How to Maximize High Balance End Mills

High speed machining is becoming increasingly widespread in machine shops all over the world due to the proven benefits of greater efficiency and productivity through increased spindle speeds and metal removal rates.  However, at such high spindle speeds, otherwise negligible errors and imperfections can cause negative effects such as reduced tool life, poor surface finish, and wear on the machine itself. Many of these negative effects stem from an increase in total centrifugal forces leading to vibration, commonly referred to in the industry as chatter. A key contributor to vibrations and one of the more controllable factors, is tool unbalance.

Why Balance is Critical to Machining

Unbalance is the extent to which the tool’s center of mass diverges from its axis of rotation.  Small levels of unbalance may be indistinguishable at lower RPMs, but as centrifugal force increases, small variations in the tool’s center of mass can cause substantial detrimental effects on its performance. High Balance End Mills are often used to help solve the problem of vibrations at the increased spindle speeds. Balancing is used to make compensation for the intrinsic unsymmetrical distribution of mass, which is typically completed by removing mass of a calculated amount and orientation.

infographic showcasing all aspects axii for high balance machining

Image Source: Haimer; Fundamentals of Balancing

Helical Solutions offers High Balance End Mills in both 2 and 3 flute options (see Figure 2), square and corner radius, along with coolant-through on the 3 fluted tools. These end mills are balanced at the industry standard of G2.5 at 33,000 RPM: G stands for the potential damage due to unbalance, which can be expressed as “Balancing Quality Grade” or G and 2.5 is the vibration velocity in MM per second. These tools are designed specifically to increase performance in highly balanced machining centers that are capable of elevated RPMs and feed rates. With high balance tooling, improved surface finishes are also achieved due to reduced vibrations during the machining process. Additionally, these end mills have been designed around current high-end tool holding, and come in a variety of neck lengths at specific overall lengths. These dimensional combinations result in maximum rigidity and reduced excess stick out, allowing for optimal performance and the ability to push the tools to the limit.

cnc high balance end mills in both 2 and 3 flute designs

High Balanced Tooling Cost Benefits

Machinists who choose to use High Balance End Mills will see certain benefits at the spindle, but also in their wallets. Cost benefits of opting to run this type of tool include:

Utilizing Tap Testers

What Tap Testers Do

Vibrations are your applications worst enemy, especially at elevated RPMs and feed rates. Using resources such as a Tap Tester can help decrease vibrations and allow you to get the most out of your High Balance End Mills by generating cutting performance predictions and chatter limits.

How Tap Testing Works

how to properly tap test a cnc tool

Image Source: Manufacturing Automation Laboratories Inc.

Tap Testing generates cutting performance predictions and chatter limits. In a tap test, the machine-tool structure is “excited,” or tested, by being hit with an impulse hammer. In milling, the machine-tool structure is usually flexible in all three directions: X, Y, and Z, but in milling applications where High Balance Tooling is used, the flexibility is commonly only considered in two planes – the X and Y directions. By hitting the X and Y directions with the impulse hammer, the impact will excite the structure over a certain frequency range that is dependent on the hammer’s size, the type of tool being used, and the structure itself. The frequencies generated from the initial hit will produce enough information that both the impact force measurement and the displacement/accelerometer measurement are available. Combining these two measurements will result in the Frequency Response Function, which is a plot of the dynamic stiffness of the structure in frequencies.

After the information from the Tap Test is gathered, it will then process the information into useful cutting parameters for all spindles speeds such as cut depths, speed rates, and feed rates. In knowing the optimum running parameters, vibrations can be minimized and the tool can be utilized to its full potential.

High Balanced Tooling Summarized

Keeping vibrations at bay during the machining process is extremely important to machining success. Because one cause of vibration is tool unbalance, utilizing a balanced tool will result in a smoother job, a cleaner final product, and a longer life of both the tool and spindle. Machinists who choose to use High Balance Tooling can utilize a Tap Tester, or a method for generating the perfect running parameters for your tool and machine setup to ensure that machining vibration is as minimal as possible.

Shank Tolerances, Collet Fits, & h6 Benefits

A cutting tool’s shank is one of the more vital parts of a tool, as it’s critical to the collet-tool connection. There are several types of shanks, each with their own tolerances and suitable tool holder methods. One of the most popular and effective tool holding styles is a shrink fit tool holder, which works with h6 shanks, but what does this mean and what are the benefits of it? How is this type of shank different from a shank with standard shank tolerances? To answer these questions, we must first explore the principals of tolerances.

The Principals of Tolerances

Defining Industry Standard Tolerances

There are two categories of shank tolerances that machinists and engineers operating a CNC machine should be familiar with: hole basis and shank (or shaft) basis. The hole basis system is where the minimum hole size is the starting point of the tolerance. If the hole tolerance starts with a capital “H,” then the hole has a positive tolerance with no negative tolerance. The shank basis system is where the maximum shank size is the starting point. This system is relatively the same idea as the hole basis system but instead, if the tolerance starts with a lowercase “h,” the shank has a negative tolerance and no positive tolerance.

