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Show Us What You #MadeWithMicro100

Are you proud of the parts you #MadeWithMicro100? Show us with a video of the parts you are making, the Micro 100 Tool used, and the story behind how that part came to be, for a chance to win a $1,000 grand prize!

With the recent addition of the Micro 100 brand to the Harvey Performance Company family, we want to know how you have been utilizing its expansive tooling offering. Has Micro 100’s Micro-Quik™ system helped you save time and money? Do you have a favorite tool that gets the job done for you every time? Has Micro 100 tooling saved you from a jam? We want to know! Send us a video on Instagram and show us what you #MadeWithMicro100!

How to Participate

Using #MadeWithMicro100 and @micro_100, tag your video of the Micro 100 tools machining your parts on Instagram or Facebook. Remember, don’t share anything that could get you in trouble! Proprietary parts and trade secrets should not be on display.

Official Contest Rules

Contest Dates:

  • The contest will run between December 5, 2019 to January 2, 2020. Submit as many entries as you’d like! Entries that are submitted before or after the contest period will not be considered for the top prizes (But we’d still like to see them!)

The Important Stuff:

  1. Take a video of your Micro 100 tool in action, clear and visible.
  2. Share your video on social media using #MadeWithMicro100 and tagging @Micro_100.
  3. Detail the story behind the project (tool number(s), operation, running parameters, etc.)

Prizes

All submissions will be considered for the $1,000 grand prize. Of these entries, the most impressive (10) will be put up to popular vote. All entries put up to vote will be featured on our new customer testimonial page on our website with their name, social media account, and video displayed for everybody to see.

We’ll pick our favorites, but the final say is up to you. Public voting will begin on January 6, 2020, and a winner will be announced on January 13, 2020.

The top five entries will be sent Micro 100’s Micro-Quik™ tool change system with a few of our quick change tools. The top three entries will be offered a spot as a “Featured Customer” on our “In The Loupe” blog!

The Fine Print:

  • Please ensure that you have permission from both your employer and customer to post a video.
  • All entries must be the original work of the person identified in the entry.
  • No purchase necessary to enter or win. A purchase will not increase your chances of winning.
  • On January 13, 2020, the top 5 winners will be announced to the public. The Top 5 selected winners will receive a prize. The odds of being selected depend on the number of entries received. If a potential winner cannot be contacted within five (5) days after the date of first attempt, an alternative winner may be selected.
  • The potential winners will be notified via social media. Each potential winner must complete a release form granting Micro 100 full permission to publish the winner’s submitted video. If a potential winner cannot be contacted, or fails to submit the release form, the potential winner forfeits prize. Potential winners must continue to comply with all terms and conditions of these official contest rules, and winning is contingent upon fulfilling all requirements.
  • Participation in the contest constitutes entrants’ full and unconditional agreement to and acceptance of these official rules and decisions. Winning a prize is contingent upon being compliant with these official rules and fulfilling all other requirements.
  • The Micro 100 Video Contest is open to residents in US and Canada who are at least 18 years old at the time of entry.

Selecting the Right Chamfer Cutter Tip Geometry

A chamfer cutter, or a chamfer mill, can be found at any machine shop, assembly floor, or hobbyist’s garage. These cutters are simple tools that are used for chamfering or beveling any part in a wide variety of materials. There are many reasons to chamfer a part, ranging from fluid flow and safety, to part aesthetics.

Due to the diversity of needs, tooling manufacturers offer many different angles and sizes of chamfer cutters, and as well as different types of chamfer cutter tip geometries. Harvey Tool, for instance, offers 21 different angles per side, ranging from 15° to 80°, flute counts of 2 to 6, and shank diameters starting at 1/8” up to 1 inch.

After finding a tool with the exact angle they’re looking for, a customer may have to choose a certain chamfer cutter tip that would best suit their operation. Common types of chamfer cutter tips include pointed, flat end, and end cutting. The following three types of chamfer cutter tip styles, offered by Harvey Tool, each serve a unique purpose.

