While many factors impact the outcome of a machining operation, one often overlooked factor is the cutting tool’s helix angle. The Helix angle of a tool is measured by the angle formed between the centerline of the tool and a straight line tangent along the cutting edge.
A higher helix angle, usually 40° or more, will wrap around the tool “faster,” while a “slower” helix angle is usually less than 40°.
When choosing a tool for a machining operation, machinists often consider the material, the tooling dimensions and the flute count. The helix angle must also be considered to contribute to efficient chip evacuation, better part finish, prolonged tool life, and reduced cycle times.
Helix Angles Rule of Thumb
One general rule of thumb is that as the helix angle increases, the length of engagement along the cutting edge will decrease. That said, there are many benefits and drawbacks to slow and high helix angles that can impact any machining operation.
Slow Helix Tool <40°
Benefits
Enhanced Strength – A larger core creates a strong tool that can resist deflection, or the force that will bend a tool under pressure.
Reduced Lifting – A slow helix will decrease a part from lifting off of the worktable in settings that are less secure.
Larger Chip Evacuation – The slow helix allows the tool to create a large chip, great for hogging out material.
Drawbacks
Rough Finish – A slow helix end mill takes a large chip, but can sometimes struggle to evacuate the chip. This inefficiency can result in a sub-par part finish.
Slower Feed Rate – The increased radial force of a slow helix end mill requires running the end mill at a slower feed rate.
High Helix Tool >40°
Benefits
Lower Radial Force – The tool will run quieter and smoother due to better shearing action, and allow for less deflection and more stability in thin wall applications.
Efficient Chip Evacuation – As the helix angle increases, the length of cutting edge engagement will decrease, and the axial force will increase. This lifts chips out and away, resulting in efficient chip evacuation.
Improved Part Finish – With lower radial forces, high helix tools are able to cut through material much more easily with a better shearing action, leaving an improved surface finish.
Drawbacks
Weaker Cutting Teeth – With a higher helix, the teeth of a tool will be thinner, and therefore thinner.
Deflection Risk – The smaller teeth of the high helix tool will increase the risk of deflection, or the force that will bend a tool under pressure. This limits how fast you can push high helix tools.
Increased Risk of Tool Failure – If deflection isn’t properly managed, this can result in a poor finish quality and tool failure.
Helix Angle: An Important Decision
In summary, a machinist must consider many factors when choosing tools for each application. Among the material, the finish requirements, and acceptable run times, a machinist must also consider the helix angle of each tool being used. A slow helix end mill will allow for larger chip formation, increased tool strength and reduce lifting forces. However, it may not leave an excellent finish. A high helix end mill will allow for efficient chip evacuation and excellent part finish, but may be subject to increased deflection, which can lead to tool breakage if not properly managed.
https://www.harveyperformance.com/wp-content/uploads/2020/02/Feature-Image-High-and-Low-Helix-Angles-IMG.jpg6001599Harvey Performance Companyhttp://www.harveyperformance.com/wp-content/uploads/2018/08/Logo_HarveyPerformanceCompany-4.pngHarvey Performance Company2020-02-05 16:07:562021-11-22 11:24:27Benefits & Drawbacks of High and Low Helix Angles
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.
Pointed and Flat End Chamfer Cutters
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.
