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Mini Project 312022 Mini Project Introduction to manufacturing engineering NGUYEN TRONG DAT 20195766 HANOI UNIVERSITY OF SCIENCE AND TECHNOLOGY Name Nguyễn Trọng Đạt Student ID Course code. The project discuss about permanent metal mold to molding metal in a shape
3/1/2022 Mini Project Introduction to manufacturing engineering Name: Nguyễn Trọng Đạt Student ID: 20195766 Course code: ME2036 Class code: 128364 No: 15 Product: Mold NGUYEN TRONG DAT 20195766 HANOI UNIVERSITY OF SCIENCE AND TECHNOLOGY Mini project Introduction of manufacturing engineering Part I: Introduce the product 1.1 Basic characteristics and applications -Molding is the process of manufacturing by shaping liquid or pliable raw material using a rigid frame called a mold or matrix This itself may have been made using a pattern or model of the final object -Permanent mold casting is a metal casting process that employs reusable molds ("permanent molds"), usually made from metal The most common process uses gravity to fill the mold, however gas pressure or a vacuum are also used In such molds, the two mold halves are mounted and aligned on a pin There is no mechanical connection between the mold parts, and they can be completely separated from each other after casting When the mold halves are closed, the space between the closed mold parts is the shape of the casting Liquid metal is transferred to the mold cavity through tapping spout and riser The mold cavity should be designed appropriately so that the air inside the mold can escape during casting + Two halves of mold are made from material with high resistance to erosion and thermal fatigue: Iron, steel, bronze, graphite, or refractory metal alloys + Precise products made by pouring low melting alloys (Al, Mg, Zn) into CNC machined steel (or grey iron) molds under gravity, centrifugal force, or low pressure -Based on the design characteristics indicated above, there are different types of molds available Die Casting Permanent Metal mold - Metal Molds can be applied in: Transport: Automobile, aerospace, railways, and shipping; Heavy Equipment: Construction, farming, and mining; … 1.2 Dimension and features of metal mold -In this project, I will introduce the features, specifications, manufacture, and applications of Permanent metal mold - As the name implies, Metal mold casting is pouring liquid metal into a metal fabrication mold with two halves of mold - Because the metal mold has different physical and mechanical properties than the sand mold material, it has the following characteristics: + Advantages: It produces castings with a good surface finish, close dimensional tolerances, uniform and good mechanical properties, and high production rates, Labor costs are kept low by automating the process, Rapid heat transfer to the mold results in finer grain structures, better strength properties than casts made by sand casting method, less subject to shrinkage and gas porosity than sand castings, no entrapped gas +Disadvantages: Metal molds have no settlement properties and are not capable of venting gases, this will cause casting defects Mold manufacturing costs are high This method is only suitable for mass production with simple, small, or medium castings Equipment costs can be high because of high die costs Part II: Choose the material -Because the permanent molds that are exposed to very high temperatures and changes in temperature Permanent molds can be made up by cast iron, steel such as H10, H11, H12, H13, H21, X38CrMoV5-3, ……… I choose AISI H13(medium carbon steel, hot work mold steel) - AISI H13 steel is the most popular and most versatile, hot work mold steel, providing a good balance of toughness, heat check resistance, and high temperature strength, in addition to moderate wear resistance H13 steel can resist softening to 550°C and has good resistance to heat checking • Chemical properties: Element AISI H13 C Si Mn P S Cr Mo V 0.32-0.45 0.90-1.25 0.20-0.60 0.030max 0.030max 4.75-5.50 1.10-1.75 0.80-1.25 • Physical properties: Density (20 °C) 7.80 g/cm3 Melting point 1427°C Specific Gravity 7.75 Modulus of elasticity (kg/m3) 8138 • Mechanical properties: Tensile strength, ultimate (20 °C) 1200-1590 MPa Tensile strength, yield (20 °C) 1000-1380 MPa Reduction of area (20 °C) 50.00% Modulus of elasticity (20 °C) 215 GPa Poisson’s ratio (20 °C) 0.27-0.30 Elongation at break (HRC) 35-45 • AISI H13 applications: AISI H13 steel is an air hardening, 