Posts By: CNC Masters


How Has CNC Machining Changed the Manufacturing Industry?

Machine ShopComputer Numeric Control (CNC) machining has been around since the 1940s. These days, with the help of computer aid design (CAD), high-speed automation and advanced production capabilities, CNC machining is a fully-integrated manufacturing technology. Since its introduction nearly 80 years ago, CNC machining has become a critical part of technology development. Let’s look at the ways CNC machining has empowered the manufacturing industry since its inception.

Speed

Before the advent of CNC machining, mills, lathes, drills and routers were run by operators. They would read a drawing and determine the best way to create the necessary features on the parts. A complex part might need to be remounted and reoriented by hand, and engineers had to include orienting features to ensure these operations maintained critical dimensions. This could be time consuming for both design and manufacturing.

Now, 3D modeling CAD files are read directly by CNC machines and a computer can automatically plan machining operations. An engineering design can include dimensional dependencies to maintain critical dimensions. Furthermore, advanced automated CNCs have articulating tables and heads to reorient parts and tools without ever unmounting a part. Rather than manually controlling each step in the process, operators can simply program CNC machines to interpret CAD files.

As result of computer integration and automation, more complex components are made faster than ever.

Repeatability

In addition to making components faster, CNC machining has enabled greater precision and accuracy as well. Since parts are not remounted and operations are carried out by a high-precision machine, errors are less likely to occur. The accuracy of the first part is largely dependent on the accuracy of the CNC machine itself. The precision from part to part is largely dependent on how constantly each part is initially mounted in the machine.

Better accuracy and precision allow higher-quality components to be made with less waste.

Scalability

CNCs also have advantages for scalability over traditional machining. Some machines can complete more than one operation at a time. And, they can run almost continuously, 24 hours a day.

Faster, more repeatable continuous operations mean greater quantities of parts can be made in a shorter period of time.

Turning Ideas Into Products

Probably the greatest impact CNC machining has had on manufacturing is its ability to take and idea and turn it into a product quickly. This has made CNC machining ideal for prototyping and testing early in the design process. Engineers and designers can come up with a new product concept, mock it up in CAD and have machined prototypes within days. This makes it possible to modify concepts or try alternatives with little risk, allowing them to fine tune a design before releasing it for production.

More prototyping contributes to the production of robust, well-tested and innovative designs throughout the manufacturing industry.

Interested in learning more about how a CNC machine can benefit your unique operation? Give us a call or contact us online to speak with the team at CNC Masters today!


Notable Differences Between CNC Turning and CNC Milling

CNC MillMilling and turning are everyday operations in a machine shop. Both techniques use a cutting tool to remove material from a solid block to make 3D parts. Removing material is what classifies them as subtractive manufacturing processes, but there are key differences to these operations.

Turning is an operation for a lathe.

The name ‘turning’ refers to the workpiece because it rotates about a central axis. The cutting tool remains stationary and is moved in and out of the workpiece to make cuts. Turning is used to create cylindrical parts and derivatives of cylinders; think of parts shaped like baseball bats, shafts, balusters and columns, for example.

A chuck holds the workpiece centered on a rotating spindle. A base secures the cutting tool so it can move along the axis of the workpiece and in or out radially. Feeds and speeds come from the rate of rotation of the part, the radial depth of cut and the rate the tool moves along the axis of the piece.

Turning operations include OD and ID cutting and grooving, boring, treading and drilling. Since the cutting tool exerts a force on the workpiece perpendicular to its axis, it is crucial to support the piece to reduce deflection.

In milling operations, on the other hand, the cutting tool rotates while the workpiece is fastened securely to a worktable.

The cutting tool or the table can move orthogonally in the X, Y or Z direction for cutting. Milling can create more complex shapes than turning. It can even produce cylindrical shapes, but for cost effectiveness, those shapes are best left to a lathe.

In a CNC mill, a chuck holds the tool in a rotating spindle. The tool is moved relative to the workpiece to create patterns on the surface of the workpiece. Feeds and speeds are calculated based on the rate of rotation of the cutting tool, the cutting tool diameter and number of flutes, the depth of the cut and the rate the cutting tool moves across the part.

The limitation of milling pertains to whether or not a tool can access a cutting surface. Using longer and thinner tools can improve access, but these tools can deflect, causing poor machining tolerances, bad surface finishes and more wear and tear on the tool. Some advanced milling machines have articulating heads to allow for angular cuts and improved access.

