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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.

Contouring Considerations

What is Contouring?

Contouring a part means creating a fine finish on an irregular or uneven surface. Dissimilar to finishing a flat or even part, contouring involves the finishing of a rounded, curved, or otherwise uniquely shaped part.

Contouring & 5-Axis Machining

5-axis machines are particularly suitable for contouring applications. Because contouring involves the finishing of an intricate or unique part, the multiple axes of movement in play with 5-axis Machining allow for the tool to access tough-to-reach areas, as well as follow intricate tool paths.

 Recent Contouring Advances

Advanced CAM software can now write the G-Code (the step-by-step program needed to create a finished part) for a machinists application, which has drastically simplified contouring applications. Simply, rather than spend several hours writing the code for an application, the software now handles this step. Despite these advances, most young machinists are still required to write their own G-Codes early on in their careers to gain valuable familiarity with the machines and their abilities. CAM software, for many, is a luxury earned with time.

Benefits of Advanced CAM Software

1. Increased Time Savings
Because contouring requires very specific tooling movements and rapidly changing cutting parameters, ridding machinists of the burden of writing their own complex code can save valuable prep time and reduce machining downtime.

2. Reduced Cycle Times
Generated G-Codes can cut several minutes off of a cycle time by removing redundancies within the application. Rather than contouring an area of the part that does not require it, or has been machined already, the CAM Software locates the very specific areas that require machining time and attention to maximize efficiency.

3. Improved Consistency
CAM Programs that are packaged with CAD Software such as SolidWorks are typically the best in terms of consistency and ability to handle complex designs. While the CAD Software helps a machinist generate the part, the CAM Program tells a machine how to make it.

Contouring Tips

Utilize Proper Cut Depths

Prior to running a contouring operation, an initial roughing cut is taken to remove material in steps on the Z-axis so to leave a limited amount of material for the final contouring pass. In this step, it’s pivotal to leave the right amount of material for contouring — too much material for the contouring pass can result in poor surface finish or a damaged part or tool, while too little material can lead to prolonged cycle time, decreased productivity and a sub par end result.

The contouring application should remove from .010″ to 25% of the tool’s cutter diameter. During contouring, it’s possible for the feeds to decrease while speeds increases, leading to a much smoother finish. It is also important to keep in mind that throughout the finishing cut, the amount of engagement between the tool’s cutting edge and the part will vary regularly – even within a single pass.

Use Best Suited Tooling

Ideal tool selection for contouring operations begins by choosing the proper profile of the tool. A large radius or ball profile is very often used for this operation because it does not leave as much evidence of a tool path. Rather, they effectively smooth the material along the face of the part. Undercutting End Mills, also known as lollipop cutters, have spherical ball profiles that make them excellent choices for contouring applications. Harvey Tool’s 300° Reduced Shank Undercutting End Mill, for example, features a high flute count to benefit part finish for light cut depths, while maintaining the ability to reach tough areas of the front or back side of a part.

Fact-Check G-Code

While advanced CAM Software will create the G-Code for an application, saving a machinist valuable time and money, accuracy of this code is still vitally important to the overall outcome of the final product. Machinists must look for issues such as wrong tool call out, rapids that come too close to the material, or even offsets that need correcting. Failure to look G-Code over prior to beginning machining can result in catastrophic machine failure and hundreds of thousands of dollars worth of damage.

Inserting an M01 – or a notation to the machine in the G-Code to stop and await machinist approval before moving on to the next step – can help a machinist to ensure that everything is approved with a next phase of an operation, or if any redundancy is set to occur, prior to continuation.

Contouring Summarized

Contouring is most often used in 5-axis machines as a finishing operation for uniquely shaped or intricate parts. After an initial roughing pass, the contouring operation – done most often with Undercutting End Mills or Ball End Mills, removes anywhere from .010″ to 25% of the cutter diameter in material from the part to ensure proper part specifications are met and a fine finish is achieved. During contouring, cut only at recommended depths, ensure that G-Code is correct, and use tooling best suited for this operation.

Milling Machines vs. Lathe Machines

Most modern manufacturing centers have both milling machines and lathe machines. Each machine follows the same machining principle, known as subtractive machining, where you begin with a block of material and then shape that material into the desired specifications. How the part is actually shaped is the key difference between the two machines. Understanding the differences in more depth will help in putting the right part in the right machine to maximize their capabilities.

 

cnc lathe

An Example of a Lathe Machine

cnc milling machine

An Example of a Milling Machine

Operation

The major difference between a milling machine and a lathe machine is the relationship of the workpiece and the tool.

Lathe Machines

In a lathe, the workpiece that is being machined spins about it’s axis, while the cutting tool does not. This is referred to as “turning”, and is effective for creating cylindrical parts. Common operations done on a lathe include drilling, boring, threading, ID and OD grooving, and parting. When looking to create quick, repeatable, and symmetrical cylindrical parts, the lathe machine is the best choice.

cnc lathe

Milling Machines

The opposite is true for milling machines. The tool in a milling machine rotates about its axis, while the workpiece does not. This allows the tool to approach the workpiece in many different orientations that more intricate and complex parts demand. If you can program it, you can make it in a milling machine as long as you have the proper clearance and choose the proper tooling.

milling machines

Best Practice

The best reason to use a milling machine for an upcoming project is the versatility. The tooling options for a milling machine are endless, with hundreds of available specialty cutting tools and various styles of end mills which make sure you are covered from start to finish on each job. A mill can also cut more complex pieces than a lathe. For example, it would impossible to efficiently machine something like an intake manifold for an engine on a lathe. For intricate parts like that, a milling machine would be required for successful machining.

While lathe machines are more limited in use than a milling machine, they are superior for cylindrical parts. While a mill can make the same cuts that a lathe does, it may need multiple setups to create the same part. When continuous production of cylindrical parts is necessary, a lathe will outperform the mill and increase both performance and efficiency.