Three Types of Harvey Tool Chamfer Cutters

Type I: Pointed

This style of chamfer cutter is the only Harvey Tool option that comes to a sharp point. The pointed tip allows the cutter to perform in smaller grooves, slots, and holes, relative to the other two types. This style also allows for easier programming and touch-offs, since the point can be easily located. It’s due to its tip that this version of the cutter has the longest length of cut (with the tool coming to a finished point), compared to the flat end of the other types of chamfer cutters. With only a 2 flute option, this is the most straightforward version of a chamfer cutter offered by Harvey Tool.

Type II: Flat End, Non-End Cutting

Type II chamfer cutters are very similar to the type I style, but feature an end that’s ground down to a flat, non-cutting tip. This flat “tip” removes the pointed part of the chamfer, which is the weakest part of the tool. Due to this change in tool geometry, this tool is given an additional measurement for how much longer the tool would be if it came to a point. This measurement is known as “distance to theoretical sharp corner,” which helps with the programming of the tool. The advantage of the flat end of the cutter now allows for multiple flutes to exist on the tapered profile of the chamfer cutter. With more flutes, this chamfer has improved tool life and finish. The flat, non-end cutting tip flat does limit its use in narrow slots, but another advantage is a lower profile angle with better angular velocity at the tip.

Type III: Flat End, End Cutting

Type III chamfer cutters are an improved and more advanced version of the type II style. The type III boasts a flat end tip with 2 flutes meeting at the center, creating a center cutting-capable version of the type II cutter. The center cutting geometry of this cutter makes it possible to cut with its flat tip. This cutting allows the chamfer cutter to lightly cut into the top of a part to the bottom of it, rather than leave material behind when cutting a chamfer. There are many situations where blending of a tapered wall and floor is needed, and this is where these chamfer cutters shine. The tip diameter is also held to a tight tolerance, which significantly helps with programing it.

In conclusion, there could be many suitable cutters for a single job, and there are many questions you must ask prior to picking your ideal tool. Choosing the right angle comes down to making sure that the angle on the chamfer cutter matches the angle on the part. One needs to be cautious of how the angles are called out, as well. Is the angle an “included angle” or “angle per side?” Is the angle called off of the vertical or horizontal? Next, the larger the shank diameter, the stronger the chamfer and the longer the length of cut, but now, interference with walls or fixtures need to be considered. Flute count comes down to material and finish. Softer materials tend to want less flutes for better chip evacuation, while more flutes will help with finish. After addressing each of these considerations, the correct style of chamfer for your job should be abundantly clear.

The Geometries and Purposes of a Slitting Saw

When a machinist needs to cut material significantly deeper than wide, a Slitting Saw is an ideal choice to get the job done. A Slitting Saw is unique due to its composition and rigidity, which allows it to hold up in a variety of both straightforward and tricky to machine materials.

What is a Slitting Saw?

A Slitting Saw is a flat (with or without a dish), circular-shaped saw that has a hole in the middle and teeth on the outer diameter. Used in conjunction with an arbor, a Slitting Saw is intended for machining purposes that require a large amount of material to be removed within a small diameter, such as slotting or cutoff applications.

Other names for Slitting Saws include (but are not limited to) Slitting Cutters, Slotting Cutters, Jewelers Saws, and Slitting Knives. Both Jewelers Saws and Slitting Knives are particular types of Slitting Saws. Jewelers Saws have a high tooth count enabling them to cut tiny, precise features, and Slitting Knives are Slitting Saws with no teeth at all. On Jewelers Saws, the tooth counts are generally much higher than other types of saws in order to make the cuts as accurate as possible.

Key Terminology

Why Use a Slitting Saw?

These saws are designed for cutting into both ferrous and non-ferrous materials, and by utilizing their unique shape and geometries, they can cut thin slot type features on parts more efficiently than any other machining tool.

