What is Face Milling? Process, Tools, And Applications

Face milling is a process used in the manufacturing of precise and flat surfaces. It efficiently removes material while providing high accuracy and quality of surface finish. In this article, we’ll look at what face milling is and how it works. You’ll get to know its types, advantages, and disadvantages.

Face milling produces flat surfaces with the cutter axis generally perpendicular to the machined face. It can be performed on suitable manual or CNC machines and is not limited to metal sheets.

Face milling is used for flat features on components in automotive, aerospace, mould-making, and general manufacturing. The drawing and qualified process determine the accuracy required; other machining or finishing methods may also meet it.

The following steps outline a face-milling setup. Accuracy also requires suitable tooling, controlled conditions, and inspection.

Just like other techniques, the first step is to securely place the workpiece. This step is very important for ensuring accuracy. Otherwise, if the workpiece vibrates or shifts during the process, we’ll end up with an uneven surface.

Clamps, vises, or fixtures are used to secure the workpiece on the milling table. 

Position and align the cutter relative to the required face, normally with its axis perpendicular to that face. Establish the work and tool offsets and check clearance; CNC positioning follows the verified program and setup.

Two important parameters that need to be adjusted during the milling are feed rate and spindle speed. If these are not adjusted correctly, it causes a poor surface finish. The proper parameters depend on the material being used, the required width, and the depth of the cut. Let’s look at both these factors:

• Feed Rate: This is the relative feed speed between cutter and workpiece. Select feed per tooth and table feed for the cutter, engagement, material, and finish; excessively low feed may cause rubbing rather than improve the surface.

• Spindle Speed: Select RPM from the recommended cutting speed and effective cutting diameter, within the tool and machine limits. Material hardness alone does not determine a suitable speed.

After verifying setup, offsets, toolpath, and cutting data, run the face-milling operation using the machine’s approved procedure. CNC executes programmed movements, but automation alone does not guarantee accuracy or remove the need for monitoring and inspection.

For achieving your desired outcomes in CNC machining, it’s very important to choose the right tools. The right tools will help you in achieving the desired accuracy, efficiency, and smooth surface finish. 

Let’s look at some factors you should consider when choosing the face milling cutter for milling operations:

Match the cutting material and geometry to the actual workpiece. Aluminium and hardened ferrous materials require different selections; hardness alone does not justify using PCD inserts. PCD commonly suits selected non-ferrous and abrasive nonmetallic applications, not general steel cutting.

Select coatings for the substrate, workpiece, and cutting conditions. Diamond coatings and PCD cutting tips are different constructions; neither is a universal solution to tool wear. Tool geometry describes the insert and cutting-edge shape.

• Square Inserts: Square inserts have 90° corners, but the mounted cutting angle and application depend on the complete cutter design.

• Ball Head Inserts: Ball-nose geometries are mainly associated with curved-surface profiling; they should not be confused with round inserts used in face mills.
• Wiper Inserts: A wiper land can improve surface finish when its setting and feed match the cutter design; it does not guarantee a polished surface.

• End Mills: End mills are utilized when dealing with small and precise work. These are used for detailed, intricate parts. 

• Shell Mills: Shell-mounted cutters can suit roughing or finishing, depending on their design. Select diameter, engagement, and cutting data for the face and machine capacity.

• Fly Cutters : These may suit surface finishing when cutting diameter, balance, retention, speed, and machine rigidity are appropriate; they are not automatically suitable for every large workpiece.

Use cutting-speed data for the specific tool grade and workpiece, then determine the appropriate RPM for cutter diameter. Avoid a universal high-speed-for-soft, low-speed-for-hard rule.

Roughing prioritises material removal while retaining the stock needed for finishing. Finishing uses suitable geometry, edge condition, feed, and setup to meet the specified surface requirement; merely using a mill does not guarantee a polished result.

It’s crucial to consider the power of your machine when selecting the tool. For heavy-duty milling, you need a machine with high spindle power. 

The following four common face-milling approaches serve different purposes. Choose according to the material, surface requirements, and production conditions; this is not an exhaustive classification of milling.

General face milling creates flat surfaces to specified dimensions and finish. Cutter selection, entering angle, and cutting data remain important; general-purpose milling does not mean an operation without specifications.

Heavy face milling targets substantial material removal or demanding stock conditions. Match the cutter, inserts, workholding, and machine power and torque to the load; a larger diameter alone does not permit deeper cuts.

High-feed milling combines suitable chip-thinning geometry with a shallow axial cut to support high feed per tooth. Tool wear still occurs, and the resulting surface may need finishing. Use the tool’s stated application limits.

Wiper inserts can improve finish when the cutter setting, feed, and machine condition suit the application. Measure the finished surface against its specification before deciding whether grinding or polishing can be omitted.

Face milling is a common operation used in a variety of industries for the purpose of producing smooth and flat surfaces. The following are some advantages of face milling: 

• High Material Removal Rate

Face milling removes large quantities of material quickly using multiple cutting edges. Hence, it is highly beneficial for roughing operations. 

• Versatility

You can use face milling for a wide range of materials and operations. From roughing to finishing operations, face milling is utilized widely. 

• Smooth Surface Finish

Appropriate tools and cutting conditions can produce a consistent finish. Perpendicular cutter-axis orientation alone does not establish the resulting surface quality.

• Excellent Flatness

Achievable flatness depends on alignment, cutter runout, rigidity, workholding, thermal behaviour, and the machining sequence. Verify it by measurement.

Just like any other process, face milling also has some limitations. Here are a few of them: 

• High Tool and Setup Cost

Tooling and setup costs vary with the machine, cutter, workholding, and production volume. Face milling is not necessarily more expensive than every other machining method.

• Limited to Flat Surfaces

Face milling is specifically used for flat surfaces. It cannot be used for complex geometries or deep cavities. 

Face milling is commonly used in a variety of industries where flatness and efficiency are critical. The following are some of the common applications of face milling in different industries:

Automotive Industry

In automotive applications, face milling is used to manufacture flat surfaces within performance-critical parts. Engine blocks, transmission housings, and brake components are examples of automotive parts that are manufactured using face milling.

Electronics Industry

Face milling is also employed to produce heat sinks, casings, and substrates that require flatness and uniformity. 

Aerospace 

Face milling can machine specified flat features on structural aircraft components and other aerospace parts when the tool suits the material. It does not by itself guarantee the required tolerance or material integrity.

Mold & Die Industry

In mould and die manufacture, face milling can produce flat features on mould bases and die inserts used for plastic injection moulding and metal casting.

General Manufacturing 

In general manufacturing, face milling is utilized to produce large machinery frames, industrial equipment plates, and other flat components.

Medical Devices 

The medical industry uses face milling for surgical tools, orthopedic implants, and other precision medical components.

In milling operations, the quality of tools used directly influences the outcomes of the process. This is where Sundi Cutting Tools excel. They specialize in high-precision PCD (Polycrystalline Diamond) and CBN tools. With years of experience, they deliver high-performing solutions for industries like automotive, aerospace, and electronics. 

PCD face milling cutters use polycrystalline diamond cutting edges for suitable materials and operations. Confirm the particular cutter’s specification before applying the following potential capabilities:

• Suitable designs support high-speed cutting within their rated conditions
• Potential for useful tool life, verified in the intended application
• Material compatibility must be checked for the specific PCD grade and workpiece
• Permitted operations depend on the cutter design; do not assume that every PCD face mill can rough, contour, or profile.

Contact us for PCD and CBN tools and custom solutions

Face milling is used to produce flat features across many industries. Select tooling and cutting data for the material and specification, and verify the result. Curved profiles and complex cavities may require other tools or operations.