Valor Drills Excel in Stainless Steel and Titanium

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At Valor Holemaking, we know that drilling stainless steel and titanium isn’t just difficult, it’s one of the most demanding challenges manufacturers face. These materials are unforgiving, known for their toughness, low thermal conductivity, and tendency to work harden, which often result in significantly reduced tool life.

Before releasing Valor Holemaking’s High Performance Drills for Stainless Steel & Titanium in September 2025, Harvey Performance Company engineers performed extensive testing, during which time more than 117,000 holes were drilled across multiple materials and setups.

Our objective was to evaluate tool life, hole quality, and tolerance under production-level parameters. By benchmarking the performance of the Valor drill against several best-in-class competitors, we aimed to provide data-driven insight into how it performs in demanding stainless steel and titanium applications.

Testing in 316L Stainless Steel

Stainless Steel Testing Information

MaterialAISI 316L (200 HB)
Valor DrillSKU: V623060-X
Diameter: 12.7 mm
L/D: 5XD
Coating: Val-Max-X
HolderCat40 Hydraulic Holder
ParametersDrilling Depth: 2.3000”
Speed & Feeds: 200 SFM, 0.010 IPR
Coolant: Blaser Vasco 7000 (9%) at 1,000 PSI

Tool Life in Stainless Steel

This chart displays the total number of holes drilled in AISI 316L stainless steel before tool failure or test completion. The Valor drill reached the testing limit of 2,000 holes with no signs of failure, while other tools showed significant variation in tool life, ranging from more than 200 holes to 1,300. This proves that this Valor high-performance drill can run longer, compared to that of top competitors, particularly in stainless steel where premature wear is common.

Finished Hole Diameter Consistency in Stainless Steel

The data in the chart to the left shows the average finished hole diameter across the test range for each tool. The Valor drill consistently held the nominal 12.7 mm diameter within the IT7 tolerance band. All competitors drifted into the IT9 range, indicative of inefficient chip formation or inefficient cutting.

Measuring hole diameter consistency of testing blocks

Valor Drill – Finished Hole Diameter Consistency Across 2,000 Holes

This chart displays the finished hole diameters measured from Valor’s drill over the course of 2,000 holes in 316L stainless steel. Each point represents an actual measurement, and the data shows the drill maintained exceptional consistency throughout the test. The variation across all holes was just 8 microns, with every measurement falling within the IT7 tolerance band.

What is an IT Band?

In the context of precision machining, IT stands for International Tolerance grade—a standardized system used to define the allowable variation in hole dimensions. The lower the IT number, the tighter the tolerance and the higher the precision. For example, a hole finished within IT6 tolerances is more precise than one within IT8.

IT band values vary depending on the nominal diameter of the hole being machined. In our testing, we focused on a 12.7 mm drill diameter, so the range of acceptable deviation for each IT band is scaled accordingly.

Geometric Accuracy in Stainless Steel:

In addition to maintaining tight hole diameters, Valor’s High Performance Drills for Stainless Steel & Titanium held excellent geometric tolerances throughout the stainless steel test.

  • True Position: 43 µm
  • Cylindricity: 24 µm
  • Straightness: 11 µm

These results indicate that the Valor drill stayed stable in the cut, minimizing drift and taper even after 2,000 holes. For parts where positional accuracy is critical, this helps reduce the need for secondary operations or in-process adjustments.

Inspecting Tool Edge Wear

Testing in 6Al-4V Titanium

Titanium Testing Information

Material6Al-4V (33HRC)
Valor DrillSKU: V623060-X
Diameter: 12.7 mm
L/D: 5XD
Coating: Val-Max-X
HolderCat40 Hydraulic Holder
ParametersDrilling Depth: 2.3000”
Speed & Feeds: 200 SFM, 0.010 IPR
Coolant: Blaser Vasco 7000 (9%) at 1,000 PSI

Tool Life in Titanium vs. Leading Competitors

In this titanium drilling comparison, the chart illustrates total hole count before tool failure or the test’s 1,200-hole cap. The Valor drill, again, reached the maximum without failing, whereas all competitor tools experienced failure beforehand.