Both turning and milling operations are useful for creating complex parts. The primary difference will be in the shape of the final part. For cylindrical parts, go with turning. For most other parts, milling works best.


Unique Advantages of Subtractive Manufacturing

Subtractive ManufacturingAdditive manufacturing, better known as 3D Printing, first started in the 1980s. Back then, it was a novelty concept reserved for advanced engineering research laboratories. In the 1990s, 3D printing made waves in the medical arena thanks to its ability to create custom medical devices. By the early 2000s, the open-source movement brought 3D printing into the homes of hobbyists and entrepreneurs During this time, people hailed it as the future of all manufacturing. It remains a promising technology, but subtractive manufacturing still offers many advantages over 3D printing.

Subtractive manufacturing techniques are those that remove material from a block to make a 3D part.

They are what we might call traditional manufacturing processes like milling, turning and even injection molding. Additive manufacturing processes, on the other hand, build up 3D parts by successively adding layers of material.

Although the cost for 3D printers continues to decrease, it’s still more expensive to 3D print many parts than it is to machine them. The printers themselves can be cost competitive, but the materials used in 3D printers are costly – especially if metals are involved.

Printing a part is a little bit like making pancakes – the first one usually gets tossed in the trash. This constitutes a waste of high-cost materials. Furthermore, 3D printers are more finicky and require frequent calibration and re-calibration when they’ve sat unused or when operators are swapping materials.

3D printed parts also require additional post-processing to achieve attractive surface finishes.

The additive component of the manufacturing process means pieces right out of a 3D printer have striations and stepped edges around radiuses. These surfaces require a subtractive manufacturing process to finish. Most subtractive manufacturing processes can produce finished surfaces.

Even if the striated surfaces of additive manufacturing is acceptable, 3D printer technology remains less reliable than subtractive manufacturing. High-reliability machines with good repeatability are expensive and require frequent maintenance while low-end devices typically cannot produce parts with consistent quality.

3D printing can be appealing for prototypes, but it is often limited to fit-and-feel prototypes. Because there are limited 3D printing materials available and the final mechanical properties are not always as good as those for machined parts, 3D-printed parts may not be robust or accurate enough for testing purposes. So, it sometimes makes sense to prototype with subtractive manufacturing processes and production materials instead.

Generally, subtractive manufacturing techniques are more familiar to designers.

Many designers even rely on certain functions that are common in CNC mills and lathes. For these folks, 3D printing can add cost for no discernible benefit. And with many machine shops capable of producing parts overnight using traditional techniques, the relative speed of 3D printing is rendered moot.

While additive manufacturing is attractive in some applications, good old milling, turning and molding are often better suited for the job at hand.


Essential Tips for Machining Aluminum Components

Machining AluminumCommon complaints among people new to machining Aluminum alloys include poor surface finish, gummy deposits on cut faces or tool edges, and a smeared appearance. All materials have different properties that require adjustments and care to achieve the optimal finishes.

Aluminum is a soft and ductile metal that has high thermal conductivity. The former means it cuts easily but creates long chips. The latter means it is susceptible to heat build-up. Following these tips when machining aluminum can help mitigate both these concerns.

Use the Right Cutting Tool

Although aluminum is soft and ductile, it requires a good cutting tool for best results. Don’t use high-speed steel or cobalt tools for this job; use carbide cutting tools instead. Also, it is sometimes better to use a tool with fewer flutes. Since Aluminum produces long chips, a tool with fewer flutes will allow chips to escape more easily. Using the right tool with the correct number of flutes will allow you to employ a broader range of spindle speeds.

Keep it Cool

As mentioned above, aluminum has a high thermal conductivity. It gets hot when cut, and that heat can build up fast. This, in turn, can result in a finish with a smeared appearance, workpiece warpage, and leading edge build up (that gummy problem). Proper coolant flow will move chips away from the cutting zone and keep the cutting surfaces properly lubricated.

Horsepower is Your Friend

While aluminum may be softer than other metals, it is still a metal and machining it requires a great deal of power. If your machine can’t keep up with the power requirements for a cut, it will result in chatter and deflection. It may be necessary to use horsepower “derating” in feed and speed calculations when using smaller, lightweight machines for aluminum milling.

A Note on Chip Management

Aluminum’s high ductility results in long unbroken chips that can quickly build up around a tool. This can cause tool breakage, leading edge buildup (more gummy problems) and heat buildup (that smeared finish). When cutting aluminum, be vigilant about cleaning chips. Whether it is with a fixed air blast system, high coolant flow rates or chip conveyors, chip removal should be integrated into your process.

