 Hello friends. Myself, Professor Narendra Katikar, Assistant Professor of Mechanical Engineering, Valachand Institute of Technology, Solapur. Today I am going to present a topic design of plastic part. The learning outcome for the same at the end of this session student will be able to design the plastic part. The content for the same will flows likewise. Introduction, Essential Factors of Part Design, Plastic Part Design Methodology and Approach. Case Study, A Bottom Leg Support of Steel Chair, Design Procedure, Final Drawing of the Part with the Dye and References. In the introduction, let us see the some of the points for the discussion, plastic material. Now, as we can imagine and we are in experience that many of the material, metal, non-metal has been now replaced or tried to be replaced with the means of plastic material. This is just because of its very numerous advantages over the metal, non-metal, etcetera from the expectations of the particular part to be worked in a ideal working environment like thorough transparency through to the thorough openness, weight to strength ratio, easily moldable properties and so many others. Thus, the need of plastic material products is going to be increased day by day. Now, regarding the plastic part manufacturing, as we know there are number of processes machines which are be there for production of plastic part manufacturing. According to the specifications, the plastic parts are going to be considered for design in consideration with manufacturing constraints. Now, the basic concept of design that is as like our general mechanical design for any particular part of the machinery or mechanical element, the same procedure is going to be there for the plastic part manufacturing. Now, essential factors of part design, different factors used for part design in general for any material, let us recall an end list, the same will be applicable for the plastic part design. Now, let us see those in detail the plastic part design methodological approach, step wise procedure for development of plastic part, those are as follows defined requirement and service conditions, design to get specifications and selection of materials that is for trials, decision about manufacturing process and detail. Let us see the design rather the plastic part design with a case study. Case study for bottom leg support of a steel chair, problem statement, a product has to be designed for assembly of steel chair of a 7 kg bed having a 4 leg supports requires plastic bottom support bushes, this is to avoid noise during the handling and scratching marks on the ground during the pulling and pushing, the plastic bush has to fit it to the pipe leg of chair by a 4 mm diameter, fully threaded slotted cheese head screw to the pipe 50 mm diameter with a flat support on the ground, this is the problem statement. Now, let us proceed with the iterative process of plastic part design. This is the sketch which is initially to be imagined the flat bottom, the plastic bush support 5 4 mm screw is the requirement and 50 mm diameter for the steel pipe that is of the leg is given one. Now, the decision about to manufacturing details, it is a medium carbon steel die and let us consider with the previous knowledge and experience that it is to be manufactured through the means of injection molding. Now, in the step 2, let us see the 1 chair that means there are 4 bushes, the weight of the chair is 7 kg, the weight of the average person is 70 kg, total weight is maximum about 77 kg, each bush loaded with the 77 by 4 that is around 20 kg, pipe diameter is about 50 mm, hence bush diameter is about 25 let us say 26 mm, the even complete number, the hole is through the hole is through and for the height 10 millimeter and let us start our now designing. This is the preliminary sketch, very cylindrical in nature and let us consider 11 mm, then 4 millimeter hole for the screw, then 11 millimeter and then let us height is the 10 millimeter to accommodate the screw, the wall is of 11 millimeter to bear the load of 20 kg. So, the calculation about the that is 94.98 millimeter square, then let us calculate the sigma, sigma is 20 kg divided by the above figure and it comes out to be 0.210 kg per mm square, the factor of safety we are considering the 2 times and for PVC, we are selected the material PVC, the tensile strength is 450 kg per mm square, the softening point for the same is 75 degree Celsius, shrinkage is about 0.5 to 0.7 degree Celsius, this is the ready-recognized data which we had got. The uniform wall thickness is to be there and it is considered about 2 millimeter, then the geometry is varied likewise, but this is not feasible for manufacturing point of view. Now, the design demands the horizontal insert and shutoffs, hence to modify. Now, the geometry has been redefined this redefinition with the experience and knowledge itself. Now, the iteration moves with the further, here 4 mm hole is in the boss, so guideline is L is equal to 4D, if hole diameter is less than 4.8 millimeter and L is equal to 6D, if it is more than 4.8 millimeter. Our constraint on the length is 10 millimeter, so L is equal to 4D, so thus D comes out to be 2.5, but our requirement is D is equal to 4, so strengthening of our wall of the boss is required. Parting line decision and according to the modifications has to be done. Now, for parting line we can observe that the bottom most part surface is considered for the parting line and considering the 4 mm particular hole at the center to accommodate the screw, the geometry has been modified, the uniform 2 mm thickness for the job is there. Now, the further process now the in the further step strengthening of the wall of the boss, we have to provide the ribs. Now, the guidelines for web design is as follows, the rib thickness must be less than the wall thickness, the rib thickness must be about 60 to 80 percent of wall thickness, let us consider about 70 percent. The rib thickness is 0.7 into wall thickness that is 2 millimeter and rib thickness is about to 1.4 millimeter. Now, taper provision for the walls is with the ready rickner that is 2 degrees. For example, tan 2 degrees is to be there then how the x dimension is calculated that they are shown x by 10 and likewise 3.49 millimeter on one side. Likewise calculation of all the taper diameters are dimensionized and it can be shown over there. At the end we can see over there that the provision of shrinkage allows to all the sides that is about 0.6 percent. So, part drawing is finalized and modified dimensions are shown over here, the part geometry ultimately the cavity is shown over here in the two halves, parting line is shown over there, ejector pins also shown over there and you can observe that the sectional front view as well as top view. This is the die assembly without obviously the gating system and at the end of this particular design rather the manufacturing the plastic part design which we had considered as a case study. The part will be visualized something like this. You can observe the four different views for the plastic parts. This is our expected output the hole is at the centrally located four ribs, uniform thickness and taper geometry and little bit radiance radius given for at the every end corner. The references for this particular presentation fundamentals of plastic mold design by Professor Dr. Sanjay K Nayak Tata McGraw-Hill publication New Delhi. Thank you.