Inside Story Issue 6

In-The-Field---History
The word “micrometer” is a neoclassical coinage from the Greek “micros” (“small”) and “metron” (“measure”). Before the advent of the industrial age and the need to machine precise parts, there was little interest in accurately measuring very small linear dimensions. But then came the industrial revolution…
Issue 6
1st Quarter
2008
A Mitutoyo America Publication

Early period
While the concept of the screw thread was known in ancient times, its first application to measurement was in 1638 by William Gascoigne, a British Astronomer. Gascoigne used a screw thread to fine-adjust the angular displacement of his telescope as he moved it to observe and record the position of stars.

Micrometer-of-wattAbout a century later, the industrial revolution was beginning to take hold and machine tools were introduced (originally to meet watchmakers’ need for small, accurate parts). Shortly thereafter, the manufacture of steam engines and other complex mechanisms made it necessary to reliably determine measurements to ensure design specifications.

As a result, in 1772, James Watt, who is credited with the first practical steam engine, devised the first instrument that functioned in the way of a modern micrometer.

Watt’s micrometer was bench-mounted and consisted of a rack-and-pinion mechanism connected to rotating threads. In practice, a measuring blade attached to the rack was advanced to make contact with an object to be measured. The movement of threads was read by a large graduated disc attached to the end of the threads, which, in turn, rotated a smaller disc. The large disc indicated revolution of threads, while the smaller one indicated fractions of an inch. The smallest reading on the large dial face was 0.0001”. Watt’s “U”-shape frame became standard on subsequent micrometers.

Another Englishman, Sir Henry Maudslay, who conceived the first modern machine shop and first envisioned surface grinding and milling machines, produced a bench-mounted micrometer in 1805. Called the “Lord Chancellor” for its use in settling disputed measurements taken on other devices, the instrument was so precise that a series of tests performed on it in 1918 found it still to be accurate.

Maudslay

A recognizable configuration takes form
Today’s standard micrometer features a “U”-shaped frame and is operated by one hand. Many manufacturers share this common design – the origin of which traces back to the French inventor J. Palmer, who received a patent for the design in 1848. Palmer’s design also incorporated many other features of the modern micrometer including the thimble, sleeve, spindle and anvil. The reading edge of Palmer’s thimble was slightly tapered-down to meet graduations on the sleeve. The circumference of the thimble was divided into 20 equal parts, providing 0.05mm as its smallest reading. Thus, in Palmer’s design, the basic modern micrometer was established. But it was left to an early American manufacturer to bring the device to the mass market.

palmer

Brown & Sharpe was orginally a clock repair business founded in the early 1800’s in Providence, Rhode Island, by David and Joseph Brown and their partner Lucian Sharpe. Having witnessed the Palmer micrometer at the 1867 International Exposition in Paris, Brown & Sharpe decided to improve on the design and subsequently to promote their instrument’s use in average machine shops around the world.

Brown&Sharp

While the drawings of Palmer’s patent were carefully rendered, his design was not executed as well as it might have been. For example, it offered no spindle clamp. More importantly, the graduated lines were not evenly spaced. Brown & Sharpe improved on the original design by utilizing a spindle with a much finer pitch of 40 threads per inch. Thus it was that the micrometer, conceived in England and nurtured in France, was to come of age in America.

Mitutoyo in the modern era
In Japan, the Meiji Period (Period of “Enlightened Rule,” 1867–1912) was characterized by a national aspiration to become a technologically advanced society. This was typified by an international search for knowledge that would support the rise of the domestic economy – including the development of a state-of-the-art manufacturing base.

It is against this backdrop that the story of the development of the micrometer in Japan continues…

Japanese modernization calls for micrometers
By the turn of the 20th century, Japan’s rapidly growing manufacturing sector was calling for more and more micrometers. Because import of micrometers from America and Europe was limited at that time, some Japanese manufacturers attempted to make their own instruments – with varying degrees of success.

By 1934, a number of micrometer manufacturers emerged – including among them, Mitutoyo.

In 1934, Mitutoyo was founded by Yehan Numata, who initially devoted three years to micrometer R&D prior to introducing his first commercial model in 1937.

The-first-micrometer

Yehan Numata concluded that an educated, motivated work force was essential in order to manufacture micrometers trusted by all parties for performance and accuracy. It was as a reflection of this insight that Mitutoyo’s founding corporate principals of “Good Environment, Good People and Good Technology” were established. These principals, much ahead of their time in the early 20th century, were to provide a foundation for the growth of what would become the world-leading metrology company that today is Mitutoyo.

Throughout the period of the Second World War, and even thereafter, micrometer production in Japan encountered enormous difficulty. Mitutoyo’s own Kamata factory had been rendered inoperable. But, by 1949, the factory was ready to resume full micrometer production.

Mitutoyo leadership emerges
As the ‘50’s rolled along, the domestic demand for consumer goods such as electronics and automobiles increased, giving momentum to application of micrometers in manufacturing. By adopting enhanced specifications as requested by various customers, Mitutoyo micrometers became comparable to their foreign counterparts – even exceeding them in quality, while besting them in price.

Some of the technical improvements of the ‘50’s and ‘60’s that enabled Mitutoyo micrometers to achieve world-leading performance included: satin-chrome finishes for improved graduation contrast and longer life, thimble ratchet-stops, hardened- and-ground spindle threads, carbide-tipped faces and mechanical digital counters.

Then, in 1979, Mitutoyo introduced its first electronic, digital display micrometers, and the focus shifted from careful interpretation of a graduated scale to glancing at easy-to-read LED and LCD readouts. A new breed of micrometer had emerged incorporating microchip technology and promising productivity improvement.

Today, Mitutoyo digital micrometers offer output ports for uploading measurements to integrated metrology data platforms such as Mitutoyo’s MeasurLink® system which combines real-time data acquisition, on-line SPC analysis, integrated networking and quality information sharing to create a comprehensive quality management system.

Looking to the future
With the introduction of QuantuMike®, Mitutoyo continues to provide micrometer design and engineering leadership. With Digimatic® display, IP65 coolant protection, SPC data connectivity and an advanced spindle drive that cuts measuring time as much as 35%, with QuantuMike®, the future of micrometers is available today.

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