What is G code

G code is simply a language used to tell machine.
G code has many variants, but it is the common name for the most widely used Numeric Control (NC) programming language.
G code is mainly used in computer-aided manufacturing for controlling automated machine tools.
In a modern-day desktop CNC machine and software, you will never have to enter G-code manually, unless you want to. 
The CAD/CAM software and the machine controller will take care of all of this for you. 

Now let we know some most common programming code with example and how its use and how it work?

G0 - Rapid motion 

Code for a figure - G0 X7 Y18

The G0 command moves the machine at maximum travel speed to whatever coordinates follow G0. 
The machine will move in a coordinated fashion, and both axes complete their travel at the same time. G0 is not used for cutting. Instead, it’s used to move the machine quickly to begin a job or move to another operation within the same job. 

G1 - Controlled motion

Code for a figure - G1 X7 Y18 F500

A G1 command is similar to G0.
G1 tells the machine to move at a specified rate called the feed rate (F).

G2 - Clockwise motion 

Code for a figure - G21 G90 G17

                         G0 X0 Y12

                                      G2 X12 Y0 I0 J-12

G2 is used for specifying the offset from the centre creates clockwise motion between the starting point and specified ending point.

Another figure for G2

G3 - Counterclockwise motion

Code for a figure - G21 G90 G17

                         G0 X-5 Y25

                                     G3 X-25 Y5 I0 J-20

Just like G2, the G3 command creates an arc between two points. Whereas G2 specifies clockwise motion, G3 specifies counterclockwise motion between the points as shown in the figure. 

G17/G18/G19 - Working Planes

These codes are used to set the plane to be machined. 

Typically G17 is used and is the default for most hobby machines, but two other planes can be used in a three-axis machine:

• G17 = x/y plane
• G18 = z/x plane
• G19 = y/z plane

G20/21 - Inches or Millimeters

The G21 and G20 commands used for units, either inches or millimetres.

• G21 = millimeters
• G20 = inches

Here’s an example that’s set to inches:

G21 G17 G90

G28 - Referencing Home

A simple G28 command sends the machine to its home position. 
Code - G28 Z0

G90 - Absolute Mode

G90 causes units to be interpreted as absolute coordinates. 

This is the most common mode for hobby-grade CNC machines; it’s the default mode.
Absolute coordinates will be interpreted as exactly that absolute. 

If we write code G0 X10 will send the machine to x = 10. It will not send the x-axis to “10 more” units from where it’s currently located.

G91 - Incremental Mode

G91 is the opposite mode of G90. 

Setting an incremental mode means that every command issued will move your machine the specified number of units from its current point not like that in G90 likes from x-axis only.

For example, in incremental mode, G1 X1 will advance the machine 1 unit in the x-direction, regardless of its current location.

G code and M code list

In CNC machining G code and M code are used for control machining that language known as a numeric control programming language. There is some difference between the G code and M code. We can see a list of G code and M code below.

What is the G code?

G code is a type of function used in numeric control programming language for CNC machine.

G code contains the information to position a tool to do the actual work.
G code is a way for you to tell the machine to move to various points at the desired speed, control the spindle speed, turn on and off various coolants, and all sorts of other things.

