01-09-2014, 10:45 AM
It is my esteem privilege, to express deep sense of gratitude and indebtedness to my major advisors, Mr. Balbir Singh {personnel department officer} & Mr. P S Nanda (Manager of the Unit) GNA Duraparts {GNA auto parts}, Mehtiana for their expert and inspiring guidance, constructive criticism and constant encouragement during the course of this practical industrial training. I am very thankful to my contact persons i.e. incharges of the various shops/departments and personnel department officers who gave me such a use full guidance. I would be failing in my duties if I do not thank Mr.Gurdeep Singh Director, GNA Duraparts – Mehtiana, Who allowed me to undergo practical industrial training. Thanks are also due to all staff members of GNA Duraparts and others who took lots of interest in assisting me during the training period and in making the repot a success.
PROJECT
The training manager of industry, assigned me a project of developing a die of CHOKE COVER component for pressure die casting process . he give me a drawing of choke coverand tell me to developed a core and cavity inserts for choke cover die by using creo2.0 software according to proper dimensions. CHOKE COVER He tells me that , this is my responsibility to decide the materials of die and choke cover that are cheap and reliable for the following applications:- - To cover the electrical wiring in the automobiles. - To cover the electrical wiring in the tube light. Before starting the design, I need to get the proper knowledge about the process of pressure die casting , materials of die, for pressure die casting process , materials of component that produced by this process , that help me to decide the best material for die and choke cover that are less expensive and reliable and fulfill the customer requirement. CASTING PROCESS The process in which molten metal is used for producing the products is known as casting process. In this process, firstly the slab and scrap of metals are put into the furnace in which solid state of metals are converted into liquid molten state. This molten metal is poured into the mould box, which is made with the help of master piece of that product . this master piece is either of wood or metal according to the requirement. After passing some time, the molten metal becomes solidify and the same products are produced as the master piece. The casting process is subdivided into two distinct subgroups:- 1 - Expendable mould casting:- ( sand, plastic, shell, and investment (lost-wax technique) mouldings.) 2 - Nonexpendable mould casting:- ( permanent , die, centrifugal, and continuous casting). DIE CASTING:- According to the instructions of the industrial training manager, mainly die casting method is used for making a choke cover. Die casting is the one of non expendable type mould casting method. In Industry, many types of die casting methods are used. The classification of die casting methods are given below :- CLASSIFICATION OF DIE CASTING:- (a)Gravity Die Casting (b)Pressure Die Casting According to the instructions of the industrial training manager, for making a choke cover, pressure die casting method is used. The details of various processes of pressure die casting are given below:- PRESSURES DIE CASTING:- In this casting method, various processes are performed for produced a products. These various processes of pressure die casting method are given below:- 1.) MELTING THE METAL:- In this process, a melt tower furnace is used for melting the metal. The furnace oil is used for running the furnace. The capacity of the furnace is 2 ton. This process is carried out according to the following way:- • Put the silly (solid metal block) and runner (scrap) in 50:50 ratio i.e. ; one trolley silly and one trolley runner. • When the metal reaches at a holding chamber, then properly shake the metal by long iron rod. • When the metal temp. is reached at greater than 680 (°C) then add 5 – 6 kg. Cover focus for separate the molten metal from dust and carbon. Cover focus is generally in white and red colors). • Shake properly the cover focus into the molten metal. • Clean the molten metal from dross (burnt particles and carbon), properly from the furnace. • Check the burner flame is in right cone (45 °). • Check the temperature of the furnace oil is in the limits (80 – 95 °C). • Check the temperature of the escaped hot air is not greater than 200 °C • When the metal temperature is reaches at 700 - 740°C, then escape the molten metal from the furnace into the ladle. The capacity of ladle is 300 kg.. • Now the molten metal is ready for D – Gassing. 2.) D – GASSING:- After melt the metal, put it into the ladle and ladle is placed on to the D – Gassing Machine. This process is used for remove the carbon, air and dust particles from the molten metal. In this process, the nitrogen gas is delivering in to the ladle and it is mixed regularly with molten metal by the revolving rod. After passing 6 minute, escape the impurities from the top of the metal surface with the help of iron rod and clean the melt metal. This is very important process because if the air is leave into the molten metal then it is caused for the creation of blow holes, in to the produced product after casting. In this process a dry nitrogen gas is used , because it is lighter then the impurities. The pressure of the nitrogen gas is about 8 kg /cm2. for this process. METAL CARRING LADLE 3.) R. A. T. S. TEST:- The full form of R. A. T. S. is reduced atmosphere testing system. This process is done after the completion of the D – Gassing process of the molten metal. This is very important process, for check that, the D – Gassing of molten metal is done properly or not. This process is carried out according to the following way:- • Before starting the machine, first of all , check that there are not any water or moisture on the disc. • Never run the machine on any moisture place.. • Put the molten metal in the cup of the machine and then the cup is covered by the cylinder vessel. • Before starting the machine, set the place of cylinder vessel. • Set the timer switch of machine, at 1 minute and run the machine. • Don’t touch the cup which is used on this machine, for carrying molten metal, because it is very hot. The material which is used for making the cup , is iron metal. • When the machine is running , not put out the cylinder vessel because in the cylinder vessel, pressure is introduced. • Wait for reach the timer switch , at zero position and when the • Pressure is reduced to zero position, put out the cylinder vessel. • Put out the sample from the cup and then wait for cooled out • the sample. The sample cool time is approx. 