Common Applications:

  1. Separating Two Pieces of Material
    1. If an application calls for cutting a piece of material, such as a rod, in half, then a slitting saw will work well to cut the pieces apart while increasing efficiency.
  2. Undercutting Applications
    1. Saws can perform undercutting applications if mounted correctly, which can eliminate the need to remount the workpiece completely.
  3. Slotting into Material
    1. Capable of creating thin slots with a significant depth of cut, Slitting Saws can be just the right tool for the job!

When Not to Use a Slitting Saw

While it may look similar to a stainless steel circular saw blade from a hardware store, a Slitting Saw should never be used with construction tools such as a table or circular saw.  Brittle saw blades such as slitting saws will shatter when used on manual machines, and can cause injury when not used on the proper set up.

In Conclusion

Slitting Saws can be beneficial to a wide variety of machining processes, and it is vital to understand their geometries and purpose before attempting to utilize them in the shop. They are a great tool to have in the shop and can assist with getting jobs done as quickly and efficiently as possible.

What To Know About Helical Solution’s Zplus Coating

Non-ferrous and non-metallic materials are not usually considered difficult to machine, and therefore, machinists often overlook the use of tool coatings. But while these materials may not present the same machining difficulties as hardened steels and other ferrous materials, a coating can still vastly improve performance in non-ferrous applications. For instance, materials such as aluminum and graphite can cause machinists headaches because of the difficulty they often create from abrasion. To alleviate these issues in non-ferrous machining applications, a popular coating choice is Helical Solution’s Zplus coating.

zplus coating

What is Helical Solutions’ Zplus Coating?

Helical’s Zplus is a Zirconium Nitride-based coating, applied by a Physical Vapor Deposition (PVD) process. This method of coating takes place in a vacuum and forms layers only microns thick onto the properly prepared tool. Zirconium Nitride does not chemically react to a variety of non-ferrous metals, increasing the lubricity of the tool and aiding in chip evacuation.

zplus coating

When Should a Machinist Use Helical Solution’s Zplus?

Working with Abrasive Materials

While Zplus was created initially for working in aluminum, its hardness level and maximum working temperature of 1,110°F enables it to work well in abrasive forms of other non-ferrous materials, as well. This coating decreases the coefficient of friction between the tool and the part, allowing it to move easier through more abrasive materials. This abrasion resistance decreases the rate of tool wear, prolonging tool life.

Concerns with Efficient Chip Evacuation

One of the primary functions of this coating is to increase the smoothness of the flutes of the tool, which allows for more efficient chip removal. By decreasing the amount of friction between the tool and the material, chips will not stick to the tool, helping to prevent chip packing. The increased lubricity and smoothness provided by the coating allows for a higher level of performance from the cutting tool. Zplus is also recommended for use in softer, gummy alloys, as the smooth surface encourages maximum lubricity within the material – this decreases the likelihood of those gummier chips sticking to the tool while machining.

Large Production Runs

Uncoated tools can work well in many forms of non-ferrous applications. However, to get a genuinely cost-effective tool for your job, the proper coating is highly recommended. Large production runs are known for putting a lot of wear and tear on tools due to their increased use, and by utilizing an appropriate coating, there can be a significant improvement in the tools working life.

When is Zplus Coating Not Beneficial to My Application?

Finishing Applications

When your parts finish is vital to its final application, a machinist may want to consider going with an uncoated tool. As with any coating, ZrN will leave a very minor rounded edge on the tip of the cutting edge. The best finish often requires an extremely sharp tool, and an uncoated tool will have a sharper cutting edge than its coated version.

 

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

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.

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.

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.

drill 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.

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.

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 Corner Rounding End Mill, 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

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

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.

Front or Back

Choosing between a Corner Rounding End Mill and a Back Corner Rounding End Mill 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.

Flute Count

Corner Rounding End Mills are often offered in 2, 3, and 4 flute styles.  2 flute Corner Rounding End Mills 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 Corner Rounding End Mills 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 Rounding End Mill 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 Rounding End Mill 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.

