Corner Comparison: Corner Chamfer vs. Corner Radius

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Using Finite Element Analysis (FEA) simulations by Third Wave Systems’ AdvantEdge CAE product, we tested different end mill corner geometries to compare their effects on both the tool and the workpiece. We studied and compared four 4 flute tools with either a 0.010” or 0.030” radius or chamfer. All tools were tested in 304 stainless steel at 1865 RPM, 244 SFM, and 0.0045 IPT for one revolution.

Both Corner Radius and Corner Chamfer tools offer advantages over Square End Mills by improving tool strength and reducing wear, though their benefits vary. One drawback of corner radius end mills is chip thinning along the radius, which can generate excess heat due to changes in chip thickness. This can lead to premature tool wear, poor surface finish, and potential work hardening. On the other hand, Corner Chamfers have the disadvantage of sharp corners where the chamfer meets the outer diameter (OD) and the end of the tool, causing local stress concentrations.

Force Analysis

The graphs above demonstrate the force exerted on the tool during cutting and how the corner size impacts the required force. As each flute engages, the forces peak in each direction. The 0.010” Chamfer generates the greatest force, while the 0.030” Chamfer requires the least. The forces with the radiused tools are very similar and fall between those of the two chamfered tools.

Temperature Analysis

The peak tool temperature graph shows the impact of chip thinning on corner radius tools and the overall corner size. The 0.030” Radius generated the most heat, while the 0.030” Chamfer generated the least. The temperature differences between the 0.010” Chamfer and 0.010” Radius was minimal, with the 0.010” Radius generated slightly less heat.

Chip and Workpiece Temperature

Understanding the temperature of the chip and workpiece is crucial for assessing tool performance. The contours above illustrate that the most heat is generated along the 0.030” Radius, followed by the 0.010” Radius. Corner Chamfer tools performed better, maintaining a lower overall temperature due to the absence of chip thinning.

Stress Analysis

The minimum principal stress on the backside of the flute indicates areas prone to tool failure. While there were slight differences between the chamfers and radii, the most notable finding was the reduction in stress with increased corner break size.

Similarly, the Mises stress analysis shows where stress is concentrated within the tool, potentially leading to failure. Again, the most significant observation was the reduction in stress with larger corner breaks.

Corner Chamfer vs. Corner Radius: Wrapped Up

Considering all factors, the 0.030” Corner Chamfer proved to be the best overall tool for 304 stainless steel. This is partly due to 304’s tendency to work harden, making excess heat generation particularly detrimental. When working with heat-sensitive materials, Corner Chamfer tools are preferable, especially during roughing, as they generate less heat due to the absence of chip thinning. Although there are minor stress concentrations at the sharp corners of Corner Chamfer tools, these are outweighed by the benefits of reduced heat generation. Larger radii exacerbate chip thinning’s impact on heat generation. While both tool styles offer advantages over square end mills, Corner Chamfer tools are more beneficial in high-heat applications where work hardening and tool wear are concerns.

Harvey Tool offers a range of Corner Chamfer Tools, with sizes ranging from 0.047” to 0.500” and various chamfer sizes to suit different applications.

Recycling Carbon Fiber: Importance & Process

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Carbon fiber is a woven cloth made of crystalline filaments of carbon cured with a polymer, which can be layered and shaped around a mold. It is an ideal material due to its impressive strength-to-weight ratio , meaning it’s very strong, but not heavy. Carbon fiber is five times lighter than steel with an equal elastic modulus, making it a better choice for many applications. Further, it is corrosion-resistant, non-flammable, and non-toxic, properties that make it an ideal material to use in aerospace, medical, construction, and military industries.

Machining Carbon Fiber

Machining Carbon Fiber can be challenging. The layered structure of the carbon fiber material can lead to delamination, uncut fibers, fiber tear-out, uneven tool wear, and poor surface finishes. Luckily, many cutting tool companies, like CoreHog, specially design tooling with different geometries that can help eliminate these manufacturing problems:

  • Straight Flute End Mills: Apply all the cutting forces radially, which helps prevent delamination.
  • Compression Cutters: Create opposite cutting forces, stabilizing material removal and preventing delamination, fiber pullout, and burrs along the surface.
  • Chipbreaker Cutters: Shear the fibers and shorten the chips, preventing fiber buildup around the cutter.
  • Diamond Cut End Mills: Utilize both left-hand and right-hand flutes to break up and shear through the fibers, ideal for roughing and profiling carbon fiber.

Explore CoreHog’s Wide Offering of Composite-Laminate Cutters, each specially engineered to cut difficult-to-machine laminate materials like carbon fiber.

