Week 7. Computer-Controlled Machining¶
Group Assignment¶
In this week’s group assignment, together with Rudolf Igityan and Mkhitar Evoyan, we explored the basic principles of operating a CNC milling machine and learned about the tools and components used during the machining process.
We examined the machine interface, power controls, different types of milling bits used for cutting materials, as well as the safety rules that must be followed when working with CNC machines to prevent accidents and ensure the protection of both the operator and the equipment.
Understanding these components is important for operating the CNC machine safely and achieving accurate machining results.
CNC Machine Overview and Safety¶
Working with a CNC machine requires following several safety rules to prevent accidents and ensure proper operation of the equipment.
Before starting the machine, it is important to check that the workpiece is securely fixed to the machine bed. A loose material can move during machining and cause damage or injury. The cutting tool must also be installed properly and tightened in the spindle.
During operation, the operator should always wear appropriate personal protective equipment (PPE) such as safety glasses and hearing protection. Loose clothing, jewelry, or long hair should be secured to avoid getting caught in the moving parts of the machine.
It is also important to keep hands away from the cutting area while the machine is running. The CNC machine should never be left unattended during operation. In case of any unusual sound, vibration, or malfunction, the machine must be stopped immediately using the emergency stop button.
After finishing the job, the machine should be turned off and the working area should be cleaned from chips and dust. Proper cleaning helps maintain the machine and ensures a safe workspace for the next operation.
It is also important to have a fire extinguisher and a fire blanket available in the workspace in case of a fire emergency, in order to respond quickly and ensure safety.
Machine Power Switches¶
The machine has main control switches, including the MASTER ON/OFF switch, which controls the overall power supply, and the SPINDLE switch, which turns the spindle motor on and off. These switches ensure safe operation and allow the machine to be fully powered down when necessary.
Collet Set¶
The image shows a set of ER collets used in the milling machine to hold cutting tools.
The collets are inserted into the spindle and securely clamp the milling bit or cutting tool. Different collets are designed for different tool diameters to ensure precise and stable machining.
Types of Milling Bits¶
In CNC machining, several types of cutting bits are used. The most common ones are upcut, downcut, and straight bits. Their working principles are described below.
1. Upcut bits pull the chips upward while rotating clockwise. This helps remove the cutting debris efficiently from the cut. However, if the bit is worn, the upper surface of the machined part may not be very clean.
2. Downcut bits push the material downward while rotating clockwise. This usually results in a cleaner and smoother top surface of the part. However, if the dust extraction or ventilation is not strong enough, the chips and dust may accumulate inside the cut. քանւի որ մենք մեր լաբում downcut չունենք, մերը compresion է, բայց սրա վերևը downcut է
3. Straight bits have straight cutting edges and do not direct the material either upward or downward during cutting. They are commonly used for general cutting operations, grooves, and simple shapes. Compared to upcut and downcut bits, chip removal is less efficient, which can sometimes affect the cutting quality.
To start working in Aspire, you first need to create a new project (New Project).
Next, set the main parameters of the working area:
- Length
- Width
- Thickness
In the following step, define the Z Position (0), which can be set either:
- on the machine table surface, or
- on the material surface, depending on the machining requirements
The X/Y (0) origin point should be set at the bottom-left corner to ensure it matches the CNC machine’s zero position.
The file can then be imported (Import), which is a reliable method for loading the design into the project.
After that, go to the Toolpath tab and open the Material Setup Settings, where safety and working parameters are defined:
- Clearance (Z1) — 100 mm (safe height)
- Z Gap Above Material — 100 mm
These settings ensure that the tool moves safely above the material surface, preventing damage and ensuring proper operation.
Universal Code Sender¶
After turning on the machine, sometimes the computer may not recognize it. In that case, it is necessary to first perform the initial setup of the software.
First, go to Machine → Setup Wizard. In the opened window, click Next step by step, then enable the Enable Homing option.
Click Next again, and at this stage do not make any changes.
In the next step, enable Enable Soft Limits, and finally click Finish to complete the setup.
After that, it is important to check the machine’s position. It is possible that the machine has lost its position information (for example, after being powered off).
In that case, you need to press the Home Machine button, which will automatically return the machine to its zero position and restore the correct coordinates.
With the current settings, the X and Y zero point (0,0) is located at the bottom-right corner of the table.
Before starting the machining process, it is also necessary to properly set the Z-axis zero.
To do this, lower the Z axis, then change the Step Size Z value from 1 mm to 0.1 mm in order to achieve more precise control of the movement.
After that, gradually lower the Z axis until the tool reaches the correct position, approaching the surface of the material.
Once you are sure the position is correct, press the Zero Z button to set this point as the zero reference.
Since I had already clearly decided on the exact dimensions for my CNC cutting design at the initial stage, I did not create the design parametrically. In other words, the dimensions were predefined and fixed, and I had not planned to modify them later.
However, later on, taking into account material consumption and the thickness of the material used, I realized that to avoid such issues, I would have to manually adjust each detail or dimension one by one. Therefore, I decided to redesign my model and make it parametric, so that changes could be made easily and quickly across the entire structure.
For this purpose, I created a spreadsheet where I defined the main parameters, such as the material thickness, overall dimensions, and the sizes of individual parts. This approach allowed the entire design to automatically adapt to new values whenever a change was made, without the need to modify each element separately.
In addition to the main parameters, I also defined values that are calculated automatically. For example, I set the joint width as a value dependent on the material thickness, so that the width of the joints always matches the material being used. Similarly, I defined the front detail height parameter, which is calculated based on the overall height and other dimensions.
Since my design included an inclined section, it was necessary to determine its angle precisely. For this purpose, I performed the appropriate mathematical calculations to obtain the value of the angle of the slanted line.
This calculation was important to ensure that the bottom plane of the design and the front closing part do not interfere or collide with each other, thereby ensuring correct assembly and proper functionality of the structure.