Letter Designations

The limits of tolerance for a shank or hole are designated by the appropriate letter indicating the deviation. For instance, the letter “k” has the opposite minimum and maximum designations as “h”. Tolerances beginning with “k” are exclusively positive, while tolerances beginning with “h” are exclusively negative. The number following the given letter denotes the International Tolerance (IT) grade. For example, a tolerance with the number 6 will have a smaller tolerance range than the number 7, but larger than the number 5. This range is based on the size of the shank. A hole that has a 0.030” diameter will have an h6 tolerance of (+0.0000,-0.0002), while a 1.00” hole with have an h6 tolerance band of (+0.0000,-0.0005).

It is important to note that most sources list IT tolerances in millimeters, while the graph below has been translated to inches. Operations that require more precise manufacturing, such as reaming, will have lower IT grades. Operations that do not require manufacturing to be as precise will have higher IT grades.

graph showing shank tolerances vs diameter

Preferred Collet Fits

Different types of combinations of hole basis and shank basis tolerances lead to different types of collet fits. The following table offers insight into a few different types of preferred fits and the shank tolerances that are required for each.

infographic of collet fits and the associated clearance
Image: Machinery’s Handbook 29th Edition.

Shrink Fit Tool Holders

The shrink fit holder is one of the more popular styles of tool holders because of its ability to be more customizable, as evident in the chart above. In this method, a collet is heated to expand, then cooled to contract around the shank of a tool. At room temperature, a cutting tool should not be able to be inserted into a shrink fit holder – only when the holder has undergone thermal expansion due to the introduction of a significant amount of heat should the tool fit. As the holder cools, the tool is held tighter and tighter in place. Typically, a holder is heated through a ring of coils by an induction heater. It is important to heat the holder uniformly, paying mind to not overheat it. Doing so could cause the shank that is being held to expand within the holder and remain stuck.

shrink fit tool holder

Benefits of Shrink Fit Tool Holders

  1. Gripping power. The shank is held flush and uniform against the holder, resulting in a tighter connection.
  2. Low runout. A more secure connection will result in extended tool life, and a higher quality surface finish.
  3. Better balance for high RPM. With a tighter tool-to-holder connection, the opportunity exists for more aggressive running parameters.

Explore More About Tool Holders With Our Cutting Tools Explained Webinar

Shank Tolerances Summarized

Understanding shank tolerances is an intricate part of the machining process as it impacts which tool holder is appropriate for your job. A secure holder connection is vital to the performance of the tool in your application. With an h6 shrink fit holder, the result is a secure connection with stronger gripping power. However, only certain shanks are able to be used with this type of holder. From the letter designation assigned to a shank, to whether that letter is upper or lowercase, each detail is vital to ensuring a proper fit between your tools shank and its corresponding shrink fit holder.

Drill / End Mills: Drill Style vs. Mill Style

Drill / End Mills are one of the most versatile tools in a machinist’s arsenal. These tools can perform a number of different operations, freeing space on your carousel and improving cycle times by limiting the need for tool changes. These operations include:

  1. Drilling
  2. V-Grooving
  3. Milling
  4. Spot Drilling
  5. Chamfering

Shop Harvey Tool Dill/End Mills Today – Fully Stocked in Multiple Styles

The ability of the Drill / End Mill to cut along the angled tip as well as the outer diameter gives it the range of operations seen above and makes it an excellent multi-functional tool.

5 unique drill mill operations

Drill Style vs. Mill Style

The main difference between Drill / End Mill styles is the point geometry.  They are defined by how the flutes are designed on the end of the tool, using geometry typically seen on either an end mill or a drill.  While mill style tools follow the features of an end mill or chamfer mill, the drill style geometry uses an S-gash at the tip.  This lends strength to the tip of the tool, while giving it the ability to efficiently and accurately penetrate material axially.  While both styles are capable of OD milling, mill style tools will be better for chamfering operations, while drill style will excel in drilling.  The additional option of the Harvey Tool spiral tipped Drill / End Mill is an unprecedented design in the industry.  This tool combines end geometry taken from our helical flute chamfer cutters with a variable helix on the OD for enhanced performance. Versatility without sacrificing finish and optimal performance is the result.

graphic showcasing the tool face differences between and mill and drill mills
Left to Right: 2 Flute Drill Style End, 2 Flute Mill Style End, 4 Flute Mill Style End

Drill Mills: Tool Offering

Harvey Tool currently offers Drill / End Mills in a variety of styles that can perform in different combinations of machining applications:

Mill Style – 2 Flute

This tool is designed for chamfering, milling, drilling non-ferrous materials, and light duty spotting. Drilling and spotting operations are recommended only for tools with an included angle greater than 60°. This is a general rule for all drill mills with a 60° point. Harvey Tool stocks five different angles of 2 flute mill-style Drill / End Mills, which include 60°, 82°, 90°, 100° and 120°. They are offered with an AlTiN coating on all sizes as well as a TiB2 coating for cutting aluminum with a 60° and 90° angle.

harvey tool 2 flute mill style drill end mill

Mill Style – 4 Flute

4 flute mill-style Drill / End Mills have two flutes that come to center and two flutes that are cut back. This Drill / End Mill is designed for the same operations as the 2 flute style, but has a larger core in addition the higher flute count. The larger core gives the tool more strength and allows it to machine a harder range of materials. The additional flutes create more points of contact when machining, leading to better surface finish. AlTiN coating is offered on all 5 available angles (60°, 82°, 90°, 100°, and 120°) of this tool for great performance in a wide array of ferrous materials.

harvey tool 4 flute mill style drill mill

Drill Style – 2 Flute

This tool is specifically designed for the combination of milling, drilling, spotting and light duty chamfering applications in ferrous and non-ferrous materials. This line is offered with a 90°, 120°, and 140° included angle as well as AlTiN coating.

