Evolving beyond Craftsmanship:
Mass Production of High-quality Thermometers
Making glass thermometer tubes using intuition and craftsmanship
A craftsman making glass tubing
Japanese people excel at making things because they are dexterous and diligent. Japanese craftsmanship appears not only in the arts and crafts themselves, but also in industry. For many years, traditional craftsmanship has been applied to the glass tubes manufactured by Terumo.
The traditional method of making glass capillary tubes and round tubes for the constriction in a thermometer involved a worker spiraling a gob of kiln-heated melted glass onto the tip of a metal tube (called a blowpipe) and then another worker (called a runner) running 50 or 60 meters at speeds he varied depending on the changing consistency of the glass with this bar in his hand. In the early days, runners used to joke among themselves that they could someday become marathon runners. The speed at which they ran was determined by the softness of the type of glass and the only way runners could know the correct speed was through their intuition and their experience as craftsmen. Craftsmanship and intuition were the two secrets of Terumo thermometers.
However, this method produced glass tubing of widely varying shapes, dimensions, and inner diameters. As such, it was not suited to mass production.
Success after five years of trial and error: Terumo creates an automated glass tube manufacturing process
“If we don’t develop a way to mass produce high-quality glass tubes, we won’t be able to transform the thermometer business into a modern industry.” This was Terumo’s driving idea as it began researching how it could shift its manufacturing process to a more modern automated glass tube manufacturing process.
The illustration below shows how glass tubes were made using the new process. Raw materials were put into the automated glass tube machine, which melted it, cleared it of impurities, and then shaped it. The machine then injected air from below as it pulled the glass upward.
However, the automated glass tubes manufactured using the new process did not turn out well. No matter how much the machines pulled and stretched the glass, the resulting product was not of the necessary high quality. Terumo associates worked for days to try to solve the problems in the new process. Finally, they discovered that the balance between the amount of raw material they put into the machine and the amount of glass being pulled upwards affected the level of the melted glass in the machine and when this balance was not at the proper level, some material on the inner walls of the apparatus would dislodge and get pulled upwards along with the glass. It was this that resulted in poor quality glass.
In 1965, after five years of work, Terumo finally succeeded in creating an automated manufacturing process that consistently produced high-quality glass tubes. This marked Terumo’s entrance into a new age of mercury thermometers.
Automated glass tube manufacturing system