pretty big orders for a local equine facility, and our VMCs were just not fast enough. So, we were looking for something different, something easy to program and control, and with faster feeds and speeds in aluminum.”
During their research to find the ideal machine for this project, they came across the DATRON M8Cube, a German-engineered high-speed milling machine with a 40”x30” work area and spindle speeds up to 60,000 RPM. Strippelhoff says, “It just seemed perfect for the horseshoe job. Additionally, we had a date stamp screw job for the mold industry that we had earmarked for the M8Cube.”
A trip to IMTS in Chicago in September 2016, solidified the company’s excitement about DATRON technology, but what they saw exhibited by DATRON altered their plans just slightly. Strippelhoff explains, “They were demonstrating a smaller machine called DATRON neo and the newer touch-screen control on that machine just blew us away. Our kids these days are using their fingers on touchscreens to do everything! We decided, that we really had to get one of these in our shop and be on the front end of this technology and embrace it.”
Carbide Products purchased the DATRON neo almost as an experiment, but with their long-term goals still focused on larger DATRON machines. Strippelhoff says, “We decided to get started with the DATRON neo in hopes that the same software and touchscreen would be added to the M8Cube and M10 Pro machines so that we could replace our traditional VMCs with those. The price point on the DATRON neo was good and it doesn’t take up much floor space, so it gave us a chance to get involved with DATRON and see if we like the support that they have and the product that they have without making any huge investments.”
This “experiment” has turned out quite well according to Strippelhoff who was surprised that even the DATRON neo with its 20.5″ x 16.5″ X, Y travel has been able to supplant the company’s smaller Haas machines. He explains, “Currently, we’re making some special lightbulb parts on the DATRON neo that we were making on our Haas Super Mini Mills − and by using the vacuum chuck to hold sheet material on the neo, we’re able to batch machine these parts which has reduced cycle time by nearly 50%.” During the course of purchasing and installing the machine, Carbide Products has been able to get a feel for the American-based service that DATRON offers to support their German-made machining centers. Strippelhoff says, “Our plan to ‘get our feet wet’ with DATRON has worked out well. On a scale of 1-10, I’d give their support a 10 … it’s been really, really great. So, we’re excited now to get into that M8Cube. Everybody there has always been Johnny-on-the-spot and available.”
In terms DATRON neo’s overall ease-of-use, and the ability to quickly setup the machine and integrate it into the production flow, Strippelhoff is extremely pleased and admits, “Honestly, I haven’t personally programmed a CNC mill or written a program or anything for 22 years, and I was able to use this machine right away. The controller with the integrated probe and camera system for part location makes it incredibly easy to set up a job and operate. You don’t have to have your workpiece set up and trammed in, it does the skew alignment for you.” Although Carbide Products had never used HSMWorks before, Strippelhoff praises DATRON for strongly recommending this software, as well as how well it integrates with the DATRON neo in terms of tool libraries. He explains, “What I didn’t know upfront, but was glad to see, is that there’s a tool catalog in HSMWorks for DATRON and all we have to do is plug in a 5-digit number, drop the tool in and all the information is there which is so simple it’s crazy.”
Ultimately though, the “proof is in the pudding” as they say, and all the bells and whistles in the world amount to nothing if the machine isn’t making money for you. Strippelhoff says that is NOT the case with the DATRON neo. He explains, “I currently have 6 different 200-piece jobs running on the DATRON neo all being made with aluminum sheet material. Running multiple parts out of a sheet is completely new to us, instead of making solid-piece parts one up. What this does is gives you the ability to keep your number of tool changes down over a 200-piece order, because while your tool is in the spindle it does all of its work.” As an example, he says, “I’m getting 105 parts out of a sheet and the drill is going to drill all the holes before the machine makes a tool change – and then the machine doesn’t have to pick the drill up anymore. Reducing the number of tool changes has a huge impact on cycle time and this is a big difference between the DATRON and our VMCs.”
