POURING SYSTEM DUCTILE IRON DROSS POURING SYSTEM DUCTILE IRON

DROSS Mg + S  MgS Mg + O  MgO WHAT IS DROSS? SMALL SIZE COMPARED TO SAND AND SLAG INCLUSIONS

DROSS WHAT IS DROSS?

DROSS AMOUNT OF DROSS Mg INCREASE, DROSS INCREASE Mg/S INCREASE, DROSS INCREASE Vmetal INCREASE, DROSS INCREASE

DROSS Mg MUST COMPENSATE S IF Mg/S IS HIGH, MUCH Mg IS NOT USED FOR THE REACTION Mg + S  MgS LOT OF Mg FOR THE REACTION Mg + O  MgO

DROSS THE MORE CONTACT SURFACE WITH THE AIR, THE MORE THE REACTION WILL PERFORM Mg + O  MgO

DROSS THE FOLLOWING CASES HAVE A HIGH CONTACT WITH AIR:

DROSS THE FOLLOWING CASES HAVE A HIGH CONTACT WITH AIR:

DROSS THE FOLLOWING CASES HAVE A HIGH CONTACT WITH AIR:

DROSS THE FOLLOWING CASES HAVE A HIGH CONTACT WITH AIR:

DROSS POURING SYSTEM

DROSS

DROSS POURING BOX: Collecting metal for good filling SPRUE: Vertical transport RUNNER: Horizontal transport INGATES: Connection to casting, preferred horizontal

DROSS WHERE IS DROSS CREATED?

DROSS WHERE IS DROSS CREATED?

DROSS POURING BOX

HOW TO PREVENT ENTERING OF DROSS IN SPRUE POURING BOX HOW TO PREVENT ENTERING OF DROSS IN SPRUE

AMOUNT OF DROSS IN LOWER PART OF SPRUE DEPENDING ON HEIGHT

AMOUNT OF DROSS IN LOWER PART OF SPRUE Sprue diameter 30 40 50 60 mm Maximum height 400 500 650 700 mm Sprue diameter 70 80 90 100 mm Maximum height 900 1000 1100 1250 mm

DROSS SPEED AT BOTTOM SPRUE v = (2 * g * h)1/2 IMPACT AT BOTTOM RUNNER E = m * (v)2 / 2

DROSS SOLUTION? NO SOLUTION EXCEPT SPLIT LINE SO THAT MINIMUM HEIGHT IS OBTAINED

DROSS BOTTOM OF RUNNER

DROSS SOLUTION: SPRUE PIT

LOT OF DROSS IN RUNNER, WHICH SHOULD NOT ENTER MOULD CAVITY RESULT: LOT OF DROSS IN RUNNER, WHICH SHOULD NOT ENTER MOULD CAVITY

DROSS MUST FLOAT UP TO THE TOP RUNNER MUST HOLD DROSS DROSS MUST FLOAT UP TO THE TOP

DROSS RUNNER MUST HOLD DROSS v = dm2 * (ςs – ς) * g / 18 * γ Where: v is the flotation speed (m/s), dm is the diameter of the particle (m), ςs is the specific density of the liquid (iron) and ς the specific density of the particle phase (both in kg/m3), g is the gravity constant (9,81 m/s2), and ,γ is the viscosity of the liquid iron (Ns/m2 or kg/ms).

DROSS RUNNER MUST HOLD DROSS v = dm2 * (ςs – ς) * g / 18 * γ Typical non-metallic particles or inclusions in cast iron have a specific density between 2 and 4 g/cm3. Iron has a density close to 7 g/cm3, which means that most particles are less than half the density of iron.

DROSS FLOATING IN STILL METAL

DROSS FIRST METAL NO INGATE UNDER RUNNER!

DROSS FIRST METAL

DROSS FIRST METAL: SLAG PIT AT END OF RUNNER

DROSS CONTINUOUS POURING: SLAG AT TOP OF RUNNER

DROSS SLAG ON TOP OF RUNNER

DROSS Weight Vrunner = ------------------------------------- Density x tP x Section runner In m / s and should be < 0,5 m/s

DROSS If the runner holds all previous created slag, the casting will be fairly clean The slag made in the mould cavity, due to the high entering speed and high Mg and or Mg/S, will be located in the casting

DROSS

Amount of dross depending on the speed in the ingate Weight Vingate = ------------------------------------- Density x tP x Section ingate In m / s and should be < 1,0 m/s

DROSS

DROSS Ssprue / Srunner / Singate PRESSURISED 1 / 2 / 0,7 – 0,9 NON PRESSURISED 1 / 2 / 2

DROSS

DROSS

RUNNER DECREASE METAL SPEED IN ORDER TO LET THE DROSS FLOAT TO THE TOP

DROSS RUNNER DECREASE METAL SPEED IN ORDER TO LET THE DROSS FLOAT TO THE TOP What if there is no runner?

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