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Since its founding in 1888, Morgan Construction Company has been a leader in the manufacture of rod and bar mills for rolling both ferrous and non-ferrous products. Although, Morgan's first experience with metrication came in the 1920's, it was not until 1970 that a concentrated effort was made to convert its design and manufacturing operations to the metric system. The decision to “go metric” resulted in part from a desire to accommodate foreign licensees; the major pressure for change, however, came from an increasing foreign market.
In August of 1970, Morgan set up a twenty-man task group, representing a cross section of its drafting talent, to start a pilot program converting an existing design from traditional inch dimensions to metric. The task was not easy. There was no single set of standards for metric design; instead, there was a proliferation of standards. The first step was to catalog existing metric standards, and develop a single interim metric standard for use at Morgan. The conversion processes started concurrently with the development of standards.
After some trial and error, it was determined that the most effective method of converting an existing inch drawing to metric is to: photographically generate an undimensioned copy of the inch drawing; calculate new dimensions in millimeters; round off calculations in accordance with the interim standards; and then add the new dimensions to the photographic copy to make a new drawing. The finished metric drawing is then checked and processed in the same manner as inch drawings. New drawings with no inch drawing equivalent are developed entirely in the metric system.
Manufacturing from metric drawings progressed well; however, there were problems working with machine tools with inch readouts. All new machine tools have been purchased with both inch and metric readouts to simplify the problem. Metric gearing can be cut on existing gear cutting machines, but metric threads required new tools. The inspection department uses instruments with metric readouts.
Continuing problems include the availability of metric components; the lack of standard metric structural shapes and plate thicknesses; a lack of English-language reference books; and the variety of existing metric standards. The people problem remains as a major hurdle. Draftsmen, long accustomed to thinking in inches, have difficulty thinking in millimeters; and, once a draftsman has become adjusted to metric standards, he frequently has difficulty reverting to inch standards.
Overall, Morgan has made many crucial decisions that have led to a relatively smooth transition to both metric design and manufacture. Morgan has not solved all the problems of converting to metrics, but has now produced more than 10 000 metric drawings that have been used to manufacture and install 16 mills in seven countries successfully.
metric system, units of measurement, standards, weights and measures
Chief Engineer, Morgan Construction Company, Worcester, Mass.