At the time that DATRON introduced the DATRON neo to the North American market, it was met with some skepticism on social media forums – mostly by traditional VMC operators who couldn’t imagine that this compact machine was anything but a toy. Within Carbide Products, this has not been the case. Strippelhoff says, “The other machinists in the shop walk by the DATRON neo and they kind of take a step back and are pretty impressed with what they’ve seen so far compared to running their VMCs. They can’t believe the technology that they’re seeing on this machine. Everybody in the shop is excited about it, even the people who aren’t running CNC mills – the lathe guys, guys and gals in the grinding department, everybody just loves watching that thing run.”
Innovative manufacturers logically find innovative ways to use new technologies — sometimes pushing the limits or using a machine for a process that it was not specifically designed for. That is certainly the case with Carbide Products, and they quickly found a unique use for the DATRON neo that further leverages their capital investment. In this case, they decided to replace the cutting tool with a diamond grinding wheel to use the DATRON neo like a jig grinder to grind a counter bore in solid carbide rolls. Paul says, “This was a task for our very expensive Agie Sinker EDM, but this too has changed.” Some manufacturers find it hard to think outside the box — and when they spec a machine for a job, that’s the job the machine will do until it’s at capacity, and then, they buy another machine to pick up the slack. But, Carbide Products’ methodology is to find every imaginable way to use a piece of equipment even if it means reaching capacity quicker. Strippelhoff says, “Another DATRON, probably the M8Cube, is on the horizon anyway. It has a larger bed size and that will come in handy. And if we do things right, that machine will be as busy as the DATRON neo is.”
As the example above illustrates, it is not simply the technology that drives innovation, but rather the skilled personnel who find the best ways to use it to impact efficiency, capability and ultimately the company’s bottom line. Carbide Products President/CEO, Danny Strippelhoff, says, “It takes the best of the best employees to be successful enough to have the opportunity to invest in the latest and greatest manufacturing technologies. The DATRON neo that we’ve installed is a testimony to their hard work.”
When engaged in the machine qualification process, we often ask our customer, “Who are you assigning to operate or manage the machining system?” You might ask yourself, “Why should DATRON care who operates the system?” The short answer is, to us, it’s just as important that you have the right CNC operator, as it is that you select the correct machining system.
Over the past 20 years, we have built our business on implementing high-speed machining systems that increase product efficiency and quality. Our reputation has grown on the success stories and reference companies we have accumulated over the past two decades. Truly, the DATRON milling system is only one piece of the equation for a successful implementation. The other piece is who the CNC operator is after the machine installation is complete.
Why Selection of the Right CNC Operator is Critical to Success
As a machine tool distributor, it is our responsibility to not only make sure you have the right machine configuration for your needs but also to make sure you are prepared to leverage your capital investment by assigning the right CNC operator to the DATRON machine. As expected, we go through extreme testing and scrutiny to qualify our machine tool for the given application, but sometimes, not enough scrutiny or consideration is given on which CNC operator will have the responsibility for the installed equipment. Unfortunately, there have been instances where customers have not selected the right CNC operator to run the equipment. In those cases, when the wrong CNC operator is chosen, it often leads to unsatisfactory results from the machine in terms of output – and a frustrating and costly implementation for both DATRON and the customer.
Choosing the right CNC operator or system manager varies depending on the equipment, application and production demand. I highly recommend you discuss these details with the DATRON representative who is managing your project. Clearly setting expectations such as; the learning curve, ramp-up time before you are in full production, education and experience of the CNC operator, number of days and people involved in the training, secondary processes, third-party equipment, and budgeting for advanced CNC operator training at a future date are just some of the considerations for a complete and successful implementation.
It is our goal at DATRON that every system implementation is performed on-time, quickly, efficiently, smoothly and stress-free. A successful installation is just as rewarding for us, as it is for our customers.
Bill King, President DATRON Dynamics, Inc.
Learn More about How DATRON Handles Customer Care:
Machinists ask me all the time, “When do I go fast and when should I go slow with a single flute end mill?” Well, as you can imagine, there are a lot of variables at play regarding feed rates for single flute end mill, but let’s try to break it down.
Slow (60″/min) – Finishing – If you need an exceptional quality in the finish of a floor or wall, it helps to slow the machine down to take a fine chip and decrease cutter load/cutter deflection.
