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The Advances of Multiaxis Machining

CNC Machine Growth

As the manufacturing industry has developed, so too have the capabilities of machining centers. CNC Machines are constantly being improved and optimized to better handle the requirements of new applications. Perhaps the most important way these machines have improved over time is in the multiple axes of direction they can move, as well as orientation. For instance, a traditional 3-axis machine allows for movement and cutting in three directions, while a 2.5-axis machine can move in three directions but only cut in two. The possible number of axes for a multiaxis machine varies from 4 to 9, depending on the situation. This is assuming that no additional sub-systems are installed to the setup that would provide additional movement. The configuration of a multiaxis machine is dependent on the customer’s operation and the machine manufacturer.

Multiaxis Machining

With this continuous innovation has come the popularity of multiaxis machines – or CNC machines that can perform more than three axes of movement (greater than just the three linear axes X, Y, and Z). Additional axes usually include three rotary axes, as well as movement abilities of the table holding the part or spindle in place. Machines today can move up to 9 axes of direction.

Multiaxis machines provide several major improvements over CNC machines that only support 3 axes of movement. These benefits include:

  • Increasing part accuracy/consistency by decreasing the number of manual adjustments that need to be made.
  • Reducing the amount of human labor needed as there are fewer manual operations to perform.
  • Improving surface finish as the tool can be moved tangentially across the part surface.
  • Allowing for highly complex parts to be made in a single setup, saving time and cost.

9-Axis Machine Centers

The basic 9-axis naming convention consists of three sets of three axes.

Set One

The first set is the X, Y, and Z linear axes, where the Z axis is in line with the machine’s spindle, and the X and Y axes are parallel to the surface of the table. This is based on a vertical machining center. For a horizontal machining center, the Z axis would be aligned with the spindle.

Set Two

The second set of axes is the A, B, and C rotary axes, which rotate around the X, Y, and Z axes, respectively. These axes allow for the spindle to be oriented at different angles and in different positions, which enables tools to create more features, thereby decreasing the number of tool changes and maximizing efficiency.

Set Three

The third set of axes is the U, V, and W axes, which are secondary linear axes that are parallel to the X, Y, and Z axes, respectively. While these axes are parallel to the X, Y, and Z axes, they are managed by separate commands. The U axis is common in a lathe machine. This axis allows the cutting tool to move perpendicular to the machine’s spindle, enabling the machined diameter to be adjusted during the machining process.

A Growing Industry

In summary, as the manufacturing industry has grown, so too have the abilities of CNC Machines. Today, tooling can move across nine different axes, allowing for the machining of more intricate, precise, and delicate parts. Additionally, this development has worked to improve shop efficiency by minimizing manual labor and creating a more perfect final product.

The Multiple Uses of a Chamfer Mill

A chamfer mill, or a chamfer cutter, is one of the most common tools used by machinists daily. When creating a part, machining operations can oftentimes leave a sharp edge on a workpiece. A chamfer mill eliminates sharp edges, leaving a sloped surface, or a chamfer, instead. In doing so, the part will be stronger and more aesthetically appealing to its eventual user.

This singular tool can provide many cost-saving benefits to machinists. Aside from the namesake operation it performs on a part, a chamfer mill can be used for several machining operations including beveling, deburring, countersinking, and spotting.

Chamfer Mill for Beveling

The terms “chamfer” and “bevel” are often used interchangeably. These two features, while similar, actually have two different definitions. While a chamfer impacts a portion of the side of a workpiece – specifically the edge of a part, a bevel angles the entire side of what was a squared-off part feature. Thus, the side of a part can feature two chamfers, or only one bevel (Figure 1).

A chamfer mill, however, can perform both operations. The two features are equivalent in both geometry, and how they are machined.  A chamfer mill will create both part features in the exact same fashion; a bevel just may use a larger portion of the cutting surface, or may require multiple passes to create a large part feature.

Chamfer Mill for Deburring

Like many other versatile tools, a chamfer mill can be used to easily and swiftly deburr a part during the CNC machining process. In doing so, efficiency is maintained as manual deburring – a time exhaustive process – isn’t necessary.

