DROSS POURING SYSTEM DUCTILE IRON DROSS WHAT IS

DROSS POURING SYSTEM DUCTILE IRON

DROSS WHAT IS DROSS? Mg + S Mg. S Mg + O Mg. O SMALL SIZE COMPARED TO SAND 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 Mg. S • LOT OF Mg FOR THE REACTION Mg + O Mg. O

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

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

DROSS POURING BOX HOW TO PREVENT ENTERING OF DROSS IN SPRUE

DROSS AMOUNT OF DROSS IN LOWER PART OF SPRUE DEPENDING ON HEIGHT

DROSS AMOUNT OF DROSS IN LOWER PART OF SPRUE Sprue diameter Maximum height 30 40 500 50 60 700 mm 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

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

DROSS RUNNER MUST HOLD DROSS MUST FLOAT UP TO THE TOP

DROSS RUNNER MUST HOLD DROSS v = dm 2 * (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/m 3), g is the gravity constant (9, 81 m/s 2), and , γ is the viscosity of the liquid iron (Ns/m 2 or kg/ms).

DROSS RUNNER MUST HOLD DROSS v = dm 2 * (ςs – ς) * g / 18 * γ Typical non-metallic particles or inclusions in cast iron have a specific density between 2 and 4 g/cm 3. Iron has a density close to 7 g/cm 3, 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 t. P 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

DROSS Amount of dross depending on the speed in the ingate Weight Vingate = ------------------Density x t. P 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

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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