Feature Article


The Innovation Gap Concept


by David Ford


had been discovered in an archaeology excavation. In particular, the archaeologists wanted to know if they were made by investment casting or from a stone mould. This was difficult to be sure, but the axes had a decoration which had the appearance of having been originally created by a wax addition, although the archaeologist suggested the pattern could also have been produced by a lost leather process which was apparently not unusual in Britain. However, for myself it was the associated artifacts that were the most interesting. These included cast sprues which were designed for casting several heads, many with the same principles as gating systems we use today. In one example at the base of the pouring funnel were several gates which had matching cut-off blocks to separate the axe heads from the sprue. These cut-off blocks had the remains of saw slots which were around 0.025” wide, which is not only the width of a hacksaw blade but also apparently the optimum width of a saw made from bone. Unfortunately, the Museum has been unable to locate these particular artifacts to photograph in time for this article, but were able to locate axes and casting scrap from a c800 BC bronze age hoard discovered in a site near the Severn estuary in Bristol UK. Examples are shown in Figures 1 and 2 and show that even in those distant days the foundries were casting several axes from the same mould. Without a doubt these early foundrymen had already discovered the beginnings of mass production. It is unknown (at least to the author) if there are any records of investment casting gating systems until the 20c, in which case the dark ages for our industry lasted at least 2 millennium. Although this time lapse


S 14 ❘ February 2023 ®


ome years ago I was asked by the Bristol Museum to help examine bronze axe heads that


Ball-point pen Zip fastener


Fluorescent lighting Helicopter


Kodachrome Television


Investment Casting I.C. for Jet Engines


Invention 1888


1891 1901 1904 1921 1923


c.4000B.C. 1943


Production 1946


1923 1938 1936 1935 1936


20c A.D. (Engineering)


1947 Table 1: The Innovation Gap For Everyday Products Concept


High temperature alloys (Nimonic 80)


Vacuum Casting (arc melting)


Ceramic, quartz and soluble cores (patents)


Vacuum induction melting Directional solidification Robotic shell moulding


Hot Isostatic Pressing Additive Manufacture


Invention Production Gap Years


1942


1953 1953


1955 1960 1970 1955 1985


1947*


1955 1955


1960 1972 1974 1975 1997


5


2 2


5


12 4


20 12


Table 2: The Innovation Gap For The Major Technologies In European Foundries. *Bristol Theseus Turbo Prop Engine


is extreme, the time gap between innovation and production has been historically significant and many common everyday products often took many years to reach production: It took the urgencies of the second


World War and the development of the gas turbine engine to accelerate the innovations that would drive the


investment casting industry to the heights of precision manufacture. Although many of the technologies used today have their genesis in other applications it is the investment casting industry that has exploited the technology. Some examples of technologies that have changed the fortunes of the industry, and given their


Gap Years 58


32 37 32 14 13


c.6000 4


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