How To Calculate Feeders

Edition 12/03

Leaflet – Feeding Technology ST 6.79 E

How to calculate feeders
Part 1: Determination of feeders for steel, malleable iron, light and copper-base alloy castings 1. Determination of modulus
1.1 Divide the casting into sections and determine the important volume-to-surface ratios according to table 1. Use centimetres (cm) as unit of dimensions.
M= V ( cm3 ) S (cm2 ) = (cm)M = modulus, V = volume, S = cooling surface

1.2 Determine the required feeder modulus (MF) using the factor 1.2
M F = M C ⋅ 1.2

MF = modulus feeder, MC = modulus casting

1.3 Provisional determination of the feeder from the feeder tables.

2. Determination of the number of feeders

2.1 Determination of the feeding distance factor (FD) from tables 2 and 2a. 2.2 Calculation of thenumber of feeders (nF). Use millimetres (mm) as unit of dimensions.
nF = L (m m) d (m m ) + FD ⋅ T (m m )

nF = number of feeders, L = casting length or mean circumference, d = provisional feeder diameter, FD = feeding distance factor, T = thinnest section through which feeding is to be ensured

3. Calculation of the feedable casting weight

The feeders obtained from the calculation ofmodulus and of number of feeders do not always satisfy the shrinkage requirements. In these cases feeders must be increased. For their calculation the following data are required: 3.1 Weight of the casting or casting cluster to be fed 3.2 Feeder weight 3.3 Shrinkage in percent (see table 3) 3.4 Feeding capacity of the feeder. If exothermic/insulating feeder sleeves are used this is at least 33 %.Pour-through sand feeders render up to 16 %, all others 14 %. 3.5 Feedable casting weight (W) W= 1 Feeder weight (kg ) ⋅ 100 ⋅ 3 Shrinkage (%)

4. Determination of the feeder neck

4.1 Top feeder: No determination of feeder neck required. If possible, feeder sleeves should be used with breaker core. 4.2 Side feeder: The required feeder neck (N) is obtained from the calculation of modulus usingthe bar equation or diagram table 5.
MN = a⋅b 2(a + b)

MC : MN : MF = 1 : 1 : 1.2

Foseco GmbH, 46322 Borken, Germany · Hausanschrift/Works Location: Gelsenkirchener Str. 10 46325 Borken (Westfalen) · Telefon +49 (0)2861/83-0 · Telefax +49 (0)2861/83-338 · www.foseco.de

Part 2: Determination of feeders for flake graphite and spheroidal graphite iron castings 1. Modulus consideration toensure that the feeder will remain fluid sufficiently longer than the casting/casting section

i CASTING MODULUS
MC = V (cm3 ) S (cm )
2

= (cm)

MC = Casting modulus, V = Volume, S = Cooling surface area For simple modulus calculation Table 1 should be used.

ii FEEDER MODULUS CONSIDERATION Determination of shrinkage time from diagram 4. With known C-content move along IsoCarbon line tothe appropriate (Si + P) content at point A. Extrapolate this line vertically until it intersects the casting modulus line at point B. Extend the line horizontally on the left hand side until it intersects with the line representing estimated casting temperature of the iron in the mould at point D. Read off shrinkage time (ST) in percentage of solidification time. This graph attempts to estimateduring which proportion of the solidification time shrinkage occurs. Effective feeder modulus is determined as follows:

M F = M C ⋅ 1.2 ⋅

ST 100

MF = Feeder modulus, MC = Casting modulus, ST = shrinkage time

2. Feeding distance consideration

- to determine the number of feeders required to feed the casting/casting sections. Table 2 and Table 2a help to estimate feeding distance.nF = number of feeders required, L = casting length or mean circumference of casting, dF = calculated feeder diameter, FD = feeding distance factor, T = thinnest casting section through which feeding is to be ensured

nF =

dF

L (m m ) (m m ) + FD ⋅ T (m m )

3. Feed metal consideration

- to ensure that an adequate volume of metal is available in the feeder to feed the solidifying...