Knee mills are versatile machine tools capable of performing many different machining operations. They’re useful for everything from prototyping to tool room work, repairs, and general job shop tasks.
There are both manual and CNC (computer numerical control) knee mills. Both types play important roles in manufacturing processes. This article will explore the different types of knee mills and their specific applications.
Understanding the Mechanics and Functionality of Knee Mills
Knee mills are known for their versatility and precision. They achieve this through a combination of carefully designed components working in concert.
Key Components and Their Functions
- The “Knee”: This component supports the saddle and table, providing vertical movement along the Z-axis, allowing for precise adjustment of the workpiece height.
- The Saddle and Table Assembly: This assembly facilitates movement in the horizontal plane, along the X and Y axes. It also provides a stable platform for securing the workpiece.
- The Spindle and Quill: The spindle houses and drives the cutting tool. On some models, the quill enables Z-axis movement independent of the knee.
How a Knee Mill Works
Knee mills can be operated manually or via CNC (Computer Numerical Control).
- Manual Operation: The operator uses handwheels to control the movement of the table and knee, manually controlling the feed rate and depth of cut.
- CNC Operation: Computer-controlled movement enables automated machining processes with greater precision and repeatability.
Manual Knee Mills: Applications and Advantages
Manual knee mills are versatile machines that can perform a variety of machining operations, including:
- Drilling and tapping holes
- Milling keyways
- Facing and slotting operations
Compared to CNC mills, manual knee mills are simpler to operate and faster for smaller, less complex jobs. Because they are manually operated, no programming is required. Also, the R8 spindle taper allows for quick tool changes.
The Bridgeport knee mill is a particularly well-regarded and durable design. It’s a standard in many machine shops.
CNC Knee Mills: Precision and Automation
CNC knee mills offer increased precision and automation over their manual counterparts. The movements are computer-controlled, which reduces the chance of operator error, and they can run complex programs, leading to faster production speeds.
Types of CNC Knee Mills
There are two main types of CNC knee mills:
- 2-Axis CNC Knee Mills: These mills move in two axes, typically X and Y, and are suitable for simpler milling operations.
- 3-Axis CNC Knee Mills: These mills move in three axes (X, Y, and Z), giving them greater versatility when working with complex parts.
Control Systems
Popular control systems for CNC knee mills include the Acu-Rite Millpwr G-2 and the FAGOR 8055i.
Manual or CNC Knee Mill: Which is right for you?
When deciding between a manual and CNC knee mill, think about:
- How complex is your project and how many parts do you need to make?
- What’s your budget?
- What are your operators’ skill levels?
Manual knee mills still have a place even in shops with CNC machines. They’re great for quick repairs and secondary operations. They also give you flexibility for smaller jobs that don’t require CNC programming.
Choose a manual mill for smaller, simpler operations when you don’t want to program anything. Choose a CNC mill for high-precision, automated work, especially if your parts are complex and need to be made within very tight tolerances.
Putting It All Together
Knee mills are versatile and important machines suitable for many different machining tasks. Whether you opt for a manual or CNC version, a knee mill can bring unique advantages to your shop.
In modern manufacturing, manual and CNC machines often play complementary roles. Even in shops dominated by CNC equipment, manual knee mills remain relevant. And CNC knee mills combine the precision of computer control with the power and flexibility needed for a wide range of jobs.