2 flute drill mills drill style

Helical Tip – 4 Flute

The Helically Tipped Drill / End Mill offers superior performance in chamfering, milling and light duty spotting operations. The spiral tip design allows for exceptional chip evacuation and surface finish. This combined with an OD variable helix design to reduce chatter and harmonics makes this a valuable tool in any machine shop. It is offered in 60°, 90°, and 120° included angles and comes standard with the latest generation AlTiN Nano coating that offers superior hardness and heat resistance.

4 Essential Corner Rounding End Mill Decisions

A Corner Rounding End Mill is typically used to add a specific radius to a workpiece, or in a finishing operation to remove a sharp edge or burr. Prior to selecting your tool, mull the following considerations over. Choosing the right tool will result in a strong tool with a long usable life, and the desired dimensional qualities on your part. Choosing wrong could result in part inaccuracies and a subpar experience.

Selecting the Right Pilot Diameter for Your Corner Rounding End Mill

Corner Rounding End Mill with dimension callouts

The pilot diameter (D1 in the image above) determines the tool’s limitations. When pilot diameters are larger, the tool is able to be run at lower speeds. But with smaller pilot diameters, the tool can be run faster because of its larger effective cutter radius. The effective cutter diameter is determined by the following equations depending on the radius to pilot ratio:

For a Radius/Pilot Ratio < 2.5, Effective Cutter Diameter = Pilot Diameter + Radius
For a Radius/Pilot Ratio ≥ 2.5, Effective Cutter Diameter = Pilot Diameter + .7x Radius

Larger pilot diameters also have more strength than smaller pilot diameters due to the added material behind the radius. A smaller pilot may be necessary for clearance when working in narrow slots or holes. Smaller pilots also allow for tighter turns when machining an inside corner.

Flared or Unflared Corner Rounder

Putting a full radius on a part has the potential to leave a step or an over-cut on a workpiece. This can happen if the tool isn’t completely dialed in or if there is minor runout or vibration. A slight 5° flare on the pilot and shoulder blends the radius smoothly on the workpiece and avoids leaving an over-cut.

A flared Corner Rounding End Mill leaves an incomplete radius but allows for more forgiveness. Additionally, this tool leaves a clean surface finish and does not require a second finishing operation to clean leftover marks. An unflared corner radius leaves a complete radius on the workpiece, but requires more set-up time to make sure there is no step.

2 flute and 4 flute corner rounding end mills with 5° flares

Front or Back

Choosing between a Corner Rounding End Mill and a Back Corner tool boils down to the location on the part you’re machining. A Back Corner Rounding End Mill should be utilized to put a radius on an area of the part facing the opposite direction as the spindle. While the material could be rotated, and a front Corner Rounding End Mill used, this adds to unnecessary time spent and increased cycle times. When using a Back Corner Rounding End Mill, ensure that you have proper clearance for the head diameter, and that the right reach length is used. If there is not enough clearance, the workpiece will need to be adjusted.

harvey tool back Corner Rounding End Mill

Flute Count

These tools are often offered in 2, 3, and 4 flute styles.  2 flute styles are normally used for aluminum and non-ferrous materials, although 3 flutes is quickly becoming a more popular choice for these materials, as they are softer than steels so a larger chip can be taken without an impact on tool life. 4 flutes should be chosen when machining steels to extend tool life by spreading out the wear over multiple teeth. 4 flute versions can also be run at higher feeds compared to 2 or 3 flute tools.

Corner Rounding End Mill Selection Summarized

The best corner rounding end mill varies from job-to-job. Generally speaking, opting for a tool with the largest pilot diameter possible is your best bet, as it has the most strength and requires less power due to its larger effective cutter diameter. A flared Corner Rounder is preferred for blending purposes if the workpiece is allowed to have an incomplete radius as this allows more forgiveness and can save on set up time. If not, however, an unflared Corner Rounder should be utilized. As is often the case, choosing between number of flutes boils down to user preference, largely. Softer materials usually require fewer flutes. As material gets harder, the number of flutes on your tool should increase.

Ideal Tooling for Machining Composites

Composite Materials

A material is classified as a composite if it is made up of at least two unique constituents that when combined yield beneficial physical and mechanical properties for a number of different applications. A binding agent that is the matrix material is filled with either particles or fibers of a second material that act as reinforcements. The combination of strength, weight, and rigidity make composites extremely useful for the automotive, aerospace, and power generation industry. Often the matrix material of particulate-reinforced composites is some form of plastic, and the reinforcement material is either glass or carbon particles. These are sometimes called “filled plastics,” and are typically very abrasive materials. Many composites are layered with varying fiber orientations, which increase the strength of the material and are called fiber-reinforced composites.

