Milling machines have
been around since the early 19th century.
Driven by the need to manufacture large numbers of muskets for a young
America’s military, the government funded entrepreneurs, including Eli Whitney
– inventor of the cotton gin, to help.
In an iterative manner, these manufacturers developed new technologies
to create similar metal parts for the guns, thus giving birth to the milling
machine. These early machines were used
to “rough out” parts, requiring additional hours to smooth out the edges. Though relatively primitive, these milling
machines gave birth to an industry that supports the American economy.
Early milling machines
could only move in two dimensions, which limited their utility. In 1861, just in time for the Civil War,
Joseph Brown of Brown & Sharpe invented a universal milling machine that
added a third dimension to the milling process.
This machine was very successful, enabling Brown & Sharpe to build a
dominant position in the industry.
After World War One,
milling machines were in great demand for creating tool and die for the nascent
automobile industry. Engineers began to
find ways to use tracer controls so that
parts could be cut directly from drawings instead of having to create a
jig. This idea of bypassing the manual
creation of intermediate pieces would drive the development of more advanced
methods for controlling milling machines.
Towards the end of
World War Two and into the early 1950s, engineers started to use numerical controls
on milling machines to create smoother cuts, but such operations remained very
labor-intensive. In 1952, MIT developed
a very complex milling machine that relied on punch tape for numerical input
and used 240 vacuum tubes to create smooth cuts. Such a program was not suitable for
production use, but it demonstrated that numerical control could work for
milling. Unfortunately, the labor
intensity of it changed so that now the bulk of the labor time was in programming
the punch or magnetic tapes.
Fortunately, the late
1950s and early 1960s saw the advent of the computer, which reduced the time
necessary for such programming. In one
instance, use of a computer reduced programming and milling time from 8 hours
to 15 minutes. Soon, companies developed
languages that allowed for easier programming for milling parts and the field
of computer aided design (CAD) was born.
Improvements in CAD along with the fall in pricing of computer cycle
time meant that it became much easier to design parts in computer languages
that could be easily understood numerically controlled milling machines. As the microcomputer developed, it became
easier to directly feed CAD programs directly into numerically controlled
machines and today’s computer numerically controlled (CNC) mills were
born.
Moore’s Law ensured
that the power of microcomputers increased exponentially, while prices
continued to drop. Soon, CNC machines
were within reach of small production shops.
Such a shop could purchase a CNC lathe for a few thousand dollars,
quickly recovering the cost and investing in more such machines.
Today, you can
purchase a CNC machine online for yourself or your company. Hobbyists buy CNC machines for use in their
garages. Some even build them from
inexpensive, spare parts. If you already
own a laptop computer, you can download free CNC software from the web. For less than $100, a person who is
mechanically inclined can build a CNC machine for his or her own use.
On the commercial
side, the principles of CNC are being applied to using other methods of cutting
and machining. For example, laser and
plasma cutting use CNC to guide the cuts, which result in smooth surfaces
because lasers and plasma torches melt the cut materials. On the other hand, if the material being cut
is sensitive to high temperatures, a CNC approach can be used to guide a
waterjet cutter. A waterjet uses a
stream of very high pressure water to cut through materials, while taking
advantage of the heat dispersing characteristics of water. CNC machining today applies the basic
techniques to a number of technologies. For more information about milling machine please visit cncmasters.com.
