1. POURING SYSTEM DUCTILE IRON
DROSS
POURING SYSTEM
DUCTILE IRON

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

3. DROSS
WHAT IS DROSS?

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

5. 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

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

7. DROSS
THE FOLLOWING CASES HAVE A HIGH CONTACT WITH AIR:

8. DROSS
THE FOLLOWING CASES HAVE A HIGH CONTACT WITH AIR:

9. DROSS
THE FOLLOWING CASES HAVE A HIGH CONTACT WITH AIR:

10. DROSS
THE FOLLOWING CASES HAVE A HIGH CONTACT WITH AIR:

11. DROSS
POURING SYSTEM

12. DROSS

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

14. DROSS
WHERE IS DROSS CREATED?

15. DROSS
WHERE IS DROSS CREATED?

16. DROSS
POURING BOX

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

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

19. AMOUNT OF DROSS IN LOWER PART OF SPRUE
Sprue diameter mm
Maximum height mm
Sprue diameter mm Maximum height mm

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

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

22. DROSS BOTTOM OF RUNNER

23. DROSS SOLUTION: SPRUE PIT

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

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

26. 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).

27. 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.

28. DROSS FLOATING IN STILL METAL

29. DROSS
FIRST METAL
NO INGATE UNDER RUNNER!

30. DROSS
FIRST METAL

31. DROSS
FIRST METAL:
SLAG PIT AT END OF RUNNER

32. DROSS
CONTINUOUS POURING:
SLAG AT TOP OF RUNNER

33. DROSS
SLAG ON TOP OF RUNNER

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

35. 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

36. DROSS

37. 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

38. DROSS

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

40. DROSS

41. DROSS

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

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

44. DROSS

45. DROSS

46. DROSS

47. DROSS

48. DROSS

49. DROSS

50. DROSS

51. DROSS