Medium Feed Rates for Single Flute End Mill
Medium (120″/min) – Slotting – Something a single flute does particularly well is slotting, which is a tool path that has 100% of the tool diameter engaged in the material. Using a proper depth cut (25% of tool diameter), you can cruise along at a decent pace without worrying about clogging up on chips.
Fast Feed Rates for Single Flute End Mill
Fast (180″/min) – Traditional Roughing – When you are using a normal milling strategy, in the range of 33-50% depth of cut (2-3mm) with a 50-70% stepover, you can be fairly safe kicking the speed up, just keep an eye on your spindle load.
Very Fast Feed Rates for Single Flute End Mill
Very Fast (240″/min) – Trochoidal Roughing – If you are using Mastercam (Dynamic milling) or Fusion 360 (Adaptive clearing) you may have heard of this strategy before. Instead of going about the traditional method, this method utilizes more of the flute to boost efficiency. For instance, we could use 100-200% depth of cut (6-12mm) with this strategy because our stepover would be decreased to 10-20%. In many cases, this prolongs the life of the tool and puts less strain on the spindle, so you can safely bump the feed rate up.
Extremely Fast Feed Rates for Single Flute End Mill
Extremely Fast (300″/min) – Shallow roughing – If you are taking off less than 10% depth of cut (0.60mm), then you should be safe cranking the feed way up. With such a shallow cut, you won’t have to worry about overloading the tool or spindle.
Question: “Should I use a drill vs. end mill?” DATRON Application Technician, Dann Demazure answers, “It depends on what you’re trying to achieve.
When to Use a Drill vs. End Mill
If you’re making a very small hole, say, less than 1.5mm in diameter, go with a drill. End mills under 1.5mm become increasingly fragile, and subsequently cannot be run as aggressively, as a drill can be.
If you need to make a very deep hole – in excess of 4x your hole diameter, choose the drill. Past this point, chip evacuation can become very difficult with an end mill, which will quickly wreck your tool and your part.
Are you making a lot of holes? Drilling is probably the way to go. In most instances, a drill will best the fastest time you can achieve with an end mill.
Need to make an extremely precise hole? While milling is typically perfectly acceptable, sometimes the tolerances require a drill and a reamer for the perfect finish.
When to Use an End Mill vs. Drill
However, there’s a lot to be said for using an end mill instead.
Need to make a big hole? Big holes need big drills and lots of horsepower, this is where helical milling shines. Use an end mill that’s 60-80% the diameter of the hole you’re making to quickly clear out while leaving plenty of room for chips to escape.
Print calls for a flat bottomed hole? Normal drills can’t do that, so you might be better off milling the feature.
Making lots of different size holes? Try to use the end mill, you’ll save time on tool changes and room in your tool changer.
Rapid prototyping? End mills will be appealing for their flexibility. Being adaptable to take on some features that may normally be drilled means you can spend less time CAMing a part and more time making chips.
With either one, there are two simple rules to remember:
Break your chip – don’t try to be a hero and blast through your hole in one go, program a quick retract to get the chip out and let the coolant in.
Turn up the coolant – unless you have through tool coolant, you’re going to want to be sure to turn up the coolant flow and decrease your air pressure. The coolant needs to be able to flow into the hole during your retract.
Since the equipment our company offers is ideal for sign engraving and processing flat sheet material, we’ve seen the inside of a good number of sign companies over the years. But, walking into Ellis & Ellis Sign Systems in Sacramento, CA becomes a different experience as soon as you pass through the lobby and corporate office of this family-owned business. That’s because the overall size of the place is impressive. Well, it has to be really, considering the work they do – this includes billboards, architectural signage, landmark signs, amusement park signs and even those dazzling neon jobs enticing patrons at the many casinos in Reno. They even made a 16-foot tall Tyrannosaurus Rex, a gigantic Frankenstein and a not so menacing (but still sizable) Curious George for Universal Studios.
But not everything they do at Ellis & Ellis is so big. Take for example the Braille required for way-finding signs and architectural signage. This is intricate work often done on smaller signs that must be ADA compliant for elements like position and tactile height. Braille can be produced using a variety of different processes. For example, Photopolymer Braille uses UV light and a chemical process to remove negative space material. In contrast, Route-in-Place with Raster Braille is a process where small acrylic beads are mechanically pressed into predrilled holes.
