research paper
Development Stage Of CNC Machinery 10
Development Stage of Computer Numerically Controlled Machinery
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4/18/2015
Table of contents
List of Illustrations....................................................................................................pg. 3
Abstract.....................................................................................................................pg. 4
Introduction..............................................................................................................pg. 5
What CNC Is............................................................................................................pg. 6
Historical Background of CNC................................................................................pg. 7
Push and Pull Forces Throughout the Development of CNC.................................pg. 10
Technological Recourses .......................................................................................pg. 11
Conclusion..............................................................................................................pg. 11
References.................................................................................................. ............pg. 12
List of Illustrations
Illustration 1: X,Y,Z axis........................................................................................pg. 6
Illustration 2: Music Box Cam...............................................................................pg. 7
Illustration 3: Blanchard Lathe...............................................................................pg. 8
Illustration 4: Punched Tape...................................................................................pg. 9
Illustration 5: CNC Machines.................................................................................pg. 9
Abstract
Computer Numerically Controlled (CNC) Machinery is a technology that allows for a mass production of high quality parts through the use of a computer controlling servo motors which orientate specific tooling in order to create the part. The development of CNC technology relies on a number of inventors throughout history dating back to the 1700's who saw a need for a new technology and then simply used already existing technology to fulfill that need. The main forces behind the development of CNC technology were primarily the huge demand of weapons and high quality air craft parts from the United States military, along with individuals who saw this demand and recognized the need for a technology that substantially increased the rate of production for these weapons and parts. These individuals were able to take existing technologies and create a new technology to fulfill these demands. This process eventually led to CNC technology which was nothing more than the merger of the already existing IBM computer with the already existing servo controlled NC machinery. This technology today has been refined to the point where consumers are able to have their own personal table top CNC mills in their home garages.
Introduction
Purpose:
The purpose of this document is to fulfill one subtopic of a major topic that was split among our group of three people.
Description:
Our group decided to do our report on CNC technology and how it has effected society. After selecting this topic our group then divided it into subtopics for each group member to cover. I was assigned the development stage of CNC technology so that is the subtopic the this document covers.
Scope:
This document covers the development stage or stage one of the S-curve of CNC technology. This includes; the push and pull forces behind the development of the technology in terms of historical background.
Document Organization:
This document covers the development of CNC technology by utilizing the following five subsections:
· What CNC is
· Historical Background of CNC
· Push and Pull Forces Throughout the Development of CNC
· Technological Resources
· Conclusion
The five subsections above are discussed throughout the document in the order of the bulleted list above.
What CNC Is
CNC stands for Computer Numerically Controlled operations. It is the ability to operate machinery by way of computer. Simply put, it is the merger of the common types of machinery, such as lathes and milling machines, with computers. It is the computer which operates servo motors which orientate the tooling along an X,Y,Z axis.(Ryan, 2009) Non CNC machinery requires manual operation to orientate the tooling. The use of computers to operate the machines allows for a much higher quality with much tighter tolerances. For example, when you need to perform a machining process that involves the change of only one axis at a time it is very easy to accomplish by hand. Now consider an operation such as milling a sphere out of a cube. This process would involve simultaneous changes in multiple axis. This would be near impossible by hand and the CNC process would be the optimal solution. The Illustration below depicts the X,Y,Z axis.
Illustration 1: X,Y,Z axis
Historical Background of CNC
The origins of CNC machinery actually dates back to 1770 and the creation of musical boxes. The father of the music box is Louis Favre who was a Swiss inventor from Geneva. The early music boxes would utilize a small cylinder with pins which would spin and activate the musical machine as depicted below. A cylinder with pegs is basically a cam. In order to change songs you would need to physically change the pin layout on the cylinder which typically meant changing cylinders. (Pfirrmann, 2001-2014)
Illustration 2: Music Box Cam
In 1818 Thomas Blanchard utilizing the cam design found in music boxes, used that design to operate machining equipment used to make gun barrels. Again, in order to change the operation of the machining, one would need to change the cam layout. However just as the music box could play the same song over and over repeatedly without variation, so could Blanchard's first replicating machine in regards to musket barrels. Immediately after designing his first cam controlled cutter, Blanchard created what is called the "Blanchard lathe" which is actually not a lathe but is a shaper. It basically used an exact model as a template to control the X,Y,Z axis which it was then able to reproduce multiple exact quantities.(Springfield Armory) An 1822 Blanchard stock making replicating lathe is illustrated on the top of the next page in illustration 3.