A chamfer mill’s angled cutting surface makes it a great tool for deburring workpiece edges.  Because a very small amount of the chamfer cutter’s cutting face will be used, a simple adjustment to running parameters will allow for simple deburring operations using a very light cut depth.

Chamfer Mill for Spotting & Countersinking

Drilling precise, clean, and aesthetically appealing holes into a part is not a one-step process. In fact, some use up to four different tools to machine a perfect hole: spotting drill, drill, flat bottom counterbore, and countersink. However, a chamfer cutter is often used to perform two of these operations simultaneously.

By using a pointed chamfer cutter with a diameter larger than that of the hole being drilled, a machinist can spot and countersink the hole in one operation prior to its creation. Tipped-off Chamfer  Cutters are unable to perform a spotting operation because they are non-center cutting. By spotting a hole, the drill has a clear starting point. This works to alleviate walking during the drilling process, which in turn drastically reduces the chance of misaligned holes. By countersinking a hole, the screw sits flush with the part, which is often a requirement for many parts in the aerospace industry.

One consideration to keep in mind is that a carbide spot drill should always have an angle larger than that of the drill following it. However, many countersinks have angles that are smaller than most drill points.  This creates a dilemma in choosing a chamfer tool for both spotting and countersinking, as they can reduce the number of tools needed, but do not see the full benefit of a spot drill with a proper angle.

Key Takeaways

A chamfer mill, also known as a chamfer cutter, is a tool that can perform several machining operations including chamfering, beveling, deburring, spotting, and countersinking. Due to this versatility, chamfer mills are an essential part of every machinist’s arsenal.  All that’s needed to run them is these various operations is a slight change to running parameters and depth of cut.

Most Common Methods of Tool Entry

Tool entry is pivotal to machining success, as it’s one of the most punishing operations for a cutter. Entering a part in a way that’s not ideal for the tool or operation could lead to a damaged part or exhausted shop resources. Below, we’ll explore the most common part entry methods, as well as tips for how to perform them successfully.


Pre-Drilled Hole

Pre-drilling a hole to full pocket depth (and 5-10% larger than the end mill diameter) is the safest practice of dropping your end mill into a pocket. This method ensures the least amount of end work abuse and premature tool wear.

tool entry predrill

 


Helical Interpolation

Helical Interpolation is a very common and safe practice of tool entry with ferrous materials. Employing corner radius end mills during this operation will decrease tool wear and lessen corner breakdown. With this method, use a programmed helix diameter of greater than 110-120% of the cutter diameter.

helical interpolation

 


Ramping-In

This type of operation can be very successful, but institutes many different torsional forces the cutter must withstand. A strong core is key for this method, as is room for proper chip evacuation. Using tools with a corner radius, which strengthen its cutting portion, will help.

ramping

Suggested Starting Ramp Angles:

Hard/Ferrous Materials: 1°-3°

Soft/Non-Ferrous Materials: 3°-10°

For more information on this popular tool entry method, see Ramping to Success.


Arcing

This method of tool entry is similar to ramping in both method and benefit. However, while ramping enters the part from the top, arcing does so from the side. The end mill follows a curved tool path, or arc, when milling, this gradually increasing the load on the tool as it enters the part. Additionally, the load put on the tool decreases as it exits the part, helping to avoid shock loading and tool breakage.


Straight Plunge

This is a common, yet often problematic method of entering a part. A straight plunge into a part can easily lead to tool breakage. If opting for this machining method, however, certain criteria must be met for best chances of machining success. The tool must be center cutting, as end milling incorporates a flat entry point making chip evacuation extremely difficult. Drill bits are intended for straight plunging, however, and should be used for this type of operation.

tool entry

 


Straight Tool Entry

Straight entry into the part takes a toll on the cutter, as does a straight plunge. Until the cutter is fully engaged, the feed rate upon entry is recommended to be reduced by at least 50% during this operation.

tool entry

 


Roll-In Tool Entry

Rolling into the cut ensures a cutter to work its way to full engagement and naturally acquire proper chip thickness. The feed rate in this scenario should be reduced by 50%.

tool entry

 

6 Uses of Double Angle Shank Cutters

A Double Angle Shank Cutter is often referred to as the “Swiss Army Knife of Machining” due to its extreme versatility. This singular tool can be used for chamfering, back chamfering, V-groove milling, deburring, and countersinking. Below, we’ll learn the nuances of each operation, and why a Double Angle Shank Cutter might is an excellent tool to have on hand in any machine shop.


