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The authors would like to acknowledge the ASTUTE 2020 (Advanced Sustainable Manufacturing Technologies) operation supporting manufacturing companies across Wales, which has been part-funded by the European Regional Development Fund through the Welsh Government and the participating Higher Education Institutions.

The paper explores the use of a shear plate technique paction process and this includes both compression and to measure the frictional characteristics between a ejection. compacted powder and a target surface. The study A number of investigations have been reported in the con rms that the shear plate technique is valid to literature that focus on friction measurement. Essentially measure these frictional characteristics and that any most of the tests described in the literature can be grouped variability in the data is a physical characteristic of according to two methods based on a shear plate apparatus the powder being tested. Surface roughness and hardor die compression test. The latter has also been carried ness were explored fully for both iron and an alumina out under actual pressing conditions on specially adapted powder. This con rmed the major impacts of surface toolsets. hardness, roughness, and roughness orientation on Examples of shear plate type tests are described in Refs the friction coeYcient. The static and dynamic values 4 and 5. The study described in Ref. 4 was concerned with were found to be a minimum for the hardest surface a ceramic powder type and the investigation included a (tungsten carbide). With regard to static friction, bene t consideration of details such as wall surface topography, may be obtained by using a very smooth surface particle size, and the hardness of the surface and particle. nish, however, the minimum level of dynamic frictionThe results from this study showed that particle and surface coeYcient is not always associated with the smoothest topography had a signi cant impact on friction and that the surface.PM/1006 ratio of particle size to die surface roughness was important for softer particles. The mechanism of particles locking into

The paper presents a micromechanical discrete-element modelling technique to investigate the friction mechanisms that are present between the powder and tool set surfaces in die compaction. The technique includes particle kinematics and deformations to be accounted for together and has allowed a theoretical exploration into particle sliding over smooth surfaces and locking into the asperities of rough surfaces. A two-dimensional model has been developed to represent a shear-plate technique that is used to measure friction in compacted powder systems and in this study assumes that the consequent cylindrical rods are of identical diameter.In the case of smooth surfaces and with no friction coefficient between the tool set surfaces and the powder, the particles simply slide over the surface and are not subjected to gross deformations. The mechanical resistance that may be expressed as a friction coefficient is small under these circumstances. When fine powders are used (fine in comparison with the roughness of the surface), the particles form a sticking layer and the consequent friction coefficient due to particle deformation is large due to the need to shear the powder mass. It is also noted that harder powder particles lead to a lower friction level. When mechanical friction is included between the powder and tool set surfaces, the combination is offset by the friction coefficient that is used between the powder and tool set surfaces. NomenclatureF contact force x displacement k stiffness t halo thickness (equation (1)) or time c damping v velocity

We investigate the influence of the specimen velocity on the magnetic flux leakage with the aim of selecting the optimum sensor locations. Parametric numerical simulations where the specimen velocity was in the range [0.1-20] m·s −1 were carried out. As the specimen velocity is increased, the magnetic field varies from being symmetrical to being asymmetric. For the radial magnetic induction, the peak to peak value moves from the centre of the bridge towards the direction of the specimen movement. For the axial magnetic induction, the specimen velocity influence is dependent on the sensor location and a signal-velocity independent region was discussed.