Computer Numerical Control (CNC) based Two-Dimensional Cutter

Project Title

Computer Numerical Control (CNC) based Two-Dimensional Cutter

Project Area of Specialization 3D/4D PrintingProject Summary

Summary:

In a highly competitive situation manufacturing high quality products with time saving and cost saving is a basic need of industry operators. Industrial sectors have to expand their production capacity every year to meet the ever increasing consumer demand. They have to make more products in less time with minimal waste produced. To meet these requirements a need arises to automate the reshaping, cutting and engraving of materials. It can be the core process for some industries and for others it can be a conditioning process. Therefore, it is essential to employ a computer system to assist in manufacturing [1].

In this work the Computer Numerical Control (CNC) machine will be used for three different applications that is as plotter for drawing, as engraving tool for carving and as a cutter for shaping and sizing. Challenging aspects are mechanical system design, electronic system and wiring, and software. Electronics parts are integrated on mechanical framework and controlled by a computer software. A software program installed in a microprocessor commands the electronics parts which then operate the mechanical structure on the work-bed [2.

This research covers the design and development of Computer Numerical Control machine. The proposed system comprises of a microcontroller connected to a computer. Aspire is a software to design shapes and objects. The software serves the purpose of both CAM and CAD. After designing it creates the G-Code of that object. Another software called Grbl controller takes that G-Code and feeds it to the controller. Controller then commands the stepper motors to move in two dimensional plane. The spindle motor mounted on z-axis pulley has drilling bit which is used for cutting the processed material [3].

The proposed machine will automate the process of drawing, cutting, designing and engraving on paper, soft wood and acrylic. The final CNC machine is expected to be easy to use and fully controlled by a computer program. Tested and calibrated Computer Numerical Control machine will be the final product.

1. Ahmed, B. J. S. A. A. "Design and Analysis Mini CNC Plotter Machine." (2018).
2. A. Quatrano, M. C. De Simone , Z. B. Rivera, D. Guida"Development and Implementation of a Control System for a Retrofitted CNC Machine by  Using Arduino" Department of Industrial Engineering, Via Giovanni Paolo II, 84135 Fisciano (SA), Italy
3. Flavio Maldonado Bentes, Marcelo de Jesus Rodrigues Nóbrega, F. B. D. S. Martins, Hildson Queiroz "CNC Machine Building Through Open Sources Projects and Programs", Rio de Janeiro, Brazil

Project Objectives

Objectives:

The project’s main objectives are given as follows:

1. In CNC machining the fundamental goal is to get the desired form of processed material with minimum or no human involvement. Automation takes place when a microcontroller replaces human mind and gives instructions to the actuators. But there must be a mechanical framework so the movement of actuators is utilized properly. Therefore, our first goal is Designing A Computer Numerical Control based Cutter.
    
2. Once mechanical assembly is acquired and overall circuit design is finished, the next step or goal is to Enabling the machine to follow two dimensional trajectory. The stepper motors work as actuators which take instructions from microcontroller. These motors mounted on x and y-axis shafts are responsible for x,-x,y and –y movement.
    
3. Developing a two dimensional ink plotter is next goal. A marker attached to Z-axis rail is used for plotting and painting. The marker is fixed or can be moved in z and –z direction manually.
    
4. ???????Extending the idea to engraving and possibly dry etching of PCB board is next main goal. A spindle motor with drilling bit, mounted on z-axis replaces the marker setup, is used for automated cutting and engraving of wood, plastic and acrylic.
    
5. ???????Introducing three dimensional movement so that manually bringing down the z-axis drilling bit or marker is also automated.
    
6. Computer aided designing and computer aided manufacturing.
    
7. Rectifying vibrations of stepper motors, drilling bit and working bed. These vibrations can affect the output badly.
    
8. Finally the mechanical system integrated with stepper motors and development board is interfaced with software and tested for desired output.

Project Implementation Method

PROJECT IMPLEMENTATION

The purpose of this project is to develop a computer numerical control based two dimensional machine so that it can cut in two dimensions as well as do engraving. This can be used to work in a more efficient way towards cutting and engraving 

Stepper Motors are used to drive the spindle motor to cut and engrave in three dimensions. They are controlled by current supplied by stepper motor driver IC. The Stepper Motor ICs are being controlled by Arduino in our case. The flow of the project is as follows

1. A design is created in Designing software. We used Autodesk Fusion 360 and Aspire to design our product in 2-D and 3-D.
2. Design is then converted into our machine friendly language, G-Code. The G-code programming language is the most extensively used CNC programming language. It has various variations and is mostly used in computer-aided manufacturing to control automated machine tools. G-code instructions are sent to a machine controller (in this case, an Arduino) that informs the stepper motors where to go, how fast they should go, and what path they should take.
3. This code is run on Arduino running GRBL, which gives instructions to stepper motor drivers, A4988. The A4988 is a full-featured micro-stepping motor driver with an integrated translator for simple operation. With an output drive capacity of up to 35 V and 2 A, it can operate bipolar stepper motors in full, half, quarter, eighth, and sixteenth-step modes. A preset off-time current is included in the A4988. Regulator that can function in either Slow or Mixed decay modes.
4. Stepper Motor Driver IC then gives current to stepper motors and drives in specific instructed ways to cut/ engrave the instructed design.

Benefits of the Project

1. Reduced physical manipulation
   Main purpose of automation is to minimize manual interference. One does not have to go to the work on field. The whole production process can be operated and controlled by computer.
    