Common Carbon Fiber Applications

In the aerospace industry, carbon fiber is used in plane structures to replace alloys, creating lighter planes and thus, reducing fuel consumption. Recreational sports also utilize carbon fiber to decrease weight. It is often seen as a leading material in skis, bikes, and tennis rackets, as the lighter weight can help improve performance. In professional sports leagues like Formula 1 and NASCAR, carbon fiber has grown in prevalence in recent years. Another advantageous quality of carbon fiber is its suitability in X-ray machines, allowing imaging to pass through without interruption, making it useful in many medical devices and implants.

Recycling Carbon Fiber

Why is Recycling Carbon Fiber Difficult?

Carbon fiber sheets require a significant amount of energy to produce. These large sheets are then cut down to the part size needed, and the excess material is often discarded, increasing waste production. This material is not biodegradable and is typically sent to a landfill where it will remain permanently. Further complicating recycling, carbon fiber is built to hold its shape and strength and cannot be melted down and reshaped like many plastics. When recycled, its properties are heavily degraded, rendering it useless for applications that experience heavy forces or loads.

How is Carbon Fiber Recycled?

Solvolysis

Solvolysis uses a chemical solvent to break down the polymer encasing the carbon fiber cloth. The waste carbon fiber is shredded into smaller pieces, increasing the surface area. The solvent, chosen based on the polymers used in the carbon fiber, breaks down the polymer chains, separating the carbon fiber from the polymer. Techniques like centrifugation are used to separate the substances. The carbon fiber can be further purified to restore its properties and then combined with virgin fibers to create new fabric or used by itself. This process enables the recovery of carbon fiber without sacrificing material properties.

Pyrolysis

Pyrolytic utilizes heat to break down the polymer encasing the carbon fiber cloth. The waste carbon fiber is shredded into smaller pieces and then heated in a controlled environment with limited or no oxygen. At high temperatures, the polymer undergoes thermal decomposition, producing gases, vapors, and char. The gases and vapors can be used as an energy source or further processed, while the char, which is carbon fiber and any original additives, is purified to ensure mechanical properties are maintained. The resulting carbon fiber can be used alone or combined with virgin fibers. Pyrolysis is effective for high-quality fiber recovery and energy recovery from gas byproducts.

Carbon Fiber Considerations

As we innovate with new technology, it is important to consider its impact on our planet. Carbon fiber is an amazing material that can improve many aspects across industries; however, the waste generated is not going anywhere but a landfill. Many companies are investing in producing high-quality recycled carbon fiber. With a shift in focus to designing closed-loop systems for composite materials, the future looks bright.

Traditional vs. Free Cutting Finishing Core Tools: Which Is Right for Your Application?

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Precision cutting plays a pivotal role in the manufacturing of honeycomb core. CoreHog, a leading provider of composite cutting solutions, offers two distinct styles of Finishing Core Tools: Traditional Finishing Core Tools and Free Cutting Tools. In this post, we explore the advantages and limitations of both Traditional Finishing Core Tools and Free Cutting Core Tools, helping you determine the right choice for your unique manufacturing needs.

CoreHog’s Large Core Finishing Tool

Advantages of Traditional Finishing Core Tools:

CoreHog’s Finishing Core Tools are designed to handle substantial cutting tasks, efficiently. With three size ranges available, they excel at removing high volumes of material and boast excellent tool life, making them ideal for production applications.

Assembly Configuration of CoreHog’s Large & Free Cutting Finishing Core Tools


However, these tools may pose limitations in specific applications. Traditional tools exert tool pressure, but depending on the tool geometry and part profile, the pressure may be too much for the part. This becomes more pronounced when cutting knife edge features such as chamfers and bevels, where the pressure exerted by the tool can cause the part to arch, dislodging it from the table, and ultimately causing it to deviate from specifications.

Introducing Free Cutting Core Finishing Tools:­­

To address the limitations of traditional honeycomb core finishing tools when cutting knife edge features, CoreHog offers Free Cutting Finishing Core Tools. The innovative design reduces tool pressure seen in both the Coreslicer and CoreHogger. The Free Cutting Coreslicer features a more acute and sharper angle, reducing the upward pressure exerted on the part during cutting.

 Differentiation of angle between the Large Coreslicer and the Free Cutting Coreslicer

Further, these tools feature a CoreHogger with a reduced diameter, allowing for greater offset between the CoreHogger and Coreslicer. This allows the Coreslicer to be more forward and free cutting, engaging with the material prior to the CoreHogger and reducing the resulting pressure typically exhibited by the CoreHogger.  

Reduced diameter design of Free Cutting CoreHogger decreases tool pressure on the part.

When to Use Free Cutting Tools:

CoreHog’s Free Cutting Core Finishing Tools are particularly well-suited for applications involving chamfering, beveling, and cutting angled profiles in honeycomb core materials. By reducing pressure and preventing lifting on the part, these tools ensure precise cuts without compromising part quality.

