Friction measurement in powder die compaction by shear plate technique

Abstract

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

An Investigation For Optimal Tool Kinematics In Powder Compaction Cycle To Minimize Density Gradient In Green Powder Compacts

“…From the presented results it can be observed that the friction coefficient decreases with an increase of normal stress or density of the powder compact, and a steep increase in friction coefficient is observed with increase of sliding velocity from 0 to roughly 30 mm/s, after which point it becomes relatively steady. Similar trends were observed in other studies [10,13,24,25,33,51,66,80,89,90,109,110,111,114,[124][125][126] Further, the influence of temperature on friction coefficient was studied. For this the slab was fitted with thermal resistors and several tests were conducted between 20 and 80°C to assimilate manufacturing conditions, where due friction and high production rate, temperature of the tools and the ejected green compact may reach close to 70°C [19,21,27,86].…”

“…Thus, knowing frictional behaviour at powder-tool interfaces is essential for controlling these limiting factors. At present there are a number of friction measuring devices among which the most commonly used are the instrumented-die and the shear-plate device [10,13,19,21,31,45,86,89].…”

An Investigation For Optimal Tool Kinematics In Powder Compaction Cycle To Minimize Density Gradient In Green Powder Compacts

“…Consequently, the volumetric strain increment is expressed as [106] dε v = dε 1 + dε 2 + dε 3 = − dρ ρ = dλ 2 9 β 2 σ m (12) Further, the plastic work, dW, done per unit volume of powder (or porous) body may be expressed as a function of yield stress, σ , and effective strain increments, dε , as [106] dW = σ 1 dε 1 + σ 2 dε 2 + σ 3 dε 3 = ρ σ dε (13) This is because a unit volume of powder (or porous) body with relative density ρ consists of the matrix material of volume ρ , thus, dW is not directly equivalent to σ dε [106].…”

A combined finite-discrete element method for simulating pharmaceutical powder tableting

“…The powder compaction industry acknowledges that friction between the powder and tool surfaces is a key parameter that leads to inhomogeneity in engineering components made via this route. Consequently, significant effort has been expended in measuring friction and assessing its impact on compact quality [18]. Studies of this type have identified that the friction coefficient between the powder and the tool set surface is affected by a range of parameters.…”