Tips for Machining Gummy Materials

Machinists face many problems and challenges when manufacturing gummy materials. These types of materials include low carbon steels, stainless steels, nickel alloys, titanium, copper, and metals with high chromium content. Gummy materials have a tendency to produce long, stringy chips, and are prone to creating built-up edge. These common problems can impact surface finish, tool life, and part tolerances.

Continuous Chip With a Built-Up Edge

Continuous chips are long, ribbon-like chips that are formed when the tool cuts through a material, separating chips along the shear plane created by the tool’s cutting edge. These chips slide up the tool face at a constant flow to create a long and stringy chip. The high temperatures, pressures, and friction produced when cutting are all factors that lead to the sticky chips that adhere to the cutting edge. When this built up edge becomes large enough, it can break off leaving behind some excess material on the workpiece, or gouge the workpiece leaving a poor surface finish.

Coolant

Using large amounts of coolant can help with temperature control and chip evacuation while machining gummy materials. Temperature is a big driving force behind built-up edge. The higher the temperature gets, the easier and faster a built-up edge can form. Coolant will keep local temperatures lower and can prevent the material from work hardening and galling. Long, stringy chips have the potential to “nest” around the tool and cause tool failure. Coolant will help break these chips into smaller pieces and move them away from the cutting action by flash cooling them, resulting in fracturing of the chip into smaller pieces. Coolant should be applied directly to the contact area of the tool and workpiece to have the maximum effect.

Tool Engagement

Running Parameters

The tool should be constantly fed into the workpiece. Allowing the tool to dwell can cause work hardening and increase the chance of galling and built up edge. A combination of higher feed rates and lower speeds should also be used to keep material removal rates at a reasonable level. An increase in feed rates will raise the temperature less than an increase in speed. This relates to chip thinning and the ability of a tool to cut the material rather than rub against it.

Climb Milling

Climb milling is the preferred method as it directs more heat into the chip than the tool. Using climb milling, the largest chip cross section is created first, allowing the tool to cut through the material much easier. The heat generated from friction when the tool penetrates the workpiece is transferred to the chip rather than the tool because the thickest part of the chip is able to hold more heat than the thinnest.

climb milling

Initial Workpiece Engagement

Sudden, large changes in force, like when a tool initially engages a workpiece, have a negative impact on tool life. Using an arc-in tool path to initially engage the material allows for increased stability with a gradual increase in cutting forces and heat. A gradual tool entry such as this is always the preferred method over an abrupt straight entry.

Tool Selection

A tool with a sharp and robust cutting edge should be selected to machine gummy materials. Helical has tooling specifically designed for Titanium and Stainless Steel to make your tool selection process easy.

Additionally, choosing a tool with the correct coating for the material you are machining will help to protect the cutting edge and result in a far lower chance of built up edge or galling than an uncoated tool. A tool with a higher flute count can spread tool wear out over multiple cutting edges, extending tool life. Tool wear is not always linear in gummy materials; as soon as a little bit of wear appears, tool failure will happen relatively quickly. Changing the tool at the first sign of wear may be necessary to ensure that parts are not scrapped.

Gummy Materials Summarized

Every material machines somewhat differently, but understanding what is happening when the tool cuts the workpiece and how this affects tool life and finish will go a long way to successfully completing any job.  Built-up edge and excess heat can be minimized by selecting the correct tool and coating for the material, and following the tips and techniques mentioned above. Finally, be sure to check your machine’s runout and ensure maximum rigidity prior to beginning your machining operation.

Tips for Maintaining Tight Tolerances

In manufacturing large production runs, one of the biggest difficulties machinists experience is holding tooling to necessary tolerances in holes, walls, and threads. Typically, this is an iterative process that can be tedious and stressful, especially for inexperienced machinists. While each job presents a unique set of challenges, there are rules of thumb that can be followed to ensure that your part is living up to its accuracy demands.

What is a Tolerance?