­­Traditional vs. Free Cutting Core Finishing Tool: Summarized

In conclusion, choosing the right cutting tool is crucial for achieving precise results in composite manufacturing. While traditional finishing core tools excel in handling substantial tasks, they may pose challenges when cutting angled profiles in honeycomb core materials. CoreHog’s Free Cutting Core Finishing Tools offer a solution by minimizing pressure on the part, making them ideal for chamfering, beveling, and most other angled profiles. However, in finicky applications where the knife edge part is extremely shallow, a Valve Stem Cutter may still be necessary to achieve your desired cut. By understanding your specific cutting requirements, you can select the most suitable tool for your application, ensuring optimal results in your honeycomb manufacturing processes.

Maximize Efficiency With Micro 100’s Innovative New Tool Holders

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The Micro 100 Spring 2024 Product Catalog will feature hundreds of new products, including a significant increase to its offering of both standard-style and quick change-style tool holders. These unique additions include several Double-Ended styles: Standard Double-Ended Similar ID, Standard Double-Ended Dissimilar ID, Standard Double-Ended ER, Quick Change Double-Ended Similar ID, Quick Change Double-Ended Dissimilar ID, and Quick Change Double-Ended ER.

These new Double-Ended Holders were designed to be utilized with each other to reduce set up time, and eliminate the time a machinist often spends searching for the correct size tool holder.

As an example, when a Swiss Machine is loaded with multiple combinations of holders, such as a Similar ID, Dissimilar ID, Standard with ER, and Quick Change with ER, a machinist can have all of the ID connections they require residing right in the machine, thereby reducing time spent searching for a correct holder. Holders can be flipped end-for-end to utilize a different size ID at the spindle of your choosing, and – if programmed properly from part-to-part, minimal tool position changes would be required.

The following animations are designed to provide a look at the functionality of each holder style, and the unique benefits they provide for machinists.

Standard Double-Ended Similar ID Holders

In the above animation of Standard Double-Ended Similar ID Holders, the holder enters from the left side of the screen and shows how a standard style turning tool can be entered from each end, and secured with a set screw on each side. Please note that this holder requires tools with the same shank diameter size be utilized on each side.

On the right side, the screw is then removed and the tool is removed, slightly, from the holder, before the set screw is replaced. This showcases that the tool can be positioned in several different ways in this holder, and can accommodate a project with any reach length.

Shop Standard Double-Ended Similar ID Holders

Standard Double-Ended Dissimilar ID Holders

With the Standard Double-Ended Dissimilar ID Holders, the same benefits apply as with the Standard Double-Ended Similar ID Holders. The only difference between the two styles is that one end of the Dissimilar ID Style Holders accommodates a shank diameter size one size larger than the other. Overhang can be set to meet customers’ reach and harmonics requirements.

Shop Standard Double-Ended Dissimilar ID Holders

Standard Double-Ended ER Holders

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With Standard Double-Ended ER Holders, we see the holder enter from left, and a standard tool is first inserted into the “B Side” of the holder. Then, we see a tool inserted into a Micro 100 ER Collet, before it’s connected to the “A Side” of the holder. This holder provides maximum versatility to machinists who need to utilize a rotating-type tool in static applications, such as for drilling, reaming, or spotting.

Shop Standard Double-Ended ER Holders

Quick Change Double-Ended Similar ID Holders

Designed to be used with Micro 100’s Quick Change Tooling, these Quick Change Double-Ended Similar ID Holders work by inserting a tooling with the same shank diameters into each side, until it reaches an internal locating and locking pin. A set screw then secures the tools in place on each side. Note that because of the locating and locking pin, reaches cannot be adjusted with Quick Change holders.

Shop Quick Change Double-Ended Similar ID Holders

Quick Change Double-Ended Dissimilar ID Holders

In this animation, a Micro 100 Quick Change tool with a ¼” shank diameter is inserted into the “A Side” of the holder. A Micro-Quik tool with a shank diameter one size larger, 5/16”, is then inserted into the “B Side.” Both sides are then locked into place with a set screw.

Shop Quick Change Double-Ended Dissimilar ID Holders

Quick Change Double-Ended ER Holders

In the above animation of Micro 100’s Quick Change Double-Ended ER Holders, a Micro-Quik tool is inserted into the “B Side,” and locked into place with a set screw, before a Micro-Quik drill is inserted into a Micro 100 ER Collet, before being screwed into the “A Side” of the holder.

Similar to the standard style of this holder, this allows one end of the holder to house a rotating tool in static applications.

Shop Quick Change Double-Ended ER Holders

Quick Change Double-Ended Holders in Machine

In this animation, three Quick Change Double-Ended holders slide into the Y-Axis tooling block, and screws tighten down to lock the holders in place. The Quick Change Double-Ended Dissimilar ID Holder is removed from the Y-Axis tooling block, and flipped around, showcasing the ability of most of Micro 100’s Double-Ended Holders to be flipped end-for-end without having to take apart the assembly, reducing the amount of set up time needed between tool changes. Next, the ER Collet, Nut, and Spotting Drill are removed from the Quick Change Double-Ended ER Holder and replaced with a Miniature Drill, highlighting the ability to change tools on the ER end without having to remove the holder from the machine.