Sign Engraving with ADA Compliant Braille
Having tried both of these processes, Ellis & Ellis experienced significant obstacles as follows:
Photopolymer Braille: First and foremost, the Braille was not completely round and was, therefore, subject to ADA liability. They also found the necessary raw materials to be expensive. Ellis & Ellis Director of Manufacturing, Bill Rogers, explained, “The excessive costs of the materials were compounded by costs associated with the human labor required for processing and finishing.”
Route-in-Place with Raster Braille: Similar to Photopolymer Braille, Ellis & Ellis found that additional human labor was required for finishing in the Raster Braille process because of the excessive glue that remains after tactile copy is placed and engraved. Bill Rogers said, “Additionally, the alcohol, solvents and cleaning products would cause crazing to occur on the acrylic beads which often shattered them.” Plus, they found this process to be limited in terms of surface finish possibilities.
Eventually, Ellis & Ellis decided to research other processes and equipment to produce the intricate ADA compliant Braille they needed to manufacture these way-finding signs. Ultimately, they decided on a DATRON M8 high-speed machining center after demonstrations proved that the machine was not only capable of producing spot-on Braille, but could also perform many other functions – thereby adding flexibility to their shop floor. (See aluminum and acrylic letters at bottom of Blog).
Plus, there were other factors involved in their decision. Rogers said, “Well clearly floor space in California has a premium cost associated with it and the DATRON’s footprint fit nicely into the small enclosed space that we designated for this process.” He added, “With the small footprint, it’s amazing that this machine provides such a large work envelope.”
Sign Engraving CNC Machine for Batch Machining
In fact, the DATRON M8 (as well as the newer M8Cube) has a 40” x 32” machining table made of solid polymer concrete that provides exceptional rigidity delivering the accuracy that Ellis & Ellis needs. The large work envelope is not diminished by the 15-station automatic tool changer located at the back of the table. This covered pneumatic unit includes a tool-length sensor which allows Ellis & Ellis to monitor tool life as a means of maintaining a high level of quality. In many cases, the signs that they manufacture are produced in batches and the tool length sensor helps in allowing them to run these parts unattended. Here’s how it works. Within the machine’s control software is a macro program that can be set up to run a tool check after executing a number of lines of code. For instance, a tool check macro can initiate a check after every 500 lines of code. This is known as an “if/then” statement, in other words, “Measure this tool; if the length is shorter than the listed parameter, then change the tool.” As a result, if a tool becomes dull in the middle of running a batch of signs, it is replaced automatically even if the machine operator is not present. This helps to maintain quality and minimize waste.
However, running batches of signs, whether unattended or with the operator present, requires the ability to accommodate and fixture sheet material from which the individual signs are milled. So, Ellis & Ellis was pleased to find that DATRON manufactures their own vacuum table workholding. In the case of their M8 machine, the vacuum chuck is affectionately known as a QuadraMate due to its four independently activated 12” x 18” segments – which can also be simultaneously activated providing a full 24” x 36” of workholding.
Bill Rogers said, “The vacuum table combined with the machine’s integrated probe makes it so easy to set up a job – it’s faster and takes out the element of human error.”
That’s because once the operator sets the material on the table, even if it is not situated perfectly straight, the probe takes measurements that compensate for that. In fact, even if there are irregularities in the material such as surface variance, the measurements are fed into the control software and the program is adjusted accordingly. Since Ellis & Ellis performs so much alphanumeric engraving and milling to produce their signs, this guarantees an even depth of those characters even if the material topography is not consistent. According to Rogers, “All of this equates to more efficiency, higher quality, less waste and ultimately cost reduction.”
The machining center itself is not the only area where DATRON has helped Ellis & Ellis add efficiency to their operation — and Bill Rogers says that they have become quite a proponent of DATRON solid carbide cutting tools. “We saw the exceptional performance of DATRON tools being used with the DATRON machine in terms of cut quality and tool life, so we decided that we’d give them a try on some of our larger machines.” Those larger machines include MultiCam CNC Routers, and as they anticipated, the DATRON tools did, in fact, improve the performance of those larger machines. Bill said, “In terms of tool life, we’re looking at an improvement of about 3 to 1 which is a big cost saving over time.”