A tolerance is an allowable amount of variation in a part or cutting tool that a dimension can fall within. When creating a part print, tolerances of tooling can’t be overlooked, as tooling tolerances can result in part variations. Part tolerances have to be the same, if not larger, than tool tolerances to ensure part accuracy.

Cutting tool tolerances are oftentimes applied to a tool’s most critical dimensions, such as Cutter Diameter, Length of Cut, Shank Diameter, and Overall Length. When selecting a cutting tool for a job, it’s critical to choose a brand that adheres to strict tolerance standards and reliable batch-to-batch consistency. Manufacturers like Harvey Tool and Helical Solutions prominently display tolerances for many critical tool dimensions and thoroughly inspect each tool to ensure that it meets the tolerances specified. Below is the table header for Harvey Tool’s line of Miniature End Mills – Square – Stub & Standard.

tolerances

Tolerances help to create repeatability and specificity, especially in an industry in which even a thousandth of an inch can make or break a final product. This is especially true for miniature tooling, where Harvey Tool is experienced in the designing and manufacturing of tooling as small as .001” in diameter.

How are Tolerances Used?

When viewing a tolerance, there’s an upper and lower dimension, meaning the range in which the dimension of the tool can stray – both above and below what its size is said to be. In the below example, a .030″ cutter diameter tool’s size range would be anywhere between .0295″ and .0305.”

tooling tolerance

Maintaining Tolerances in Holemaking Operations

Holes oftentimes mandate the tightest dimensional tolerances, as they generally are meant to align perfectly with a mating part. To maintain tolerances, start first by testing the runout of both your machine and your tool. This simple, yet often overlooked step can save machinists a great amount of time and frustration.

Spotting Drills

Spotting Drills allow for drills to have a very precise starting point, minimizing walking or straying from a desired path. This can be especially beneficial when machining irregular surfaces, where accessing a hole’s perfect location can be more difficult.

spotting drills

Reamers

Reaming is great for any very tight tolerance mandate, because many Miniature Reamers have much tighter tolerances than a drill. Harvey Tool’s Miniature Reamers, for example, have tolerances of +.0000″/-.0002. for uncoated options and +.0002″/-.0000″ for AlTiN coated tools. Reamers cut on their chamfered edge, removing a minimal amount of material within a hole with the ultimate goal of bringing it to size. Because the cutting edge of a reamer is so small, the tool has a larger core diameter and is thus a more rigid tool.

miniature reamers

Maintaining Tight Tolerances While Machining Walls

Be Wary of Deflection

Maintaining tolerances when machining walls is made difficult by deflection, or the curvature a tool experiences when a force is applied to it. Where an angle is appearing on a wall due to deflection, opt for a reached tool to allow for less deflection along the tool’s neck. Further, take more axial depths of cut and machine in steps with finishing passes to exert less pressure on the tool. For surface finish tolerances, a long fluted tool may be required to minimize evidence of a tool path left on a part. For more information on ways to minimize deflection, read Tool Deflection & Its Remedies.tool deflection

Corner Radius End Mills

Corner radius End Mills, because they do not feature a sharp edge, will wear slower than a square end mill would. By utilizing corner radius tooling, fracturing on the tool edge will be minimized, resulting in an even pressure distribution on each of the cutting edges. Because the sharper edge on a square tool is less durable and more prone to cracking because of the stress concentration on that point, a corner radius tool would be much more rigid and thus less susceptible to causing a tolerance variation. For this reason, it’s recommended to use a roughing tool with a corner radius profile and a finisher with a square profile for an edge tolerance. When designing a part and keeping manufacturing in mind, if there is a potential for a wall with a radius as opposed to a wall with a square edge, a wall with a radius allows for easier machineability and fewer tool changes.

Maintaining Tight Tolerances While Threading

Making threads to tolerance is all about chip evacuation. Evacuating chips is an issue commonly overlooked; If chips within a hole have not been removed before a threading operation, there could be interference in the tool tip that leads to vibration and chatter within a thread. This would decrease the continuity of the thread while also altering the points of contact. Discontinuity of a thread could be the difference between passing and failing a part, and because threading is typically the last application when machining to decrease damaging the threads, it also increases the likelihood of chips remaining within the hole from other applications.