Aluminum is ductile, lightweight, thermally, and electrically conductive with excellent strength characteristics. With a few adjustments to machining techniques, it can be a great material for many parts and projects.


Up in Flames: Fire Precautions for Milling Combustible Materials

CNC SparksFlint on steel coupled with some easily-combustible kindling makes for a cozy fire. That combination is just one of the tricks up a scout’s sleeve for survival. However, that same formula can spell trouble when milling woods, plywood, or even plastics. Fast-moving metal tools cutting against combustible materials can result in a not-so-cozy fire on a workpiece, in piles of cuttings and shavings, or in a dust collector.

CNC fires are not only costly, they are dangerous and potentially deadly. To mitigate the potential risks associated with machining combustible materials, here are four tips to help you prevent machining fires.

Know Combustible Materials

For a fire to start, there needs to be a spark and an oxygen source. For it to catch, it needs fuel. In the context of CNC machining, that fuel is a combustible or flammable material. Wood, plywood, and paper materials are common sources of fuel. Plastics are also excellent fuel sources – after all, they are made of petroleum. However, as outlined by OSHA, dust is also a common source of combustible fuel, including metal dust. With this in mind, it’s wise to adhere to fire prevention procedures no matter what material is being machined.

Check Feeds and Speeds

Maintaining proper feeds and speeds is important for addressing all sorts of machining concerns, from poor surface finishes to improper tool wear. So, it should be no surprise that using proper feeds and speeds is a beneficial for fire prevention as well. Incorrect feeds and speeds can increase friction, which in turn generates heat. With materials like wood, it’s also essential to adjust the cutting depth so you’re not cutting into the spillboard to prevent heat buildup.

Don’t Dwell

A spinning tool sitting and dwelling can generate a great deal of heat in a short amount of time. That heat buildup can quickly reach the point of combustion and spark a fire. In addition to potentially burning a workpiece, that hot spot can easily ignite chips or dust. Smoldering dust and chips can carry flames into collections systems, causing a fire to spread.

Have a Fire Safety Plan

Any shop’s safety plan should include fire response procedures. Fire extinguishers should be readily available, in an accessible location, and in proper working condition. Some operations, especially those handling a large number of flammables or generating a significant amount of dust, should consider a fire suppression system, facility alarms, automated emergency call systems, and evacuation procedures. Even for small or single-person facilities, a fire response plan is critical.

The good news is, machining combustible and flammable materials can be safe and easy as long as the risks are mitigated with proper precautions.


Benefits Of The CNC MAX Milling Machine

CNC MAXAt CNC Masters, we’re proud to produce some of the some of the best tabletop milling machines on the market. One of these tabletop machines, however, is a different breed from the rest.

The CNC MAX sets itself apart from the pack with its versatility and ease of operation.

The CNC MAX tabletop milling machine is the first mill of its kind to have true ball screw accuracy in not one or two, but all three axes. It is built durably and precisely, with a cast-iron body, sliding dovetail ways and tapered gibs on the square column. These features give the machine superior accuracy, repeatability and alignment.

One of the best attributes of the CNC MAX mill is that it offers the performance capabilities of larger CNC mills in a more compact package.  

Thanks to its flexibility and user-friendly design, this mill can be a great investment for manufacturing plants, machine shops, research institutions, high schools, universities and even small business owners who want to save money by machining their own components.

The CNC MAX mill is compatible with ordinary PCs running a Windows 8 or 10 64-bit operating system, and a convenient “teach mode” allows the machine to automatically write each line of a tool path as the operator manually jogs each axis with a mouse, keyboard or optional handheld keypad. As such, amateur machinists can easily mill simple parts on the CNC MAX without the need to learn specialized CAD programming languages.

More experienced operators, meanwhile, can enjoy many of the same features they’re accustomed to finding on larger, more expensive CNC mills.

The CNC MAX mill is proudly manufactured and assembled right here in America, combining both American-made and imported parts that allow us to offer competitive pricing while retaining a high degree of quality and durability. All of our milling machines come with a one-year hardware warranty against manufacturer defects, and they undergo a rigorous quality assurance and pre-shipping inspection upon purchase. Our USA-based customer support team is also available to answer any technical questions you might have about the CNC MAX mill for as long as you own the machine.

To learn more about the CNC MAX tabletop milling machine or any of the other products we offer at CNC Masters, feel free to give us a call or contact us online today!


