30-07-2012, 12:39 PM
STUDY ON PRINCIPLE AND OPERATIONS OF CNC MACHINES IN VARIOUS FABRICATION PROCESSES
STUDY ON PRINCIPLE.ppt (Size: 1.64 MB / Downloads: 88)
Introduction
CNC stands for "Computer Numerated Control." A CNC machine directs a cutting tool, which may range from a small scalpel to a woodcutting blade or router, based on directions that the operator has entered into a computer that controls the movement of the head holding the cutter. This leads to results that are far faster and more accurate than cutting by hand or on manually controlled power tools.
HISTORY
CNC, or computer numerical control, allows a computer to dictate the moves a machine makes to perform cutting function. Originally, all machines were operated manually with the distinct possibility of mistakes.
The CNC machine performs these same actions with more precision as well as more speed. The first CNC machines were manufactured in the 1970s to speed up production at large manufacturing plants and were very expensive and difficult to use.
Types of CNC Machines
There are few main types of CNC machines used in metal shops as well as production shops around the world today.
These machines uses computer controls to make intricate movements to cut and shape metal, wood and plastics.
By learning the specific types available for use, you can choose the correct one for your application
CNC Mills
These machining centers use computer controls to cut different materials.They are able to translate programs consisting of specific number and letters to move the spindle to various locations and depths.Many use G code, which is a standardized programming language that all CNC machines understand, while others use proprietary languages created by their manufacturers. These proprietary languages are often simpler than G code, but not transferable to other machines.
CNC Lathes
Lathes are machines that cut metal that is often turning at fast speeds.
CNC lathes are able to make fast, precision cuts using indexable tools and drills with complicated programs for parts that normally cannot be cut on manual lathes. These machines often include 12 tool holders and coolant pumps to cut down on tool wear.
CNC lathes have similar control specifications and can read G code as well as the manufacturer's proprietary programming language.
CNC Grinders
Grinding metal is a process that uses a coated wheel that slowly removes metal to create a part. Through the years, grinding was done on a manual machine, but with the advent of CNC technology, the grinding process has advanced dramatically. Enter the program, which includes the various passes that the wheel will make,and hit start. It is one of the easiest types of CNC machines to work with as they often only contain a single grinding wheel.
Benefits
CNC machines offer many benefits over manual machines of the same type.
Since the machines are using complicated programs, many parts that were not previously possible are now being created with 3D computer-aided manufacturing software.
You can design a part and convert the dimensions to G code.
You can often do this right at a CNC control and run the program immediately.
These machines save time and money, resulting in cost saving due to lower amounts of waste from mistakes.
Applications of the CNC Machines
These days the CNC machines are found in almost all industries, from a small scale industry to big companies. There is hardly any facet of manufacturing that is not touched by the automated CNC machining center. Everyone involved in the manufacturing should know what a CNC machine can do for their company. Due to extensive applications of CNC machines in various industries, there is a great surge in the demand of the CNC programmers. To meet these demands a number of schools have come up that teach the operation and programming of the CNC machines
. CONCLUSION –
The Vocational training at BHEL Hardwar helped me in improving my practical knowledge and awareness regarding Principle and Operations of CNC Machines in fabrication processes to a large extent.
Here I learnt about how various fabrication processes are done using sophisticated equipments and how different machines are operated in order to get certain process done.
At least I could say that the training at BHEL Hardwar is great experience for me and it really helped me in making or developing my knowledge about the CNC Machines , about its functions, purposes, applications and various processes done using it so as to fabricate certain parts of hydro turbines and water boxes and other equipment installed in the heavy fabrication department.