Face milling is a machining process in which the tool is placed perpendicular to the workpiece. The tool is typically placed "face down" on top of the workpiece. Once turned on, the end mill grinds the top part of the workpiece to remove some material. If you're looking for a precise flat surface or a finish that will make your part shine, plane milling can help you with that.
How does face milling work and why is it important in surface machining?
During face milling, operators divide the process into four parts, which include:
1. Positioning of the workpiece
Before starting the process, they make sure that the object being machined is securely attached to the machine table. Firmly attach the object being machined to the table to prevent it from slipping.
2. Setting up the mill
The next thing to do is to make sure that the router is in the right location. The cutter will be set perpendicular to the workpiece. In this way, the top part of the cutter works on the material.
3. Adjusting the feed and spindle speed on the face surface
Next, adjust the feed rate and the speed of the tool movement through the machine (spindle speed). These two elements are crucial to ensure that the machine cuts in the right place.
4. Machining
After setting up the machine, the machining begins. Because in the case of CNC machining, the computer receives the machining process code, it does all the work producing the desired shape and form on the machined object.
Types of face milling operations
Mechanics often use various types of face milling operations. This section explains the different processes and the best optimization techniques for each of them.
1. Conventional face milling
This process is a standard face milling process without special considerations. The lead angle is very important in the general face milling process, and a face mill with a 45° lead angle is the best choice. Some other tips for optimizing general face milling programs include:
- The tool diameter should be larger than the diameter of the workpiece (minimum 20%, maximum 50%).
- The entry point to the workpiece should be outside the center to make the chips as thin as possible.
- Don't forget about the spindle size and machine power.
2. Heavy face milling
This type of facing requires a vast amount of materials and large machining centers. In this type of cladding, mechanics have to remove large amounts of material, which requires immense power. For this operation, the best choice is a face mill with a 60° lead angle. They have high feed rates, which increases their efficiency and allows to cut more material. Additional tips for optimizing heavy face milling programs indicate that:
- This process generates a lot of heat. If you need to change the inserts halfway, wear gloves.
- It also generates a lot of chips. These chips can clutter the workspace and re-enter the cutting path of the workpiece. Continuous chip removal causes insert wear. Therefore, workplace organization is so important.
3. High feed milling
High-feed milling involves procedures requiring high cutting speeds and feeds. These are typically cutting speeds above 1000 m/min. A high-feed face mill with a small lead angle is the best choice for this procedure. In this process, only the degree of access matters. An angle of about 10° is preferred as it allows for large feeds.
4. Finishing of the lapping plate
Face milling can also be used to achieve a clean surface finish using finishing inserts in addition to standard inserts. Wiper inserts are mainly used for surface preparation. They typically come in various lengths and are made in left and right versions. Whether a finishing insert is required for this process depends on the type of standard insert used. The higher the feed per revolution produced by the standard inserts, the greater the demand for finishing inserts.
Face milling vs peripheral milling: What's the difference?
Face milling and peripheral milling are two basic types of milling operations. They work very similarly, but they differ in configuration and usefulness for component production. For example, the cutting tool for peripheral milling is positioned parallel to the workpiece.
The peripheral milling process
The unique configuration of peripheral milling ensures that the tool's side grinds the top part of the workpiece. Therefore, peripheral milling effectively removes a large amount of material from the workpiece. On the other hand, face milling uses the tool's tip to remove a small amount of material, making it more suitable for applications requiring precise surface finishing.
Choosing the perfect tool for face milling
The face milling process can accurately produce a wide range of components. However, the success of this process also depends on choosing the perfect face mill. Let's take a look at the blades presented below.
- Spindle mill 1
End mills typically have cutting edges (or teeth) on the tip and shank, which are used to create a plane along the axis of a high-speed spindle. This unique design makes them perfectly suited for creating complex patterns, small areas, contours, and grooves during the surface finishing phase of a product.
- End cutter
However, they may be ineffective when it is necessary to remove bulk material in the initial stages of processing.
- Drill
End mills are the most commonly used end mills in face milling operations. The cutting tool has many cutting teeth and blades on its outer edge, as shown in the figure below.
- CNC tool - three-sided mill
The unique design of the shell mill provides even cutting force and precise control over the amount of material removed by the mill at high speeds. For this reason, mechanics often choose shell mills to achieve high quality and uniform surface finish. However, with regular end mills, it may sometimes be necessary to replace the insert depending on the material of the workpiece being machined.
- Throwing knife
The flying cutter is a single-point tool, primarily used for machining large surfaces. "Single point" means that the cutting tool has a single cutting edge, which removes large pieces of material at once.
- CNC flying mill
In contrast to face mills and end-face mills, which provide impressive cuts and surface finishes at high speeds, fly cutters can achieve better cuts and surface finishes at lower speeds. This means that the driver will need less energy to perform high-quality cuts with a throwing knife. When operators want to achieve excellent surface finish, and speed is not an issue, they often choose throwing knives.
Tips for Face Milling
The face milling process is a great way to produce precise and economical products, provided that the operator is qualified and follows basic principles. The text below contains several tips that apply to all types of face milling processes. They include advice on optimizing the face milling process.
- Tools matter
During face milling, make sure that the tool is suitable for the given process. The right tools will ensure the highest level of productivity and streamline the workflow.
- Special settings for face milling of shaped surfaces
Do not use the same settings for face milling as for other machining programs. Specific settings should be made for different types of machining programs. This helps improve the accuracy of various machining procedures.
- Make sure the milling parameters are correct for the surface being machined
Various technical parameters are associated with the face milling process. Some examples include cutting depth, feed per tooth, feed per revolution, etc. Before starting the procedure, make sure that each of these parameters is correct. This way, you won't unnecessarily waste material, and the cutting speed will be maintained. Remember to pay attention to whether you are performing the operation at a shallow cutting depth and to the surface roughness.
- Make sure your tools are sharp
Using blunt cutting tools will only slow down the finishing process. Moreover, blunt instruments are easily broken, as they are ineffective with harder materials. Therefore, it is very important that all tools are sharp and easily accessible during surface milling. During surface machining, concurrent milling can also be applied. It is recommended in all cases as long as we have the possibility of its installation in surface milling.