Shop Quick Change Double-Ended ER Holders

Multi-Axis Finishers: The Key to Amazing Surface Finish

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A Key to Improving Surface Finish

In today’s Manufacturing Industry, part finish and machining efficiency are key to a successful machine shop. It’s no surprise, therefore, that the popularity Multi-Axis Finishers has never been greater. Helical Solutions is a leader in the manufacturing of Multi-Axis Finishers, and its customers utilize this impressive tool when faced with extremely high surface finish requirements, oftentimes swapping out a traditional Ball End Mill to dramatically improve finish while minimizing cycle times.

Multi-Axis Finisher Basic Principles

A Multi-Axis Finisher can be easily recognized by its large radius included in the profile of the tool. With a larger radius, a far greater stepover can be used pass-to-pass while keeping the same cusp height as a Ball End Mill. This decreases the cycle time by a known value called the Benefit Multiple.

A Multi-Axis Finisher with a Benefit Multiple of 8 will reduce the cycle time to 1/8 of the cycle time for a Ball End Mill of the same shank diameter – an 87.5% time savings! If a Multi-Axis Finisher is used with the same pass-to-pass stepover as a Ball End Mill, the finish will be drastically improved due to exponentially smaller cusp heights. Most situations allow both reduced cycle time and improved surface finish to be achieved.

The images below show the comparison of a ball end mill to an Oval Shape Multi-Axis Finisher with a benefit multiple of 4.

Due to their large radii, Multi-Axis Finishers are best suited for wide open, flowing, and somewhat flat surfaces. Smaller spaces, especially tight corners, will generally not see as much benefit from these tools due to limited use of the major radius.

Multi-Axis Finisher Tool Selection

The Manufacturing Industry’s leader in Multi-Axis Finishers, Helical Solutions offers 3 distinct profiles, each fully stocked and available to ship the day of purchase.

Oval Form Multi-Axis Finishers

The oval form includes 2 tangential radii and offers the most versatility in smaller spaces where a slightly varied approach angle is required, such as impellers or fan blades.

Taper Form Multi-Axis Finishers

The taper form includes 3 tangential radii and a taper angle. It allows for the largest radius, and therefore greatest potential improvement of finish and reduction of cycle time. They are best used where a specific approach angle is needed and where maximum performance gain is desired.

Lens Form Multi-Axis Finishers

The lens form includes 2 tangential radii on the end of the tool and is used for work mostly on the face of a part. Tilt angles of approximately 5 degrees are recommended for these tools to avoid working on-center.

Programming Multi-Axis Finishers

Programming Multi-Axis Finishers requires some additional consideration compared to a typical end mill. Luckily, many modern CAM packages offer support for these unique profiles, including many of Helical’s CAM partners. Each software has their own name for these toolpaths, so reach out to your CAM or Helical sales rep to find how you can program yours!

For more information on Multi-Axis Finishers, and to learn if this advantageous tool is right for you, read our Multi-Axis Finishers Q&A.

10 CNC Drill Geometries Every Machinist Must Know

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A CNC drill has many different features and geometries that directly impact the tool’s performance, productivity, and tool life in the specific material it’s machining. It is important to understand the different geometries of a drill to ensure you’re not only recognizing how they affect an application, but also which geometries you should be looking for when selecting your next drill.

1.    Point Angle

This drill geometry refers to the angle of the cutting edge of the drill. As the point angle increases on a drill, the radial forces decrease, making the angle size a huge factor in what type of material the drill is optimized for and what types of applications should be run. The smaller the point angle, the better it will perform in through hole applications. This is because the smaller angle reduces the axial forces, allowing less of the chip to be pushed out and more cutting to occur.

118° & 120° Point Angle

Many machinists opt for this angle when machining soft gummy materials.

135° Point Angle

This point angle size is an excellent choice for machining aluminum and stainless steels.

140° Point Angle

This larger point angle size is great for machining steels.

150° Point Angle

Large angles are often used for spot drilling applications, but the optimal spot drill angle is determined by the size of the angle of the final drill being used. Selecting the proper spot drill is essential to eliminating the chance of drill walking and ensuring a more accurate final product. Learn which spot angle should be used for your next drilling job in this in-depth guide.

2.    Chisel and Cutting Edges


Although the chisel edge of a CNC drill does not provide any cutting action, it is responsible for the centering of the drill, as it extrudes the material towards the cutting edges. The cutting edges are then able to start the process of producing chips, which then travel up the flutes of the drill.

