Posts Categorized: CNC Milling


Cut Your CNC Manufacturing Costs with These Tips

Milling Metal Thanks to their ability automate machining processes and make them highly repeatable, CNC mills have helped to significantly reduce manufacturing costs in a wide variety of industries. That said, there are additional steps machine shops can take to reduce their CNC machining costs even further.

Today we’ll consider a few tips to help companies cut their CNC manufacturing costs and increase their profit margins.

Stay Away From Sharp Edges

Because CNC end mills are cylindrical in shape, it can be difficult (and expensive) to create sharp edges and precise 90-degree corners. Instead, make the radius of each corner as wide as possible, since larger tools can remove material more efficiently. If you need sharp edges for your product’s design, include an undercut at each corner so it can be more easily accessed by the end mill.

Choose the Right Material

You might think that you should always use the hardest available materials, such as stainless steel, but think again. These materials are expensive to machine because they are more difficult to manipulate. Consider turning to other materials, such as aluminum, which is typically the least expensive metal to use in CNC manufacturing.

Avoid Thin Walls and Features

Thin walls and features are more prone to breakage, which will inevitably drive up manufacturing costs. If your product design allows it, keep walls and features at least 0.02 inches thick.

Break Your Design Into Parts

It can often be less expensive to manufacture several discrete parts that fit together rather than milling a product out of a single block of material.

At CNC Masters, we’re proud to offer high-quality CNC mills and turning centers at prices our customers can afford. To learn more, feel free to give us a call at (626) 962-9300 or contact us online today!


Achieve Tight Machining Tolerances With These Helpful Tips

CNC End MillSo, you’ve reviewed the drawing with the engineers and designers. You’ve verified the dimensions and double and triple-checked the features. You’ve asked the team if they have any flexibility. You’ve explored every option, but alas that +/-0.0005 tolerance (or tighter sometimes) is correct. Now, you have to make the part. Here are some tips for maintaining tight tolerances.

Calibration

Machine maintenance is critical for the best performance. While CNC mills are designed to have minimal deflection, things move over time. It is a good idea to contact the manufacturer to service and calibrate machines annually. They can use specialized tools like the interferometers and laser calibration systems to ensure machines are in tip-top shape.

Warm-Up

A warmup routine might be standard procedure for any milling operation, but these routines are mostly designed to ensure the lubrication and bearings are warmed up. A high-precision operation should include a more aggressive routine to warm up all the internals. This exercise will minimize any dimensional changes that occur as the machine reaches operating temperature.

Thermal Stabilization

Thermal stabilization is different than warm up. While getting to operating temperature is essential, it is also vital for the environmental temperature to be stable. Shop temperatures might fluctuate throughout the day, or a specific machine might be near a vent, window or sunny spot. All these things can cause the workpiece or the machine to change dimensionally. Don’t forget to stabilize the material’s temperature too. If it is stored outside or in a cold room, it should be allowed to stabilize to an ambient temperature near the machine before starting.

Tooling

The right tooling is a necessity for achieving tight tolerances. Consider using radiused tools for rough cutting to reduce tool wear and allow for faster machining. Then use a sharp, square end tool for finishing. The tool should have the maximum number of flutes allowable. For holes, a reamer has better precision than a bit and leaves a fine polished finish.

For more helpful CNC milling tips, stay tuned for the latest updates from our blog or give us a call today to speak with a representative!


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.


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!


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.


Improve the Surface Finish of Your CNC Projects With These Tips

Precision MetalworkThe finishing cut is the last step before a part reaches inspection, and after all the time and effort that goes into making a precision part, it is critical that this final step produces a quality surface finish. Incorporating a few key practices can help prevent the need to scrap parts in this last stage and ensure your surface finishes are always up to snuff.

Feeds and Speeds

It may seem like an obvious point, but dialing in the correct feed and speed is essential for achieving a high-quality surface finish. Increasing the tool speed reduces the built-up edge (BUE), while reducing the feed decreases flank wear. Both can reduce the possibility of tool failure and prolong the life of your tools. A word of caution, however: don’t dial the depth of the cut back so far that the tool rubs against the surface instead of cutting it This will result in a smeared finish.

Chip Breakers

Although seeing a long-coiled chip come off a tool tip can look satisfying, those long chips may mean the cutting pressure is too high. This can result in accelerated tool wear and create a mess of metal strips that damage the part surface. Adding a chip breaker improves chip removal and control. Factors such as part ductility, tool shape, milling setup and coolant usage all influence chip breaker selection, but once the right one is implemented, it’s easy to clean away chips before they contact the finished surface.

Positive Rake Angle

In addition to reducing the BUE and breaking up chips with a chip breaker, increasing the rake angle helps produce more manageable chips as well, thereby improving cutting efficiency and decreasing tool wear for a more precise surface finish.

