31947377 How to Calculate Feeders

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Foseco (FS) Limited, Tamworth, Staffordshire, B78 3TLTel: +44 (0)1827 289999 Fax: +44 (0)1827 250806 www.foseco.co.uk

Date: December 2003 Feeding Systems Product Data Sheet

How to calculate feedersPart 1: Determination of feeders for steel, malleable iron, light and copper-base alloy castings

1. Determination ofmodulus

1.1 Divide the casting into sections and determine the important volume-to-surface ratiosaccording to table 1. Use centimetres (cm) as unit of dimensions.

MV cm

S cmcm= =

( )

( )( )

3

2 M= modulus, V= volume, S= cooling surface

1.2 Determine the required feeder modulus (MF) using the factor 1.2

M MF C= 12. MF = modulus feeder,MC= modulus casting

1.3 Provisional determination of the feeder from the feeder tables.

2. Determination of thenumber of feeders

2.1 Determination of the feeding distance factor (FD) from tables 2 and 2a.2.2 Calculation of the number of feeders (nF). Use millimetres (mm) as unit of dimensions.

nL m m

d m m F D T m mF =

+

( )

( ) ( )

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

3. Calculation of thefeedable castingweight

The feeders obtained from the calculation of modulus and of number of feeders do notalways 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 fed3.2 Feeder weight3.3 Shrinkage in percent (see table 3)3.4 Feeding capacity of the feeder. If exothermic/insulating feeder sleeves are used this is atleast 33 %. Pour-through sand feeders render up to 16 %, all others 14 %.3.5 Feedable casting weight (W)

WFeederweight kg

Shrinkage=

1

3

100( )

(%)

4. Determination of thefeeder neck

4.1 Top feeder: No determination of feeder neck required. If possible, feeder sleeves shouldbe used with breaker core.

4.2 Side feeder: The required feeder neck (N) is obtained from the calculation of modulususing the bar equation or diagram table 5.

Ma b

a bN =

+2( ) MC: MN: MF= 1 : 1 : 1.2


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Part 2: Determination of feeders for flake graphite and spheroidal graphite iron castings

1. Modulus consideration - to ensure that the feeder will remain fluid sufficiently longer than thecasting/casting section

i CASTING MODULUS

MV cm

S cmcm

C= =

( )

( )

( )3

2 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 Iso-Carbon line to the appropriate (Si + P) content at point A. Extrapolate this line vertically untilit intersects the casting modulus line at point B. Extend the line horizontally on the left handside until it intersects with the line representing estimated casting temperature of the iron inthe mould at point D. Read off shrinkage time (ST) in percentage of solidification time. Thisgraph attempts to estimate during which proportion of the solidification time shrinkageoccurs. Effective feeder modulus is determined as follows:

M MST

F C= 12

100. MF= Feeder modulus, MC= Casting modulus, ST= shrinkage

time

2. Feeding distanceconsideration

- to determine the number of feeders required to feed the casting/casting sections.

Table 2 and Table 2a help to estimate feeding distance.

nL m m

d m m F D T mmF

F

=

+

( )

( ) ( )

nF= number of feeders required, L = casting length ormean circumference of casting, dF= calculated feederdiameter, FD = feeding distance factor, T =thinnest casting section through which feeding is to beensured

3. Feed metalconsideration

- to ensure that an adequate volume of metal is available in the feeder to feed thesolidifying casting/casting sections.

Feeders so far determined may not be necessarily large enough from a shrinkage point ofview. In such a case larger feeders must be used.

i Determination of shrinkage percentage from Diagram 4 on the right hand side. Frompoint B on the casting modulus line draw a horizontal line till it cuts the castingtemperature line at C. Read vertically contraction/expansion.

ii Add shrinkage percentage + shrinkage due to mould wall movement (0 - 2 %) forhigh pressure moulding lines to obtain total feed metal requirement of the casting.

iii Feed metal from the feeder: hot sand feeders = 16 %cold feeders = 10 %Exo/Iso feeders = 33 % at least

iv Feedable casting weight (W)

W

Feederweight kg

Shrinkage= 1

3

100( )

(%)

4. Determination offeeder neckdimensions

- so that the neck remains open just long enough to satisfy feed metal demand ofthe casting/casting sections.

i Top feeder: Feeder neck dimensions are not called for. Whenever possible, breakercores of adequate design and quality should be used.

ii Side feeder: Necessary dimensions of feeder neck N are determined throughmodulus calculation in the bar formula or from the diagram in Table 5.

Ma b

a bN =

+2( ) M M M

ST ST C N F: : : : .= 1 1

10012

100


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Table 2

FEEDING DISTANCE WITH CARBON STEELCASTINGS

For the mathematical calculation of the number of feedersrequired, the feeding distance factors (FD) as shown inTable 2a are to be used in the formula

nL m m

d m m F D T mmF

F

=

+

( )

( ) ( )

FD T = 2 FZ

The examples shown below refer to steel with 0.25 % C.

Key to abbreviations: see below.

Table 2a

FEEDING DISTANCE FACTORS OF CASTINGALLOYS

Casting alloySteel (0.25 % C)Steel (0.20 % C)Steel (0.60 % C)

FD4.05.04.5

Malleable iron 5.0

Al (99.99 %)Al Cu 4.5Al Si 7Al Si 12Al Si (6 - 13)

10.06.06.0

10.05.0

Cu (pure)Cu Ni (30 % Ni)

8.02.0

Brass 5.0

Al BronzeNi Al BronzeSn Bronze

5.02.03.0

Flake graphite iron (GGL)GGL, CE = 3.0GGL, CE = 3.4GGL, CE = 3.9GGL, CE = 4.3

6.57.78.8

10.0

Spheroidal graphite iron (GGG)GGG, CE = 3.6GGG, CE = 4.2GGG, CE = 4.3

GGG, CE = 4.4

6.06.57.0

9.0

Table 3

Shrinkage of principal casting alloys

Casting alloy Shrinkage %

Carbon steelAlloyed steelHigh alloy steel

6.09.0

10.0

Malleable iron 5.0AlAlCu4Ni2MgAlSi 12AlSi5Cu2MgAlSi9MgAlSi5Cu1AlSi5Cu2AlCu4AlSi10AlSi7NiMgAlMg5SiAlSi7Cu2Mg

AlCu5AlMg11SiAlZn5Mg

8.05.33.54.23.44.95.28.85.04.56.76.5

6.04.74.7

Cu (pure) 4.0

BrassBronze

6.57.5

Al BronzeSn Bronze

4.04.5

Flake graphite iron and SG iron see diagram Table 4

Conversion scale

Degree of saturation SC =%

. (% % )

C

Si P4 31

3 +

Carbon equivalent CE = % C + 1/3 (% Si + % P)

Key to abbreviations

dF = Feeder diameterEZ = End zone

FD = Feeding distance factorFZ = Feeder zoneL = Casting length or mean circumferenceMF = Feeder modulusMC = Casting modulusMN = Feeder neck modulusN = Feeder necknF = number of feeders requiredS = Cooling surface areaST = Shrinkage timeT = Section thicknessV = VolumeW = Feedable casting weight


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Tabel 4


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Foseco (FS) Limited, Tamworth, Staffordshire, B78 3TL Tel: +44 (0)1827 289999 Fax: +44 (0)1827 250806 www.foseco.co.uk

Table 5

Determination of feeder neck as well as any rectangular section if the modulus is known. Alternatively, determination ofmodulus if rectangular dimensions are known.

31947377 How to Calculate Feeders

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