 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 Design of Compression Mold Part 3. At the end of this session, student will be able to understand the design concept for compression mold design, as well the student will be able to apply the design concept for mold design. Introduction, compression molding, design process for compression mold design and some numericals we are going to see as a part of content in this presentation. Let us briefly introduce about the plastic material and its need. As we know, the plastic is the advanced material nowadays going to be used not only to build the new product, but for replacement of the existing material for particularly products. This is just because of the many advantages over the metal as well as non-metal itself. Considering the various parameters, there are varieties of plastic part manufacturing methods are developed. Out of that, we know the compression molding process is there. This is one of the setup of compression molding. As we know, as we apply the compression force over the particularly charge, it is flow into the mold cavity and it gets the exactly the size shape geometry replica as that of the mold cavity itself. If we see in a three stage wise, the compression molds look like this. In a first stage, charge is loaded, second one, the compression force is applied. In the third stage, it can be ejected back the finished product. The compression molding machine look like this. At this stage of this session, are you able to recall, share some of the applications or products that can be manufactured with the compression molding process. Earlier seen or known somewhere in real time just enlist. Thank you. I hope that you had enlisted the varieties of the product that can be manufactured with the compression mold. Now this is exactly how the compression molds look like. You can see the finished products are placed on the mold which are being manufactured with the same mold. Let us go with the design process for compression mold design. To know the particularly design process, we should know the various kind of concepts related to the same. We will see some of the terminologies and how it can be calculated individually. Bulk factor, it is the ratio of volume of the loose plastic powder to the volume of the molding. Volume of the part is equal to WP by rho. The WP stands for weight of the plastic. In kg, the rho stands for the density of the plastic. If the K is the bulk factor, then the loose powder volume required for the molding W into the K divided by rho. You can see the flash allowance will be also taken into account. That will be 10 to 20 percent extra. Then loose powder volume will be 1.1 to 1.2 in multiplication with WP into the K divided by rho. The K 2 to 3 for general material and most mineral fillers whereas the K 8 to 15 for light fabric filler and so on. Design of land, the land dimension that is the distance between the actual cavity dimension and the vertical wall of the powder well. For normal size molding, L is equal to 4 mm to 9 mm. For large size molding, 9 mm to 16 mm. You can see the land area over here. Design of loading chamber has to be designed with the flare of one third to one degree. Generally start of the flare should be lie only 4 to 6 mm above the compacted molding. The upper edge should be rounded off with the radius 2 to 5 mm as shown in this particular figure. Loading chamber design, the calculation of loading chamber depth VT minus VC upon AP that will be in centimeter for example over here. The depth of loading space from the top of the cavity to the punch of land VC stands for volume of the actual cavity space in a cubic centimeter. VT stands for total volume of the loose powder in cubic centimeter. AP stands for projected area of the loading chamber in square centimeter. Projected area is the total area of the molding when viewed in the direction of the molding in the plane normal to the press opening. The total projected area for this particular figure as abbreviation B B into H bracket minus B into H. This is the plane normal to the opening. Plasticness, the excess material flow out from the cavity and form a thin layer of a plastic film called flash over land portion of the mold before solidifying the material as shown below. The plasticness allowance you can see over here it is mentioned in a different cases separately. The flash thickness adds to the total thickness to the part and this thickness must be subtracted from the basic cavity depth in order to the finished piece may have the desired thickness. Next parameter clamping force. Clamping force is the force which is required to hold both the mold half enclosed position press against the compression pressure. Clamping force projected area of the molding multiplied by compression force of the plastic material compression pressure. You can see for phenolic and melamine the figures are mentioned. Design of ejector pin diameter of ejector pin is equal to the wall thickness of the part length of the ejector pin is obviously the addition of various length. These lengths are length in a contact with the mold plate ejector stroke a small allowance of 1 to 1.5 millimeter. Let us go with the one of the exercise numerical for compression mold design. Whatever the concept just we had learned we are going to use the same for particularly design problem on compression mold design. The given thing the question is design a compression mold for the component shown in the figure which is made up of phenol formaldehyde thermoset plastic and some data is given bulk factor they had given as a 3 compression pressure required for the same 180 kg per square centimeter density they had given that 2 grams per cubic centimeter. The dimensions are shown for this simple particular part. Similarly we have to calculate the volume of this particular part as you can see on the screen segmental wise this part volume is calculated horizontal 3 distinct elemental geometries 2 vertical elemental geometries. The total comes out to be 56 cubic centimeter loose powder volume. Now just recall back whatever the formula we had learned so 1.2 into k Wp by rho so the putting the values over here as we know the volume is equal to weight by rho so it is placed over here. So loose powder volume is comes out to be over here for reference case 201.6 cubic centimeter to manufacture this component we required large size mold hence the land dimension is L is equal to 12 millimeter. Now let us go to the calculation of projected area so as we recall back it is in the direction of opening so projected area 10 into 2 that is 20 square centimeter depth of loading chamber as we have seen the formula Vt minus Vc upon Ap volume of actual cavity space that is calculated then the D comes out to be 2.28 centimeter. Last thickness allowance for all compound it has been referred directly 0.13 millimeter clamping force with the formula we have to calculate Ap into PC it comes out to be 3600 kilogram design of ejector pins the diameter is exactly as that of the thickness of the wall thickness 2 centimeter length of the ejector pins addition of three distinct length it comes out to be 18.5 centimeter design of punch it is something like this we had used the dimensions and the drawing is like this. Let us see one more example as a part of exercise the given thing is design a compression mold for the component shown in the figure which is made up of melamine material take K as a 2 compression pressure 19 kg per square centimeter density is about 1.79 it is a very simple part considering a cap 2 centimeter high fillet radius 2 millimeter they had shown the thickness uniform wall thickness 4 millimeter and the diameter that it shows that it is a round shape geometry diameter is 4 centimeter initially we have to calculate the VP we can recall back whatever the geometry is flashed in a previous slide the VP is calculated the volume of loose powder is also calculated VP and Vt using that the land dimension to manufacture this component to be required a large-size mold hence land dimension is 12 millimeter projected area is also calculated depth of loading chamber D is calculated flash thickness is considered 0.13 millimeter clamping force is calculated 1130.4 kg ejector pin total length is calculated 18.5 centimeter design of punches comes out to be like this references for this presentation and discussion modern plastic handbook fundamental of plastic mold design CI PET government institute website NPTEL study material thank you