Abstract: To ascertain when individual foundry molds and cores, bonded by a chemical method, have reached the requisition hardness, or still have the requisite hardness, a probe is pushed into the mold or core with a predetermined force, then withdrawn, and after a time interval it is pushed into a fresh point on the mold or core. This is repeated a number of times, each time in a different place, until the penetration is less than a predetermined value, indicating that the requisite hardness has been reached. Apparatus for doing this automatically can be portable and may signal by lamp and/or sound when the hardness has reached the required value. It may be modified to check whether the hardness of a core or mold made some time earlier has fallen below a given minimum value.

Abstract: Foundry moulds and, more especially, cores are made by the use of a binder comprising ammonium polyacrylate and zinc oxide or a metal salt to form a complex ammonium metal polyacrylate which is mixed with the sand and after the core or mould has been formed in a warm box warm air is passed through it to drive off the ammonia and form a water-insoluble metal polyacrylate which bonds the grains of sand together. The resulting core or mould has a good shelf life combined with excellent knock-out behavior.

Abstract: In the ultrasonic testing of a casting for defects an ultrasonic probe is mounted in a tank of water and scans across a surface of the casting which faces downwards just below the surface of the water. A pantograph linkage interconnects the probe with a pointer that is movable by an operator over a facsimile of the surface scanned by the probe. The interconnection is such that each position of the probe is represented by a corresponding position of the pointer and as the pointer is moved over the facsimile of the surface the probe scans the surface of the casting. The water ensures that there is good acoustic coupling between the probe and casting and the pantograph linkage reduces the skill and concentration required by the operator. Conveniently, only anomalous signals arising from defects are passed on from the probe to the operator.

Abstract: A foundry binder of the water-soluble alkali metal polyacrylate type having additives that include lime is cured by the use of the vapour of a low-boiling point organic ester having not more than three carbon atoms, primarily methyl formate, entrained in a carrier gas, e.g. carbon dioxide or nitrogen.

Abstract: A binder for a foundry core or mould consists of an alkali metal salt of a polybasic organic acid or of a polymerized monobasic organic acid, for example sodium polyacrylate, an alkaline earth metal hydroxide such as calcium hydroxide, one or more polyvalent metal oxides, preferably magnesium oxide, and calcium citrate, together with water. The mixture may also include another polyvalent metal oxide, for example zinc oxide. The inclusion of calcium citrate in the binder composition, particularly in the presence of magnesium oxide, has been found to reduce the problem of `softening back` in which the strength of the core or mould interior deteriorates over storage periods of a few days due to the continued absorption of carbon dioxide from the atmosphere in damp conditions.

Abstract: A binder for a foundry mould or core comprises an alkali metal salt of a polyvalent organic acid or a polymerized monovalent organic acid, for example sodium polyacrylate, and an alkaline earth hydroxide such as calcium hydroxide, together with a suitable solvent. Up to 80% of the calcium hydroxide may be replaced by a polyvalent metal oxide or hydroxide. The mixture may include small proportions of other materials, such as aluminum sulphate. It is important that the pH of the organic acid salt solution before mixing with the alkaline earth hydroxide should not be too high and it should preferably be between 5 and 8, in particular between 5.7 and 6.6.

Abstract: Apparatus for adding materials, especially powdered or granular materials, to a flowing stream, e.g. of molten metal, comprises a nozzle for compressed gas, blowing the additive into the stream, and a detector that detects the stream and switches the flow of additive on and off according to whether the stream is present or absent. The detector is preferably of a non-contact type, sensing radiation from the stream, preferably visible light. The rate of flow of additive can be adjustable. There can be a fail-safe optical detector arrangement monitoring the flow of additive and signalling an alarm if the flow fails or if the nozzle is blocked. The timings of the start and end of the flow in relation to the detection of the metal stream are independently adjustable to ensure that the additive and metal coincide.

Abstract: An apparatus for use in a so-called knock-out or shake-out system for foundries comprises a beam which may be resiliently suspended by a stirrup and bellows. A pair of tubular frames depend from the ends of the beam and a pair of rectangular clamp frames are vertically slidable in the tubular frames. A mold box comprising a pair of box-frames and containing a metal casting in a sand mold is located between the two pairs of frames. Two sets of bellows one associated with each clamp frame are inflated to raise the clamp frames and clamp the box between the lower crosspiece of these frames and some other part of the structure such as the lower cross-piece of the tubular frames. The mold is vibrated by vibrators so that the sand and casting are shaken out of the box.

Abstract: A work holder for locating a workpiece of arbitrary or irregular shape during treatment comprises a flat horizontal table in which is mounted a two-dimensional array of vertically disposed spaced-apart rods which protrude upwards through the surface and can be moved upwards individually, either manually or by springs or by fluidpressure means such as rams, then clamped in position so that their tips form a cradle conforming to the shape of the workpiece, in which the workpiece rests.