Face milling is the most typical milling process, which can be performed with a variety of tools. Face milling is a versatile machining procedure used by engineers to flatten and smooth the surface of machined objects.
The manufacturing sector has gone a long way and made many developments throughout the years to become what we know today. For example, in the 18th century, skilled laborers created pieces with traditional hand tools. Unfortunately, this procedure not only resulted in long lead times but was also prone to costly errors, making parts worthless. However, as of today, we have various production technologies and methods that can meet the most severe product design specifications. One such industrial method is known as face milling.
Interesting Science Videos
What is Face Milling?
Face milling is a machining technique that uses a flat-faced milling blade to remove materials from a workpiece. The cutter and workpiece surfaces are perpendicular to one another. The machinist is capable of face milling on a variety of CNC machining centers. However, this procedure is usually performed using a CNC router.
Some individuals may confuse face milling on these machines with that done on a CNC lathe. Notably, the workpiece is rotating on the lathe machine. However, during the “real” face milling, the workpiece remains immobile. It is also worth noting that the material is machined on the lathe using a single-point cutting tool.
There are other varieties of face milling, which we will explore later in this post. Whatever the type, a proper milling operation should result in a smooth and flat surface on the part.
How does Face Milling Work?
Face milling is a sequence of systematic operations aimed at effectively sculpting a workpiece’s surface. Here’s an overview of the normal process:
Workpiece Setup: The first step is to secure the workpiece firmly onto the machine table. It is critical to guarantee adequate positioning and secure fastening to avoid unwanted movement during milling.
Machine Alignment: After the workpiece has been secured, the milling machine or machining center must be positioned. Alignment is crucial here to guarantee that the cutting tool remains perpendicular to the workpiece surface.
Adjusting Speed and Feed Rate: Before beginning the milling operation, it is critical to fine-tune the spindle speed and feed rate. These parameters control the speed and precision of material removal and must be tuned for efficiency and quality.
Beginning Machining: Once the machine and workpiece are properly set up, the milling operation can begin. This phase often entails following pre-programmed instructions and guiding the cutter through the material to obtain the required form and characteristics on the workpiece surface.
By methodically following these processes, machinists may ensure smooth and accurate face milling operations, resulting in precise workpiece geometries that meet design specifications.
Tools Used in Face Milling
In face milling, there are different types of tools used to shape surfaces:
Flat End Mills: These are like versatile pencils with flat bottoms. They’re great for making flat surfaces very precisely. People often use them for regular face milling jobs.
High-Feed Cutters:.They’re designed to remove material super fast. They’re especially good for rough jobs or when you’re working with tough materials.
Shell Mills: They’re big and strong, perfect for quickly covering large areas. They often have parts that can be easily replaced, which helps keep them working efficiently.
Indexable Face Mills: They have little parts that can be swapped out when they wear down. This makes them flexible and long-lasting. You can use them on different materials and for different finishes.
Fly Cutters: Fly cutters are simple and effective for making surfaces super smooth. They might not be the fastest, but they’re great for fine finishing touches.
Carbide Cutters: They’re incredibly tough and can handle high heat without losing their edge. That makes them perfect for fast jobs and hard materials.
High-Speed Steel (HSS) Cutters: They might not be as tough as carbide, but they’re strong and can handle a variety of tasks.
TiAlN (Titanium Aluminum Nitride) or TiCN (Titanium CarboNitride) Coatings: They make them harder, reduce friction, and help them last longer.
Tips to Choose Face Milling Tools
Choosing the correct face milling tool for a given task can make a significant difference in the quality of the output. Here are some tips to help choose the ideal tool:
Consider the Workpiece Material: Different materials require different types of milling tools. For hard materials like steel, opt for carbide bits. For softer materials like aluminum, high-speed milling tools are suitable.
Select the Appropriate Tool Type: Use shell mills for harder surfaces as they have the right cutting-edge design for this purpose. End mills, with their multiple cutting teeth, are great for intricate designs.
Match the Tool to Material Hardness: Delicate or softer materials should be milled using fly cutters because they are designed for lower speeds and gentler cutting.
Entering Angle: Typically, an entering angle between 45 to 90 degrees works well, but there can be exceptions based on specific requirements.
Consider CNC Machining for Durability: If the durability of the cutting edge is crucial, consider using CNC machining instead of manual face milling.
