Casting SuJin Kim Gyeongsang National University Outline 1

Casting (주조) Su-Jin Kim Gyeongsang National University

Outline 1. Casting Physics 2. 3. 4. 5. Sand Casting Investment Casting Die Casting Gravity casting 6. Cost/Quality Casting Su-Jin Kim @ GNU

Casting • Casting(주조) is a manufacturing process by which a liquid metal(용융금속) is poured into a mold(주형), which contains a hollow cavity of the desired shape, and then allowed to solidify. • Bronze, iron age, light metal age? Casting Su-Jin Kim @ GNU

Casting is Versatile • Many types of metals • Wide range of shapes and sizes • Complex parts as an integral unit Disadvantage • Poor dimensional accuracy and surface quality Casting Su-Jin Kim @ GNU http: //www. youtube. com/watch? v=mx 1 qte. RUYw. I Sand, Investment, Lost form SME 6: 16

Basic requirement (요구사항) 1. Mold cavity (주형 공동) : Single-use molds(1회용 주형), Multiple used molds (재사용 주형) 2. Melting process (용융공정) 3. Pouring technique (주입기술) 4. Solidification process (응고과정) 5. Mold removal (주형분리) 6. Cleaning(세척), Finishing(다듬질), Inspection(검사) Casting Su-Jin Kim @ GNU

사형 1. 사형 2. 탕도계 3. 분리 Casting Su-Jin Kim @ GNU

Sand casting mold (사형) • • Pattern(모형), Molding material(주형재료), Flask(주형상자) Cope(상형), Drag(하형) Pouring basin (cup) Core(코어), Mold cavity(주형공동) Open riser Vent Riser(라이저) Flask Blind riser Sprue Cope Core (sand) Parting line Well Drag Sand Mold Gate cavity Casting Su-Jin Kim @ GNU Runner

Gating system (탕도계) 1. 2. 3. 4. 5. Pouring cup (주입컵) = Pouring basin(탕구 웅덩이) Sprue (탕구) Pouring basin (cup) Runner (탕도) Open riser Vent Gate (주입구) Flask Vent (배기공) Blind riser Sprue Cope Core (sand) Parting line Well Drag Sand Mold Gate cavity Casting Su-Jin Kim @ GNU Runner

Parting (분리) • Parting line (분리선) = Parting surface (분리면) • Draft (드래프트) • Core box (코어박스) Open riser Flask Pouring basin (cup) Vent Flask Blind riser Sprue Cope Core (sand) Parting line Well Drag Sand Casting Su-Jin Kim @ GNU Mold Gate cavity Runner

Cast structure (주조조직) of alloying • Solidification begins when temperature drops below the liquidus(액상점), TL, and complete when solidus(고상점), TS, called freezing range(응고범위) • For normal cooling cored dendrites(유심구조 수지성장) are formed. Surface has a higher concentration of alloying elements. (ºC ) s idu u Liq L+α Liquid, L 1300 s du oli 35 % 1200 40 % S Solid, α Casting Su-Jin Kim @ GNU 110 0 20 40 (wt%

Fluid flow (유동) of mold filling Gravity casting: pouring cup→sprue →well →runner →riser → cavity →open Pouring basin (cup) Open riser Vent riser Bernoulli’s equation Flask Blind riser Sprue Cope Core (sand) h = elevation p = pressure at elevation v = velocity of the liquid ρ = density of the fluid Su-Jin Kim @ GNU Gate Drag Velocity of the molten metal leaving the gate Casting Parting line Sand Mold cavity Runner Well ©정하림GNU

Fluid flow of mold filling • Reynolds number, Re v = velocity of the liquid D = diameter of the channel ρ = density n = viscosity of the liquid. • Ordinary gating system: Re = 2, 000 ~ 20, 000 mixture of laminar and turbulent flow Casting Su-Jin Kim @ GNU

Heat transfer (열전달) • Heat flow (열유동) depends on casting material and the mold and process parameters. • Temperature distribution (온도분포) in the mold-liquid metal interface is shown below. Mold Solid Temperature Melting point Air Room temperature Casting Su-Jin Kim @ GNU Distance Liquid

Solidification time • Solidification time (응고시간) is a function of the volume of a casting and surface area (Chvorinov’s rule). C = constant n = 2 if Sand casting n = 1 if Die casting • Ex) Sand casting 4 2 . 5 4 Casting Su-Jin Kim @ GNU 2 2

