Powder part to be pressed.) ,third sintering (is

Powder is divided into very small and light particles. Powder metallurgy is a metal processing technology with metallic powders.There are powder metallurgy production squence. firts of all blending and mixing , secondly pressing  (these are two sections; upper puch and  lower punch. Puncing and molding tool is used for the part to be pressed.) ,third sintering  (is carried out at a temperature below the melting point of the metal).Powder metallurgy is very important.Because ;The PM parts are produced in a net shape or close to the net shape, by the next processing need to be removed from the middle or  this requirement is reduced ,PM process produces very little material as garbage (about 97% of the piece is converted into product) , PM parts can be made with a specific pore level to produce porous metal parts. Examples: filters, oil impregnated bearings and gears.Metals that are difficult to manufacture by other methods can be shaped by powder metallurgy. For example incandescent lamp bulbs are produced with tungsten filaments PM. It is only found in metals made using the PM method. There is no other method that can only shape these metals by PM method. PM measurement control compares most casting processes. PM production methods can be automated for economic production.There are limitations and disadvantages associated with PM operation. These are : (1) the cost of equipment is high, (2) the metallic powders used are expensive, and (3) they have difficulties in storage and handling of processed metal parts (eg metal deterioration over time and certain metals and fire hazards). Along with these, (4) there are limits to the part geometry, (5) material densities throughout the part can be a problem in PM (for complex part geometry).Characterization of engineering powders, there are two categories. first of all geometric features  and secondly other features.The geometry features devided ; (1) particle size and distribution,(2)particleshapeandinternalstructure,and(3)surfacearea.Particle size refers to the dimensions of the powders. If the particle is spherical, only one dimension is sufficient. Other forms require two or more dimensions. There are several methods for obtaining particle size data. One of the common methods is to use screens with different mesh sizes. Meshcount is used to specify the number of openings per linear inch of screen. The higher the number of mesh, the smaller the particle size.Mesh count – the number of openings per linear inch of the screen.Mesh count  , the number of openings per linear inch of the screen.A mesh number of 200 means that there are 200 openings per linear inch. Since the mesh is square, the number is the same in both directions, and the total number of openings per inch is 200 squares of 40,000. A higher number of weaves means smaller particle size.1Particle Shape and Internal Structure, Metal dust can be catalyzed into several types of shapes. The particle size may vary. it may also be added to a dust-collecting particle form. Microscopic techniques are needed to determine shape properties. Loose dust should contain pores between bulk particles. These are also called open pores because they are outside of separate particles. Open pores are spaces into which a liquid such as water, oil or molten metal can penetrate. together with closed pore-interior voids in a single particle structure. The presence of these internal pores is usually small and has little effect when they exist, but they can affect the density measurements as we will see later.Surface Area : If we assume that the particle shape is a perfect sphere, then the area A and the volume V given by Characterization of engineering powders in secondary part is other features . Other features of engineering powders include interparticle friction, flow characteristics, packing, density, porosity, chemistry, and surface films.Friction between particles and flow properties Friction between particles affects the ability of a powder to flow and tightly packed. A common measure of intergranular friction is the angle of inclination at which an aggregate powder forms when a narrow funnel is poured, as in figure 1.1. Larger openings indicate increased friction between the particles. Smaller particle sizes show more friction and upright angles. The spherical shape causes the lowest friction between the particles. Flow characteristics during filling and pressing are important. There is a certain amount of change in automatic mold filling and there is a consistent flow of orders. Pressure, resistance, increases the density changes in the safety particles; density gradients are generally undesirable. A general disadvantage is that it reduces the flow (weight) of the standard sized funnel sweeper. It prevents faster flows and friction between smaller particles. In order to reduce friction between the particles and facilitate flow during pressing, lubricants are frequently added to the powders in small amounts.Packaging, Density and Porosity Packaging properties depend on two density measures. First, it’s true density. it is the intensity of the actual volume of this material. Second, the bulk density. the density of loose dust after the spill containing the effect of the gaps between the particles. Due to the density of the pores, the bulk density is below the true density. For loose loads, values in the interval between 0.5 and 0.7.If there are dusts of different sizes, the smaller dusts will be taken up with the air and they will fit into the gaps of the larger ones, which is called the high packing factor. The pressure applied during compression allows for a large increase in bulk through deformation of the particles and the rearrangement of the dust problem: some of the particles are complicated by the presence of closed pores. Chemical and Surface Films; Metallic powders are classified as either an element of pure metal. Possible surface films include oxides, silica, adsorbed organic materials and nematode. As a general rule, these films must be removed before the shape is processedFigure 1.1 (interparticle friction is indicated by the angle of repose of a pile of powders poured from a narrow funnel. Larger angles indicate greater interparticle friction.)2