CNC G codes

G00 - Positioning at rapid speed; Mill and Lathe
G01 - Linear interpolation (machining a straight line) Mill and Lathe
G02 - Circular interpolation clockwise (machining arcs) Mill and Lathe
G03 - Circular interpolation, counter-clockwise; Mill and Lathe
G04 - Mill and Lathe, Dwell
G09 - Mill and Lathe, Exact stop
G10 - Setting offsets in the program; Mill and Lathe
G12 - Circular pocket milling, clockwise; Mill
G13 - Circular pocket milling, counterclockwise; Mill
G17 - X-Y plane for arc machining; Mill and Lathe with live tooling
G18 - Z-X plane for arc machining; Mill and Lathe with live tooling
G19 - Z-Y plane for arc machining; Mill and Lathe with live tooling
G20 - Inch units; Mill and Lathe
G21 - Metric units; Mill and Lathe
G27 - Reference return check; Mill and Lathe
G28 - Automatic return through reference point; Mill and Lathe
G29 - Move to location through reference point; Mill and Lathe (slightly different for each machine)
G31 - Skip function; Mill and Lathe
G32 - Thread cutting; Lathe
G33 - Thread cutting; Mill
G40 - Cancel diameter offset; Mill. Cancel tool nose offset; Lathe
G41 - Cutter compensation left; Mill. Tool nose radius compensation left; Lathe
G42 - Cutter compensation right; Mill. Tool nose radius compensation right; Lathe
G43 - Tool length compensation; Mill
G44 - Tool length compensation cancel; Mill (sometimes G49)
G50 - Set coordinate system and maximum RPM; Lathe
G52 - Local coordinate system setting; Mill and Lathe
G53 - Machine coordinate system setting; Mill and Lathe
G54~G59 - Workpiece coordinate system settings #1 t0 #6; Mill and Lathe
G61 - Exact stop check; Mill and Lathe
G65 - Custom macro call; Mill and Lathe
G70 - Finish cycle; Lathe
G71 - Rough turning cycle; Lathe
G72 - Rough facing cycle; Lathe
G73 - Irregular rough turning cycle; Lathe
G73 - Chip break drilling cycle; Mill
G74 - Left-hand tapping; Mill
G74 - Face grooving or chip break drilling; Lathe
G75 - OD groove pecking; Lathe
G76 - Fine boring cycle; Mill
G76 - Threading cycle; Lathe
G80 - Cancel cycles; Mill and Lathe
G81 - Drill cycle; Mill and Lathe
G82 - Drill cycle with dwell; Mill
G83 - Peck drilling cycle; Mill
G84 - Tapping cycle; Mill and Lathe
G85 - Bore in, bore out; Mill and Lathe
G86 - Bore in, rapid out; Mill and Lathe
G87 - Back boring cycle; Mill
G90 - Absolute programming
G91 - Incremental programming
G92 - Reposition origin point; Mill
G92 - Thread cutting cycle; Lathe
G94 - Per minute feed; Mill
G95 - Per revolution feed; Mill
G96 - Constant surface speed control; Lathe
G97 - Constant surface speed cancel
G98 - Per minute feed; Lathe
G99 - Per revolution feed; Lathe

What is the M code?

M code is an auxiliary program command.

M code contains the information to coolant OFF/ON like operating the various machining parts like door, coolant, spindle etc.

CNC M Codes

M00 - Program stop; Mill and Lathe
M01 - Optional program stop; Lathe and Mill
M02 - Program end; Lathe and Mill
M03 - Spindle on clockwise; Lathe and Mill
M04 - Spindle on counterclockwise; Lathe and Mill
M05 - Spindle off; Lathe and Mill
M06 - Tool change; Mill
M08 - Coolant on; Lathe and Mill
M09 - Coolant off; Lathe and Mill
M10 - Chuck or rotary table clamp; Lathe and Mill
M11 - Chuck or rotary table clamp off; Lathe and Mill
M19 - Orient spindle; Lathe and Mill
M30 - Program end, return to start; Lathe and Mill
M97 - Local sub-routine call; Lathe and Mill
M98 - Sub-program call; Lathe and Mill
M99 - End of subprogram; Lathe and Mill

Will converting to LPG affect the engine performance?

Yes, LPG tends to down vehicle's performance by a small percentage. But not that much effect did on engine performance. We all know LPG has lower calorific value than petrol so LPG gives less potent as an internal combustion engine as a fuel.

On the other hand, LPG is less than half of the price than petrol and it has a high octane rating than petrol so it is more easily mixed with air. So that reason LPG is also much helpful in such case but after all, if you use LPG in your car as fuel your car maintenance increases and as time goes some part of the car will need frequent replacement.

What is LPG conversation

You know conversation of LPG that before should know first the full meaning of LPG and what does LPG stands for and other related information.

Converting your car to LPG will save you money. 
LPG is typically at least 50 per cent cheaper than other fuels, allowing you to recover the cost of an LPG installation in a relatively short time.
Almost all vehicles use petrol and diesel as a fuel they all are converted to LPG operation at a reasonable cost.
Dual fuel LPG systems allow a vehicle to operate on either LPG or petrol and it can double a vehicles' range.