Common Problems When Machining Composites

  1. Delamination of composite layers
  2. Uncut Fibers
  3. Fiber tear-out
  4. Uneven tool wear
  5. Poor surface finish due to “competing” materials

These problems are all caused by unique conditions created by composite materials, and can be very tricky to correct.  The simple fact of cutting a combination of multiple materials at the same time introduces many factors that make it difficult to strike the right balance of the proper tool for the job and appropriate running parameters.  The following tool styles provide solutions for a wide array of composite concerns.  Composite Drilling Applications can face the same issues, and proper drill choice can help as well.

Straight Flute End Mill

Straight Flute Composite Cutters are designed to prevent delamination of layered materials by applying all cutting forces radially, eliminating axial forces from a typical helical cutting edge. Cutting action is improved with a high positive rake angle for shearing fibers and eccentric relief for improved edge life. Shallow ramping operations can be performed with this tool, but the largest benefits are seen in peripheral milling applications.

straight flute end mill

Compression Cutters

The Compression Cutter consists of an up cut and down cut helix. The top portion of the length of cut has right-hand cutting teeth with a left-hand spiral. The lower portion of the length of cut has right-hand cutting teeth with a right-hand spiral. This creates opposing cutting forces to stabilize the material removal process when cutting layered composites to prevent delamination, fiber pullout, and burs along the surface. Compression of the top and bottom of the workpiece keeps the layered bonded together.

compression cutter end mill

Chipbreaker Cutter

The Chipbreaker Cutter is ideally suited for roughing and profiling composites with a high percentage of fiber fill. The notch-like chipbreakers shear fibers and shorten chips for improved material evacuation. This specialized geometry is great for keeping chips small and avoiding “nesting” of stringy fibrous chips around the cutter.

chipbreaker for composite materials

Diamond Cut End Mill

Diamond Cut Composite Cutters come in two different geometries: End Mill Style and Drill Mill Style. Although the end mill style tool is center cutting, the drill mill style has a 140° point angle, making it more suitable for plunge cutting. This is great for clearing out pockets in the middle of composite sheets.

diamond cut end mill for composites

End Mills for Composites – Diamond Cut – End Mill Style

diamond cut drill mill for composites

End Mills for Composites – Diamond Cut – Drill Mill Style

Both the end mill and drill mill style share the same downcut geometry on the outside diameter. This diamond cut tool receives its name from the combination of left-hand and right-hand teeth. The tool is predominantly a downcut style – a geometry that allows for these tools to effectively rough and profile high fiber reinforced or filled composites, breaking up chips and shearing through fibers.

Diamond Cut vs. Chipbreaker Style

The diamond cut tools have a higher flute count, which some may intuitively think would lead to a better finish, but this is not the case as this line of tools contains right-hand and left-hand teeth. There is a trade-off between an increased ability to shear fibers and leaving a poorer finish. The chipbreaker style tool, although not as effective as shearing fibers, is ultimately designed for the same purpose but leaves a better finish as all of the flutes are facing the same direction.

Composite Finisher

The Composite Finisher has optimized geometry for finishing in composite. A slow helix and high flute count for more contact points ultimately renders a smooth finish by minimizing fraying of fiber-reinforced and layered materials.

finishing end mill for composites

Coating or No Coating?

Composite materials, especially those with glass or carbon fiber, can be particularly abrasive and have a tendency to wear down the cutting edge of carbide tools. If one is looking to achieve the best tool life and maintain a sharp cutting edge, then choosing an Amorphous Diamond coated tool is the best option. This thin coating improves lubricity and wear resistance over its uncoated counterpart. Using a tool with CVD diamond coating can be very beneficial in extreme cases, when fiber fill percentage is very large. This is a true diamond coating, and offers the best abrasion resistance, but a slightly less sharp cutting edge as it is a thicker coating. PCD diamond tooling offers the best tool life. If it a solid diamond wafer brazed to a carbide shank, and can maintain the sharpest edge of any diamond tooling. However, PCD is limited to straight flutes, and can come at a higher price.

Composite materials are being increasingly utilized in today’s manufacturing world for their impressive strength to weight ratio. This growth has stimulated innovative techniques of cutting composites seen in the tool choices above. Harvey Tool’s variety of geometries helps any machine shop tackle composite cutting applications and will continue to offer groundbreaking solutions to these types of manufacturing problems.

Shining a Light on Diamond End Mills

Diamond tooling and diamond-coated end mills are a great option when machining highly abrasive materials, as the coating properties help to significantly increase tool life relative to uncoated carbide tools. Diamond tools and diamond-like coated tools are only recommended for non-ferrous applications, including highly abrasive materials ranging from graphite to green ceramics, as they have a tendency to break down in the presence of extreme heat.