Maintain Rigidity

It is important that the toolholder remains rigid throughout the cutting process. Any pockets of movement in the setup can cause chatter and result in a scalloped surface. In addition, using best practices like a short tool reach and proper feeds and speeds to minimize tool deflection will also minimize chatter.

Use a Finishing Tool

Roughing tools and finishing tools are distinctly different beasts. Although it may seem like a cost saving measure to use the same tool for both, it can result in greater volumes of scrap after the finishing stage. Additionally, the desired surface finish may require different cutter and insert geometries than those of roughing cuts. A different nose radius, a finer pitch or a wiper insert might be considered for the finishing cut.

If your finding your surface finishes lacking, try implementing some of these practices to improve your final products.


Get a Grip: Strategies to Reduce Tool Deflection

CNC Cutting Tool To produce parts with accuracy, precision and high-quality surface finish, it is important to minimize tool deflection. Tool deflection occurs when the force of cutting overcomes the stiffness of the tool, causing the tool to bend. The tool may not perceptibly bend during the operation, but the proof is in the final measurements. Parts made with a tool that is deflecting may be misshapen, out of tolerance, suffer from variability or exhibit a ‘chattered’ surface finish.

Tool deflection also accelerates tool wear and increases the likelihood of tool breakage.  So, in addition to improving part repeatability and quality, preventing tool deflection saves money by reducing tool replacement frequency and machine downtime for tool changes.

What is tool deflection?

A cutting tool is held tightly in a chuck. All the parts of the chuck and the machine are stiff and tight; they prevent the tool from moving and limit its ability to bend inside the chuck. Similarly, the part being machined is ideally immovable and tightly clamped and supported on the stage.

Between these two extremes is the unsupported and cantilevered cutting part of the tool. During a cutting operation, the tool pushes against the material. But the material is immovable. Some of that force goes to cutting the material, but some of it pushes against the cantilevered cutting part. This pushing causes the tool to bend away from the centerline like the tip of a fishing pole bending under the weight of a fish on line.

This article details factors affecting tool deflection, but how much the tool bends can be summarized with two key factors:

  • Unsupported Length – the amount of tool hanging out of the chuck.
  • Tool Stiffness – this is also influenced by several factors including:

To minimize tool deflection, the amount of cantilevered length should be minimized. The amount of tool hanging out the chuck should be the least required to accomplish the cut. More passes and smaller cuts reduce tool deflection. These factors should be balanced with specifics of the part geometry and finish requirements.

In the category of tool stiffness, there are multiple influences including tool condition, tool material, and tool size and shape – number of flutes, core diameter and shank diameter. If the tool is worn and dull, it cuts less efficiently, and more force is required to achieve the same cut and finish as a sharp tool. So, more tool deflection occurs. High-quality tools made with stronger and stiffer materials result in less tool deflection. Finally, a larger diameter, more specifically a larger core diameter tool is stiffer. So, the largest tool allowable for the part geometry should be used.

It may not always be possible to use a larger diameter or shorter tool. Some operations may require a long reach or long flute tool. In these cases, tools should be matched to the operation. For a deep feature that requires minimal cutting surface, a long reach tool with a larger diameter and thus stiffer shank is more appropriate. An operation for a seamless slot wall, on the other hand, calls for a long flute tool.

In summary, optimizing tool selection and set-up geometry to minimize unsupported length and maximize tool stiffness results in less tool deflection for improved part quality and lower tooling cost.


Upgrade Your CNC Machine With a 4th Axis Rotary Table

4th Axis Rotary TableWhen you first start creating your own CNC designs, a three-axis machine will typically offer enough control and flexibility to bring any of your designs to life. Eventually, however, you may find that you feel somewhat constrained by the limits of an X, Y and Z axis.

Maybe you’re making a cylindrical component, for example, that needs holes or cut-outs milled in its sides. This type of work can be done with a three-axis machine, but it will often be a slow and somewhat inefficient process. By adding a fourth cutting axis to your CNC machine, you can reduce lead time and complete complex projects in fewer steps.

A fourth axis rotary table offers a convenient, cost-effective way to take CNC milling to the next level.

This compact 6” rotary table makes it easy to seamlessly machine challenging components by adding a fourth rotational axis around the X or Y axis, depending on how it’s mounted. The fourth axis can be programmed in the same manner as the X, Y and Z axes, and its motion can be interpolated with that of the other three axes. It also uses the same size 34 motor as the X, Y and Z motors, offering 1200 in/oz. of torque. If you’re working on a project that only requires three cutting axes, the rotary table can be easily removed from your CNC mill as well.

To learn more about our fourth axis rotary table or any of the other machines and accessories we offer at CNC Masters, feel free to give us a call or contact us online today!