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To ensure the reliable monitoring of machining operations, e.g. by lathes, the forces generated during the metal removal process must be detected with the utmost precision. Almost every type of lathe can be straightforwardly monitored for these factors with a force sensor which not only measures forces in three directions but which also incorporates the necessary electronics to amplify the output signals.

Only continuously monitoring cavity pressure allows the detailed recording of the injection molding process in the injection, compression and holding pressure phases. It alone correlates with all significant molding features such as weight, morphology, degree of forming, burr formation, shrink marks and cavities as well as shrinkage and deformation. The cavity pressure not only optimizes the timing of the switching point from the compression to the holding pressure phase, but also serves directly as a criterion for the switching. Molding weights and countless other quality characteristics thereby vary considerably less than with switching based on hydraulic pressure, screw travel or time. Quartz sensors have proved particularly successful for direct and indirect measurement of pressure. Advocates the use of cavity pressure sensors for monitoring and control of the injection molding process and describes commercial products that are available.

This paper aims to explore the influence of the materials used in moulding blocks of hybrid moulds on the injection moulding setup and the properties of the mouldings.

An instrumented (pressure and temperature) hybrid mould with exchangeable moulding blocks, produced by rapid prototyping and tooling techniques (RPT), was used to produce polypropylene tubular mouldings. The configuration of the mould was varied with combinations of moulding block materials, namely, an epoxy resin composite processed by vacuum casting and steel. The processing conditions were adjusted to obtained steady processing conditions. The mouldings were assessed in terms of the microstructure and the shrinkage.

Due to the properties of the moulding block obtained by RPT being different from tool steel, the injection moulding processing conditions and the plastics parts properties are different when hybrid moulds are used. The cycle time depends on the moulding block properties and must be adjusted to the desired running temperature. The morphology of the mouldings is strongly affected by the thermal properties of the moulding block materials. When different materials are used in the core and the cavity asymmetric structures develop in the part. The shrinkage of the mouldings, when resin cores are used is also affected by the deformation of the core caused by the injection pressure.

This paper makes a contribution to understanding the morphology of semi‐crystalline mouldings obtained using hybrid moulds and enhances the importance of the core deformation on the shrinkage of the mouldings.

A hygrometer calibration unit consists of a large water reservoir, a diffusion tube and a cell through which the gas is passed. It operates at moisture levels up to 1,000ppm and functions accurately at discreet levels of, say 1,5, and 10ppm. It operates on most gases. Price is £39. Delivery is 3 to 4 weeks.

A novel numerical formulation of the two‐phase macroscopic balance equations governing the flow field in incompressible porous media is presented. The numerical model makes use of the weighted average flux method and total variation diminishing flux limiting techniques, and results in a second‐order accurate scheme. A shock tube study was carried out to examine the interaction of a normal shock wave with a thin layer of porous, incompressible cellular ceramic foam. Particular attention was paid to the transmitted and reflected flow fields. The numerical model was used to simulate the experimental test cases, and their results compared with a view to validate the numerical model. A phenomenological model is proposed to explain the behaviour of the transmitted flow field.

The type 9271A measuring platform is based on a two component annular cell mounted highly pre‐stressed between the base and the cover plate. It measures axial compression forces up to 2,000kgf and tensile forces up to 500kgf as well as torques about this axis up to 1,000kgf/cm. The use of quartz gives a rigid transducer with small deflections. Approximate price is £435. Delivery: ex stock.