3.    Flutes

The most recognizable part of a drill is its flutes. They are the deep grooves that allow for chip evacuation to occur. When one thinks of a drill, they are likely imagining a spiral flute drill. These spiral flutes complement the point angle, chisel edge, and the cutting edges. They work like an elevator system to lift the chips out of the hole, allowing them to provide excellent chip evacuation. They work great in most material types and provide good hole quality.

4.    Helix Angle

The helix angle is the angle formed by the leading edge of the land with a plane containing the axis of the drill. The main function of the helix angle is to transfer the chips out of the hole and a specific angle is relevant to the type of material that is being machined in and the particular application being run.

Low Helix

A low helix of 12° – 22° is recommended for materials like cast iron, brass, and hardened steels. In these “short chipping” materials, the chips move more freely, and the coolant provides enough assistance to properly evacuate the chips out of the hole.

Medium Helix

The most widely used helix angles are medium as they provide optimal chip evacuation and strength to the drill. Medium helix angles range from 28° – 32° and are recommended for any general purpose drilling applications.

High Helix

A high helix angle of 34° – 38° is recommended for long chipping material such as softer non-ferrous materials like brass, aluminum, and plastics. Drills with a high helix are also beneficial in deep hole applications as the chips can evacuate more easily.

5.    Web Thickness (Core)

The web is the core section of the drill body, which connects the two flutes. The thickness of the web determines the torsional strength of a drill. A drill with a larger web diameter will have more torsional strength than a drill with a smaller web diameter.

The proper web thickness is determined by the material type to be machined. Long chipping materials will require a drill with a smaller web thickness to provide adequate clearance for chip removal. When drilling short chipping materials such as cast iron, the drill web can be increased for additional strength.

6.    Corner Chamfer


A corner chamfer or radius is often added to eliminate the sharp edge at the intersection of the flutes and the outside diameter of a drill. This helps to eliminate material breakout when exiting a hole, while also helping to reduce the size of the entrance and exit burrs. This feature is also widely known to significantly extend tool life.

7.    Drill Margin

Margin(s) are the surfaces along the outer diameter of the drill which provide stability to the hole as they support the radial forces that are directed radially by the drill point.

Size of Drill Margin

The size of the margin will determine the overall quality of the hole. Wide marginswill stabilize the drill better, hold a tighter hole diameter tolerance, and improve the circularity of the hole. Narrow margins reduce friction and heat, eliminate work hardening, mitigate built-up edge, and provide better tool life.

Number of Drill Margins

The number of margins on a drill is usually determined by the type of hole being machined. Single margin drills are very common in non-interrupted holes. Double or triple margin drills are common in interrupted or intersecting holes. The more margins there are, the better the guidance is to help the drill stay straight through interrupted cuts, cross holes, and irregular or angled surfaces on exit. While adding margins does provide these benefits for irregular style cuts, they also increase friction, which causes the drill to produce more heat. This causes wear to be accelerated, reducing the life of the tool.

8.    Land of a Drill

The land is the outer portion of the body of the drill between two adjacent flutes. Land width will determine how much torsional force a drill can withstand before catastrophic failure. The smaller the land is, the more chip space there is, producing less torsional strength. The larger the land is, the less chip space there is, providing more torsional strength.

9.    Coolant-Through Channels


Not only do coolant-through channels offer any drilling application a multitude of benefits, but they are also highly recommended for hole depths that exceed 4XD (4 times diameter). Coolant-Through Drills allow for higher speed and feed rate capabilities, increased lubricity, better chip control, improved surface finish, and enhanced tool life.

10.  Shank

The shank is a very important yet overlooked drill geometry as it is the drive mechanism and is what is mounted into a Tool Holder. It is essential that the shank is held to proper diameter tolerance and considerations are being made depending on the holder being used. For example, a shank with an h6 tolerance is essential when a shrink fit style tool holder is being used.

Learning the different geometries of a CNC drill can greatly assist you in ensuring you are selecting the right drill for your next job, while understanding the functions of these features will allow you to trouble shoot any potential machining hiccups you may encounter in your future CNC drilling applications.

3 Tips for Avoiding Misaligned Holes

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One of the most common issues machinists face during a drilling operation is hole misalignment. Hole alignment is an essential step in any assembly or while mating cylindrical parts. When holes are properly aligned, the mating parts fit easily in each other. When one of the pieces to the puzzle is inaccurate, however, machinists run into issues and parts can be scrapped. The two types of common misalignment woes are Angular Misalignment and Offset Misalignment.

Angular Misalignment

Angular misalignment is the difference in slope of the centerlines of the holes. When the centerlines are not parallel, a shaft will not be able to fit through the hole properly.

Offset Misalignment

Offset misalignment is the distance between the centerlines of the hole. This is the position of the hole from its true position or mating part. Many CAD software programs will help to identify if holes are misaligned, but proper technique is still paramount to creating perfect holes.