1. Thread Milling

Both in purpose and look, a Double Angle Shank Cutter is very similar to that of a single-form thread mill. Single-form thread mills are more versatile than multi-form thread mills, as they are not locked into a fixed pitch. Double Angle Shank Cutters that have a 60° angle can create internal and external 60° Unified National (UN) and metric threads. Double Angle Shank Cutters with a 55° angle can be used to thread 55° British Standard Pipe Threads (BSPT). To determine the thread sizes that various Double Angle Shank Cutters can produce, it’s helpful to consult thread fit charts, which pair appropriate cutter diameters to the thread size needed.


2. Chamfering

Depending on the requirements of your chamfering operation, and the angle of the chamfer you’re creating on your part, a Double Angle Shank Cutter might be appropriate. The angle of the top or bottom of the cutting face of the tool (called out below in as a B1 dimension), will determine the angle of your part’s chamfer. The area marked in red in Figures 2 and 3 below indicate the cutting portion for your chamfering and back chamfering (leaving a chamfer on the bottom of a part) operation.

For more information on the angles of Double Angle Shank Cutters, view Harvey Tool’s helpful guide: “Angles Untangled.”


3. Back Chamfering

Consider a through-hole that has a burr or tear-out caused from drilling the back of a workpiece. Reorienting the workpiece and relocating the hole is time-consuming, and it may be difficult to accurately finish the hole. In a case like this, back chamfering the burred hole without changing the setup is a preferred method. Put simply, the ability to accurately chamfer not only the top – but also the bottom of a part without needing to refasten the workpiece in your machine will save valuable time and money.

For best results when chamfering with Double Angle Shank Cutters, use a stepping over technique with diminishing passes as the radial engagement increases. This strategy helps to manage the amount of contact along the angle and can significantly avoid tool deflection.


4. Machining V-Grooves

A Double Angle Shank Cutter is commonly applied for machining V-groove profiles because of its cutting head, which is perpendicular to the tool centerline. This provides effective cutting action, even at a low spindle speed. A low tip speed can lead to issues with other tools, such as Chamfer Cutters, where the pointed profile is on-center of the tool.


5. Deburring

The task of hand-deburring parts can be tiresome for you, and cost inefficient for your shop. It can also lead to inaccuracies in parts that require precise dimensions. Double Angle Shank Cutters can be used to debur a part right in your CNC machine. By doing so, the process of finishing a part is made simple, fast, and accurate. Of course, ensuring proper clearance prior to machining the bottom of a machined hole is pivotal.

Other useful and versatile tools to have on-hand for quick CNC deburring include deburring end mills, back deburring mills, undercutting end mills, and chamfer cutters.


6. Countersinking

Countersinking a part  is done so a screw, nail, or bolt is able to sit flush with the part surface. Using specialty profile tooling can help enlarge the rim of a drilled hole and bevel the sides for a screw to sit accurately. A Double Angle Shank Cutter can also perform this operation by using the bottom portion of its cutting face.


Because of its ability to perform six different operations, Double Angle Shank Cutters are an ideal tool to keep in your tool carousel. In a bind, these tool forms can mill threads, chamfer, back chamfer, machine v-grooves, deburr in your CNC machine, and countersink. This versatility makes it a machining favorite and can offer shops boosted productivity by eliminating the need to flip parts, deburr by hand, or carry multiple tool forms.

For more on Harvey Tool Double Angle Shank Cutters, Click Here.