Use a CNC Mill to Create Your Own Printed Circuit Boards

Printed Circuit BoardElectrical engineers and technicians often use breadboards for prototyping and testing circuit designs. Breadboards are typically plastic plates with grids of spring-loaded receiving holes for inserting wires and components. While breadboards are great for quickly mocking up circuit layouts, they have several drawbacks. They are large, so they easily don’t fit into mechanical housings. They can get cluttered, which makes it difficult to chase down defects on complex layouts. Since they are not soldered, they are also not very robust.

For these reasons, designers are often eager to have Printed Circuit Boards (PCBs) manufactured as early in the design process as possible. A PCB is a flat board with conductive lines called traces on its surface for electrically connecting electronic parts and components.

Unfortunately, between tooling costs, high prices for low quantities, slow turnaround times and limits in redesign flexibility, a small manufacturing run for a PCB can be prohibitive. As a result, some designers have turned to milling their own PCBs using in-house, engraving CNC machines.

In order to mill a PCB, a wiring diagram must first be translated into a CAD model.

Since CAD modeling is an important step in product design, creating models early is an excellent habit for product development. Next, these models need to be translated to the CNC programming language G-code with a CAD/CAM translation software. Once the G-code is generated, you are ready to mill a circuit board.

There are a few things to keep in mind when milling PCBs.

  1. Drill, Mill, Cut: There are three processes for creating a PCB. First vias (holes for components) are drilled. Second, the clearances for the traces are milled. Finally, the board is cut to shape.
  2. Tooling: Each process should use the appropriate tools. Drills for holes; endmills, either square or v-tipped, for trace clearances; and endmills for shaping.
  3. Machine Performance: There are a variety of small CNC machines on the market with significant differences in built quality. Some are preassembled, while others require assembly on-site. The stiffness and build quality of the machine will dictate how accurately and precisely it mills. A lower-quality machine does not necessarily mean it can’t be used for prototyping PCBs, it just means you may need to account for larger trace clearances, use deeper cuts or use larger tooling.
  4. PCB Materials: Circuit boards consist of a copper layer bonded to a composite substrate that is often made of a flame-retardant material. FR-4 is one of the most popular substrates in use today. It is a glass-filed, epoxy resin. That glass fill makes the material highly abrasive, which will result in fast tool wear. Precautions should also be taken to avoid inhaling FR-4 dust, which is hazardous to one’s health.
  5. Finishing: The copper layer is prone to oxidization, which can diminish its electrical performance. So, once your PCB is milled and the components are soldered in place, it is important to coat the copper. Luckily, a quick coat of nail polish can address this issue.

Interested in milling your own PCBs with a CNC machine? Give us a call or contact us online to find the machine that’s right for you today!


Generative Design: An Innovative Approach to Manufacturing

Generative Design ConceptEngineers and designers for companies like General Electric, Airbus and General Motors are using a new tool called generative design to explore thousands of design iterations with geometries that are automatically generated within their software.

Although generative design is most applicable to additive manufacturing processes (aka 3D printing), developers are quickly integrating the technique traditional manufacturing processes as well. In April 2018, Autodesk commercially introduced its generative design tool on the Autodesk Fusion 360 platform. This example on their websites shows how they optimized a skateboard truck design with this technique.

In contrast to other automated manufacturing techniques, generative design requires no preliminary CAD instructions.

Engineers input a set of design parameters – special constraints, loading, materials and manufacturing methods. Then, using cloud-based software, hundreds or even thousands of possible designs that meet these criteria are created. Many of the geometries are other-worldly looking with swooping curves and intricate lattices that human designers are not accustomed to thinking up and are very difficult to model parametrically.

Generative design techniques are still in the early stages of development and are not yet practical for large scale production. However, there have been some notable success stories. The Adidas Futurecraft 4D high-performance sneakers, for example, were generatively designed and are set to go into production this year. Meanwhile, Airbus has been exploring generative design techniques to create lightweight interior panels for its planes as well.

The current potential of generative design is still somewhat restricted by hardware limitations, but this novel approach is sure to become more useful and applicable to real-world design challenges with time. In essence, generative design mimics natural evolutionary processes to find optimal solutions through rapid-fire iteration. If and when engineers are able to overcome generative design’s current limitations, this technique could have a transformative effect on the structure and appearance of tomorrow’s industrial design.


