Originally Gravity Aluminium Dies were an extension of Sand Casting. This method resulted in a large amount of work because the sand molds could only be used once and were then destroyed. In an attempt to increase productivity the molds were made out of Cast Iron, held together with “G” clamps, and prised apart with pinch bars. These dies were made by pattern makers and certainly increased production compared to sand molding; but they were very crude, often giving poor setting times with difficulty in extracting the casting, which in turn made it arduous for the worker.
Some pattern makers evolved in to making gravity dies using different clamps, and some dies used a Tenon to guide the die sides.
This is where some foundries have stopped, for them evolution has never happened, with often more than one man required to work a die; which in turn results in low productivity, low wages and expensive castings. This tempted customers to look outside the UK for their castings and encouraged the demise of foundries in this country.
More enlightened foundries developed toggle operated dies, which meant that die sides, could be opened quickly with one lever: therefore increasing productivity and enabling one man to operate two small dies together.
The development of dies was changing; some foundries used Hydraulic Cylinders, whilst others used Air Cylinders. Both methods worked quite well, but the air cylinders had a dangerous drawback, which was, in the event of a dies side sticking the air pressure would rise dramatically until it would open or shut like a bullet, with the potential to seriously injure the die caster.
Here at Hall & Botterill we have chosen to use hydraulic cylinders, but , we have gone a step further:-some castings are more sensitive than others and need very careful timing during the setting time; therefore we have introduced a method of casting using a PC controller which makes for more accurate timing and no interference from the die caster.
We are continually looking for methods that produce better castings and improve the lot of the die caster. Evolution goes on!!