From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Comparison of early plastic molding compounds (Redmanol, Condensite, Bakelite) and the types of dies required for their use.
| Identifier | ExFiles\Box 39\3\ Scan095 | |
| Date | 24th May 1921 guessed | |
| -2- complicated or delicate inserts, which may be displaced in the operation of molding by any inequalities of pressure in the mold. The three compounds are very nearly identical as regards the operations of molding and the same dies may be used on all three compounds. Redmanol is cheaper, and rather less satisfactory as regards freedom from moisture, weatherproofness, etc. Condensite and Bakelite are almost indistinguishable, except that the characteristic semi-transparent red-brown color of brown Bakelite can not be quite reproduced in Condensite. The grades of material referred to above do not quite correspond in Bakelite and Condensite, but materials can be obtained from both companies which work equally well in any set of dies. The further remarks apply to either Bakelite or Condensite:- (2) FORM OF MATERIAL. The forms in which the material is sold by the makers are powder, plastic sheet, or liquid gum. The latter is only used as varnish on built up jobs like aeroplane propellers. The plastic sheet is used for large flat moldings, or parts of moldings, or in preform work, as described for our steering wheel in my letter of May 19th. The powder is used for the greater number of moldings. (3) DIES. The dies are case hardened machine steel, or hardened tool steel, except in cases where very small numbers are to be produced, when a though bronze is sometimes used. The die surfaces are brought to a brilliant polish in order to get the bright finish on the molding desired, since the molding reproduces the finish of the die. No buffing is necessary on moldings from a good set of dies. It is stated by a local molding concern that a good set of dies, well hardened and polished in the first place, will improve with age, resisting the abrasive action of the compound, and getting a higher and higher polish. There is no corrosive action of the raw Bakelite on the steel. A soft die will not continue to give a high finish, and is liable to distort under the heavy fluid pressures. | ||