Guide to Face Mills: Definition, Types, and Considerations

Face mills are specially designed to efficiently remove material from the surface of a workpiece. These tools play a critical role in achieving smooth surface finishes, precise dimensions, and fast material removal, making them crucial for various machining operations such as milling and shaping.

Knowing about the various kinds of face milling cutters with inserts and how they're used, and also understanding what to think about when choosing the right cutter, can really make a big difference in how well face milling works and how efficient it is.

What is Face Mill?

Face mills are mainly used to mill a flat surface on a plate or bar. Instead of cutting with the sides, they're mostly used to cut with the ends of the cutter. When it comes to milling a "face," it means making a flat surface on the piece of metal being worked on. Face mills are often bigger around than the width of the material being worked on, so they can process the whole surface in one go.

The special things about face mills are as follows: high productivity, excellent rigidity, and can handle high-speed cutting; multiple teeth on the cutter work together to cut at the same time, which keeps the work steady.

What is Face Milling Used for?

Face milling is when you use a milling machine, either manual or CNC, to work on the surface of an object. The main goal is to make the surface flat and to remove any extra material.

Whether you use a manual mill machine or a CNC one depends on how tricky the job is and how accurate you need to be.

Face milling is handy for a bunch of things, like:

• Making surfaces flat and even
• Shaping objects just right
• Cleaning up extra material without altering the shape
• Boring holes in oddly shaped objects

Types of Face Mills

On Structure

Face mills come in two types:

The first type involves fixing the cemented carbide blade onto the cutter teeth using brazing, and then installing the cutter teeth on the milling cutter body; this is known as an insert face milling cutter.

The second type is to directly install the carbide insert on the milling cutter body and then secure it with screws; this is called an indexable clip-on milling cutter. Face milling cutters have two rake angles: the axial rake angle and the radial rake angle. The direction of these two rake angles is chosen based on the material and cutting conditions of the object being processed – it can be positive +, negative -, or zero.

On Geometry

Face mills can come in a solid structure or with holders and inserts. They offer different end or tip options like square end, ball nose, radius tip, and chamfer tip.

• The square end tip on a face mill has a straight edge without any curves or angles.
• For ball nose face mills, the tip is like a ball that has a radius equal to half the cutter diameter. This type of tip is great for cutting semicircle grooves.
• Radius-tipped face mills have straight blades with a rounded tip ground on them.
• Chamfer tip face mills have tips with angled sections, making it easy to create beveled edges on the workpiece.

Considerations for Selecting a Proper Face Mill

Materials

The kind of material used for the face mill is crucial for knowing how tough the cutting tool is. Hard materials like carbide, cobalt, and diamond can handle high-speed cutting, while steel is good for general metal work. There's also micrograin carbide, often used for surface finishing, and ceramic as other options for face mill materials.

Finish

When choosing a face mill, it's crucial to think about what kind of finish you want. Usually, you have two options: roughing/hogging and finishing. Roughing/hogging mills are made to quickly and heavily remove material, getting workpieces close to their final dimensions. Then, finishing face mills come in to give a precise fit and a really smooth surface.

Coatings

Coatings for face mills can protect the tool from rust and wear, making it harder, helping it move smoothly, and making it last longer.

The thickness of the coating depends on how it's done and can be anywhere between two to twelve micrometers. There are two main ways to coat inserts: chemical vapor deposition (CVD) and physical vapor deposition (PVD).

CVD coating happens through chemical reactions of gases, while PVD coating is done by putting gases on the tool. PVD coatings are usually thinner than CVD coatings and work well for tools that need really sharp edges or low cutting forces, like end mills, drills, or turning inserts for heat-resistant super alloys. CVD-coated inserts are thicker and resist wearing out better.

The type of coating also affects how you use coolant, with PVD coatings being better when you need to use coolant.

Construction Options

Different construction options for face mills include the number of flutes of cutting edges. This number can change depending on the cutter's size, the material being milled, and other things. Two-flute face mills are good for materials that make long chips, while face mills with more flutes can help reduce chip load and shaking.

Size

When thinking about the size of face mills, you need to consider a few things:

• The cutting diameter
• The shank or arbor diameter
• The flute or cutting edge length
• The overall tool length is important too
• The radius dimension and angle

Number of Inserts Used

The more inserts on a face milling cutter, the faster it can cut. But having more inserts can also make the cutting tool shake more and make the surface finish not as good. So, it's important to think about how strong the machine is when picking a cutter with the right number of inserts, to stop the cutting forces from being too much.

In milling, two key cutting measures to consider are diagonal engagement (ae) and depth of cut (ap). Diagonal engagement shows how much of the cutter is in contact with the workpiece diagonally, while depth of cut indicates how deeply the cutter goes into the material along its length.

Different Kind of Insert Used

Wiper inserts are a different kind of insert that can be used in face milling cutters. They have a bigger cutting edge than regular inserts, which can make the cutting tool shake more. However, they can also give a better finish on the surface or let you cut faster. Wiper inserts aren't only for face milling cutters; they can also be used for turning. For example, they can be helpful when turning gearbox parts made from low carbon steels to make the chips break better and cut faster.

There are face milling cutters that use round inserts too. These inserts have a strong cutting edge and are good for making tough materials like stainless steel and super alloys. Some inserts, whether for turning or milling, are covered with layers of ceramics to make them resist wearing out and high temperatures better. Coating materials can include things like titanium carbide (TiC), titanium nitride (TiN), aluminum oxide (AL2O3), and titanium carbon nitride (TiCN).

The Entering Angle

Another important aspect is the entering angle of the face mill, which is the angle between the cutting edge of the insert and the workpiece surface. Different entering angles, like 45 and 90 degrees, are suitable for different tasks.

For example, with a small entering angle like 10 degrees, the tool enters and exits the workpiece smoothly, reducing diagonal forces during milling. This allows for faster feed rates, making high-feed face mills great for small angles. In contrast, 45-degree angle face mills are versatile for many tasks, and 90-degree angle face mills are perfect for creating right-angle edges or steps.

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Face milling is a crucial process in machining, and our ASIATOOLS indexable face milling inserts and bodies are perfect for cutting flat surfaces in different materials. We offer various sizes, cutting edges, and precision grades to meet your needs. ASIATOOLS indexable face mills are reliable and well-designed for any application.