In addition to using DATRON tooling with the MultiCams, they also decided to try DATRON’s coolant with these routers and that too helped to impact cutting quality.
Bill Rogers said, “Staying competitive means trying new things, new technology, and always looking for ways be more efficient.” To that end, Bill and his team are frequent visitors at the DATRON Technology Center in Livermore, CA. According to Rogers, “DATRON has informal events like TechDay at their facility where we can go see advancements in the technology. I can always count on their guys to get us the answers we need. It’s a great partnership.”
In the world of computer-controlled milling equipment, there’s always been something of an understanding when it comes to work envelope and precision: as the ability of a machine to achieve ever smaller numbers when it comes to positional accuracy and repeatability goes up, the size of the work envelope (and therefore the largest part you can physically fit in the machine) must go down. Now, like any rule of thumb, there are exceptions to this out there – but these exceptions generally carry with them one significant caveat: they’re expensive as all get-out. Enter DATRON MLCube LS Large Format Milling Machine with linear scales.
There are many legitimate reasons that this convention has become the norm. In ball-screw-driven machine tools, using a ball screw with a very tight pitch to achieve stellar accuracy and repeatability usually results in a decrease in the maximum rapid rate – which is a real bummer if you need the machine to move large distances. Technologies such as linear motors are capable of moving very fast over long distances, but sacrifices often need to be made when it comes to resolution and accuracy of the encoders that feedback the motors motion to the machine’s control system. Even linear scale technologies, while being readily able to increase a numerically controlled machining system’s ability when it comes to accuracy and repeatability, must by default be an additional piece of hardware which accompanies the linear motor or ball screw/linear guide system. Any additional hardware, as any engineer will tell you, is subject to damage, misalignment, or in the case of milling equipment -contamination from the chips, dust and coolant that are part of the milling process. It would seem that the combination of large, capable, precise, and economical has been an elusive one in machine tool industry.
Fortunately, this very problem that the DATRON MLCube LS has been created to solve.
Linear Scales for Precision in Large Format Milling
The ML Cube LS represents the latest in a long lineage of ever improving portal/gantry designed CNC milling equipment from DATRON. Building on the success of the DATRON MLCube, which provides 3 m/s2 acceleration, advanced dynamics and jerk control, 0.1 micron resolution, and the ability to exercise up to 60,000 RPM across its 60“ by 40” work envelope, the MLCube LS makes the significant addition of an integrated linear scale system on X and Y axes.
To avoid the hurdles common to achieving tight accuracy across a large area, DATRON engineers have employed a unique combination of technologies that together present a robust and highly precise positioning system: the integrated measurement system. This integrated system marries the accuracy and repeatability advantages of the external linear scale, with the well-established and optimized mechanics of the ball screw-driven / linear guide axis. In the same way that unifying a servo motor with the associated ball screw by eliminating the drive belt, the ball screw/linear guide/linear scale system benefits in its operation and longevity overall by combining components and optimizing the system.
Benefits of Large Format Milling Machine MLCube:
Benefits if this unification are numerous, but in the case of the MLCube LS the most significant benefits show themselves where they matter most:
System is free of wear or maintenance
Highly resistant to contamination
Exact positional measurement is achievable even under dynamic load changes
Effects of thermal expansion are essentially eliminated
Scale system is completely free of external influence by magnetic fields or electromagnetic vibration
Positional accuracy is improved by 50% compared to the same machine without linear scales
But at the end of the day, the real question is: Why should I care about this machine? Well, fortunately, that’s the simple part:
With a starting price of just under $250,000 including typical options and a positional accuracy of ±25µ across nearly 17 square feet of workspace, the MLCube LS arguably offers the most capability, across the largest work envelope, with the highest degree of positional accuracy, for the least amount of money.
So whether you need to produce a few very large and precise parts, or you need to batch machine hundreds of small precise parts in one long unattended machining session – the MLCube LS offers advantages that are not easily matched.