Finished Hole Diameter Consistency in Titanium

This chart compares the average finished hole diameters produced by Valor’s drill and several leading competitors in Ti-6Al-4V. Valor’s drill consistently held hole size within the IT6 tolerance band, the tightest shown, while other drills produced holes that fell into IT7 or IT8 ranges. This distinction highlights Valor’s ability to maintain high dimensional accuracy even in a challenging material like titanium. The tighter tolerance indicates better tool stability, less deflection, and more reliable performance across extended runs, which is critical for precision-focused industries like aerospace and medical manufacturing.

Valor Drill – Finished Hole Diameter Consistency Across 1,200 Holes

This chart illustrates the finished hole diameters recorded from Valor’s drill over the 1,200 holes drilled in titanium. Throughout the entire run, the drill consistently held dimensions within the IT6 tolerance band, with hole sizes deviating by only 9 microns from the nominal diameter (12.7mm).

Geometric Accuracy in Titanium

Valor’s drill also demonstrated tight geometric control throughout the titanium test.

  • True Position: 46 µm
  • Cylindricity: 23 µm
  • Straightness: 7 µm

These values remained consistent across all 1,200 holes, reinforcing the tool’s ability to cut clean, accurate features in a challenging material. This level of consistency is especially beneficial in aerospace or medical applications where tight tolerances are required.

Valor Holemaking Application Engineers Inspecting Drills After Test

Conclusion

These internal tests offer insight into how Valor High Performance Drills for Stainless Steel & Titanium perform under consistent parameters in stainless steel and titanium. In both tests, the drills showed the ability to maintain hole quality over extended cycles, potentially improving cost-efficiency and reducing downtime in production settings. While results may vary depending on material, fixturing, and machine setup, this testing provides a data-driven starting point for evaluating suitability in demanding drilling applications.

Explore Valor’s High Performance Drills for Stainless Steel & Titanium

The Benefits of Combined Drill & Countersinks

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Two of the most frequently recurring operations across a variety of applications are CNC drilling and countersinking. Since these two processes are often interdependent, managing space in the tool crib and time lost on tool changes can become cumbersome when using dedicated tools for each operation. Using combined drill and countersinks eliminates these concerns and has become a go-to tool across machine shops.  

valor holemaking combined drill and countersink tools on a table with a slide caliper and ruler
Variety of Combined Drill & Countersinks

What is a Combination Drill & Countersink Tool?

A Combined Drill & Countersink is a specialized tool designed to perform two critical operations in one step: drilling a hole and creating a countersink. These tools are typically short and rigid, ideal for producing either a shallow conic or a center hole. Their double-ended design minimizes downtime by enabling quick transitions between tasks.

Valor Holemaking’s Combined Drill & Countersink

Key Features of Combined Drill & Countersinks

They feature a smaller drilling pilot and larger diameter countersink. The drill pilot resembles a spot drill, making it useful for predrilling applications. The stub length of the drill mitigates deflection and ensures accurate location of a hole’s center. When preparing a spot hole for a longer drill, it prevents walking or wobbling off-center. 

Common Applications for Combined Drill & Countersinks

Many holemaking applications begin with spotting and end with countersinking, making combination multi-functional tools cost-effective and time efficient. As the tool drills into the material, the larger countersink diameter chamfers the top edges, allowing fasteners to sit flush with the surface.

Where and How to Use a Combined Drill & Countersink

The primary use of a combined drill and countersink is to create center holes in materials that will be turned between two centers. These centers help accurately position a workpiece along its axis between a lathe chuck and tailstock. Live centers are used in applications requiring a high level of concentricity and support. They typically feature a 60° included angle, which is the angle most combined drills and countersinks are manufactured with. For this reason, combined drill and countersinks are often referred to as center drills.