Understanding the Properties of Diamond Coatings

To ensure proper diamond tooling selection, it’s critical to understand the unique properties and makeup of the coatings, as there are often several diamond coating variations to choose from. Harvey Tool, for example, stocks Amorphous Diamond, CVD Diamond, and PCD Diamond End Mills for customers looking to achieve significantly greater tool life when working in non-ferrous applications.

Diamond, the hardest known material on earth, obtains its strength from the structure of carbon molecules. Graphite, a relatively brittle material, can have the same chemical formula as diamond, but is a completely different material; while Graphite has a sp2 bonded hexagonal structure, diamond has a sp3 bonded cubic structure. The cubic structure is harder than the hexagonal structure as more single bonds can be formed to interweave the carbon into a stronger network of molecules.

diamond tool coatings

Amorphous Diamond Coating

Amorphous Diamond is transferred onto carbide tools through a process called physical vapor deposition (PVD). This process spreads a mono-layer of DLC coating about 0.5 – 2.5 microns thick onto any given tool by evaporating a source material and allowing it to condense onto that tool over the course of a few hours.

amorphous diamond coating graphic showcasing thickness added

Chemical Vapor Deposition (CVD)

Chemical Vapor Deposition (CVD) is a coating process used to grow multiple layers of polycrystalline diamond onto carbide tooling. This procedure takes much longer than the standard PVD coating method. During the coating process, hydrogen molecules are dissociated from the carbon molecules deposited onto the tool, leaving a diamond matrix under the right temperature and pressure conditions. Under the wrong conditions, the tool may be simply coated in graphite. 6% cobalt carbide blanks allow for the best adhesion of diamond and a substrate. CVD diamond coated end mills have a typical thickness of coating that is between 8 and 10 microns thick.

CVD Diamond Coating graphic showcasing thickness added by coating

Polycrystalline Diamond (PCD)

Polycrystalline Diamond (PCD) is a synthetic diamond, meaning it is grown in a lab and contains mostly cubic structures. Diamond hardness ranges from about 80 GPa up to about 98 GPa. PCD end mills have the same diamond structure as CVD diamond tools but the binding technique is different. The diamond starts in a powdery form that is sintered onto a carbide plate using cobalt as a solvent metal substrate. This is done at an extreme temperature and pressure as the cobalt infiltrates the powder, causing the grains to grow together. This effectively creates a thick diamond wafer, between 010” and .030” in width, with a carbide base. This carbide base is then brazed onto the head an end mill and sharpened.

PCD Diamond Coating showcasing brazed on cutting edgeHow Diamond Coatings Differ

Coating Hardness & Thickness

Polycrystalline tools (CVD or sintered) have a much higher hardness, thickness, and max working temperature than Amorphous Diamond oated tools. As mentioned previously, a PCD tool consists of a diamond wafer brazed to a carbide body while a CVD tool is a carbide end mill with a relatively thick layer of polycrystalline diamond grown into it. This grown layer causes the CVD tools to have a rounded cutting edge compared to PCD and Amorphous Diamond coated tools. PCD tools have the thickest diamond layer that is ground to a sharp edge for maximum performance and tool life. The difference between PCD tools and CVD coated tools lies in the thickness of this coat and the sharpness of the cutting edge. Amorphous Diamond tools maintain a sharper edge than CVD coated tools because of their thin coating.

Flute Styles

Harvey Tool’s line of PCD end mills are all straight fluted, CVD coated tools are all helically fluted, and Amorphous Diamond tools are offered in a variety of options. The contrast between straight fluted and helically fluted can be seen in the images below, PCD (top) and CVD (bottom). Electrical discharge machining, grinding or erosion are used cut the PCD wafer to the specifications. The size of this wafer limits the range of diameters that can be achieved during manufacturing. In most situations a helically fluted tool would be preferred over a straight fluted tool but with true diamond tooling that is not the case. The materials that PCD tools and CVD coated tools are typically used to cut produce a powdery chip that does not require the same evacuation that a metallic or plastic chip necessitates.

PCD Diamond ball end mill

PCD Ball End Mill

CVD Diamond ball end mill

CVD Ball End Mill

Proper Uses

CVD tools are ideally suited for abrasive material not requiring a sharp cutting edge – typically materials that produce a powdery chip such as composites and graphite. Amorphous Diamond tools have a broad range of non-ferrous applications spanning from carbon fiber to precious metals but ceramics are typically outside their range as they can be too abrasive and wear away the coating. PCD tools overlap their CVD and DLC coated counterparts as they can be used for any non-ferrous abrasive material.

Cut to the Point

Harvey Tool carries physical vapor deposition diamond-like carbon coated tools, chemical vapor deposition diamond tools and polycrystalline diamond tools. PCD tools are composed of the thickest diamond wafer brazed onto a carbide shank and are ground to a sharp edge. CVD coated tools have the diamond grown into a carbide end mill. Amorphous Diamond coated tools have the DLC coated onto them through the PVD process. For more information on the diamond coating best suited for your operation, contact a Harvey Tool Tech Team Member for immediate help.