Tolerances Summarized

If you continue to experience troubles maintaining tight tolerances despite this blog post, consult the Harvey Tool or Helical Solutions tech team, as the problem may exist outside of your machine. Temperature and humidity can vary how gummy a material is, and can lead to workpiece expansion and contraction. Additionally, the foundation of buildings can expand and contract due to outside temperature, which can result in upped runout and irregular vibration in a spindle.

Tool Deflection & Its Remedies

Every machinist must be aware of tool deflection, as too much deflection can lead to catastrophic failure in the tool or workpiece. Deflection is the displacement of an object under a load causing curvature and/or fracture.

For Example: When looking at a diving board at rest without the pressure of a person’s weight upon it, the board is straight. But as the diver progresses down further to the end of the board, it bends further. Deflection in tooling can be thought of in a similar way.

Deflection Can Result In:

  • Shortened tool life and/or tool breakage
  • Subpar surface finish
  • Part dimensional inaccuracies

Tool Deflection Remedies

Minimize Overhang

Overhang refers to the distance a tool is sticking out of the tool holder. Simply, as overhang increases, the tool’s likelihood of deflection increases. The larger distance a tool hangs out of the holder, the less shank there is to grip, and depending on the shank length, this could lead to harmonics in the tool that can cause fracture. Simply put, For optimal working conditions, minimize overhang by chucking the tool as much as possible.

extended reach tool

Image Source: @NuevaPrecision

Long Flute vs. Long Reach

Another way to minimize deflection is having a full grasp on the differences between a long flute and a long reach tool. The reason for such a difference in rigidity between the two is the core diameter of the tool. The more material, the more rigid the tool; the shorter the length of flute, the more rigid the tool and the longer the tool life. While each tooling option has its benefits and necessary uses, using the right option for an operation is important.

The below charts illustrate the relationship between force on the tip and length of flute showing how much the tool will deflect if only the tip is engaged while cutting. One of the key ways to get the longest life out of your tool is by increasing rigidity by selecting the smallest reach and length of cut on the largest diameter tool.

tool deflection

 

tool deflection

 

When to Opt for a Long Reach Tool

Reached tools are typically used to remove material where there is a gap that the shank would not fit in, but a noncutting extension of the cutter diameter would. This length of reach behind the cutting edge is also slightly reduced from the cutter diameter to prevent heeling (rubbing of noncutting surface against the part). Reached tools are one of the best tools to add to a tool crib because of their versatility and tool life.

 

When to Opt for a Long Flute Tool

Long Flute tools have longer lengths of cut and are typically used for either maintaining a seamless wall on the side of a part, or within a slot for finishing applications. The core diameter is the same size throughout the cutting length, leading to more potential for deflection within a part. This possibly can lead to a tapered edge if too little of the cutting edge is engaged with a high feed rate. When cutting in deep slots, these tools are very effective. When using HEM, they are also very beneficial due to their chip evacuation capabilities that reached tools do not have.

 

Deflection & Tool Core Strength

Diameter is an important factor when calculating deflection. Machinists oftentimes use the cutter diameter in the calculation of long flute tools, when in actuality the core diameter (shown below) is the necessary dimension. This is because the fluted portion of a tool has an absence of material in the flute valleys. For a reached tool, the core diameter would be used in the calculation until its reached portion, at which point it transitions to the neck diameter. When changing these values, it can lower deflection to a point where it is not noticeable for the reached tool but could affect critical dimensions in a long flute tool.

Deflection Summarized

Tool deflection can cause damage to your tool and scrap your part if not properly accounted for prior to beginning a job. Be sure to minimize the distance from the tool holder to the tip of the tool to keep deflection to a minimum. For more information on ways to reduce tool deflection in your machining, view Diving into Depth of Cut.