Combined drill and countersinks are also essential in any application where screws need to sit flush in the workpiece. Holes need to be drilled and countersunk across all industries. Flush-mounted fasteners are required in applications such as aircraft panels and structural components, automotive engine components, boat hulls and marine components, electronic device housings, and covers of all types.

Example of countersunk hole

Types of Combination Drill/sinks: 60°, 82°, and 90° Angles

Harvey Tool and Valor Holemaking offer combined drill and countersinks in 60°, 82°, and 90° included angles. While 60° tools are most commonly used for center drilling, 82° and 90° included angles are designed to match the angles of the most popular flat and oval head screws. These tools allow users to create countersunk fastener holes in a single step.

Important Tips for Running Combination Drills

When running a combined drill-and-countersink, it is important to ensure that chiploads (IPR) are based on the drill diameter. Since the drill diameter is always smaller than the chamfer area, it is safer to use parameters designed for the drill portion of the tool rather than calculating an effective cutter diameter for the chamfer.

Valor Holemaking Combined Drill & Countersink in the Spindle
Valor Holemaking Combined Drill & Countersink in the Spindle

Why These Tools Are Essential in Machining

Combined drill & countersinks are cost-effective and efficient tools to have in your arsenal. Whether you’re preparing a workpiece for turning between centers, spot drilling, or creating countersunk holes for fasteners, these reliable tools complete the job quickly and effectively.

Mastering Precision: Pilot Drills in CNC Machining

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When it comes to achieving precision in CNC drilling applications, the choice of tools and techniques can make a significant difference in the outcome. One essential element that often doesn’t get the spotlight it deserves is the Pilot Drill. This blog post will explore the importance of pilot drills, their applications, and best practices for integrating them into your CNC machining processes.

What is a Pilot Drill?

A pilot drill is used to create a guide hole in deep drilling applications where precision is required. This guide hole keeps the drill on center, maintaining straightness throughout the cut. By creating a pilot hole, machinists can also improve the quality of the finished product and extend the life of their tools.

The Importance of Pilot Drills in CNC Machining

1. Enhanced Accuracy

The primary advantage of using a pilot drill is the enhanced accuracy it provides. When working with harder materials or complex geometries, a small pilot hole helps maintain the alignment of the longer drill, reducing the risk of misalignment and defects.

2. Extended Tool Life

Using a pilot drill can significantly extend the life of your deep-hole drilling tools. By first creating a pilot hole, the chasing drill experiences less stress, reducing wear and tear, and the chance of breakage, ultimately leading to cost savings from longer tool life.

3. Improved Chip Removal

Pilot drilling can enhance chip removal, particularly in deep-hole drilling scenarios. The smaller pilot hole allows for better coolant flow, which is crucial for effective chip evacuation and maintaining optimal cutting temperatures.

Applications of Pilot Drills

Pilot drills are versatile and can be used in various applications, including:

  1. Deep-hole Drilling: Pilot holes create a guide when drilling deep holes for improved centering and straightness.
  2. Tapping Operations: A pilot hole can facilitate easier and more accurate tapping.
  3. Reaming: When preparing for reaming operations, a pilot drill can ensure the hole is properly aligned and sized.
  4. Screw and Bolt Holes: Pilot holes are essential for ensuring screws and bolts are inserted correctly and securely.

Best Practices for Using Pilot Drills

1. Application      

Piloting is recommended for tighter tolerance holes when drilling at depths of 8xD or greater. Valor Holemaking provides a custom tolerance of +0.0002/+0.0005 (+0.005mm/+0.013mm) to create the perfect oversized guide hole for their traditional drill lines capable of drilling 8xD or greater. Valor Holemaking’s Pilot Drills also include a +2/+1 deg angle tolerance to ensure a larger angle than the chasing drill. Piloting depth is recommended as 3xD for all applications drilling 8xD or greater.