Some facts about the conversation of LPG :

• Uses of LPG for running an engine is beneficial for cars.
• LPG is a cleaner-burning fuel than petrol.
• Engine oil and spark plug need changing less with use of LPG in cars, so service intervals can be increased.
• The time required to install an LPG system is varied.
• A typical family sedan car with a single boot-mounted tank should take only one to two days.
• A large four-wheel drive with multiple tanks might have work for two to three days.
• You should tell your insurance company of the vehicles for the conversation to LPG.
• Note that any vehicle with a compliance plate dated after December 2003 that is converted to run on LPG must be fitted with a system that has passed current emissions test standards.

When you bring your vehicle in for an LPG conversion and installation there is little that needs to be changed in the way of the car’s current structure but the following will be added 

• An LPG tank will be installed, either in the boot or under the car if there is enough clearance. 
• A convertor will be installed to convert the liquid gas into vapour.
• An air/fuel mixer or LPG injector will be installed to ensure the right mix of air and LPG is mixed to power the car.
• A fuel lock will be fitted to stop fuel flow to the engine, once it is shut off.

Types of LPG Conversion Systems :

• Converter-and-mixer systems are the oldest style, dating back decades and still widely used.

The liquid fuel is converted into vapour and then mixed with air before going into the intake manifold.

• Vapour phase injection (VPI) systems use a converter-and-mixer system, but the gas exits the converter under pressure and is injected into the intake manifold. 

Electrically controlled injectors improve the metering of fuel to the engine, fuel economy and power, as well as reducing emissions.
This has been the most popular type system in recent years.

• Liquid phase injection (LPI) systems inject liquid directly into the intake manifold, where it vaporises, not using a converter.

The fuel vaporising in the intake manifold cools and increases the density of the intake air, substantially increases power output, improves fuel economy and has lower emission, when compared to VPI systems.

• Liquid phase direct injection (LPDI) are the most advanced systems, injecting liquid LPG directly into the combustion chamber.

The LPG instantly vaporises, cooling the combustion chamber fuel-air mixture during the compression stroke, with further performance and emission improvements.

What are the uses of LPG?

LPG gas is a clean source of energy having a wide range of applications. Let us check out the uses of LPG in this article. Also, find out advantages and disadvantages of it to know more about it. 

Some highlighted points on uses of LPG are:

1. Cooking
2. Rural Heating
3. Motor fuel 
4. Refrigeration

Uses of LPG: 

• Cooking 

LPG is used in cooking. It doesn't produce smoke as compared to other ways of cooking. In this cooking process, the gas is stored in liquid form under pressure in the cylinder and then connected by using gas stove cooking is done.

• Rural Heating

LPG can be used as an excellent alternative form of rural heating like heating oil, electric heating, or kerosene.

• Motor fuel

By using LPG in motor reduces the transportation cost by consuming less fuel as compared to other sources like petrol and diesel.

By using this one more advantage is that LPG is environment-friendly gas.

• Refrigeration 

LPG is also used in the refrigeration system as a refrigerant. some times LPG is the replacement of hydrofluorocarbon and chlorofluorocarbons.

Units used in Chemistry

Physical Quantities and Their Units
SI measurement units	symbol	SI measurement units	symbol
distance	d	meter	m
mass	m	kilogram	kg
time	t	second	s
electric charge	Q	coulomb	C
temperature	T	Kelvin	K
amount of substance	n	mole	mol
luminous intensity	I	candela	cd
acceleration	a	meter per second squared	m/s2
area	A	square meter	m2
capacitance	C	farad	F
concentration	[C]	molar	M
density	D	kilogram per cubic meter	kg/m3
electric current	I	ampere	A
electric field intensity	E	newton per coulomb	N/C
electric resistance	R	ohm	W
emf	x	volt	V
energy	E	joule	J
force	F	newton	N
frequency	f	hertz	Hz
heat	Q	joule	J
illumination	E	lux   (lumen per square meter)	lx
inductance	L	henry	H
magnetic flux	F	weber	Wb
potential difference	V	volt	V
power	P	watt	W
pressure	p	pascal  (newton per square meter)	Pa
velocity	v	meter per second	m/s
volume	V	cubic meter	m3
work	W	joule	J