Download DATRON MLCube LS Large Format Milling Machine Brochure
With additive manufacturing and 3D printers being such a hot topic these days, it’s important to remember why subtractive processes like milling are still incredibly important to rapid prototyping. But first, let’s examine some of the benefits and limitations of additive rapid prototyping (or direct digital manufacturing).
Benefits of Additive Rapid Prototyping
The process of additive rapid prototyping joins and fuses materials like liquid resins together, layer upon layer to produce a 3D object from model data. Additive rapid prototyping is generally simple, relatively inexpensive and fast. Additive rapid prototyping also allows for a substantial amount of complexity within cavities or internal areas of a part that would require undercuts and may even be impossible with subtractive processes like milling.
Limitations of Additive Rapid Prototyping
The primary drawback of additive rapid prototyping is that the resulting part usually is not made of an end-use material like metal … and even if it is, it lacks structural integrity. That’s because the point where one layer is joined to another lacks the physical strength exhibited by a solid block of the same material (with no layers or joints).
Subtractive Rapid Prototyping with End-Use Materials
Subtractive rapid prototyping provides the ability to prototype in end-use materials. Since milling or machining removes material from a larger piece of material, the finished part has a solid composition rather than a layered composition as seen in additive rapid prototyping with 3D printers. This yields a higher structural integrity which is critical if the prototype part is to be used in product testing. Product testing with a part made through subtractive prototyping allows for an accurate analysis of the part’s viability and even durability since it is made from the same material that will be used to manufacture production parts.
A Wider Range of Surface Finishes and Textures with Subtractive Prototyping
Subtractive rapid prototyping processes also offer a wider range of surface finishes for the completed prototype as opposed to the standard “stepped finish” often achieved in additive rapid prototyping with a 3D printer. This could range from a completely smooth surface with a mirror-like finish to ones with milled or engraved textures. In this way, subtractive rapid prototyping with a high speed CNC milling machine is capable of producing prototype parts with a repeatability suitable for end-use production. The smooth surface finish that can be achieved with high-speed machining can be functionally beneficial if the given part needs to slide and aesthetically beneficial if the prototype is going to be used in market testing.
Additive Rapid Prototyping vs. Subtractive Rapid Prototyping
To illustrate the points made above, we asked our applications engineers to quickly prototype a part using both additive and subtractive processes. Since our favorite after-hours (wink, wink) past time is foosball, they decided to make a “replacement” foosball man for testing. This decision was based on an actual real-life need – since we had recently broken one of the men that came with our vintage 1985 foosball table. Using additive rapid prototyping (3D printing), they were able to design a very rudimentary foosball man in about 90 minutes. From there, they began printing and in just over an hour the part seen below was complete.
Using subtractive rapid prototyping (high-speed milling) programming the part took substantially longer and clocked in at 3 hrs. 45 minutes. However, milling the part below was considerably faster than 3D printing and took 28 minutes.
Product Testing an Additive Rapid Prototype vs. a Subtractive Rapid Prototype
Well, you knew we had to “test” the part right? So, in a series of 4 rather heated games using each prototype, here’s what we found. In terms of functionality and durability, the subtractive prototype was the clear winner. Not only did it last through the 4 games, the solid composition of the part made for stronger shots with high velocity. Plus, it clearly would hold up for hundreds of more games. By comparison, the 3D printed part began to show signs of delamination on its right side half way through game 3 — and by the game 4 we had to mend it with a bit of scotch tape to get through the rest of our “product testing”. The damage to the part revealed the inside composition of the 3D printed part as seen below.
The rather hollow nature of this part shined a bit of light on why we couldn’t achieve strong shots using this foosball man. In analyzing the resulting surface finish on both parts, we felt that the subtractive prototype was … well, simply more attractive. Plus, the milling process provided more flexibility to achieve different surface finishes. For example, we were able to make the majority of the subtractive prototype very smooth while giving the foot section a more textured finish for added “grip” or ball control. By contrast, the inherent “stepped” surface finish on the additive prototype served well in terms of ball control … but wasn’t very attractive over the entire part.