Shrinkage • Shrinkage (수축) in casting causes dimensional changes and sometimes cracking. • Thermal expansion Metals 주물재료 Aluminum Casting Su-Jin Kim @ GNU Contraction 수축률(%) 7. 1 Zinc 6. 5 White iron 4. 0 -5. 5 Copper 4. 9 Brass(70 -30) 4. 5 Magnesium 4. 2

Defects (주조결함) • • • Dimensional Accuracy, Surface finish Porosity : a void in the casting Shrinkage cavity(void) : internal vacancy Slag or sand inclusion Surface blowholes or pinholes Crack Casting Su-Jin Kim @ GNU

Design for Casting (설계) • Draft angle : is required to extract pattern from mold. Sand 3~5˚, Invest 0~3˚ , Die 1~2˚ • Control shrinkage : Add padding and riser to feed metal reduced as transitions from liquid to solid state. • Junction design: Fillets to distribute strains stress. Uniform section to remove shrinkage cavity. • Datum point(plane) for post machining. Draft angle Casting Su-Jin Kim @ GNU Padding, Riser Uniform section

Casting CAE • : http: // Casting Su-Jin Kim @ GNU

주조 분류 • Expendable mold (소모 주형) 1. Send casting (사형주조) 2. Investment casting • Multiple-use mold (재사용 주형) 1. Die casting (다이 케스팅) Mold Casting Su-Jin Kim @ GNU Product

Expendable Mold Casting (소모주형 주조) Permanent pattern (재사용 모형) 1. Sand casting 2. Shell mold casting 3. Plaster mold casting Expendable pattern (1회용 모형) 1. Investment casting (lost wax casting) 2. Lost foam casting Casting Su-Jin Kim @ GNU Pattern Mold

Permanent Pattern (재사용 모형) 1. Sand casting 2. Shell mold casting 3. Plaster mold casting Pattern Casting Su-Jin Kim @ GNU Mold

Sand Casting (사형주조) Create pattern Place flask(box) over the pattern plate Fill flask with sand remove pattern Pouring molten metal into mold Shakeout mold and cutoff gating system Pattern Casting Su-Jin Kim @ GNU Sand mold Pouring Product http: //www. youtube. com/watch? v=rg. L 2 Jn 5 mk 1 A Sand Casting (4 min)

Sand Casting • • • Use expendable sand molds Low production rate(1– 20 pieces/hour-mold) Low cost, Recycle sand Small quantity production Complex entire parts at one time Casting Su-Jin Kim @ GNU

Shell mold casting (셸몰딩) • Fine sand mixed with a resin is heated by the pattern and hardened into a shell around the pattern • Can produce castings with close dimensional tolerances, good surface finish and low cost. Casting Su-Jin Kim @ GNU https: //youtu. be/28_I 7 Bdz 4 y. Y Shell mold casting

Plaster mold casting (석고주형 주조) • Plaster is mixed with water and poured over the pattern. • Accurate, good surface and low melting point alloy(Al, Cu). Casting Su-Jin Kim @ GNU

Ceramic mold casting (세라믹주형주조) • Use refractory materials like Zircon. • Ceramic slurry is poured over a pattern. • High temperature alloys(Fe) Casting Su-Jin Kim @ GNU

Expendable pattern (1회용 모형) 1. Investment casting (lost wax casting) 2. Lost foam casting Pattern Casting Su-Jin Kim @ GNU Mold

Investment Casting (인베스트먼트주조) Investment casting = lost wax casting Injecting wax patterns Pattern assembly tree Slurry coating Sand coating Wax pattern melt out by heat Pouring molten metal Shakeout Wax pattern assembly Casting Su-Jin Kim @ GNU Pouring metal into shell mold https: //youtu. be/6 u 4 lwd. IPef. M (8 min)

Investment casting • A wax pattern is coated by ceramic slurry that hardens into the mold. • One pattern creates one part, which increases production time and labor costs. • Complex geometries, good surface and high melting point alloy. Casting Su-Jin Kim @ GNU Aluminum Investment Casting : http: //www. youtube. com/watch? v=f 7 FXtn. XVqz. Y

Lost foam casting (소실모형주조) • Polystyrene patterns evaporate with molten metal to form a cavity for the casting. Casting Su-Jin Kim @ GNU Molding (금형) Patterns Coating ©samhwacast. com Compact in sand Casting Shakeout Manhole cover

Permanent Mold Casting (영구주형 주조) 1. 2. 3. 4. Die casting Gravity casting Centrifugal casting Continuous casting Casting Su-Jin Kim @ GNU