2. Choose the Right Size and Point Angle

Selecting the appropriate size for your pilot drill is crucial. As a rule of thumb, the diameter of the pilot hole should be slightly larger than the diameter of the final hole. This allows for optimal support for the chasing drill while preventing excessive material removal. The pilot drill’s point angle should be equal to or larger than the succeeding drill. This allows the tip of the succeeding drill to engage the material before the flank does (see figure below).

3. Optimize Feed Rates

When using a pilot drill, ensure that the feed rates are optimized for both the pilot and the larger drill. Adjusting the feed rate can improve performance and reduce the risk of tool breakage. Valor Holemaking’s downloadable speeds and feeds tables and Machining Adviser Pro are excellent resources, and you can always consult Valor Holemaking’s Tech Team for further assistance!

4. Use Proper Coolants

Effective cooling and lubrication are vital in metal machining. Ensure that your pilot drill is adequately cooled with flood coolant or adjust speeds and feeds to maintain tool integrity and enhance cutting performance.

5. Maintain Tool Condition

Regularly check the condition of your pilot drills. Worn or damaged pilot drills can lead to inaccuracies and affect the performance of subsequent operations.

6. Integrate with CNC Programming

Incorporate pilot drilling into your CNC programs to ensure that it’s executed at the right stage of your machining process. Program one revolution or brief dwell at the bottom of the pilot hole to ensure a clean surface. This will help streamline operations and improve overall efficiency.

 

Conclusion

Pilot drills may seem like a small detail in the larger scope of CNC machining, but their impact on precision, tool life, and overall efficiency is significant. By understanding their importance and implementing best practices, machinists can enhance their processes and achieve superior results. Whether you’re a seasoned CNC operator or just starting out, incorporating pilot drills into your workflow is a smart move that can lead to greater accuracy and success in metal machining.


Mastering CNC Drilling: Geometries and Key Factors

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Selecting the proper drill for a specific application is essential to ensuring a successful cnc drilling job. Achieving a perfectly machined hole can often be challenging. There are many machining woes that can occur when drilling into a material. These can greatly affect hole quality, and regardless of the material being machined, there is often zero margin for error to ensure all components meet specifications.

To ensure you are selecting and using the correct drill, you need not only a deep understanding of drill geometries, but also the factors that influence the performance of the drill and quality of the hole. In this comprehensive guide, we’ll dive into drill geometries, while also exploring the performance factors that determine CNC drilling results. Furthermore, we’ll connect these to the strategic decisions that drive the tool selection process, so you can gain a competitive edge at the spindle.

Performance Factors Influencing CNC Drilling Success

Part Material

Different materials require different drill geometries and cutting speeds to maintain hole quality and prevent excessive wear. With different types of materials, whether it be a softer non-ferrous material like aluminum or a harder ferrous material like stainless steels, you’ll face different challenges as you manufacture your part. To ensure that you’re getting the best performance and tool life possible features and geometries must be considered.

metal blocks that have many holes from cnc drilling operations

CNC Drill Geometries

It is important to understand the different geometries of a drill to understand how they affect an application. For an in depth dive into drill geometries, read 10 CNC Drill Geometries Every Machinist Must Know. This breaks down the unique aspects of geometries and how they affect the cnc drilling process.

Drill Geometries and Drill Walking

CNC drill walking occurs when a drill lacks sufficient engagement with the material. This causes it to deviate from its intended tool path, leading to inaccuracies in hole placement and dimensions. This occurs due to various factors, often including improper drill geometry choice. Understanding how different drill geometries influence drill walking is crucial to ensure you’re achieving precision and consistency in every hole.

Point Angles

The point angle dictates cutting forces and chip evacuation. Choosing the right angle, such as 118° or 135°, based on material hardness, ensures efficient drilling and prevents walking. The shallower the point angle, the better the distribution of cutting forces on the material. Higher angles walk less, as the point grabs into the material easier. Machinists must weight these options when choosing the proper drill.