10 minutes. • When the sample is cooled , then it is cutter out by the knife • For check the blow hole. • When the blow hole is find out in the sample then that molten metal is again goes for the D – Gassing process. R. A. T. S. MACHINE 4.) PRESSURE DIE CASTING :- After the completion of the R. A. T. S. process of the molten metal, put out the molten metal in to the holding furnace, which is fitted with the pressure die casting machine. In the holding furnace, the metal temperature is maintained at between 640 – 700 (°C) by coiling heater. In this machine , the die which is used for producing the components like crank case covers , hubs and panels etc. , is made in two pieces. These two pieces of die is fitted opposite but in line to the machine. One piece of die is, movable and other piece of die , is flxedable. The cavity is made on movable die and the internal shape of product is made on fixedable die. The gate which is used for carrying the molten metal during process , is attached with the moveable die. PRESSURE DIE CASTING MACHINE DIE CASTING PROCESS FLOW In this process, firstly heat up the dies at between 170 – 230 (°C) with the help of L. P. G. gas. After heat up the dies, closed both the dies with each other by hydraulic oil pressure and nitrogen pressure. The pressure of nitrogen is very high and help, to closed both the dies perfectly. After closed both the dies , put the molten metal in to the gate of the machine with the help of putting the cup into the holding furnace and filled the cup. After this, with the help of pressure moved the plunger rod in inward direction and the shot is taken out . By this, the plunger is moved inward, and pushed the molten metal into the cavity of the die. After passing 10 – 12 seconds, the molten metal is colled out and convert from liquid to solid form. After passing this time , open the dies and put out the casted product with the help of the injector rod & injector pins. FLOW OF MOLTEN METAL IN TO THE DIES After injected out the casted product from the die, it is goes for trimming process. Now the die coat and the water mixture is sprayed on to the dies, for clean the dies from carbon particles and for cooling purposes. The function of die coat is to provide the safety to the components that , it should not be stickled with the dies and remove easily. The die coat is made by mixing the 1 Lt. of die coat with 80 – 85 Lt. water. 5.) TRIMMING / FETTLING:- After the completion of the pressure die casting , the components are going in the trimming section. In this process , the enlarged surfaces of the casted components are trimmed and cutted out by punching press or by strike the hard surface or hammer on to the casted surface. After trimming process, the components are going in filling area where sharp edges of the components are remove by filling process. 6.) SHOT BLASTING:- After the completion of the filling process, the components are going in to the shot blasting area, where the very small size shot (balls) are strike on the component by shot blasting machine. The material of the shots are steel and size of the steel shots are 0.4 – 0.5 mm. This process is very important for smooth a rough surface, shape a surface, or remove surface contaminants. COMPONENTS PLACED ON SHOT BLASTING MACHINE In this process, a special type of machine is used. In this process firstly, the components are placed on to the special type hanger and then this hanger , is goes in to the machine , where that hanger is revolved firstly in clockwise direction & then in anticlockwise direction. During the revolving of the hanger, the steel shots are strike on to the components , for make small cavities on to the components. It is very necessary to take care, of the durability of the shot blasting of the components. The specified time for shot blasting the right and left crank case covers are 75 sec. ADVANTAGES OF PRESSURE DIE CASTING • Excellent dimensional accuracy • Smooth cast surfaces (1—2.5 μm rms). • Thinner walls can be cast • Inserts can be cast-in (such as threaded inserts, heating elements ) • Reduces or eliminates secondary machining operations. • Rapid production rates. • tensile strength as high as 415 MPa . DISADVANTAGES OF PRESSURE DIE CASTING • Casting weight must be between 30 grams and 10 kg • Casting must be smaller than 600 mm • High initial cost. • Limited to high-fluidity metals. • A certain amount of porosity is common. • Thickest section should be less than 13 mm • A large production volume is needed to make this an economical. MATERIALS OF COMPONENTS FOR PRESSURE DIE CASTING PROCESS Mainly the pressure die casting process is used for making various automobile parts. For making automobile parts , by the pressure die casting process , following materials are used :- • Aluminium alloys • Zink alloys • Copper alloys Minimum wall thicknesses of components and minimum draft angles of dies , for these materials , for pressure die casting process are given