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Gravity Diecasting
Part 1. Organisation and Casting Methods at a Rolls-Royce Foundry
The Design of Dies for Merlin Components

Described herein is the highly efficient organisation of the gravity diecasting foundry installed at one of the Rolls-Royce shadow factories. Various types of dies and methods of casting are dealt with in considerable detail, and provide information that will be a valuable guide to all interested in the process.

This article first appeared in the Volume 5, Number 59 (September, 1943) issue of Aircraft Production magazine, and is presented here through the kind permission of Flight International. Thanks also to Bruce Vander Mark for furnishing volumes of Aircraft Production for scanning.


Experience in producing the aluminium alloy castings used on the Rolls-Royce Merlin engines has shown that diecast parts possess many advantages over similar parts made by ordinary sandcasting methods. These can be summarized as follows:
  1. Smoother finish and closer dimensional accuracy.
  2. Greater production speed.
  3. Conservation of raw material.
  4. Reduction of production scrap.
  5. Improved mechanical properties.

For this reason Rolls-Royce, Ltd., have adopted the policy of diecasting as many parts as possible, and the extent to which this has been carried out may be gauged from the fact that 103 of the 130 castings on the engine, or nearly 80% of the total, are produced as gravity diecastings.

The cost of the die, or permanent mould as it is sometimes termed, is usually higher than that of pattern equipment for casting by the "sandcast" method. However, if the quantities required are sufficiently large to warrant the expenditure on such a die, the reduced cost per casting would soon "write-off" the difference in cost between the two types of tooling, and the part could then be looked upon as a potential diecasting.


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