Web Thickness

Web thickness is the distance between cutting edges or flutes at the face of the drill. This is where stability is generated in a tool. Webs that are too thin can increase the likelihood of breakages, while webs that are too thick will generate unnecessary cutting forces. Finding the proper blend of stability and cutting force is a common struggle for machinists.

CNC Drill Length Considerations

Flute and overall length impact stability and chip evacuation. Matching these lengths to drilling depth prevents deflection and enhances hole quality.

While it may be easiest to purchase a long drill that will work in a variety of scenarios, it is not the best choice to ensure precision. Machinists should best match their required depth to the effective depth of a drill. This ensures that the tool will be as rigid as possible, generating the straightest holes.

As tool length increases, rigidity decreases. Therefore, a properly matched drill will be as rigid as the situation allows. This affords the machinist with the best possible outcome for their unique drilling application.

Coolant-Through Drilling

Proper cooling and lubrication extends tool life and ensures excellent hole quality. If your machine is equipped with the option to run through spindle coolant tooling, it can be extremely beneficial to your application. Unlike an end mill, where chips often have the ability to evacuate outward from the tool, the chips in a drilling operating are held captive inside the feature as it’s being drilled. Here, chips are only able to evacuate through the drill fluting

Through spindle coolant not only cools and lubricates a drill at the point of material removal, but also forcibly evacuates the chips. This can increase your tool’s life while reducing or removing the need for peck cycles all together. This means faster cycle times and higher production rates for your product.

On the other hand, coolant can be fed externally, and sprayed onto the tooling. This will aid in cooling and lubricity. The downside is it is less efficient than utilizing a coolant-through drill. In deep hole drilling applications, external coolant is often ineffective for chip evacuation efforts, and is not the ideal choice for the best results.

Speeds & Feeds

Optimizing speeds & feeds is essential for efficient and accurate drilling. There is not a “one size fits all approach” for speeds & feeds, as all tools and materials require a slightly different approach.

Finding the right balance for each material prevents tool wear and ensures effective chip evacuation. Valor Holemaking offers comprehensive starting parameters in the form of Speeds & Feeds Charts and each tool is also supported by Machining Advisor Pro. This tool allows machinist to custom generate speeds & feeds based off the exact tool path, material, and machine setup.

Rigidity and Stability

A sturdy machining setup reduces vibrations during drilling, improving hole quality. The same can be said about the drill within. A rigid tool is a stable tool, especially as the depth requirements increase. Stability is especially important for drilling heavy-duty materials. This can be impacted by several factors, most importantly the quality of the tool and its design, as well as its chip management capabilities. High precision and high-performance solid carbide drills are designed for the utmost rigidity to ensure repeatability time after time and part after part.

Software and Programming

CNC programming software simplifies creating and editing drilling programs. Compatibility with common CAD/CAM software streamlines integration. Much like machine quality, proper programming is an important step in ensuring precision in CNC drilling applications. CAD/CAM integration ensures the correct dimensions are input to the software to best ensure the tool correctly fits the required parameters.

Exploring CNC Drilling Geometries & Key Factors: Wrapped Up

There are many different drill geometries and factors that can directly impact a drill’s performance and hole quality. Understanding these features can greatly assist in your tool selection process, allowing you to improve productivity and hole quality, so you can gain a competitive edge at the spindle. Drilling is often the most precise aspect of machining, so mastering geometries is critical to success.

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 Honeycomb Core Tools

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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 Honeycomb Core Finishing 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 Honeycomb Finishing 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 infographic of corehog's honeycomb core finishing tools

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.  

large and free cutting honeycomb core finishing tools

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.

Helical x Mastercam: 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.

CFRP: Running Parameters, Tool Life, and 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”.

CFRP: Material Properties and Tool Selection

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Carbon Fiber Reinforced Polymers (CFRP) is composed of carbon fibers, bound with resin, to create a groundbreaking material that has proven to have limitless application possibilities in a wide range of composite cutting industries. Due to its attractive properties of strength, durability, corrosion resistance, and its lightweight nature, there has been a rising utilization of carbon fiber in the aerospace and automotive industries. However, it does not come without its own set of challenges in comparison to typical metal machining.

