Natives of Canada, Henry and Franklin Hardinge were both life-time engineers. Henry began his career as a machinist with the John Abell Company of Woodbridge in Ontario, a maker of portable engines and farm threshing devices. He then travelled to the United States, working at various jobs until he was taken on as a draftsman in Chicago with a firm already employing his brother as an apprentice; Franklin, however, served only two years of his original apprenticeship, before leaving to continue his studies with a watchmaker. After completing his indentures Franklin joined his bother in their first business venture, on 23 July 1890, as Hardinge Brothers making watchmakers' tools in an eight-by-eight building at the rear of a boarding house at 359 West Monroe Street, Chicago. Driven out of their inadequate premises by cold weather the two brothers found a backer in the form of a Mr. Stephen R. Dale and founded a firm known as The Horological Tool Company that operated from what could have been a hardly more salubrious room over a horse stable at 1230 Dunning Street (later Altgeld Street). However, by May 1892 the Hardinge Company were doing well enough to afford the erection of a small factory at 3135 Lincoln Avenue - where they remained until 1913 - before moving to new and larger premises at 4149 Ravenswood. Avenue, Ravenewood. In 1894 Mr. Dale had withdrawn his interest in the company and the two bothers reverted to their original title of Hardinge Brothers; however, just one year later, in 1895, Henry retired from the partnership (though what prompted this move is unknown) and Franklin continued on his own until 1908 when the company was incorporated for $100,000 under the laws of Illinois. In 1902 (or thereabouts) Hardinge acquired the rights to the Cataract range of Precision bench lathes formerly produced by the Cataract Tool and Bicycle Company (named after the waterfalls visible from the factory grounds) and  the Cataract Tool and Optical Company the latter being incorporated in Buffalo (New York). 
In the early years of the 20th century the organisation continued to grow and in 1913 a further move was made to 1770 Berteau Avenue, though administrative offices were retained at the Ravenswood Avenue site.
At around the time that Hardinge were settling into their Ravenswood works a small company was being established in Rochester, New York, by Mr. Reisinger and Mr. McDonnell, to exploit the growing market for precision work-holding devices, especially collets. The new company's unique selling point was their "inanout" collet, a design that unfortunately proved inadequate under service conditions and was abandoned; however, the awkward name stuck, and the "Inanout Collet Manufacturing Company" was born. Franklin was an accomplished engineer, machine-tool designer and inventor and contributed to work on a calculating machine for Remmington, helped the Stromberg Carlson Company with their early developments on automatic telephones systems and  developed the "scoring" machine that perforated card so that it could be easily torn where needed.
After Reisinger dropped out of the company McDonnell went into partnership with Mr. Leon Morrison and formed the Morrison Machine Products Company; in 1925 the company was purchased by Mr. Evans and Mr. Anderson and relocated to Elmira, New York. In 1931, at the height of the depression, Hardinge were in receivership and Anderson and Evans took advantage of the very low stock prices and bought them out; they then consolidated their interests by relocating them from Chicago to join their New York operation. To improve efficiency a new factory and offices were built and, by 1938, with the company employing 300 skilled workers, they were well positioned to take advantage of the great upturn in production that preceded the United States entry into World War Two.
In the mid 1930s a British manufacturing subsidiary was organised with help from a firm based in the west of London, Automotive Engineering Ltd. The new company, Hardinge Machine Tools Ltd., was formed on the 3rd of February, 1937;  85% of the stock was owned by Automotive Engineering and the first six employees worked from the corner of a factory in Twickenham making collets, form-tools and feed-fingers. In line with the American company, the years of WW2 saw a dramatic growth in output and, in 1940, the company moved into a propose-built factory at Hanworth, Middlesex, together with a temporary "shadow" factory in nearby Acton as demand for munitions, which the company were now making, grew still further. In 1943 Automotive Engineering was taken over by Sheepbridge Engineering, who then sold part of the Hardinge UK equity to Hardinge Brothers Inc. - through they still retained enough stock to maintain a controlling interest in the company. The late 1940s saw the introduction of the first HLV lathe, notable not just for its outstanding precision but also a variable-speed headstock and an independently-controlled , electrical power-sliding feed to the carriage. In order to promote the new lathe, and demonstrate its unique properties to potential customers, a war-time ambulance was converted into a demonstration van able to hold three lathes and their tooling. The HLV lathe was in competition with the Cromwell toolroom lathe, and was eventually to comprehensively outsell it. Production was relocated to Exeter in 1966 following the compulsory purchase for development of the original factory site (though sales and Administration continued to be operated from there until 1972). In 1979 Sheepbridge Engineering was bought by GKN who, two years later, sold the remaining (and majority) shareholding to Hardinge Brothers Inc. In 1977 Hardinge UK moved to new premises at Matford Park in Exeter.
In 1983 the company launched its first CNC machine, the Model HXL; although originally designed as a CNC toolroom lathe it was marketed as a production machine and, with a weak turret and cantankerous GE1050 control system, was destined not to be a success. In 1988 the popular "Conquest" range was launched but, by 1989, the manufacturing facility in the UK was uneconomic to operate and closed - the company relying upon the marketing of US-built machines and spare parts. In 1995, apart from the incomparably excellent (and now unique) HLV-H,  the entire product line became CNC. At around the same time Hardinge Brothers Inc. acquired control of the Swiss Kellrnberger grinder company and added their products to the company's lines.