2. Less dangerous to workers
   Cutting process often use equipment that in case mishandled results in serious injuries to the workers. It is obvious that when manual interaction is minimal, the working environment automatically gets more secure.
    
3. Easier operation
   Traditional cutting specially carving complex designs on wood and other different materials require high level of skill and experience. But through CNC Machining it gets easier because on field skill and experience is not required.
    
4. Increased production capacity
   CNC Machining can work 24/7 without tiring like humans resulting in increased production capacity to manufacture more products.
    
5. Quality is more consistent
   CNC machines are known for their accuracy and repeatability, which allows for parts to be made quickly and more precisely. This leads to better quality control because the parts produced will be similar in dimensions.
   Conventional machining can vary depending on how well an operator uses the machine. As described above, successful conventional machining can be very dependent on the experience of the operator and how skilled they are.
    
6. Faster production speeds are possible
   If a company is producing parts, then using CNC machining instead of conventional cutting will result in faster production times. The advanced equipment used in CNC machining allows it to produce parts in less time than conventional cutting due to better accuracy and faster feed rates.
    
7. CNC machining can produce near-net shapes
   One of the main advantages of CNC machining is that it can create near-net shapes (usually does not need further finishing) in a single operation. This means that little to no additional machining would be required after receiving a part from a CNC mill, making for increased efficiency and faster turnaround time than conventional machining techniques.

Technical Details of Final Deliverable

Block diagram:

Mathematical model:

Complete mathematical model with easily understandable and general variables. Best scenario is formulating a standard equation at the end of mathematical calculations. 

Stepper motor 1 Revolution = 200 steps

1 revolution=> 200 steps = 360º

                           1 step = 1.8º

Relationship between rotational motion of stepper motor and length of travel

      1 rev = 360º =200 steps => 8mm of linear travel

      1 step = 8mm/200   = 0.4mm

Each of these 200 steps can be further divided up to sixteenth step using Microstepping

1/16th step=0.4mm/16 => 0.025mm or 25 ?m

So, minimum distance this CNC can travel is 25 ?m

For calibration

Steps per mm = (steps per rev * microsteps) /mm per step

This gives us the steps for each axis

Steps per mm = (200 x 1 ) / 8

Steps / mm = 25

As we are using same diameter of lead-screws and same stepper motors, x, y and z axes’ steps/mm will be same i.e. 25 steps/mm.

Components:

1. The mechanical framework

   

    Technical Specifications

   Structure dimensions	360 x 330 x 220(mm)
   Working bed dimensions	300 x 180 x 45(mm)
   Material dimensions	X: 300mm, Y: 180mm, Z: 30mm or less
   Feed rate	1000 – 2000 mm/min
   Angle rotation	0 - 360º
   Time of simulate	Depend feed rate and type of processed material
   Drilling Bit	0.1mm

2. Electrical components

• 3x NEMA 17 stepper motors

                  Hybrid stepping motor with a 1.8° step angle (200 steps/revolution)

• Spindle Motor

     With max 1500rpm to rotate the drilling bit shaft

• A4988 DMOS micro stepping motor driver
• CNC Shield V3 psrovides arduino and some other development boards with power and less complicated wiring diagrams
• Arduino UNO

Open-source microcontroller board based on the Microchip ATmega328P

Circuit diagram:

Hardware prototype:

1. Hardware prototype is shown in the figure below. CNC Shield is powered by 12v DC supply. Arduino UNO is connected to PC via USB cable to get the instructions from software and command the A4988 drivers to drive the stepper motors.

1. Software (CAM and CAD) part is also shown in the figure

Above figure shows the software named Aspire 10 which is used to design and create 3D and 2D designs and objects. This process is called computer aided designing. After designing the parts, carvings or objects, next step is to convert that design into G-Code. This process is called computer aided manufacturing.

The above figure shows the G-Code of a square. It is to be carved on soft wood and the software interface shown in the above figure is GRBL Controller. This software is used to send the ‘.NC’ file (which has readable G-Code for the microcontroller) to Arduino UNO. This software can also be used as a remote control and to see the real time progress when a material is being processed on the working bed.

Structure dimensions

Working bed dimensions

Material dimensions

Feed rate

Angle rotation

Time of simulate

Drilling Bit

Final Deliverable of the Project Hardware SystemCore Industry ManufacturingOther IndustriesCore Technology 3D/4D PrintingOther TechnologiesSustainable Development Goals Industry, Innovation and InfrastructureRequired Resources

Elapsed time in (days or weeks or month or quarter) since start of the project	Milestone	Deliverable
Month 1	Proposal defense	Documentation for project proposal
Month 2	Literature review	Study of research papers and project related available data
Month 3	To understand the working of mechanical structure	Literature review of types of mechanical structure based CNC machines to choose the suitable
Month 4	To understand the working of electrical components	Electrical/electronic components selection and studying electrical circuit of the project in light of literature review
Month 5	To understand the working of software	Understanding the basics of CAM and CAD, studying the softwares (Aspire 10, Fusion 360 and GRBL controller) user interfaces
Month 6	Implementation of One dimensional cutter	Building circuit for one dimensional (x-axis) movement, x-rail movement control through computer
Month 7	Implementation of Two dimensional trajectory following machine	Working Two-Dimensional Machine
Month 8	Integration of cutter and plotter	Merging the cutter and plotter together
Month 9	Enabling Two-dimensional trajectory following machine to Two-dimensional ink plotter	Working Two-dimensional Ink plotter
Month 10	Testing	Debugging Errors
Month 11	Thesis writing	Project Report
Month 12	Thesis submission and Final Defense	Final Project Presentation