CNCmillingMachine

5-axis CNC milling machine (conceptual design)

Mini 5-axis CNC milling machine conceptual design

This project focuses on presenting a conceptual design of a compact, desktop-sized CNC milling machine. The project aims to provide an affordable, versatile solution for designers and engineers needing high-precision milling capabilities in a small, easy-to-use package.

Machine Overview

front view of the machine

birdside view (x, y, z + 4th, 5th axis, 5 degree of freedom)

3D view of the machine

Key Features of the Project:

Five-Axis Capability: The milling machine is equipped with five axes to allow for more versatile and precise machining of complex parts.
Compact Size: The machine is designed to be portable and suitable for use in office, studio, or home environments, with dimensions not exceeding 40cm x 40cm x 30cm.
Automatic Tool Change System: It includes a system for automatically changing between more than six tools, enhancing efficiency and ease of use.
Cooling system: A nozzle located next to the tool head sprays coolant during machining to prevent the metal parts from overheating. The other end of the nozzle is connected to a coolant reservoir at the base of the machine. The sprayed liquid returns to the reservoir by gravity, allowing the coolant to be reused in a continuous cycle.
User Control Panel: The machine features a dedicated user control panel for easy interaction. The control panel is equipped with a 12.1-inch display with a resolution of 1024 x 768 pixels, capable of displaying up to 16.7 million colors, and supports a brightness of 500 nits.
High Precision and Accuracy: The machine is capable of cutting with tolerances of less than +/- 0.005 cm, suitable for detailed and delicate work.
Safety Features: The design incorporates a casing to prevent debris from escaping and a cooling system to avoid overheating during operation.
Robust Spindle Motor: A spindle motor with a maximum spinning speed of over 10,000 rpm, capable of cutting materials like aluminum.

My task includes:

Mechanical Design: Designed key sub-systems of the CNC milling machine, included mechanisms of movable machining platform, coolant recycle system, and spindles replacement system.
3D Modeling: I prepared and built 2D/3D models in SOLIDWORKS, visualize and refine the design of the milling machine.
Load Analysis: Calculated the required torque for the movable machining platform.

Key Features Description

The CNC milling machine offers five degrees of freedom. The machining platform provides three adjustable axes (the z-axis for height adjustment, and the 4th and 5th axes are rotational axes). The tool-carrying platform provides adjustability in two axes (x-axis and y-axis for planar movement).

Machining platform design

The machining platform is a circular tray. A motor drives the "central gear", which in turn drives four connected gears (two "middle gears" and two "gears on the far ends"). These outer gears are connected to two screw shafts, which control the platform's rotation through rollers embedded in the base of the platform, as shown in the diagram.

Machining platform mechanical structure

Coolant recycle system

Through the nozzle, the coolant sprayed onto the machining platform returns to the storage container through a gap at the bottom left due to gravity. The liquid in the storage container is then pumped back into the nozzle for reuse in a continuous cycle. The enclosed space next to the coolant pool is used to house peripheral electronic modules, such as microcontrollers.

Close-up of the spindle and nozzle

Peripherals space

coolant storage space

Spindles replacement system

When machining complex parts, the spindle (cutting tool) may need to be changed frequently. Manual replacement is impractical as it is time-consuming and labor-intensive. To address this, I designed an automatic tool-changing system mounted on the back of the machine.

As shown in the diagram, when a tool change is required, the platform moves the currently loaded spindle to the back of the machine. Once aligned, the 'screw' first loosens the current tool, and then the 'gripper' grabs and removes the tool, placing it in the adjacent spindle storage.

The spindles are stored vertically within the storage system. A track-like mechanical structure controls the movement of various tools mounted on it. As shown in the diagram, the track rotates and delivers the tool to be replaced to the gripper. A new tool is then selected from the storage, aligned, and mounted on the machine, after which the 'screw' tightens it again.

Spindles (cutting tool) replacement system

Limitations

This project was completed during my second year at UofT, so the scope was limited to a conceptual design without any actual prototype or practical validation. We were not required to design the specific internal control systems, such as algorithms or hardware circuits.