below:- MATERIAL MIN. THICKNESS IN (MM) MIN. DRAFT ANGLE (º) Aluminum alloys 0.9 mm 0.5 Zinc alloys 0.6 mm 0.25 Copper alloys (Brass) 1.25 mm 0.7 MATERIAL FOR CHOKE COVER According to the benefiting of industry (easily availability and less expensive) and fulfilment of customer requirement , aluminium alloys are the best material for making choke cover. Aluminium alloys having properties of lightweight; high dimensional stability for complex shapes and thin walls. There are many types of aluminium alloys are used (aacording to the chemical compositions) , that are described by specific codes , which are given below:- -AA 380 (UNS A03800) -AA 384(UNS A03840) -AA 386(UNS A03860) -AA 390(UNS A03900) The configurations of these aluminium alloys are given below:- MATERIAL SILICON COPPER TENSILE STRENGTH MPA PROPERTIES AA 380 (UNS A03800) 8.5 % 3.5 % 324 Fair easy to fill AA 384 (UNS A03840) 11 % 4 % 331 Easy to fill AA 386 (UNS A03860) 9.5 % 0.6 % 317 Good corrosion resistance AA 390 (UNS A03900) 17 % 4.5 % 283 Good wear resistance MATERIALS OF DIE FOR PRESSURE DIE CASTING PROCESS A complete machine tool or die has no. of plates, that materials are different from each other. The name of these plates are given below:- FOR FIXED HALF OF THE MACHINE • BOTTOM PLATE • INJECTOR PLATE • INJECTOR RETAINER PLATE • INJECTOR ROD • SPACER BLOCK • CORE BACK PLATE • CORE RETAINER • CORE INSERT FOR M OVABLE HALF OF THE MACHINE • CAVITY INSERT • CAVITY RETAINER • CAVITY TOP PLATE • TOP PLATE • LOCATING RING • SPRUE BUSH • GUIDE PILLERS • GUIDE BUSHES The selection of materials for core and cavity inserts are depends upon the two things:- - Volume of production - Life of toll The materials of these plates for the pressure die casting process are given below:- CORE INSERT AND CAVITY INSERT -HOTTEST STEEL (H13) BOTTOM PLATES , INJECTOR PLATE, INJECTOR RETAINER PLATE , INJECTOR - MILD STEEL ROD , SPACER BLOCK , CAVITY RETAINER , TOP PLATE , LOCATING RING . GUIDE PILLER - DIE STEEL GUIDE BUSHES - GUN METAL DESIGN OF CHOKE COVER For developing the die of choke cover , firstly make a 3D model of choke cover in the design software. The various steps that are followed, for design the choke cover in CREO 2.0 are given below:- • Select the new from the data section and select the part as type and solid as sub type. • New graphic window is open. • Firstly Select the sketch from the datum group in the model tab of the ribbon and make a 2D sketch on the front principal plane , according to the proper dimensions as, • Now select the extrude from the shapes group in the model tab of the ribbon and select the sketch that is already made , for convert it to 3D model. • Select the symmetric from the option tab and put the value of third parameter according to the dimension. • Now model is converted from 2D to 3D as follow, • Now make a trajectory for sweep command as a shape of arc , on the centre of the part by using sketching command as, • Select the sweep from the shapes group in the model tab of the ribbon. • Select the trajectory , and specify the start point. • Now select the sketching and make a cross section on the start point and click ok. • This cross section moves along the trajectory. • Select the remove option to remove the material as follows, • Now select the extrude from the shapes group in the model tab of the ribbon and select the right plane for make sketch. Now sketching window will be open. • Make a circle according to the dimension at the top of the model, and click ok. • Select the through all from the option tab and select the remove option , for make a cylindrical cut out at the top surface of the model. • • Now create a datum plane as the top principal plane, at the above of the top plane according to the dimension, by selecting plane from the datum group, as follow. • Now select the blend from the shapes drop down list and click the section tab and define the plane on which sketch is made. • Now make a ellipse according to the dimensions and click ok. • • Give the offset value of sketch 2 from sketch 1 and make a second ellipse according to the dimensions and click ok. • • Now select remove option for make a cut at the one side of the model as follow , • Now select the blend1 from the model tree and select the mirror from the editing group. • Specify the right plane and click ok. • Now the similar cut is generated at the other side of the model as, • Now give the draft angle at every sides of the model according to the dimension by specify the top plane as draft hinge as follow, • Now give the round to all the edges of the model according to the dimension as follow, • Select the shell from the engineering group and specify the bottom surface as removed surface. • Give the wall thickness according to the drawing as follow, • Now make a holes by selecting hole from engineering group ,according to the dimension as follows, • Give the draft angle to the inner surfaces of the holes according to the dimensions as follows, • Now the solid model is ready for developing its die (core and cavity inserts). • Before starting development of die , it is necessary to check the dimensions, fitment and esthetic look of the choke cover. • These parameters are checked by the physical model only. • For generating the physical model , RPT technology is used. 3D MODEL PRINTING USING RPT ( REPID PROTOTYPE TECHNIQUE) Additive manufacturing or 3D printing is a process of making three dimensional solid objects from a digital model. 3D printing is achieved using additive processes, where an object is created by laying down successive layers of material. 3D Printer worked on FDM (Fused Deposition Modeling) technology 3D printing is considered distinct from traditional machining techniques (subtractive processes) which mostly rely on the removal of material by drilling, cutting etc.