Selecting the Right Harvey Tool Miniature Drill

Among Harvey Tool’s expansive holemaking solutions product offering are several different types of miniature drill options and their complements. Options range from Miniature Spotting Drills to Miniature High Performance Drills – Deep Hole – Coolant Through. But which tools are appropriate for the hole you aim to leave in your part? Which tool might your current carousel be missing, leaving efficiency and performance behind? Understanding how to properly fill your tool repertoire for your desired holemaking result is the first step toward achieving success.

Pre-Drilling Considerations

Miniature Spotting Drills

Depending on the depth of your desired machined hole and its tolerance mandates, as well as the surface of the machine you will be drilling, opting first for a Miniature Spotting Drill might be beneficial. This tool pinpoints the exact location of a hole to prevent common deep-hole drilling mishaps such as walking, or straying from a desired path. It can also help to promote accuracy in instances where there is an uneven part surface for first contact. Some machinists even use Spotting Drills to leave a chamfer on the top of a pre-drilled hole. For extremely irregular surfaces, however, such as the side of a cylinder or an inclined plane, a Flat Bottom Drill or Flat Bottom Counterbore may be needed to lessen these irregularities prior to the drilling process.

harvey tool miniature spotting drill with dimension callout marks

Tech Tip: When spotting a hole, the spot angle should be equal to or wider than the angle of your chosen miniature drill. Simply, the miniature drill tip should contact the part before its flute face does.

infographic showcasing proper spot angle for spot drilling in relation to drills included angle

Selecting the Right Miniature Drill

Harvey Tool stocks several different types of miniature drills, but which option is right for you, and how does each drill differ in geometry?

Miniature Drills

Harvey Tool Miniature Drills are popular for machinists seeking flexibility and versatility with their holemaking operation. Because this line of tooling is offered uncoated in sizes as small as .002” in diameter, machinists no longer need to compromise on precision to reach very micro sizes. Also, this line of tooling is designed for use in several different materials where specificity is not required.

harvey tool extended depth miniature drill

Miniature High Performance Drills – Deep Hole – Coolant Through

For situations in which chip evacuation may be difficult due to the drill depth, Harvey Tool’s Deep Hole – Coolant Through Miniature Drills might be your best option. The coolant delivery from the drill tip will help to flush chips from within a hole, and prevent heeling on the hole’s sides, even at depths up to 20 multiples of the drill diameter.

harvey tool miniature deep hole coolant through gun drill

Miniature High Performance Drills – Flat Bottom

Choose Miniature High Performance Flat Bottom Drills when drilling on inclined and rounded surfaces, or when aiming to leave a flat bottom on your hole. Also, when drilling intersecting holes, half holes, shoulders, or thin plates, its flat bottom tool geometry helps to promote accuracy and a clean finish.

harvey tool miniature flat bottom drill with dimension callouts

Miniature High Performance Drills – Aluminum Alloys

The line of High Performance Drills for Aluminum Alloys feature TiB2 coating, which has an extremely low affinity to Aluminum and thus will fend off built-up edge. Its special 3 flute design allows for maximum chip flow, hole accuracy, finish, and elevated speeds and feeds parameters in this easy-to-machine material.

miniature drill for aluminum from harvey tool with dimension callouts

Miniature High Performance Drills – Hardened Steels

Miniature High Performance Drills – Hardened Steels features a specialized flute shape for improved chip evacuation and maximum rigidity. Additionally, each drill is coated in AlTiN Nano coating for hardness, and heat resistance in materials 48 Rc to 68 Rc.

miniature drill for hardened steel with dimension callouts

Miniature High Performance Drills – Prehardened Steels

As temperatures rise during machining, the AlTiN coating featured on Harvey Tool’s Miniature High Performance Drills – Prehardened Steels creates an aluminum oxide layer which helps to reduce thermal conductivity of the tool and helps to promote heat transfer to the chip, as well as improve lubricity and heat resistance in ferrous materials.

miniature drill for prehardened steel with dimension callouts

Post-Drilling Considerations

Miniature Reamers

For many operations, drilling the actual hole is only the beginning of the job. Some parts may require an ultra-tight tolerance, for which a Miniature Reamer (tolerances of +.0000″/-.0002″ for uncoated and +.0002″/-.0000″ for AlTiN Coated) can be used to bring a hole to size. harvey tool straight flute miniature reamer with dimension callouts

Tech Tip: In order to maintain appropriate stock removal amounts based on the reamer size, a hole should be pre-drilled at a diameter that is 90-94 percent of the finished reamed hole diameter.

Flat Bottom Counterbores

Other operations may require a hole with a flat bottom to allow for a superior connection with another part. Flat Bottom Counterbores leave a flat profile and straighten misaligned holes. For more information on why to use a Flat Bottom Counterbore, read 10 Reasons to Use Flat Bottom Tools.

harvey tool flat bottom counterbores with dimension callouts

Key Next Steps

Now that you’re familiar with miniature drills and complementary holemaking tooling, you must now learn key ways to go about the job. Understanding the importance of pecking cycles, and using the correct approach, is vital for both the life of your tool and the end result on your part. Read this post’s complement “Choosing the Right Pecking Cycle Approach,” for more information on the approach that’s best for your application.