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Illustration 3: Blanchard Lathe
Manufacturing continued using cam operated or template operated machinery until the 1940's when John T. Parsons started the second industrial revolution. This was the period of time when IBM made a major thrust into business computing. IBM was the world's leader in tabulating equipment. John T. Parsons along with Sikorsky Aircraft utilized an IBM tabulator to tabulate the X,Y axis with 200 points instead of the previous 17 points that Sikorsky was originally using. With print out in hand, a machine operator could call out the X,Y axis coordinates to the machine operators who would actually be turning the dials and levers. Seeing how this approach worked so good, in 1948 Parsons took the next giant step with the idea of having the dials and levers operated by servo motors controlled by punched tape rather than by human operators. Punched tape was the main data storage used by IBM at the time. It was literally a long piece of tape with typically five or eight holes punched through the tape. You can kind of imagine this format as Morse code or brail. Illustration 4 depicts both a five-hole and an eight-hole tape.
Illustration 4: Punched Tape
Having pioneered the manufacturing process of numerically controlled (NC) machinery, Parsons teamed with Massachusetts Institute of Technology (MIT) to refine the process. Where Parsons original process used a series of cutting points, the process at MIT was refined so that the cutting points were refined to cutting lines which allowed for a smoother operation.(Lee, 2013-2015)
In the late 1950's numerical control (NC) was further developed into computer numerical control (CNC). CNC is basically the mating of the computer directly with the machine itself. The development of the computer along with the development of control servos allowed for greater precision and ease of operation. Computer language was being specialized for these operations which became known as computer aided design (CAD). In addition to computer automated machinery (CAM). It is now possible for a machine operator to easily make changes to the cutting operation by making an easy programming change via a directly linked computer which now a days may be a lap top.(CNC Cookbook) The picture below depicts a 1959 CNC machine. The picture to the below right depicts a currently available personal use desk top CNC mill available from littlemachineshop.com.
Illustration 5: CNC Machines
Push and Pull Forces Throughout the Development of CNC
While the original theory of the CNC history dates back to 1770's and the creation of the music boxes and cuckoo clocks, the first real production forces started in 1818. Thomas Blanchard seeing the Springfield Armory producing thousands of gun barrels for the United States military recognized the need to reduce the machining time needed to produce each gun barrel. Up until this time all milling had been performed by hand operation of the machinery. The Springfield Armory welcomed Thomas Blanchard's new technology because it greatly reduced their production costs and time. The same push-pull forces continued with Thomas Blanchard's creation of the Blanchard lathe. The United States military has always been the major purchaser of national defense weapons. The defense contractors who supply these weapons do so in mass quantities which leads for a direct need of an efficient manufacturing process to both keep the cost down and the production speed high. Both cost and speed can be critical to the military. For example, if you can produce five guns for the cost of one gun of equal or better craftsmanship, you obviously would pick the five. In war time speed becomes critical. The ability to mass produce rapidly is critical. While additional soldiers are trained, they need to be out fitted with their guns. As planes are shot down and tanks destroyed in the fields, they too must be replaced rapidly. This overwhelming demand provides the incentive for inventors to supply new innovations in the manufacturing process. In the 1940's the US Air force increased its demand for cost efficient and rapidly produced machined parts. John T. Parsons met that need with the first numerically controlled machinery. While the original needs for supply and demand where primarily based upon the militaries need, those needs have trickled down. First to consumer goods whose manufacturing need is more based upon cost rather than speed as it is in war time. Manufacturing is based on Darwinism. The strong will survive. Manufactures who make the largest profit will continue to survive. Just as the demand trickled down from the military to the large manufactures, that demand has now trickled down to the personal consumer. Personal consumers are now able to purchase their own bench top CNC milling machines for there personal use.
Technological Resources
Through the development of today's CNC machines, the technological advances have been primarily the adaption of existing technology to a manufacturing use. In 1818 Thomas Blanchard utilized the cam design which dated back to the 1700's to create his Blanchard lathe. In the 1940's John T. Parsons combined the use of an IBM punch tape to servo operated machinery. As computers continued to develop, as well as machinery controlling devices, so came the merger of the two for the development of the CNC machinery.
Conclusion
The development of CNC technology has push and pull forces that brought on its development along with an interesting historical background that dates back all the way to the 1700's. I found it to be very interesting that the origins of CNC machinery dates all the way back to 1770 and the creation of the musical box. As I would have guessed the United States military generated a pulling force on the technology through a high demand for weapons and aircraft parts. This high demand created a need for mass production which brought on CNC technology through key people such as Thomas Blanchard recognizing the need and creating a new technology to meet the demand. The invention of the new machining technologies by the key individuals generated a push force on CNC technology. I also found it interesting that each step of the development of CNC technology utilized technologies that had already existed and either used them for a new purpose or simply just combined two already existing technologies in to one such as the computer and the machining tools. As the origins of CNC dates back to the 1700's it is still being used today and is still being refined and new processes are utilizing its technology.