https://www.harveyperformance.com/wp-content/uploads/2017/08/Feature-Image-Uses-of-Chamfer-Mill-IMG.jpg5251400Harvey Performance Companyhttp://www.harveyperformance.com/wp-content/uploads/2018/08/Logo_HarveyPerformanceCompany-4.pngHarvey Performance Company2019-11-22 08:20:372021-11-19 08:37:18Selecting the Right Chamfer Cutter Tip Geometry
Boring is a turning operation that allows a machinist to make a pre-existing hole bigger through multiple iterations of internal boring. It has a number of advantages over traditional hole finishing methods:
The ability to cost-effectively produce a hole outside standard drill sizes
The opportunity to create multiple dimensions within the bore itself
Solid carbide boring bars, such as those offered by Micro 100, have a few standard dimensions that give the tool basic functionality in removing material from an internal bore. These include:
Minimum Bore Diameter (D1): The minimum diameter of a hole for the cutting end of the tool to completely fit inside without making contact at opposing sides
Maximum Bore Depth (L2): Maximum depth that the tool can reach inside a hole without contact from the shank portion
Shank Diameter (D2): Diameter of the portion of the tool in contact with the tool holder
Overall Length (L1): Total length of the tool
Centerline Offset (F): The distance between a tool’s tip and the shank’s centerline axis
In order to minimize tool deflection and therefore risk of tool failure, it is important to choose a tool with a max bore depth that is only slightly larger than the length it is intended to cut. It is also beneficial to maximize the boring bar and shank diameter as this will increase the rigidity of the tool. This must be balanced with leaving enough room for chips to evacuate. This balance ultimately comes down to the material being bored. A harder material with a lower feed rate and depths of cut may not need as much space for chips to evacuate, but may require a larger and more rigid tool. Conversely, a softer material with more aggressive running parameters will need more room for chip evacuation, but may not require as rigid of a tool.
Geometries
In addition, they have a number of different geometric features in order to adequately handle the three types of forces acting upon the tool during this machining process. During a standard boring operation, the greatest of these forces is tangential, followed by feed (sometimes called axial), and finally radial. Tangential force acts perpendicular to the rake surface and pushes the tool away from the centerline. Feed force does not cause deflection, but pushes back on the tool and acts parallel to the centerline. Radial force pushes the tool towards the center of the bore.
Defining the Geometric Features of a Boring Bar:
Nose Radius: the roundness of a tool’s cutting point
Side Clearance (Radial Clearance): The angle measuring the tilt of the nose relative to the axis parallel to the centerline of the tool
End Clearance (Axial Clearance): The angle measuring the tilt of the end face relative to the axis running perpendicular to the centerline of the tool
Side Rake Angle: The angle measuring the sideways tilt of the side face of the tool
Back Rake Angle: The angle measuring the degree to which the back face is tilted in relation to the centerline of the workpiece
Side Relief Angle: The angle measuring how far the bottom face is tilted away from the workpiece
End Relief Angle: The angle measuring the tilt of the end face relative to the line running perpendicular to the center axis of the tool
Effects of Geometric Features on Cutting Operations:
Nose Radius: A large nose radius makes more contact with the workpiece, extending the life of the tool and the cutting edge as well as leaving a better finish. However, too large of a radius will lead to chatter as the tool is more exposed to tangential and radial cutting forces.
Another way this feature affects the cutting action is in determining how much of the cutting edge is struck by tangential force. The magnitude of this effect is largely dependent on the feed and depth of cut. Different combinations of depth of cuts and nose angles will result in either shorter or longer lengths of the cutting edge being exposed to the tangential force. The overall effect being the degree of edge wear. If only a small portion of the cutting edge is exposed to a large force it would be worn down faster than if a longer portion of the edge is succumb to the same force. This phenomenon also occurs with the increase and decrease of the end cutting edge angle.
End Cutting Edge Angle: The main purpose of the end cutting angle is for clearance when cutting in the positive Z direction (moving into the hole). This clearance allows the nose radius to be the main point of contact between the tool and the workpiece. Increasing the end cutting edge angle in the positive direction decreases the strength of the tip, but also decreases feed force. This is another situation where balance of tip strength and cutting force reduction must be found. It is also important to note that the angle may need to be changed depending on the type of boring one is performing.
Side Rake Angle: The nose angle is one geometric dimension that determines how much of the cutting edge is hit by tangential force but the side rake angle determines how much that force is redistributed into radial force. A positive rake angle means a lower tangential cutting force as allows for a greater amount of shearing action. However, this angle cannot be too great as it compromises cutting edge integrity by leaving less material for the nose angle and side relief angle.
Back Rake Angle: Sometimes called the top rake angle, the back rake angle for solid carbide boring bars is ground to help control the flow of chips cut on the end portion of the tool. This feature cannot have too sharp of a positive angle as it decreases the tools strength.
Side and End Relief Angles: Like the end cutting edge angle, the main purpose of the side and end relief angles are to provide clearance so that the tools non-cutting portion doesn’t rub against the workpiece. If the angles are too small then there is a risk of abrasion between the tool and the workpiece. This friction leads to increased tool wear, vibration and poor surface finish. The angle measurements will generally be between 0° and 20°.
