 Hello friends, myself, Dr. Narendra Kartikar, Assistant Professor, Department of Mechanical Engineering, Valachandra Institute of Technology, Solapur. Now we are going to see the presentation and discussion on Injection Molding Machine Parameters. At the end of this session, student will be able to understand the design concept for injection mold design from the perspective of injection mold machine. Student will be able to apply these concepts for mold design. Contained for this presentation are introduction, injection molding, design affecting features of injection molding machine. Introduction Let us see in brief about the plastic material need of plastic material product and varieties of plastic part manufacturing processes. As we know, the plastic material is considered as one of the advanced material not only for generation of new product but also used for the replacement of existing material for whatever the products being used nowadays. Considering the varieties of particularly positive properties of plastic material, it is being used widely for such kind of product innovations also. Due to varieties of particular plastic parts, there are n number of plastic part manufacturing methods. One of them is injection molding. Let us revise in a brief about the injection molding. This is the setup for injection molding where the raw material in granule or powder form is fed to the feed hopper through the means of screw and barrel mechanism it is going to be inserted into the mold cavity. The mold cavity is open and closed through the means of stationary and movable platen. You can see the synchronized movement of all these particular elements together through the means of motor and gear drive system. This is the real-time image for injection mold in which the particular product is also shown. At this stage of this session, are you able to recall share some of the application products that can be manufactured with injection molding process? We seen or known earlier anywhere in real-time, just enlist those products. I hope you had enlisted the varieties of the particularly products that can be manufactured through the means of injection molding process. Let us go with the design affecting features of injection molding machine. The size of injection mold to be designed depends on the molding machine to be used. The data of injection molding machine are mainly short capacity, plasticizing capacity, clamping force, daylight of the machine as well as the injection pressure. Now, we will see one by one about all these particular parameters. Short capacity, it is defined as the maximum amount of plastic material to be injected in one complete cycle of the machine. That means, as we can recall back whatever the image we had seen, the particular rotation of screw into the barrel wherever the raw material is placed can be injected into the mold cavity. Thus, it is the maximum amount of plastic material which is feed through the means of this feed screw whatever stored in between the gap of screw and barrel into the mold cavity per one complete cycle is nothing but the short capacity, short weight. In a plunger type machine, short capacity is rated as a short weight, the gram per ounce with a polystyrene. Let us see the formula for the same. Short capacity for material B is equal to short capacity for material A multiplied by the numerator and denominator of density of B material, density of A material, bulk factor of B material and bulk factor of A material. Generally, polystyrene material is used as a reference material A and B is the actual material which is to be used. The screw type machine is normally rated in terms of swept volume of the injection cylinder means cubic centimeter. So short capacity can be formalized like this, short capacity is equal to swept volume multiplied by P multiplied by C where P is the density of plastic at normal temperature, gram per cubic centimeter. C is a correction for the percentage volume expansion of the plastic at the molding temperature. For crystalline material approximately C can be considered as 0.85 whereas for amorphous material C is considered 0.93. Let us move further to the next parameter, plasticizing capacity. It is expressed as the amount of material that the machine can bring per hour to molding temperature. It means approximately the material injected by the machine in an hour. The plasticizing rate of the machine of the material B can be found approximately from the machine specification chart and plasticizing rate based on polystyrene material from the formula. Let us move further, understanding the plasticizing rate of the material in the formula since specific heat of A to the specific heat of B multiplied by another numerator and denominator molding temperature of A molding temperature of B. Plasticizing rate can be also calculated from the following formula. Plasticizing rate per hour is equal to weight of the molding in kg multiplied by number of molding per hour. Moving to the next parameter, clamping force. Machines are usually characteristics by the tonnage of the clamping force that they provide. The clamping force indicates the amount of force that the clamping unit can apply to the mold to keep it securely closed during the injection of the molten plastic. For example, 80 tons means 80 ton of force as a clamping force. Generally, it is denoted on the machine as SPAT, ST130, etc., where AT130 are the clamping tonnage. Formula. The clamping force is proportional to the projected area of the molding and runner and must be opposed by the clamping force, although a proportion of the pressure produced by the induction cylinder is transmitted to the cavity. Various losses will be occurring in the heating cylinder, nozzle and gate. It can be considered that force acts on the mold to make it open. It can be calculated from the following formula. Force is equal to pressure into projected area. Force in kg, pressure kg per square centimeter, projected area centimeter square. Projected area is the area that is projected from the base. For complete calculation, calculate the runner projected area and the part projected area for more precision. Clamping force in tons is equal to projected area of the molding in square centimeter multiplied by half to the one-third of injection pressure that is defined tons per square centimeter. Thin section requires a high injection pressure to fill and does need more clamping force. Relatively, easy flowing material like high melt index polythene fills more readily and hence required a lower clamping maximum and minimum daylight. In injection molding machine, two type of daylights are there. Maximum daylight, the maximum distance between the fixed platen and moving platen. During the design of mold, maximum daylight is generally compared with the ejection stroke required for the mold to eject the component. Whereas minimum daylight, the distance between the fixed platen and moving pattern, the mold height is decided on the basis of minimum daylight available in the machine. Mold height should also be more than the minimum daylight. Machine nozzle, other parameter which controls the flow behavior of the plastic melt is a machine nozzle. The purpose of the nozzle is provided a flow path for the plastic made from the machine cylinder to the sprue bush of mold. There are two types of standard nozzles used in injection molding machine. Spherical nose, it has a hemispherical curvature which butts onto the sprue bush of the mold. Flat nose, it is a flat ended which butts on the sprue bush of the mold. Dry cycle time, the dry cycle time is a period or elapsed time between a certain point in a one cycle and the same point in the next. The steps of molding cycle in a typical injection molding are to lead the melt to the mold cavity or cavities, fill the mold cavities, cool the material, demold and eject the molded article. When the injection molding machine operates without any plastic material, the cycle time is called as dry cycle time. Thus dry cycle time has an important role in the injection mold design. It is usually for the following reasons, establishing the total shut height of the mold which are highly compared to the minimum daylight of the machine. To understand the type of locking mechanism, ejection mechanism and other features available on the molding machine. References Modern plastic handbook, Fundamentals of plastic mold design, CIPET government website, NPTEL study material. Thank you.