Scribe vs. Script: The Difference Between Marking & Engraving Cutters

It’s a bit misleading to say marking and engraving cutters are different, because marking cutters are a sub-class of engraving cutters. However, understanding the best applications for using marking cutters over other engravers is useful for efficiency, quality, and cost savings.

Metal Engraving

Engravers are typically used to machine finishing details into the surface of a part, including things like serial numbers, logo, decorative patterns or orienting marks. Since engraving cutters are tasked with doing precision work, they are usually made of carbide or high-speed steel (HSS). They also have a unique geometry that ensures the groove conforms to the desired profile. This is usually a v-shaped groove with a bottom that is either sharp, radiused, or flat.

It is the geometry of the cutter that differentiates a marking cutter from other engravers.

For engraving, the flute end of the tool comes to a point. Cutting tools for other operations have multiple cutting edges. When more than one cutting edge come to a point, it is impossible to machine a precision v-shaped groove. The overlapping cuts results in a flat-bottomed groove.

To eliminate this flat-bottomed artifact, engraving cutters have a “half-round” geometry. This means the fluted end of the tool is cut down to half a cylinder. The result is a pointed tool with a single cutting edge. The point of this tool can be pointed, radiused or tipped (flat).

Half-round engraving cutters are perfect for fine details. However, because of their half-round end, they are susceptible to breakage especially if they are not handled correctly. For this reason, they are best suited for softer materials like aluminum and wood, or for applications requiring a high degree of precision like artistic decoration or logos.

However, not all engraving applications require precisely-grooved cuts. Take serial numbers, for example. Typically, a legible serial number will suffice. Considering the costs associated with breaking an engraving tool for such an application, it is best to complete them with a marking tool.

A marking cutter is an engraving cutter that is not half-round.

Marking cutters usually have two flutes. They are only available as radiused or tipped cutters because of the flat-bottomed artifact.

Although they are not ideal for precision decorations, marking cutters offer notable benefits over half-round engraving cutters. Due to their durability, they are better suited for engraving harder materials like ferrous alloys. They are also good for repetitive operations that do not require precision like serializing.

Whether the project calls for precise scripts and artistic detail or simple a scribed serial number, selecting the right engraving tool is important. Once the right tool is selected, check with this handy  “Rotary Engraving Fact Sheet” for other ways to improve your engraving operations.


Avoid the Sizzle: Tips to Mitigate Heat Buildup

Milling CoolantIt is the nature of machining to generate heat. The friction between tool and work piece and the acts of cleaving material with a tool and breaking molecular bonds are, in fact, exothermic processes. However, excessive heat generation can shorten tool life, degrade surface finish, cause workpiece and tool warping, and generate toxic smoke.

Follow these tips to mitigate heat buildup in your tools and workpieces

High Efficiency Milling (HEM)

HEM is different from High Speed Milling (HSM) because it is focused on reducing chip thinning and maximizing tool efficiency. The HSM approach is designed to reduce the depth of cut and maximize spindle speed. HEM, on the other hand, aims to optimize tool wear by adjusting the feed rate to maintain chip thickness throughout the operation.

Most notably, HEM mitigates heat build up by cutting with as much of the cutting edge as possible. This distributes the heat over a larger area of the tool. Utilizing the whole cutting edge also reduces tool wear.

Coolant Management

Your first instinct for mitigating heat buildup in tools and workpieces might be to crank up the coolant flow. As the thinking goes:

More Coolant = Cooler Parts

This might work in most cases, but the practice is wasteful. It also does not take into consideration the effects coolant has on part finish, chip evacuation and potential material damage or warpage. It is important to select the right coolant (air, mist or liquid) and the best delivery system for the process. Then, the most efficient flow rate can be dialed in for the best part quality.

In some cases, using coolants may not be feasible. Customer requirements or certain procedures dictate machining dry. For these occasions, refer to this article to find tips for alleviating heat buildup during dry machining operations.

Climb Milling

Traditionally, milling operations put the feed direction and the tool rotation in opposing directions. This method generates a thin-to-thick chip which has multiple adverse effects. It increases the chances of undesirable surface finishes because of chip re-cutting and tool rubbing. It also pushes heat generation into the tool and workpiece.

On the other hand, climb milling puts the feed and tool rotation in the same direction. This generates a thick-to-thin chip. The heat gets pushed the chips rather than into the tool and workpiece. It also improves surface finish and helps push chips out of the part. This makes coolant flows more efficient for heat removal and chip evacuation.

Implementing these tips can ensure you are producing the highest quality parts while preserving your tools.