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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.

Understanding Threads & Thread Mills

Thread milling can present a machinist many challenges. While thread mills are capable of producing threads with relative ease, there are a lot of considerations that machinists must make prior to beginning the job in order to gain consistent results. To conceptualize these features and choose the right tool, machinists must first understand basic thread milling applications.

 

What is a thread?

The primary function of a thread is to form a coupling between two different mechanisms. Think of the cap on your water bottle. The cap couples with the top of the bottle in order to create a water tight seal. This coupling can transmit motion and help to obtain mechanical advantages.  Below are some important terms to know in order to understand threads.

Root – That surface of the thread which joins the flanks of adjacent thread forms and is immediately adjacent to the cylinder or cone from which the thread projects.

Flank – The flank of a thread is either surface connecting the crest with the root. The flank surface intersection with an axial plane is theoretically a straight line.

Crest – This is that surface of a thread which joins the flanks of the thread and is farthest from the cylinder or cone from which the thread projects.

Pitch – The pitch of a thread having uniform spacing is the distance measured parallelwith its axis between corresponding points on adjacent thread forms in the same axial plane and on the same side of the axis. Pitch is equal to the lead divided by the number of thread starts.

Major Diameter – On a straight thread the major diameter is that of the major cylinder.On a taper thread the major diameter at a given position on the thread axis is that of the major cone at that position.

Minor Diameter – On a straight thread the minor diameter is that of the minor cylinder. On a taper thread the minor diameter at a given position on the thread axis is that of the minor cone at that position.

Helix Angle – On a straight thread, the helix angle is the angle made by the helix of the thread and its relation to the thread axis. On a taper thread, the helix angle at a given axial position is the angle made by the conical spiral of the thread with the axis of the thread. The helix angle is the complement of the lead angle.

Depth of Thread Engagement – The depth (or height) of thread engagement between two coaxially assembled mating threads is the radial distance by which their thread forms overlap each other.

External Thread – A thread on a cylindrical or conical external surface.

Internal Thread – A thread on a cylindrical or conical internal surface.

Class of Thread – The class of a thread is an alphanumerical designation to indicate the standard grade of tolerance and allowance specified for a thread.

Source: Machinery’s Handbook 29th Edition

Types of Threads & Their Common Applications:

ISO Metric, American UN: This thread type is used for general purposes, including for screws. Features a 60° thread form.

British Standard, Whitworth: This thread form includes a 55° thread form and is often used when a water tight seal is needed.

NPT: Meaning National Pipe Tapered, this thread, like the Whitworth Thread Form, is also internal. See the above video for an example of an NPT thread.

UNJ, MJ: This type of thread is often used in the Aerospace industry and features a radius at the root of the thread.

ACME, Trapezoidal: ACME threads are screw thread profiles that feature a trapezoidal outline, and are most commonly used for power screws.

Buttress Threads: Designed for applications that involve particularly high stresses along the thread axis in one direction. The thread angle on these threads is 45° with a perpendicular flat on the front or “load resisting face.”         

Thread Designations

Threads must hold certain tolerances, known as thread designations, in order to join together properly. International standards have been developed for threads. Below are examples of Metric, UN, and Acme Thread Designations. It is important to note that not all designations will be uniform, as some tolerances will include diameter tolerances while others will include class of fit.

Metric Thread Designations              

M12 x 1.75 – 4h – LH

In this scenario, “M” designates a Metric Thread Designation, 12 refers to the Nominal Diameter, 1.75 is the pitch, 4h is the “Class of Fit,” and “LH” means “Left-Hand.”

UN Thread Designations

¾ 10 UNC 2A LH

For this UN Thread Designation, ¾ refers to the thread’s major diameter, where 10 references the number of threads per inch. UNC stands for the thread series; and 2A means the class of thread. The “A” is used to designate external threads, while “B” is for internal threads. For these style threads, there are 6 other classes of fit; 1B, 2B, and 3B for internal threads; and 1A, 2A, and 3A for external threads.