1.    Utilize a Spotting Drill

Using a spotting drill is a common way to eliminate the chance of the drill walking when it makes contact with the material. A spotting drill is designed to mark a precise location for a drill to follow, minimizing the drill’s ability to walk from a specific area.

valor holemaking high performance spotting drill

Valor Holemaking High Performance Spotting Drill

Although using a spotting drill would require an additional tool change during a job, the time spent in a tool change is far less than the time required to redo a project due to a misaligned hole. A misaligned hole can result in scrapping the entire part, costing time and money.

Do you know how to choose the perfect spot drill angle? Learn how in this in-depth guide so you can eliminate the chance of drill walking and ensure a more accurate final product.

2.    Be Mindful of Web Thickness

A machinist should also consider the web thickness of the drill when experiencing hole misalignment. A drill’s web is the first part of the drill to make contact with the workpiece material.

Essentially, the web thickness is the same as the core diameter of an end mill. A larger core will provide a more rigid drill and a larger web. A larger web, however, can increase the risk of walking, and may contribute to hole misalignment. To overcome this machining dilemma, machinists will oftentimes choose to use a drill that has a thinned web.

Web Thinning

Also known as a split point drill, web thinning is a drill with a thinned web at the point, which helps to decrease thrust force and increase point accuracy. There are many different thinning methods, but the result allows a drill to have a thinner web at the point while having the benefit of a standard web through­out the rest of the drill body.

A thinner web will:

  1. Be less susceptible to walking
  2. Need less cutting resistance
  3. Create less cutting force

3.    Select a Material Specific Drill

Choosing a material specific drill is one of the easiest ways to avoid hole misalignment. A material specific drill design has geometries that will mitigate the specific challenges that each unique material presents. Further, material specific drills fea­ture tool coatings that are proven to succeed in the specific material a machinist is working in.

Valor Holemaking High Performance Drills for Steels and High Performance Drills for Aluminum

Helical Solutions Teams up With Mastercam to Test Different Levels of Continuous Time In Cut (CTIC)

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Don Grandt, Harvey Performance Company National Application Engineer, met up with Jesse Trinque at the Mastercam Manufacturing Lab to demo some Helical Solutions End Mills and discuss Continuous Time In Cut (CTIC).

Continuous Time in Cut (CTIC) is the amount of time that a tool is engaged with a material. When an end mill is in a cut for too long, the friction can build and surface foot can be sacrificed, greatly affecting the performance and wear of a tool.

Check out this video to watch Jesse and Don test out how different levels of CTIC directly affect tool life and performance. This series of tests, which were facilitated by Mastercam, were conducted in Okuma’s GENOS M560-V, and utilized tool paths from Mastercam. For tooling, a standard ½” Helical Solutions HEV-6, a 6 flute, variable pitch end mill with a .03” corner radius, was used to machine 17-4 stainless steel.

All tests used the same cutting parameters, setup, material, and tool, with altered CTIC.

Take a Deeper Dive Into CTIC

Tune into this episode of In The Loupe TV to learn how you can manipulate Continuous Time In Cut (CTIC) and surface foot to reduce heat in your machining applications.

Carbon Fiber Reinforced Polymers (CFRP): Running Parameters, Tool Life, & Safety Tips

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Carbon Fiber Reinforced Polymers (CFRP) is a collection of carbon fibers that, when bound together via resin, creates a material with a wide range of application possibilities. It’s strong, durable, and resistant to corrosion, making it an advantageous material for use in several advanced industries, including the aerospace and automotive industries. Despite its unique abilities, however, machining CFRP is not without its set of challenges, all of which machinists must be cognizant of to achieve desired results. Once CFRP is properly understood and the right cutting tool is selected for the job, the next step is to properly set running parameters for your application.

Square piece of cfrp laminate carbon fiber material

Running Parameters

Comparison of Metal Machining vs Composite Machining

When machining CFRP, the suggested running parameters are to have a high RPM with low feed rates. Feed rates will need to be adjusted to account for heat minimization, while RPMs may need to be dialed back to prevent excessive fraying, tearing, or splitting of fibers when cutting.

In metal machining, the tool cuts away at material, forming chips. This is possible due to the formation of the metal having natural fracture and stress lines that can be wedged by the cutting tool to create a chip. Unlike metals, machining carbon fiber does not peel away material but rather fracture and break the fibers and resin.

Milling vs Drilling Carbon Fiber

Composite holemaking or drilling is found to be more challenging than milling carbon fiber. It generates more dust due to the drilling speed. Using specific tooling for composites will be crucial in effective drilling. When machining holes, the carbon fiber will relax, creating undersized holes which requires extensive adjustments that are best automated for efficiency.