5% chromium die steel, which is an excellent choice for a wide range of hot work and cold work applications Typical applications include die casting dies for aluminum, magnesium and zinc, extrusion dies for aluminum and brass, liners, mandrels, pressure pads, followers, bolsters, die cases, die holders and adaptor rings for copper and brass extrusion H13 steel is used to produce hot stamping and press forge dies, split hot heading dies, gripper dies, hot punching, piercing, and trimming tools Other applications include plastic molds, shear blades for hot work and hot swaging dies Part III: Manufacturing Process To make this mold, I will go through • Process 1: Cutting work piece -Choosing an AISI H13 tool steel bar with 350mm length, 210mm width, and cut a work piece for 45mm height • Process 2: Surface milling -Because the bar seems to be not smooth, using face milling to achieve the required smoothness and reach the desired size Because the length of the H13 steel bar is 350mm length, 210mm width, and 45mm height, then we mill all surfaces to reach the desired length, width, and height are 330mm, 200mm, and 40mm, respectively • Process 3: Shaping the product -In this process, using end milling to make a shape for a desired product which can be casted from the mold • Process 4: Making hold -Make holds for molds fit together Using drilling to make holds that can combine molds • Process 5: Making the other half of mold -Repeat all the processes above to make the other half with reversely detail Then we obtain havles with all detail fit together • Process 6: Check the product -Check halves mold if there are match and have no failure detail Part IV: Heat treatment - Hot-working AISI H13 tool steel offers high hardenability, excellent wear resistance and hot toughness To obtain excellent mechanical properties, we use quenching and tempering -Heat treatment process: + The hardness of 54~55 HRC can be obtained by quenching at 030 ℃, and the grains begin to grow beyond 040 ℃ Therefore, the heat treatment temperature range of 030~1 040 ℃ is recommended At the same time, special attention should be paid to pre-cooling to 20~30 ℃ (950~980 ℃) above Ac3 when coming out of the oven to reduce stress concentration and avoid cracking Heating temperature 1020 ~ 1050℃, oil cold or air cold, hardness 54 ~ 58HRC; It is required that the quenching process specification of the die mainly hot and hard, the heating temperature is 1050 ~ 1080℃, the oil is cold, and the hardness is 56 ~ 58HRC + In order to eliminate the stress and improve the high temp toughness of H13 forgings must be tempered at high temperatures, secondary tempering can be used to improve the life of the die due to the good fire resistance and secondary hardening of the alloy elements in the steel The tempering temperature (580±20 ℃) was used to obtain the hardness of 47~52 HRC The microstructure after tempering is tempered martensite and a small amount of granular carbides + Tempering should be done twice When tempering at 500℃, the secondary hardening peak appears, with the highest tempering hardness and peak value around 55HRC, but the worst toughness Therefore, according to the use of the mold needs 540 ~ 620℃ tempering is better Quenching heating shall be preheated twice (600 ~ 650℃, 800 ~ 850℃) to reduce the thermal stress generated during heating Part V: Conclusion 5.1 Results -The Permanent Mold Casting Process consists of pouring molten metal into a permanent mold, usually created from iron or steel The metal flows into the mold cavity under gravity pressure; flowing into the small crevices of the mold to produce intricate and fully formed castings - Permanent mold casting is used heavily in the automotive industry to create parts like gears, castings, suspensions, fuel injection housings, and engine pistons Aircraft parts are also often made via permanent mold casting 5.2 Comment -Permanent mold casting can be used for high production rates, and you can reuse molds many times Low labor costs using highly automated processes The finish pieces have a good surface finish and good dimensional accuracy Permanent mold casting also produces little waste -Although permanent mold casting has a lot of advantages, it also has drawbacks Because of the high tooling cost involved, a high production volume is needed in order to make this process and economically viable manufacturing option A high tooling cost and long setup time Only non-ferrous metals may be cast by this process