Three sheets of cfrp carbon fiber material on top of one another

CFRP Properties

CFRP has a high resistance to being deformed without permanent effects (elastic modulus), resistance to tension, low thermal conductivity, and low thermal expansion. While many of these properties are ideal for many applications, there are unique effects that must be considered when machining.

Abrasiveness

CFRP’s high elastic modulus makes it highly abrasive, causing challenges in tool wear and tool life that must be addressed. For example, while milling typical metals, clean chips are formed and ejected. But milling carbon fiber is like sanding, where material is removed in the form of dust particles.

Abrasion is a large issue in carbon fiber machining as it is responsible for poor tool life and dullness of the tool that can cause a part to be scrapped. As soon as a tool begins to dull, it will cause poor part finish and increase the chances of delamination and fraying.

Causes of Heat Generation

Typically, in metal machining, most of the heat is transferred into the chips with a fraction of the heat into the part and workpiece. Due to CFRP’s low thermal conductivity and no chips formed to dissipate the heat, most of the heat is transferred to the tool and part. This heat is unideal, as it will cause more tool wear and potentially cause damage, resulting in delamination.

For more information on composite delamination, read “Overcoming Composite Holemaking Challenges.”

Varying Properties

No composition of CFRP is made the same, meaning that operating parameters can vary. There is no one-solution-fits-all for every application, as it is often found to be less predictable than metals due to its varying properties. These varying components includes the fiber type, fiber density, resin type, layup orientations, thickness, matrix hardness, and heat sensitivity, which all must be taken into consideration.

Methods to Reduce CFRP Issues

Having high interval checks to monitor cutting and dimension quality to catch any errors before they may be irreversible is one way address CFRP machining issues. Another method to tackle CFRP would be through picking the right tool for the application.

Selecting a CFRP Tool

Tooling material type (substrate) and geometry both determine the quality of cutting the carbon fiber and durability of the tool.

Tooling Substrate/Coating

When selecting a tool to machine CFRP materials, it is essential to opt for a tool that is strong, sharp, and resistant to the abrasive properties that CFRP holds. Many machinists opt for solid carbide cutters with diamond coatings such as DLC, CVD, or PCD, as they provide the tooling with increased tool life and improved cutting action. These tools provide added hardness and abrasion resistance to combat the effects of machining CFRP.

Corehog end mill coating chart for selecting a tool to machine cfrp carbon fiber materials
CoreHog’s Coating Chart

While PCD diamond tools are considerably higher in price than other diamond coated tooling options, they provide the longest tool life and performance against abrasion and tool wear. Often, they are more cost effective in the long run due to their longevity, when compared to cheaper options that only save money in the short term.

Product image of a corehog square pcd diamond end mill
CoreHog PCD Diamond End Mill – Square

 

Product image of a Corehog ball nose PCD diamond end mill
CoreHog PCD Diamond End Mill – Ball Nose

In comparison to the cost of the part to be machined, the tool may be a fraction of the cost, making it worth spending the extra money to prevent greater costs that come with scrapping the part. Composite cutting tool manufacturer, CoreHog, stocks an array of PCD Diamond End Mills in Square and Ball Nose profiles.

Tooling Geometry

The geometry of a tool also plays a vital role in its machining capabilities of CFRP. There are many different geometry solutions, depending on your application, with different flutes, angle of cut approach, and profile. Corehog’s selection of CFRP Router Bits offer a great solution to your various CFRP needs.

Product image of a corehog cfrp router bit upcut burr style
CoreHog CFRP Router Bits – Burr Style – Upcut

Product image of a corehog cfrp router bit end mill upcut
CoreHog CFRP Router Bits – End Mill Style – Upcut

Product image of a corehog cfrp router bit drill point upcut
CoreHog CFRP Router Bits – Drill Point Style – Upcut

Benefits of CoreHog Assembly Style Tools 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.