For help mitigating the challenges of composite holemaking, read Overcoming Composite Holemaking Challenges and browse CoreHog’s offering of drills, specially engineered to mitigate all-too-common holemaking headaches. To achieve better finish and avoid delamination, it is recommended to utilize conventional milling over climb milling within composites contrary to what is recommended in metal machining.

Combination of corehog specific cfrp drills including helical step, dagger, 8 facet, and tapered drill reamer

Within the aerospace industry, drilling is the most common application in machining. Like milling, performing operations such as pecking may be preferred even with increased cycle time if it reduces any chances of error that result in scrapping of the part.

Running Parallel to Grain of Fibers

While every part is different, there is a method for reducing fraying, chipping, or delamination by cutting parallel to the fiber direction when possible. This can be like cutting along the grain of wood instead of cutting perpendicular or at an angle to the grain.

Coolant Applications

The use of coolant when machining CFRP can either benefit or negatively affect the part depending on the application. The preferred coolant of choice for machining carbon fiber is typically using water or a water-soluble coolant. This is due to composites having a porous surface that could allow contaminates to enter the part itself. By using water, it prevents any issues after machining where adhesives or paint may need to be applied to the part that otherwise would not have adhered properly with contaminates present.

cnc machine looking through glass window focusing on a tool in the cut with external coolant spraying the workpiece

High Scrapping Costs

Many composite parts are unique in shape and size with custom molded designs that create a large initial cost prior to the machining stage. After the part is molded near to its shape, machining is often used to finish the part or drill holes where needed to finalize the part.

Importance of Considering Machining Challenges to Avoid Scrapping

Having a set process that is consistent and reliable is important in helping to prevent scrapping. Eliminating human error with machines that can monitor the entire process while automating tool changes when tools are worn, avoids issues before they can happen. A key factor is ensuring the setup is correct, having the right tooling, tool path, and coolant option to perform the operation effectively and accurately. With some parts serving critical functions and with a high cost, there is no exception for poor finish or incorrect cuts emphasizing the importance of having a procedure that gets the job done the right way.

Composite Cutting Tool Life Management

Wear Rate & its Effects 

Due to carbon fiber’s abrasion on the cutting tools, a rapid decrease in cutting quality will occur as soon as the tool begins to dull. Fibers will be grabbed instead of fractured, causing fraying and damage to the part. Therefore, tool life should be vigilantly monitored to replace the tool before reaching the point of dullness.

Developing a Process for Success

Unlike metal machining where tools may be utilized until they show signs of wear, this method would be unideal for CFRP as the highly expensive part could be ruined or damaged causing scrapping costs and time. It is good practice to take preventative measures by taking note of typical wear of your tools and using that information to set tool changes before it dulls. Noting tool changes and having high interval checks on cutting and dimension quality will aid in avoiding poor finish or scrapping. Some machines are equipped with tool life management systems which will greatly reduce the chances of having to scrap a part because of tool dullness.

Safety Practices When Machining CFRP

Being that chips are not formed when machining CFRP, and instead, the material is fractured, it creates dust that can spread throughout the air and other surfaces. Not only does this cause hazardous conditions for anyone nearby who may inhale the dust, but the dust is also conductive, which can ruin electronics. To avoid these issues, two different extraction methods can be used depending on the needs of the application.

Wet vs Dry Extraction

The two options for dust extraction are using coolant (wet) or vacuuming (dry). Choosing between the two is dependent on the application, but mostly dictated by the size of the application. Smaller scale machining can be contained through vacuuming, but larger applications would require coolant as vacuuming a large area may be challenging. If a lot of heat will be generated, then it is necessary to have a water-soluble coolant. This would also benefit the use of diamond tooling as they will wear faster at lower temperatures in comparison to carbide tooling. Another would be the dust collection would remain contained with the liquid preventing any airborne exposure.

Disposal Considerations

One benefit of vacuuming over coolant is the disposal process. After machining, the coolant/dust mix would require post-treatment to remove excess water before being transferred to a landfill. This would incur additional costs to the process which may cause some to lean towards vacuuming if heat is not an issue.

Conclusion

With CFRP’s wide range of uses and desirable mechanical properties for its applications, comes the effect of its challenges in machining and high cost of scrapping. Refining this process will be essential for the growing demand of carbon fiber machining in the near future. For more information on CFRP, specifically related to material properties and tool selection, read In the Loupe’s complementary post “Carbon Fiber Reinforced Polymers (CFRP): Material Properties & Tool Selection”.

The Benefits of CoreHog’s Assembly Style Tooling in Composites

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Harvey Performance Company brand CoreHog, which focuses on the manufacturing of the world’s most advanced composite and honeycomb core cutting tools, fully stocks an array of “Assembly Style Cutting Tools,” which allow a machinist to build the perfect solution for their specific application’s needs. In doing so, a cutting tool can be optimized for specific materials, densities, and manufacturing styles to increase efficiency, decrease costs, and provide unbelievable machining flexibility.