Multi-Functional Tools Every Shop Should Have

If there is one thing that all machinists and shop managers can agree on, it’s that time is money. CNC tooling and material costs, employee wages, and keeping the lights on all add up, but most would agree that saving time is one of the best ways to make a shop more efficient.

Tool changes mid-job quickly add up when it comes to cycle times (not to mention tool costs), so using a tool capable of multiple operations whenever possible is an excellent first step. The following multi-functional tools are designed to save time and money at the spindle.

Drill/End Mills

harvey tool combination drill end mill

One look at Drill/End Mills or “Drill Mills” and it’s obvious that these multi-functional tools are capable of more than a standard end mill. Two of the intended operations are right in the name (drilling and milling). Besides the obvious, though, drill mills are intended for grooving, spotting, and chamfering, bringing the total to five separate operations.

infographic showcasing 5 unique drill mill operations

Considering the amount of tools normally required to perform all of these common operations, keeping a few drill mills in your tool crib ensures you’re always ready to tackle them, not to mention the potential extra spots in your tool magazine.

Undercutting End Mills

harvey tool undercutting lollipop end mill

Undercutting End Mills, also known as lollipop cutters or spherical ball end mills are surprisingly “well-rounded” tools. Besides milling an undercut feature on a part, which is typically very difficult with a standard end mill, these tools are capable of a few other operations.

infographic of four unique uses for undercutting end mills

Using an undercutting end mill to deburr in your machine is an excellent way to save time and effort. Some slotting and contouring operations, especially when 5-axis milling, are made far easier with an undercutting end mill, and in some situations, clearance challenges make them necessary.

Double Angle Shank Cutters

harvey tool double angle shank cutter

Often referred to the “Swiss Army Knife of Machining” due to their versatility, Double Angle Shank Cutters are 6-in1 multi-functional tools worth keeping on hand in any machine shop. Since these tools cut on all sides of their head, they are useful in a variety of situations.

infographic showing 6 different uses of double angle shank cutters

With the ability to thread mill and countersink, Double Angle Shank cutters are perfect for holemaking operations. On top of that, their clearance advantage over standard end mills makes them extremely well suited to a variety of finishing operations in difficult to reach places.

Flat Bottom Tools

two stacked harvey tool cnc tools, top being a flat bottom drill and bottom a flat bottom counterbore

Flat Bottom Drills and Flat Bottom Counterbores are better suited to holemaking, but they are capable of a large variety of operations. They belong in a category together since their flat bottom geometry is what sets them apart from other cnc tooling in the same category. Flat bottom geometry keeps the tool from walking on irregular or angle surfaces and help to correct, straighten, or flatten features created by non-flat bottom tools.

Flat bottom drills are designed for the following operations:

infographic showing 5 uses of flat bottom cnc tools. thin plate, cross hole, irregular surface, angled, and half hole drilling

While similar in some aspects, flat bottom counterbores are particularly well-suited for these uses:

infographic showing the five unique uses for flat bottom counterbores

Adjustable Chamfer Cutters

harvey tool adjustable chamfer mill set to 45 degrees

As discussed in a previous post, chamfer mills are capable of more than just chamfering – they are also well-suited for beveling, deburring, spotting, and countersinking. However, these adjustable chamfer cutters aren’t limited to a single angle per side – with a quick adjustment to the carbide insert you can mill any angle from 10° to 80°.

adjustable chamfer cutter inserts and hardware

When you account for the replaceable insert and the range of angles, this tool has a very high potential for time and tool cost savings.

Tools that are capable of a variety of operations are useful to just about any machine shop. Keeping your cnc tooling crib stocked with some or all of these multi-functional tools greatly increases your shop’s flexibility and decreases the chances of being unprepared for a job.

Why You Should Stop Deburring by Hand

Deburring is a process in which sharp edges and burrs are removed from a part to create a more aesthetically pleasing final product. After milling, parts are typically taken off the machine and sent off to the Deburring Department. Here, the burrs and sharp points are removed, traditionally by hand. However, an operation that takes an hour by hand can be reduced to mere minutes by deburring parts right in the machine with high precision CNC deburring tools, making hand deburring a thing of the past.

High Precision Tools

Hand deburring tools often have a sharp hook-shaped blade on the end, which is used to scrape/slice off the burrs as it passes along the edge of the part. These tools are fairly simple and easy to use, but much less efficient and precise than CNC deburring tools.

red hand deburring tool
Image Source: https://upload.wikimedia.org/wikipedia/commons/0/03/Deburring_tool.jpg

CNC deburring tools are also held to much tighter tolerances than traditional hand-deburring tools. Traditional cylindrical deburring tools typically have a diameter-tolerance window of +/- .008 versus a CNC deburring end mill which has a diameter tolerance of +/-.0005. The tighter tolerance design eliminates the location issues found in traditional deburring tools with loose tolerances, allowing them to be programmed like a traditional end mill.