Align Machine Speed with Spindle Speed: Ensure that the machine speed is compatible with the spindle speed to maintain tool integrity and prevent damage.
Avoid Face Milling Holes and Slots: To prevent issues like exit and reentry marks, avoid face milling holes and slots. It’s better to use specialized tools for such tasks.
Different Types of Face Milling Operations
There are various types of face milling operations:
Conventional Face Milling: Also known as up milling, this method involves the cutter rotating against the feed direction. It starts cutting from a minimum thickness and progresses to a maximum thickness. Conventional milling is often used for roughing operations due to its ability to handle variable depths and widths of cut.
Climb Face Milling: In contrast to conventional milling, climbing milling involves the cutter rotating in the same direction as the feed direction. This operation results in a better surface finish as it presses the workpiece against the table. Climb milling is preferred for finishing operations due to its ability to produce cleaner cuts and extend tool life.
High-Speed Face Milling: High-speed face milling utilizes advanced cutter technology and machining parameters to achieve high material removal rates and superior surface finishes. It’s ideal for non-ferrous metals and hardened steels where efficiency and finish quality are crucial.
Heavy-Duty Face Milling: This type of milling is designed to quickly remove large amounts of material with deep cuts and high feed rates. It uses robust cutters with large diameters and many teeth to handle increased loads. Heavy-duty milling is suited for roughing operations in challenging materials like cast iron and steel.
Fine Face Milling: Fine face milling focuses on achieving the highest possible surface finishes. It uses cutters with close pitch and multiple inserts to make light, precise cuts. This type of milling is often the final operation, crucial for industries requiring smooth surfaces and tight tolerances like aerospace and automotive.
Areas of Application of Face Milling
A face milling machine has several useful applications:
Leveling Surfaces: It’s great for making surfaces flat and even, whether it’s planks, beams, or blocks of wood. This is useful for creating semi-finished products from raw wood or even repurposing old wood from things like roof trusses.
Shaping Workpieces: It can be used to shape workpieces, like creating specific patterns, holes, or pockets on a surface. This versatility makes it handy for various woodworking tasks.
Optimizing Products: During manufacturing, face milling can smooth out uneven surfaces, like glued connections in wood, making them flat again. This helps improve the overall quality of the product.
Formatting Workpieces: Another task it can handle is formatting irregularly shaped workpieces, ensuring they have exact right angles and edges. This is achieved by locking the guide rails to achieve precise angles.
Handling Tree Slices: Unlike traditional planers that can cause issues with the grain, face milling is better suited for leveling tree slices or end grain surfaces. It works vertically, avoiding chipping or cracks, regardless of the grain direction.
Advantages of Face Milling
- Face milling creates surfaces with a smooth finish, ideal for applications requiring precise aesthetics or functional requirements.
- The cutting forces acting in the axial and radial directions are balanced, resulting in improved stability during machining.
- Face milling exerts less force on spindle bearings compared to other milling techniques, contributing to longer spindle life and reduced maintenance.
- Chatter, which can lead to surface imperfections and tool wear, is minimized during face milling, resulting in higher machining accuracy and consistency.
- This technique is versatile and applicable to a wide range of materials and machining requirements, making it suitable for various industries and applications.
Disadvantages of Face Milling
- Face milling is not well-suited for machining sharp corners or tight spaces, as the cutter’s geometry limits its ability to access such areas effectively.
- As the cutter exits the workpiece, it may produce chips, which can lead to issues such as chip recutting or poor surface finish if not properly managed.
- Face milling has a limited maximum depth of cut due to the cutter’s design and the nature of the machining process. This limitation may necessitate multiple passes to achieve desired depths, potentially increasing machining time.
Video Reference
References
- https://ruwi.de/en/encyclopedia-of-woodworking/milling/milling-processes-in-woodworking/face-milling/
- https://fractory.com/milling-cutters-and-tools/
- https://www.madearia.com/blog/face-milling-process-types-and-tips/
- https://waykenrm.com/blogs/what-is-face-milling/
- https://www.xometry.com/resources/machining/face-milling/
- https://www.china-machining.com/blog/face-milling-101/
- https://www.sandvik.coromant.com/en-gb/knowledge/milling/face-milling
- https://at-machining.com/face-milling/
- https://www.canadianmetalworking.com/canadianmetalworking/article/cuttingtools/about-face-milling
