Material: Cast Gray Iron GG25, EN-GJL-250 Process: Lost Foam Cast + CNC Machining Weight: 12.56 kg Application: Gearbox Housing of Heavy Duty Truck
China grey iron casting truck spare part with CNC machining services
Gray iron is cheaper than ductile iron, but it has much lower tensile strength and ductility than ductile iron. Gray iron can not replace the carbon steel, while the ductile iron could replace the carbon steel in some situation due the high tensile strength, yield strength and elongation of ductile iron.
From the iron-carbon equilibrium diagram, it can be observed that cast irons have essentially cementite and ferrite. Because of the larger percentage of carbon, the amount of cementite is high resulting in very high hardness and brittleness qualities for cast iron.
Lost Foam Casting, also called Lost Foam Casting (LFC) or Full Mold Casting, is a kind of Evaporative Pattern Casting (EPC) with dry sand casting process. The EPC is sometimes could be short for Expendable Pattern Casting because the lost foam patterns could be used only once. After the foam patterns are finished by special machined, then the foamed plastic patterns are coated with refractory coating to form a strong shell to withstand the molten metal. The foam patterns with shells are put into the sand box, and fill it with dry sand sand around them. During pouring, the high-temperature molten metal makes the foam pattern pyrolyzed and “disappears” and occupies the exit cavity of the patterns, and finally the finished desired castings are obtained.
Lost Foam Casting vs Vacuum Casting
Item
Lost Foam Casting
Vacuum Casting
Suitable Castings
Small and medium-sized castings with complex cavities, such as engine block, engine cover
Medium and large castings with few or no cavities, such as cast iron counterweights, cast steel axle housings
Patterns and Plates
Foam patterns made by moldings
Template with suction box
Sand Box
Bottom or five sides exhaust
Four sides exhaust or with exhaust pipe
Plastic Film
The top cover is sealed by plastic films
All sides of both halves of sand box are sealed by plastic films
Coating Materials
Water-based paint with thick coating
Alcohol-based paint with thin coating
Molding Sand
Coarse dry sand
Fine dry sand
Vibration Molding
3 D Vibration
Vertical or Horizontal Vibration
Pouring
Negative Pouring
Negative Pouring
Sand Process
Relieve negative pressure, turn over the box to drop sand, and the sand is then reused
Relieve negative pressure, then the dry sand falls into the screen, and the sand is recycled
▶ The Steps of Lost Foam Casting:
▶ Raw Materials Available for Sand Casting
Mechanical Properties of Gray Cast Iron |
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Item according to DIN EN 1561 | Measure | Unit | EN-GJL-150 | EN-GJL-200 | EN-GJL-250 | EN-GJL-300 | EN-GJL-350 |
EN-JL 1020 | EN-JL 1030 | EN-JL 1040 | EN-JL 1050 | EN-JL 1060 | |||
Tensile Strength | Rm | MPA | 150-250 | 200-300 | 250-350 | 300-400 | 350-450 |
0.1% Yield Strength | Rp0,1 | MPA | 98-165 | 130-195 | 165-228 | 195-260 | 228-285 |
Elongation Strength | A | % | 0,3 – 0,8 | 0,3 – 0,8 | 0,3 – 0,8 | 0,3 – 0,8 | 0,3 – 0,8 |
Compressive Strength | σdB | MPa | 600 | 720 | 840 | 960 | 1080 |
0,1% Compressive Strength | σd0,1 | MPa | 195 | 260 | 325 | 390 | 455 |
Flexural Strength | σbB | MPa | 250 | 290 | 340 | 390 | 490 |
Schuifspanning | σaB | MPa | 170 | 230 | 290 | 345 | 400 |
Shear Stress | TtB | MPa | 170 | 230 | 290 | 345 | 400 |
Modules of elasticity | E | GPa | 78 – 103 | 88 – 113 | 103 – 118 | 108 – 137 | 123 – 143 |
Poisson number | v | – | 0,26 | 0,26 | 0,26 | 0,26 | 0,26 |
Brinell hardness | HB | 160 – 190 | 180 – 220 | 190 – 230 | 200 – 240 | 210 – 250 | |
Ductility | σbW | MPa | 70 | 90 | 120 | 140 | 145 |
Tension and pressure change | σzdW | MPa | 40 | 50 | 60 | 75 | 85 |
Breaking Strength | Klc | N/mm3/2 | 320 | 400 | 480 | 560 | 650 |
Density | g/cm3 | 7,10 | 7,15 | 7,20 | 7,25 | 7,30 |