Die Casting (다이캐스팅) The molten metal is forced into the die cavity by high pressure. Ejector platen (moves) Ladle Ejector die half Ejector box Stationary die half Shot sleeve Plunger rod Pouring hole Plunger rod Closing cylinder ©갈창우 Casting Su-Jin Kim @ GNU Cover disk Metal sleeve https: //youtu. be/0 Xk. DK 46 rwv. Q Die casting Shot sleeve

Die Casting • Fast (30 ~ 60 s/part) automatic process for mass production (0. 1 million parts/mold). • Good surface finish and dimensional accuracy. • Strength-to-weight ratio increases with decreasing wall thickness. Small voids decrease strength. • It is used for aluminium, magnesium and copper alloys. https: //youtu. be/h 2 A 7 o. UMe. Lm. M Machine Casting Su-Jin Kim @ GNU https: //youtu. be/i. Sy. Bsd. Jk. Qu 8 Die Casting Process

Die Casting Aluminum Furnace Casting Su-Jin Kim @ GNU Die Casting factory

Die casting Casting Su-Jin Kim @ GNU

Die casting Casting Su-Jin Kim @ GNU

Gravity Tilt Casting (금형중력주조) • Gravity casting = Gravity die casting = Gravity tilt casting • Molten aluminum flows slowly into mold by gravity force. • The mechanical properties, tolerance and surface finish are better than sand casting. Thick aluminum parts. Casting Su-Jin Kim @ GNU Gravity casting: https: //youtu. be/Ia. SY 6 fe. Xk 7 A

Centrifugal casting (원심주조) • Molten metal is solidify in rotating mold. • It uses centrifugal force to form cylindrical parts. Centrifugal force = mv 2/r Gravitational force = mg Casting Su-Jin Kim @ GNU https: //youtu. be/Zx. VA-ht. Tun. U : Centrifugal Casting (2 min)

Local company Ceramic mold Casting Su-Jin Kim @ GNU Clamp Pouring molten metal Remove molds http: //www. untingama. co. kr

Continuous casting (연속주조) • Developed for casting metal slab or strip continuously at low cost. Continuous casting Strip casting hot rolling slab Casting Su-Jin Kim @ GNU strip Continuous Casting https: //youtu. be/d-72 gc 6 I-_E

비용 품질 시간 비교 1. Advantage and Disadvantage 2. Cost 3. Quality 4. Rate 5. Economics Casting Su-Jin Kim @ GNU

Casting process comparison (비교) Casting Su-Jin Kim @ GNU Process Advantages Disadvantages Sand Casting Almost any metal is cast; Small to large parts; Low tooling cost Low dimensional accuracy & surface quality Investment Cast Good dimensional accuracy and surface finish; Complex shape, fine detail; Ferrous and non-ferrous metals Costs are higher than Sand, Permanent Mold or Plaster process Castings Die Casting Excellent dimensional tolerances and High die cost; Part size limited; surface finish; Parts require a minimal Limited to nonferrous metals post machining; High production rate

Cost of casting (비용) Process Casting Su-Jin Kim @ GNU Tooling & Equipment Direct labor Material utilization Sand Casting Low High Low Investment Cast Moderate & Low High Low Die Casting High Low High Sand casting: Finishing costs can be high

Quality of Casting (품질) Process Casting Su-Jin Kim @ GNU Tolerance Mechanical Property Surface finish (mm) Sand Casting 0. 7~2. 0 Material property is poor Generally have a rough grainy surface Investment Cast 0. 08~0. 2 Mechanical property and microstructure depends on the method Good to excellent surface detail possible due to fine slurry Die Casting 0. 02~0. 06 Excellent surface detail Good mechanical property and microstructure due to high pressure

Rate of Casting (생산성) Process Development time (weeks) Production rate Sand Casting 2~10 OO min, t~(V/A)2 Investment Cast 5~16 OO min, t~(V/A)2 Die Casting 12~20 OO s, t~(V/A)1 Development time is also depending on the size and complexity. Production rate is depending on the cooling time. Casting Su-Jin Kim @ GNU

Economics of Casting (경재성) 4 5 6 7 8 9 100 Casting Su-Jin Kim @ GNU Investment casting Sand casting Die casting 1 2 3 Cost per pieces • Cost of equipment per casting decreases as number of parts increases. 101 102 103 104 Number of pieces 105 106

References • POSCO: http: //www. posco. com • • • http: //www. dhcasting. co. kr http: //www. edaehan. co. kr http: //www. taechangpi. co. kr http: //www. donglimms. co. kr http: //www. yeonghwa. co. kr http: //www. himet. co. kr • Casting: http: //www. custompartnet. com Casting Su-Jin Kim @ GNU