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).
Journal reprint discussing the Metalastik process of bonding metal and rubber for vibration-absorbing applications.
| Identifier | ExFiles\Box 133\4\ scan0310 | |
| Date | 29th September 1938 | |
| Reprinted from MACHINERY, September 29, 1938 The Metalastik Process Vibration-absorbing Machine Mountings and Flexible Couplings are but Two of the Numerous Interesting Applications of this Process of Bonding Metal and Rubber By means of an ingenious process involving electroplating and vulcanizing, Metalastik, Ltd., Evington Valley Road, Leicester, are able to bond rubber to metal. That the rubber is indeed securely bonded to the metal, and not merely stuck to it appeared evident from the convincing demonstration which we were recently priveleged to attend at their works. One of the tests witnessed was that of attempting to pull apart two metal discs, each of which had been attached by the Metalastik process to a cylindrical piece of rubber some 1.5 inches in diameter. In the normal manner of a tensile test, one disc was gripped in a fixed member of the machine and the other in a sliding holder to which the load was applied. A load of over 1,000 lb. per square inch was required before one of the discs was separated from the rubber, and although the rubber and the disc parted adjacent to the joint, the rubber itself was actually torn and a deposit of rubber was left on the disc. The Metalastik process is adapted to the bonding of almost any metal including aluminium with rubber and it depends largely for its success on a specially controlled plating operation. The metal parts are first plated with copper and after washing a coating of brass is applied on top of the copper, the latest type of plating baths and equipment having been installed for this purpose. The plated parts, together with the requisite quantity of rubber, are then placed in steel moulds between the platens of vulcanizing presses, and the bonding and vulcanizing are completed simultaneously. The secret of success lies in the manner of plating, in the quality and composition of the alloys used for producing the deposits of copper and brass, and in the rate of deposition and the constituents of the rubber used. From the point of view of the general engineer, the vibration absorbing mountings, the flexible couplings, the rubber springs, and the metal-rubber bushes produced by Metalastik, Ltd., are of particular interest. A typical machine or engine mounting is shown to the left in Fig. 1, and one of the flexible couplings may be seen to the right in the same illustration. The machine mounting shown comprises two metal strips in which the studs are fitted, bonded to an intermediate layer of rubber. An alternative form of machine mounting is shown applied to a large power press in Fig. 2. The feature of these mountings is that there is no direct metal-to-metal contact, since the bolts or studs do not pass through the rubber strip. The two metal parts of the flexible coupling are also bonded to the intermediate rubber element and again no bolts pass through the assembly. It may be noted here that until the load is applied, say the weight of the machine in the case of the flexible machine mounting, the rubber is quite free and not stressed in any way. This ensures that the rubber itself will not transmit vibrations. In this connection, too, the accuracy with which the hardness or flexibility of the rubber can be controlled to suit different conditions is of considerable importance. An actual application of the Metalastik rubber springs may be seen in Fig. 3. In this instance the springs, which are in the form of annular rubber rings bonded to metal plates at diametrically-opposite points, are used to support a beam carrying two motor drive units, and it was possible in this way to eliminate an objectionable high-frequency vibration. The Metalastik Dynamic Stabilizer In addition to what may be called the standard applications of the process for general engineering requirements, Metalastik, Ltd., have developed several special products of interest to the motor manufacturer. Of these special applications, the dynamic stabilizer for use on internal-combustion engines is of unusual interest. A typical example of one of these units is shown in section in Fig. 4. The stabilizer is mounted on the front end of the crankshaft, and comprises a steel drum A and a cast-iron inertia ring B, each of which is bonded to the intermediate layer of vulcanized rubber C. In the course of production the drum and the iron ring are first plated and then bonded to the rubber in the press. Each unit after vulcanizing is submitted to a torsion test and it is afterwards accurately balanced. The object of this stabilizer is to damp out torsional vibrations, thus contributing to the smoother running of the engine. The Metalastik engine suspension units applied to provide “floating power,” for which the company own the sole rights in this country, are also of value in connection with motor-car engine installations, and these units are designed on the same principle, two metal members being connected by an intermediate rubber element to which they are bonded. The principle of floating power is that a line drawn between the two specially located mountings passes through the centre of gravity of the power unit, ensuring very smooth running. Both the dynamic stabilizers and the suspension units are already used by numerous wellknown motorcar manufacturers in this country and the U.S.A. Aeroengine mountings for use with radial and in-line engines are also available. It will be appreciated that this process offers great possibilities and rubber-to-metal bonded components may be made in almost any form required. A service is offered by Metalastik, Ltd., whereby their technical representatives are prepared to give advice on the solving of vibration problems. Fig. 1. A Typical Metalastik Flexible Machine Mounting is Shown on the Left and a Flexible Coupling on the Right Fig. 2. Metalastik Mountings Applied to a Press Installation Fig. 3. Metalastik Rubber Springs are Used to Support the Beam Shown in this Illustration Fig. 4. A Sectional View of One of the Simpler Metalastik Dynamic Stabilizers for Internal-combustion Engines 3 | ||