Boring Bar Geometries Summarized
Boring bars have a few overall dimensions that allow for the boring of a hole without running the tool holder into the workpiece, or breaking the tool instantly upon contact. Solid carbide boring bars have a variety of angles that are combined differently to distribute the 3 types of cutting forces in order to take full advantage of the tool. Maximizing tool performance requires the combination of choosing the right tool along with the appropriate feed rate, depth of cut and RPM. These factors are dependent on the size of the hole, amount of material that needs to be removed, and mechanical properties of the workpiece.
When a machinist needs to cut material significantly deeper than wide, a Slitting Saw is an ideal choice to get the job done. These are unique due to their 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 tool that has a hole in the middle and teeth on the outer diameter. Used in conjunction with an arbor, this tool 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 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 saws. Jewelers Saws have a high tooth count enabling them to cut tiny, precise features, and Slitting Knives have 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. Non-Ferrous slitting saws have fewer teeth, allowing for aggressively deep depths of cut.
Common Applications:
Separating Two Pieces of Material
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.
Undercutting Applications
Saws can perform undercutting applications if mounted correctly, which can eliminate the need to remount the workpiece completely.
Slotting into Material
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, this tool should neverbe used with construction tools such as a table or circular saw. Brittle saw blades 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.
https://www.harveyperformance.com/wp-content/uploads/2019/09/Feature-Image-Slitting-Saws-IMG.jpg5251400Harvey Performance Companyhttp://www.harveyperformance.com/wp-content/uploads/2018/08/Logo_HarveyPerformanceCompany-4.pngHarvey Performance Company2019-09-10 09:30:532021-11-19 08:37:59The Geometries and Purposes of a Slitting Saw
When working with difficult-to-machine materials, such as Inconel, stainless steel, or hardened steels, utilizing an effective coating is important for sustaining the life of your tool and perfecting the outcome of your part. While looking for the right coating, many machinists try out several before finding a solution that works – a process that wastes valuable time and money. One coating gaining popularity in applications involving tough materials is Helical Solutions’ Tplus coating. This post will explore what Tplus coating is (and isn’t), and when it might be best for your specific job.
What is Helical Solutions’ Tplus Coating?
Helical’s Tplus coating is a Titanium-based, multi-layered coating that is applied by a Physical Vapor Deposition (PVD) process. This method of coating takes place in a near-vacuum and distributes micron-thick layers evenly onto a properly prepared tool. Tplus is a premium, multi-layered, titanium coating that increases edge strength, wear resistance, and tool life.
When Should a Machinist Use Tplus Coating?
When Working in Difficult to Machine Materials
Tplus coating works great in difficult-to-machine materials such as Inconel, stainless steel, hardened steels, and other alloyed steels with a hardness up to 65 Rc. It provides high hardness (44 GPa) for your tool, creating stronger cutting edges and resulting in extended tool life.
When Working in High Temperature Applications
When you are running an application in a ferrous material where extreme heat and work hardening are a possibility, Tplus is a great solution, as it’s designed to withstand high temperatures (up to 2,192°).
In the absence of coolant, fear not! Tplus coating is a viable option since it can handle the heat of machining. The low coefficient of friction (0.35) guarantees great performance in dry machining and allows the coated tool to move throughout the part smoothly, creating less heat, which is extremely beneficial in applications without coolant.
In Large Production Runs
In high production runs is truly where this coating excels, as its properties allow your tool to remain in the spindle longer – creating more parts by avoiding time in swapping out a worn tool.
https://www.harveyperformance.com/wp-content/uploads/2019/08/Feature-Image-Tplus-Coatings-IMG.jpg5251400Harvey Performance Companyhttp://www.harveyperformance.com/wp-content/uploads/2018/08/Logo_HarveyPerformanceCompany-4.pngHarvey Performance Company2019-08-05 01:39:432022-04-20 16:07:50An In-Depth Look at Helical’s Tplus Coating for End Mills
Most machinists are familiar with CNC drilling, but did you know that the common practice for holemaking is to always use a reamer? When done correctly, reaming can be a fast and highly accurate operation that results in precision holes.