ACME Thread Designations

A 1 025 20-X

For this ACME Thread Designation, A refers to “Acme,” while 1 is the number of thread starts. The basic major diameter is called out by 025 (Meaning 1/4”) while 20 is the callout for number of threads per inch. X is a placeholder for a number designating the purpose of the thread. A number 1 means it’s for a screw, while 2 means it’s for a nut, and 3 refers to a flange.

How are threads measured?

Threads are measured using go and no-go gauges. These gauges are inspection tools used to ensure the that the thread is the right size and has the correct pitch. The go gauge ensures the pitch diameter falls below the maximum requirement, while the no-go gauge verifies that the pitch diameter is above the minimum requirement. These gauges must be used carefully to ensure that the threads are not damaged.

Thread Milling Considerations

Thread milling is the interpolation of a thread mill around or inside a workpiece to create a desired thread form on a workpiece. Multiple radial passes during milling offer good chip control. Remember, though, that thread milling needs to be performed on machines capable of moving on the X, Y, and Z axis simultaneously.

5 Tips for Successful Thread Milling Operations:

1.  Opt for a Quality Tooling Manufacturer

There is no substitute for adequate tooling. To avoid tool failure and machining mishaps, opt for a quality manufacturer for High Performance Drills for your starter holes, as well as for your thread milling solutions. Harvey Tool fully stocks several types of threadmills, including Single Form, Tri-Form, and Multi-Form Thread Milling Cutters. In addition, the 60° Double Angle Shank Cutter can be used for thread milling.

thread milling

Image Courtesy of  @Avantmfg

2. Select a Proper Cutter Diameter

Choose only a cutter diameter as large as you need. A smaller cutter diameter will help achieve higher quality threads.

3. Ensure You’re Comfortable with Your Tool Path

Your chosen tool path will determine left hand or right hand threads.

Right-hand internal thread milling is where cutters move counterclockwise in an upwards direction to ensure that climb milling is achieved.

Left-hand internal thread milling a left-hand thread follows in the opposite direction, from top to bottom, also in a counterclockwise path to ensure that climb milling is achieved.

4. Assess Number of Radial Passes Needed

In difficult applications, using more passes may be necessary to achieve desired quality. Separating the thread milling operation into several radial passes achieves a finer quality of thread and improves security against tool breakage in difficult materials. In addition, thread milling with several radial passes also improves thread tolerance due to reduced tool deflection. This gives greater security in long overhangs and unstable conditions.

5. Review Chip Evacuation Strategy

Are you taking the necessary steps to avoid chip recutting due to inefficient chip evacuation? If not, your thread may fall out of tolerance. Opt for a strategy that includes coolant, lubricant, and tool retractions.

In Summary

Just looking at a threading tool can be confusing – it is sometimes hard to conceptualize how these tools are able to get the job done. But with proper understanding of call, methods, and best practices, machinists can feel confident when beginning their operation.

Get to Know Machining Advisor Pro

Machining Advisor Pro (MAP) is a tool to quickly, seamlessly, and accurately deliver recommended running parameters to machinists using Helical Solutions end mills. This download-free and mobile-friendly application takes into account a user’s machine, tool path, set-up, and material to offer tailored, specific speeds and feed parameters to the tools they are using.

How to Begin with Machining Advisor Pro

This section will provide a detailed breakdown of Machining Advisor Pro, moving along step-by- step throughout the entire process of determining your tailored running parameters.

Register Quickly on Desktop or Mobile

To begin with Machining Advisor Pro, start by accessing its web page on the Harvey Performance Company website, or use the mobile version by downloading the application from the App Store or Google Play.

Whether you are using Machining Advisor Pro from the web or from your mobile device, machinists must first create an account. The registration process will only need to be done once before you will be able to log into Machining Advisor Pro on both the mobile and web applications immediately.

machining advisor pro

Simply Activate Your Account

The final step in the registration process is to activate your account. To do this, simply click the activation link in the email that was sent to the email address used when registering. If you do not see the email in your inbox, we recommend checking your spam folders or company email filters. From here, you’re able to begin using MAP.

Using MAP

A user’s experience will be different depending on whether they’re using the web or mobile application. For instance, after logging in, users on the web application will view a single page that contains the Tool, Material, Operation, Machine, Parameter, and Recommendation sections.