Corehog tooling for machining composites

How Does Assembly Style Tooling Work?

CoreHog’s Assembly Style Tooling works by taking multiple pieces and tool components, and assembling them together to create one finished cutting tool. The concept of assembling a completed tool allows machinists greater flexibility in choosing cutting edges that are best suited for their application or material type. Further, this type of tooling is often utilized by machinists because it’s often a less expensive alternative to solid round, non-assembled tooling, as a machinist would only need to replace the cutting end components when they begin to dull, and not the arbors or shank pieces.

CoreHog’s offering of Assembly Style Tooling includes Small Size, Medium Size, and Large Size Finishing Core Tools, as well as Valve Stem Cutters and Rebating Cutters. The way in which each system is built varies by tool type.

Finishing Core Tools

Small Finishing Core Tools

Optimized to machine small, closed features in composites, such as pockets, joggles, and closed walls, Small Size Finishing Tools are engineered for the superior finishing of honeycomb core materials. This configuration includes a Small Coreslicer with three different edge options: Smooth, Sawtooth, or Staggered Tooth, and an optional Small CoreHogger. The right edge style for the Coreslicer depends largely on the material you’re working in. While a Smooth edge style works well in lighter density honeycomb core materials such as Kevlar®, Nomex®, and Aluminum, Sawtooth and Staggered Tooth options work best for honeycomb core materials with densities of 6 pounds or higher, such as aluminum core, Kevlar®, or Nomex®.


Key Benefits: Eliminating the risk of material wrapping around the spindle by disintegrating them as they approach the face of the slicer.

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Medium Finishing Core Tools

Designed for finishing honeycomb core materials, this assembly style CNC tooling is engineered for shaping smaller complex surfaces, bevels, and external radii. For this configuration, a Medium CoreHogger and a Medium Coreslicer must be utilized and fastened with a screw. Similar to the Small Finishing Core Tool options, this assembly can be used with a Smooth, Sawtooth, or Staggered Tooth Coreslicer edge.

Key Benefits: This Medium Size Finishing Tool offering includes both carbide and high speed steel options. The carbide version is uncoated, whereas the high speed steel version is TiCN coated for extended tool life and improved wear resistance.

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Large Finishing Core Tools

Designed to vastly reduce cycle times while finishing honeycomb core materials, this assembly style tooling removes large volumes of material quickly, while providing excellent surface finish and keeping tool pressure and heat low.


Large Finishing Core Tools require a slightly more complex configuration. This type of modular tool features an Arbor, which includes a washer and screw; Large CoreHogger; and Large Coreslicer. For this assembly, four types of Coreslicer edge options are available: Smooth, Sawtooth, Staggered Tooth, or Wavy. Wavy style options are best utilized in heavier density types of Kevlar®, Nomex®, and Aluminum Core, and are engineered to be useful when machining parts that contain bond lines.

Key Benefits: The Arbors in this configuration are heat treated and finish ground for extremely tight tolerances in runout, concentricity, and perpendicularity. With tighter tolerances, harmonics are minimized while longer tool life and better part finish are observed.

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Valve Stem Cutters


Different from CoreHog’s Finishing Core Tools, Valve Stem Cutters are assembly tooling engineered for machining honeycomb core materials and finishing thin features, such as bevels and knife edge parts. To build a Valve Stem Cutter, utilize an Arbor, a Valve Stem Slicer, and a screw to fasten the two together. Similar to Small and Medium Finishing Core Tools, the Valve Stem Slicer can feature a Smooth, Sawtooth, or Staggered Tooth edge profile.

Key Benefits: The Stem design of CoreHog’s Valve Stem Arbors is optimized for free flowing applications, eliminating grabbing when machining Honeycomb Core Materials.

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Rebating Cutters


Machinists may opt to use a Modular Rebating Tool if they are aiming to reduce setup, minimize cost per cutter, and obtain flexibility with varying sandwich panel configurations. For this configuration, an Arbor connects to a Core Insert, Skin Insert, and is fastened with a screw. Here, the Arbor, which features a .500” shank diameter and a 3” overall length, can be paired with multiple sizes of Core Inserts. As of September 2022, CoreHog’s offering of Core Inserts range in diameter from .875” to 1”, with a length of cut spanning from .160” to .312”. All Inserts feature TiAlN coating, which provides high hardness and high temperature resistance. Finally, the Skin Insert features a ½” diameter, and provides a machinist with the option of DLC or CVD Coating. While DLC coating provides optimal performance, true crystalline CVD diamond coating works to significantly extend tool life.

Key Benefits: The complex geometry of Sandwich Panel Cutters – Arbors helps to reduce tearing, flagging, and fuzz, while providing a rebated area to allow for edge filling or fasteners, later on.

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For more information on CoreHog’s Assembly Style Tooling, visit its website at corehog.com.