By examining a Harvey Tool Miniature Reamer and its critical dimensions, we can better understand the functionality of this useful tool. In the above image of a straight flute reamer, D1 references the reamer diameter, the specific size intended for your hole; and D2 points to the shank diameter. At Harvey Tool, reamer shanks are oversized to help maintain tool strength, stiffness, and accuracy. Shanks also have an h6 tolerance, which is crucial for high precision tool holders, such as heat shrink collets. Other critical dimensions of a reamer include its overall length (L1), margin length (L2), overall reach (L3), and chamfer length (L4).
Harvey Tool also offers Miniature Reamers – Right Hand Spiral. This tool is designed to leave a superior part finish and help with chip evacuation in blind hole applications.
The Functions of Miniature Reamers
Reamers Provide Precision – As mentioned earlier, reamers are great for machining precision hole diameters. To use a reamer properly, you must first have a pre-drilled hole that’s between 90% and 94% of the final hole diameter. For example, if you need a finished a hole of .220″, your predrilled hole should be somewhere between .1980″ and .2068″. This allows the tool to take enough material off to leave a great finish, but does not overwork it, potentially causing damage. The tolerance for uncoated reamers is +.0000″/-.0002″, while the tolerance for AlTiN coating is +.0002″/-.0000″. These tolerances provide you the peace of mind of knowing that your hole will meet exact specifications.
Achieve a Quality CNC Finish – When a high surface finish is required of a hole, reamers should always be used to reach the desired tolerance. Both the pre-drilled hole and the tool’s margin help to keep the reamer centered while cutting, leading to a better finish.
Minimize Machining Production Runs – For machine shops, consistency is a priority. This is especially true in production runs. The last thing a machinist wants to see is an oversized hole on a part they have already preformed many operations on. Remember, reamers have the benefit of offering consistent hole size, preventing an out of tolerance finish. These consistent holes lead to valuable time savings and reduced scrap costs.
CNC Machining Exotic Alloys: When machining Inconel, titanium, and other high-cost materials, reaming your hole is important to ensure that the desired finish specification is met. With reamers, a machinists can better predict tool life, leading to a better finished product and less scrap ratios. It is important to note that Harvey Tool reamers are offered AlTiN coated and fully stocked in every .0005” increment from .0080” to .0640”.
Dovetail Cutters are cutting tools that create a trapezoidal-type shape, or a dovetail groove, in a part. Due to the form of these tools, special considerations need to be made in order to achieve long tool life and superior results. This is particularly true when machining O-ring grooves, as this operation requires the tool to drop into the part to begin cutting. Using an appropriate tool entry method, specifically understanding when drop hole allowance is (and is not) needed, is important to keep common dovetail mishaps from occurring.
What is a Drop-Hole?
When designing parts featuring O-ring grooves, the consideration of drop-hole allowance is a pivotal first step. A drop-hole is an off-center hole milled during the roughing/slotting operation. This feature allows for a significantly larger, more rigid tool to be used. This is because the cutter no longer has to fit into the slot, but into a hole with a diameter larger than its cutter diameter.
Why consider adding a Drop-Hole?
When compared to tools without drop-hole allowance, tools with drop-hole allowance have a much larger neck diameter-to-cutter diameter ratio. This makes the drop-hole tools far stronger, permitting the tool to take heavy radial depths of cut and fewer step-overs. Using a drop-hole will allow the use of the stronger tool, which will increase production rate and improve tool life.
Machining Operation with Drop-Hole Allowance
A maximum of 4 radial passes per side are needed.
When Not to Drop Hole
Drop-holes are sometimes not permitted in a design due to the added stress concentration point it leaves. Common examples for where a drop-hole would not be allowed include:
In high pressure applications
In seals requiring a high reliability
Where dangerous or hazardous fluids are being used
The issue with drop-hole allowance is that the additional clearance used for tool entry can create a weak spot in the seal, which can then become compromised under certain conditions. Ultimately, drop-hole allowance requires approval from the customer to ensure the application allows for it.
Machining Operation Without Drop-Hole Allowance
A maximum of 20 radial passes per side are needed.
Drop-Hole Placement
When adding a drop-hole to your part, it is important to ensure that the feature is placed correctly to maximize seal integrity. Per the below figure, the drop-hole should be placed off center of the groove, ensuring that only one side of the groove is affected.
It is also necessary to ensure that drop-hole features are put on the correct side of the groove. Since O-rings are used as a seal between pressures, it is important to have the drop-hole bordering the high pressure zone. As pressure moves from high to low, the O-ring will be forced into the fully supported side, allowing for a proper seal (See image below).
https://www.harveyperformance.com/wp-content/uploads/2019/05/Feature-Image-Drop-Hole-Allowance-IMG-1.jpg5251400Harvey Performance Companyhttp://www.harveyperformance.com/wp-content/uploads/2018/08/Logo_HarveyPerformanceCompany-4.pngHarvey Performance Company2019-05-06 09:48:552021-11-19 08:22:40When to and Not to Use Drop Hole Allowance
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.
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.
When Should a Machinist Use Helical Solution’s Zplus?
Working with Abrasive Materials
While Zpluswas 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.
https://www.harveyperformance.com/wp-content/uploads/2019/04/Feature-Image-Zplus-Coatings-IMG.jpg5251400Harvey Performance Companyhttp://www.harveyperformance.com/wp-content/uploads/2018/08/Logo_HarveyPerformanceCompany-4.pngHarvey Performance Company2019-04-01 03:17:542022-04-20 16:07:56What to Know About Helical Solution’s Zplus Coating
Aluminum and magnesium alloys are common materials found in machine shops worldwide, and are known as an “easier” material to machine. However, machinists can still experience hiccups while machining this material if they are not prepared with the proper tooling.. When working with aluminum and magnesium alloys, it is important to choose a coating that will work to extend your tool’s life and aid in the removal of chips. A popular choice for this material bucket is Harvey Tool’s TiB2 coating.
Harvey Tool’s TiB2 coating is a Titanium Diboride, ceramic-based coating that provides superb erosion resistance during machining. TiB2 is added to a tool by a method called Physical Vapor Deposition (PVD), which is conducted in a vacuum where particles are vaporized and applied onto a surface, forming thin layers of material onto the properly-prepped tool. This method enables the coating to be corrosion and tarnish resistant.
TiB2 is identified in Harvey Tool’s product catalog with a “-C8” following the sku number. It can be found offered in Harvey Tool’s lines of Variable Helix End Mills for Aluminum Alloys and Miniature High Performance Drills for Aluminum Alloys.
When Should a Machinist Use TiB2 Coating?
Chip Evacuation Concerns
TiB2 has an extremely low affinity to aluminum, which helps with the chip evacuation process. Simply, chips of a material are able to evacuate through chip valleys easier if they don’t have a high affinity to the coating being used. TiB2 coating does not chemically react with aluminum and magnesium, which allows for smoother chip evacuation, as the chips do not stick to the coating and create issues such as chip packing. This is a common machining mishap that can cause both part and tool damage, quickly derailing a machining operation. By using a coating that increases the lubricity of the tool, chips will not have a surface to stick to and will more smoothly evacuate from the flutes of the tool.
Large Production Runs
While an uncoated tool may work fine in some applications, not all applications can succeed without a tool coating. When working with large production runs where the tools need to hold up through the process of machining large numbers of parts, using a coating is always recommended because they extend the life of your tool.
When is TiB2 Coating Not Beneficial to My Application?
Extremely Abrasive Materials
During the PVD coating process, tools can reach a temperature in excess of 500° F, which can cause the toughness of the carbide to drop slightly. This process does not normally compromise the performance of the tool due to the coating being placed over the carbide. The coating then protects the slightly weakened edge and increases tool performance in recommended materials. Micro-fractures only start appearing when the tool is being run incredibly fast through highly abrasive materials, leading to a decrease in the life of the tool.
Extremely Soft Materials
The coating, while only a few microns thick at most, still provides an ever-so-slight rounded edge to the cutting edge of the tools it is placed on. It is important to take this into consideration, as using the sharpest tools possible when working with materials such as soft plastics is recommended. The sharpest edge possible decreases the likelihood of any “pushing” that might occur on the material and increases the likelihood of proper “shearing” when machining.
When Finish Is Vital
If your part’s finish is imperative to the final product, an uncoated tool may work better for your application. A coating, like stated above, creates a microscopic rounded surface to the cutting edge of the tool. When running tools at finishing speeds and feeds in materials like aluminum, a sharp edge can create the difference between a finished part that does – or does not – pass final inspection.
https://www.harveyperformance.com/wp-content/uploads/2019/03/Feature-Image-TiB2-Coatings-IMG-1.jpg5251400Harvey Performance Companyhttp://www.harveyperformance.com/wp-content/uploads/2018/08/Logo_HarveyPerformanceCompany-4.pngHarvey Performance Company2019-03-08 09:14:352022-04-20 16:07:45What to Know About Harvey Tool’s TiB2 Coating
Knuckle Roughers and Chipbreakers are common profiles found on roughing end mills that, while fairly similar in appearance, actually serve different functions. Chipbreakers refer to the notches along the cutting edge of a tool that work to break up chips to prevent common evacuation mishaps. Knuckle Roughers refer to the serrated cutting edge of a tool, which works to enhance cutting action for an overall smoother operation.
Determining the appropriate style of tool is a very important first step to a successful roughing application.
To aid chip evacuation, Chipbreaker End Mills feature a notched profile along the cutting edge that break down long chips into smaller, more manageable pieces. These tools are often utilized in aluminum jobs, as long, stringy chips are common with that material.
Each notch is offset flute-to-flute to enhance the surface finish on the part. This works by ensuring that as each flute rotates and impacts a part, following flutes work to clean up any marks or extra material that was left behind by the first pass. This leaves a semi-finished surface on your part.
In addition to improving chip control and reducing cutting resistance, these tools also help in decreasing heat load within the chips. This delays tool wear along the cutting edge and improves cutting performance. Not only are these tools great for hogging out a great deal of material, but they can be utilized in a wide array of jobs – from aluminum to steels. Further, a machinist can take full advantage of the unique benefits this tool possesses by utilizing High Efficiency Milling toolpaths, meant to promote efficiency and boost tool life.
Knuckle Roughers
Knuckle Rougher End Mills have a serrated cutting edge that generates significantly smaller chips than a standard end mill cutting edge. This allows for smoother machining and a more efficient metal removal process, similar to Chipbreaker End Mills. However, the serrations chop the chips down to much finer sizes, which allows more chips into the flutes during the evacuation process without any packing occurring.
Designed for steels, Knuckle Rougher End Mills are built to withstand harder materials and feature a large core. Because of this, these tools are great for roughing out a lot of material. However, due to the profile on the cutting edge, tracks along the wall can sometimes be left on a part. If finish is a concern, be sure to come in with a finishing tool after the roughing operation. Knuckle Roughers have proven the ability to run at higher chip loads, compared to similar end mills, which makes this a highly desired style for roughing. Further, this style of rougher causes a lot of heat and friction within the chips, so it’s important to run flood coolant when running this tool.
Key Differences Between Knuckle Roughers & Chipbreakers
While the two geometries offer similar benefits, it’s important to understand the distinct differences between them. Chipbreakers feature offset notches, which help to leave an acceptable finish on the walls of a part. Simply, the material left on an initial flute pass is removed by subsequent passes. A Knuckle Rougher does not feature this offset geometry, which can leave track marks on your part. Where part finish is of upmost importance, utilize a Knuckle Rougher to first hog out a great deal of steel, and work a final pass with a Finishing End Mill.
A unique benefit of Knuckle Roughers is the grind they possess – a cylindrical grind, compared to a relieved grind of a Chipbreaker End Mill. Because of this, Knuckle Roughers are easier to resharpen. Therefore, instead of buying a new tool, resharpening this profile is often a cheaper alternative.
https://www.harveyperformance.com/wp-content/uploads/2019/02/Feature-Image-Chipbreakers-vs-Knuckle-Roughers-IMG.jpg5251400Allyn Hoodhttp://www.harveyperformance.com/wp-content/uploads/2018/08/Logo_HarveyPerformanceCompany-4.pngAllyn Hood2019-02-15 11:31:552022-06-08 11:39:54Chipbreaker vs. Knuckle Rougher End Mills