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On the mobile application, however, the “Input Specs” section is immediately visible. This is a summary of the Tool, Material, Operation, and Machine sections that allows a user to review and access any section. Return to this screen at any point by clicking on the gear icon in the bottom left of the screen.

machining advisor pro

Identify Your Helical Tool

To get started generating your running parameters, specify the Helical Solutions tool that you are using. This can be done by entering the tool number into the “Tool #” input field (highlighted in red below). As you type the tool number, MAP will filter through Helical’s 3,400-plus tools to begin identifying the specific tool you are looking for.

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Once the tool is selected, the “Tool Details” section will populate the information that is specific to the chosen tool. This information will include the type of tool chosen, its unit of measure, profile, and other key dimensional attributes.

machining advisor pro

Select the Material You’re Working In

Once your tool information is imported, the material you’re working in will need to be specified. To access this screen on the mobile application, either swipe your screen to the left or click on the “Material” tab seen at the bottom of the screen. You will move from screen to screen across each step in the mobile application by using the same method.

In this section, there are more than 300 specific material grades and conditions available to users. The first dropdown menu will allow you to specify the material you are working in. Then, you can choose the subgroup of that material that is most applicable to your application. In some cases, you will also need to choose a material condition. For example, you can select from “T4” or “T6” condition for 6061 Aluminum.

machining advisor pro

Machining Advisor Pro provides optimized feeds and speeds that are specific to your application, so it is important that the condition of your material is selected.

Pick an Operation

The next section of MAP allows the user to define their specific operation. In this section, you will define the tool path strategy that will be used in this application. This can be done by either selecting the tool path from the dropdown menu, or clicking on “Tool Path Info” for a visual breakdown and more information on each available toolpath.

machining advisor pro

Tailor Parameters to Your Machine’s Capabilities

The final section on mobile, and the fourth web section, is the machine section. This is where a user can define the attributes of the machine that you are using. This will include the Max RPM, Max IPM, Spindle, Holder, and work holding security. Running Parameters will adjust based on your responses.

machining advisor pro

Access Machining Advisor Pro Parameters

Once the Tool, Material, Operation, and Machine sections are populated there will be enough information to generate the initial parameters, speed, and feed. To access these on the mobile app, either swipe left when on the machine tab or tap on the “Output” tab on the bottom menu.

machining advisor pro

Please note that these are only initial values. Machining Advisor Pro gives you the ability to alter the stick out, axial depth of cut, and radial depth of cut to match the specific application. These changes can either be made by entering the exact numeric value, the % of cutter diameter, or by altering the slider bars.machining advisor pro

The parameters section also offers a visual representation of the portion of the tool that will be engaged with the materials as well as the Tool Engagement Angle.

MAP’s Recommendations

At this point, you can now review the recommended feeds and speeds that Machining Advisor Pro suggests based on the information you have input. These optimized running parameters can then be further refined by altering the speed and feed dials.

machining advisor pro

Machining Advisor Pro recommendations can be saved by clicking on the PDF button that is found in the recommendation section on both the web and mobile platforms. This will automatically generate a PDF of the recommendations, allowing you to print, email, or share with others.

Machining Advisor Pro Summarized

The final section, exclusive to the mobile application, is the “Summary” section. To access this section, first tap on the checkmark icon in the bottom menu. This will open a section that is similar to the “Input Specs” section, which will give you a summary of the total parameter outputs. If anything needs to change, you can easily jump to each output item by tapping on the section you need to adjust.

machining advisor pro

This is also where you would go to reset the application to clear all of the inputs and start a new setup. On the web version, this button is found in the upper right hand corner and looks like a “refresh” icon on a web browser.

Contact Us

For the mobile application we have implemented an in-app messaging service. This was done to give the user a tool to easily communicate any question they have about the application from within the app. It allows the user to not only send messages, but to also include screen shots of what they are seeing! This can be accessed by clicking on the “Contact Us” option in the same hamburger menu that the Logout and Help & Tips are found.

Have more questions? Check out our MAP FAQs for more information.