While hand deburring tools often have just a single blade, CNC deburring tools feature double cut patterns and a high number of flutes. The double cut pattern contains both right hand and left hand teeth, which results in an improved finish. These tools leave completed parts looking far superior to their hand-deburred counterparts, with more consistent and controlled edge breaks. Additionally, there is a large variety of CNC deburring tools available today which can take full advantage of multi-axis machines and the most complex tool paths. For example, Harvey Tool’s 270° Undercutting End Mill is a great choice for multi-axis and more complex deburring options. Further, Deburring Chamfer Cutters are multi-use tools that can perform both chamfering and deburring accurately with no need for a tool change.

examples of cnc undercutters and chamfer mills

Reduce Production Costs and Increase Profits

Having an entire department dedicated to deburring can be costly, and many smaller businesses may have pulled employees off other jobs to help with deburring, which hampers production. Taking employees off the deburring station and asking them to run more parts or man another department can help keep labor costs low while still increasing production rates.

machinist hand deburring with a motorized hand tool
Stop Deburring By Hand and Increase Your Profits

By deburring right in the CNC machine, parts can be completed in one machining operation. The double-cut pattern found on many deburring tools also allows for increased speeds and feeds. This helps to reduce cycle times even further, saving hours of work and increasing production efficiency. Deburring in the machine is a highly repeatable process that reduces overall cycle times and allows for more efficient finishing of a part. In addition, CNC machines are going to be more accurate than manual operations, leading to fewer scrapped parts due to human error and inconsistencies.

STOP Deburring by Hand With Harvey Tool’s Wide Selection of Deburring Solutions

Simply put, the precision and accuracy of the CNC machine, along with the cost and time savings associated with keeping the part in the machine from start to finish, makes deburring in the CNC machine one of the easiest way to increase your shop’s efficiency.

10 Reasons to Use Flat Bottom Tools

Flat bottom tools, or tools with flat bottom geometry, are useful in a variety of situations and operations that tools with typical cutting geometry are not. The standard characteristics of drills or end mills are useful for their primary functions, but make them unsuitable for certain purposes. When used correctly, the following flat bottom tools can make the difference between botched jobs and perfect parts.

Flat Bottom Drills

Flat Bottom Drill

Flat bottom drills are perfect for tricky drilling situations or for creating flat bottom holes without secondary finishing passes. Consider using these specialized drills for the operations below.

infographic showing 5 different Flat Bottom Drill Operations

Thin Plate Drilling

When drilling through holes in thin plates, pointed drills are likely to push some material out the exit hole and create underside burrs. Flat bottom drills are significantly less likely to experience this problem, as their flat bottom geometry generates more even downward forces.

Crosshole Drilling

When drilling a hole that crosses the path of another hole, it is important to avoid creating burrs, since they can be extremely difficult to remove in this kind of cross section. Unlike drills with points, flat bottom drills are designed to not create burrs on the other side of through holes.

Irregular/Rounded Surface Drilling

Flat bottom drills initially engage irregular surfaces with their outer edge. Compared to making first contact with a standard drill point, this makes them less susceptible to deflection or “walking” on inclined surfaces, and more capable of drilling straighter holes.

Angled Drilling

Even if the surface of a part is flat or regular, a pointed drill is susceptible to walking if it engages the part at an angle, known as angled or tilted drilling. For the same reason flat bottom drills are ideal for drilling on irregular surfaces, they are perfect for angled drilling.

Half Hole Drilling

When drilling a half hole on the edge of a part, the lack of material on either side of the drill makes the operation unstable In this situation, a pointed drill is susceptible to walking. A flat bottom drill makes contact with its entire cutting geometry, allowing for more versatility and stability when drilling half holes.

Flat Bottom Counterbores

Flat Bottom Counterbore

Flat bottom counterbores are an excellent choice when a flat bottom hole is needed and a tool without flat bottom geometry was used to create it. Keep some of these tools on hand to be prepared for the operations below.

infographic showcasing 5 different uses of flat bottom counterbores

Bore & Finish Drilled Holes

Drill geometry is designed first and foremost for factors like stability, rigidity, and chip evacuation. Some holes will need secondary finishing operations. Flat bottom counterbores are often designed with a slow helix and low rake, which help them avoid part engagement and control finish.

Straighten Misaligned Holes

Even experienced machinists may drill a less-than-perfectly-straight hole or two in new and unfamiliar jobs. Fortunately, flat bottom counterbores are well-suited for straightening misaligned holes.

Spot Face & Counterbore on Irregular Surfaces

The unique geometry of flat bottom counterbores makes them  effective at spotting on irregular surfaces. Standard drills and spot drills are susceptible to walking on these kinds of surfaces, which can potentially ruin an operation.

Remove Drill Points

When a standard drill creates a hole (other than a through hole) it leaves a “drill point” at the bottom due to its pointed geometry. This is fine for some holes, but holes in need of a flat bottom will need a secondary operation from a flat bottom counterbore to remove the drill point.

Remove End Mill Dish

The dish angle present on most standard end mills allows proper end cutting characteristics and reduces full diameter contact. However, these end mills will naturally leave a small dish at the bottom of a hole created by a plunging operation. As with drill points, flat bottom counterbores are perfect to even out the bottom of a hole.