The Ultimate Subtractive Rapid Prototyping CNC Machine:
Last year’s introduction of the DATRON neo compact high-speed milling machine makes subtractive rapid prototyping more affordable and viable than ever. Plus it’s compact size and touchscreen operation make it easy to use and easy to fit in the tightest “lab-type” environment. To learn more download the brochure by filling out the form below:
So here we are. You have read all of my eloquent, informative, and groundbreaking (perhaps a minor exaggeration) blogs. You are ready. You have a pencil behind your ear and a calculator on your desk and you’re going to trust in the numbers! Slow down there cowboy, because the most important thing to remember is the numbers, formulas, and suggestions are just that – suggestions. They give you a reasonable starting point. They get you in the neighborhood but some good old CNC machinist trial and error might be in order. I know, if you bought an expensive GPS unit for your car (who buys those anymore?) and it GUARANTEED to get you within ten blocks of your destination and left the rest up to you then you might wonder why you bothered. Well my friend, if that building you were driving to was constantly moving and changing based on the simplest of variables then ten blocks isn’t too shabby. Besides, you got my Shop Math formulae for free. Stop complaining.
Control the Variables
The point is, no matter how sophisticated your CNC machine, software, tooling, or ego is you will always have to make adjustments. Sometimes minor, sometimes major. It all depends on what you are doing and how you are doing it. There are an endless number of variables involved with machining so I won’t even attempt to touch on all of them. The name of the game is eliminating or at the very least CONTROLLING those variables to get consistent results every time. Let’s say you set up a new job on Monday morning. This job uses eight tools and takes approximately two hours. The tools do well all day Monday and when you come in Tuesday morning the second shift guy tells you he had to look busy so he swapped out all the tools. When you ask if they were worn out he replies “I dunno.” You would think they would be smart enough to put a competent human being on second shift since there is far less supervision, but trust me I know how that goes. Anyway, you have many issues now. Judging by Gomer’s attitude and general work ethic you can assume that none of the new tools were properly measured before he put them in. So it’s time to get to work – measure all your tools, check your zero points, make sure your speeds and feeds are good. Should be all set, you say? Guess again. Same program, same machine, right tools, everything looks good. That doesn’t mean it will cut the same as it did yesterday. Or even two parts ago. Depending on the tolerance you are working with something as simple as the ambient temperature and humidity can affect the final result. This is where some CNC machinist trial and error comes in.
Warm Up the Spindle
Before you decide a program is ready for production and release it to Gomer, you need to make some determinations. First off, make sure no matter what that you always warm up the spindle. If you warm up the spindle properly before running your first job of the day then you will ensure that thermal expansion in the spindle will not become one of your variables. That way the fifth part will come off just like the first. Also, any time your machine is going to sit more than a couple hours it is a good idea to do a warm up, especially if you are working with tight tolerances.
Know Your Tools & Standardize Your Tool Library
Another consideration when preparing a job for production is tool life, so you can avoid the problem mentioned above. By testing and running through some “CNC machinist trial and error” you will learn a lot about tool life and be able to compile some simple information and expectations. You will find that the more you do this, the faster and easier it will become. You will reach a point (especially if you followed my advice from my previous blogs and set up a standard tool library) that the information will just be there and suddenly your reference material will be right off the top of your head. Once you know your tool life you can be much more proactive in your approach to shift change and work flow.
Trial and Error with Feeds and Speeds
CNC machinist trial and error also comes into play when efficiency and productivity are the goals (when are they not?). So my suggested speeds and feeds get the part done in twenty minutes, but if I take a 10% lighter cut and increase my feed 20% then the part is off the machine faster, and my tool will last for eight parts rather than five. I have cut time, increased tool life and made the boss happy. What about QC? Are they still happy? OK, so my surface finish suffered a little, but it’s still within specifications so we are good. Success!
Don’t be Afraid to Push the Envelope … or Break a Tool
If there is one thing for you to remember it’s that ERROR is half of trial and error. The best machinists I ever worked with broke tools on a regular basis, just because they wanted to see what they could do. A little bit of CNC machinist trial and error, pushing the envelope, will get you farther than you may think. You will discover very quickly that the envelope is far more expansive than you imagined.
Learn More: Download the High Speed Machining White Paper: