Foseco Ferrous Foundryman''''s Handbook Part 14 potx

2000 feeder sleeves can render 64% of their volume to the solidifying casting.When using feeders with the correct modulus it is necessary to take intoaccount that the modulus of the resi

2000 feeder sleeves can render 64% of their volume to the solidifying casting.When using feeders with the correct modulus it is necessary to take intoaccount that the modulus of the residual feeder – if more than 33% of thefeeder volume is fed into the casting – may not be adequate in relation tothe casting modulus towards the end of the solidification Therefore, it isessential to calculate shrinkage as well as modulus in order to determinethe correct feeder sleeve.

FEEDEX HD V-Sleeves

FEEDEX HD V Feeder Sleeves are used for iron and steel casting alloys.FEEDEX HD is a fast-igniting, highly exothermic and pressure resistantfeeder sleeve material The sleeves possess a small feeder volume, a massivewall, but only a small riser-to-casting contact area (Fig 19.12a) They are,therefore, specially suited for use for ‘spot feeding’ on casting sections whichhave a limited feeder sleeve application area The sleeves are located ontothe pattern plate using special locating pins, the majority are supplied withshell-moulded breaker cores Owing to their small aperture, these breakercores are not recommended for steel castings, though special larger aperturescan be used

FEEDEX HD V-sleeves are particularly useful for ductile iron castingssince with its low volume shrinkage of below 3%, a modulus controlledKALMIN or KALMINEX 2000 feeder will often have more liquid metalthan is necessary The very high modulus and relatively low volume ofFEEDEX HDV gives improved yield In many ductile iron applications, thesmall breaker core aperture of the feeder means that the feeder is separatedfrom the casting during the shakeout operation and the cleaning cost isreduced

VS spot feeder sleeves without breaker cores but with a sand wedgebetween the feeder sleeve and casting are rammed up with the help of aspecial spring-loaded location pin, Fig 19.12b Moulding pressure squeezesthe VS sleeve down the pin, compacting the sand The sleeve incorporates

an exothermic locating core to prevent sand entering the feeder cavity duringcompaction and to heat the feeder neck

When used in ductile iron applications, it is important to note that thehigh temperature reached in the highly exothermic feeder can cause residualmagnesium in the iron to be oxidised so that there may be a danger ofdenodularisation on the casting-feeder interface To avoid this, residual Mgshould be greater than 0.045%, inoculation practice should be optimisedand thick breaker cores used Note that when calculating FEEDEX metalvolume, only 50% of the capacity should be assumed since part of the metal

in the feeder will be lamellar due to oxidation of the Mg in the feeder cavity.The permeability of FEEDEX sleeves is as high as the moulding sand, sosand system contamination is not a problem

Figure 19.13a and b shows examples of the use of FEEDEX HD V sleeves

on ductile iron castings

KALMINEX Feeder Sleeves

KALMINEX exothermic-insulating feeder sleeves are used for all ironand steel casting alloys They are supplied with feeder diameters from 80 to

Figure 19.12 (a) The reduction of the feeder contact area which is possible when using the FEEDEX HD V-Sleeve with a suitable breaker core (b) Sectioned spring loaded steel location pin for ram-up of a V-sleeve without a breaker core.

850 mm for the modulus range between 2.4 and 22.0 cm and are suitable forlarger sized castings.

The manufacturing process specifically developed for this insulating product and the selection of specific raw materials give a totalclosed pore volume of nearly 50% The excellent heat insulation resulting

exothermic-(a)

(b)

Figure 19.13 (a) The application of FEEDEX HD V-Sleeves to a ductile iron turbocharger casting (b) VS-Spot feeder practice The point feeding technique makes possible the production of high value, lightweight castings.

from the low density (compared with moulding sand) is enhanced by anexothermic reaction.

When determining the solidification times with KALMINEX FeederSleeves it has been found that they extend the solidification time by a factor

of 2.0 to 2.4 compared to the natural sand feeders of the same size Fromthese results modulus extension factors (MEF) of 1.3 to 1.55 have beenfound

Under practical conditions it has been found that KALMINEX Feederswhen adequately covered with KAPEX lids or a suitable APC (anti-pipingcompound) may render up to 64% of their contents into the casting Whenusing feeders with the correct modulus it is necessary to take into accountthat the modulus of the residual feeder (if more than 33% of the feedervolume is fed into the casting) may not be adequate in relation to the castingmodulus towards the end of the solidification Therefore it is essential tocalculate shrinkage as well as modulus when determining the size of thefeeder sleeves

Foseco provides tables allowing KALMINEX feeders to be selected withthe desired modulus, volume (capacity) and dimensions Several differentshapes of KALMINEX feeders are available Fig 19.14a,b,c Breaker coresare generally made of chromite sand, though they can be produced in silicasand

KALMINEX cylindrical feeder sleeves

Figure 19.14 (a) KALMINEX cylindrical feeder sleeve with breaker core and KAPEX lid (b) KALMINEX TA sleeve (c) KALMINEX oval sleeve.

KAPEX Lid

Standard Breaker Core

H

b a

(c) T

KALBORD insulating material

Although in theory there is no upper limit of inside diameter for usingprefabricated feeder lining shapes for inside diameters above about 500 mm,manufacture, transport and storage become increasingly inconvenient.For this reason Foseco has developed KALBORD flexible insulating material

in the form of jointed mats They can be easily wrapped around a feederpattern or made up into conventional sleeves as required for the production

of insulating feeders for very large steel, iron and copper based alloy castings(Fig 19.15)

Figure 19.15 KALBORD jointed mats.

Width

KALBORD mats are available with 30 mm and 60 mm thickness in widths

up to 400 mm and lengths 1020 or 1570 mm Their excellent flexibilitypermits the lining of irregular feeder shapes The mat is most easily separated

or shortened with a saw blade

Produced from high heat insulating materials, 30 mm mats achieve a 1.2fold and 60 mm mats a 1.3 fold extension of the modulus It is recommendedthat KALBORD feeders are covered with FERRUX anti-piping powder

KALPAD prefabricated boards and shapes

KALPAD has been developed by Foseco to provide a light-weight, highlyrefractory insulating material to avoid metal padding and to promotedirectional solidification If KALPAD insulating shapes are used the desiredshape of the casting need not be altered This increases yield and reducesfettling and machining costs For this purpose KALPAD is used in copper-base metal and steel foundries, in particular, however, in malleable iron andgrey iron mass production

Owing to a special manufacturing process and the use of alumina mineralfibres KALPAD shapes have a density of 0.45 g/cm3 with more than 60% ofthe volume being closed pores which are the reason for the high insulationand refractoriness During pouring KALPAD produces only negligible fumesand behaves neutrally towards moulding materials and casting metals.When evaluating solidification times on KALPAD padded casting sections

it has been found that they extend the solidification time by a factor of 2.25

to 2.5 compared with conventionally moulded castings From these results

modulus extension factors of 1.5 to 1.58 have been calculated It isrecommended to use a factor of 1.5 if KALPAD shapes of 20 to 25 mmthickness are applied The dimensions of KALPAD boards and shapes areshown in Fig 19.16.

Figure 19.16 KALPAD prefabricated boards and shapes.

300

500 KALPAD board 1001

Packing unit: 165 pieces, or as required

550

300

50 50

KALPAD jointed mat 1002

Packing unit: 120 pieces, or as required

300

45 140

r = 420

KALPAD pad 1012

Packing unit: 15 pieces

KALPAD 1001 and 1002 are standard types which can be easily sawn to the desired shapes KALPAD 1012 is an example of an insulating pad for runner wheels and gear rims Shapes made to measure for mass production upon request.

10 Segments

KAPEX prefabricated feeder lids

KAPEX LD insulating feeder lids (Fig 19.14a) are an improvement over thehot-topping powders in foundry use, being dust and fume free and givingrepeatable feeding results They can be applied to all feeders either exothermic,insulating or natural The lids have an insulator density of 0.45 g/cm3 andare purely insulating Owing to their neutral behaviour towards mouldingmaterial and casting metal they are used in light metal and copper-basefoundries as well as in high alloy steel foundries KAPEX LD lids havereplaced over 50% of the hot-topping used in Europe for sleeves of diameterbetween 100 and 350 mm and their use is still growing

For smaller neckdown feeder sleeves, KALMINEX 2000 exothermic KAPEXlids are also available

KALPUR filter feeder units

KALPUR filter feeder technology is the shortest way to a perfect casting,see pp 266, 289 There are two types of KALPUR filter feeder products; onefor mass production foundries and the other for jobbing foundries Formass production, KALPUR insert filter feeder units are inserted and securedinto the mould cavity, created by means of suitable KALPUR insert patterns.KALPUR KSET filter feeder units with upper filter location are supplied forhorizontally parted automatic moulding machines, Fig 19.17 For verticallyparted moulding lines, KALPUR units with lower filter position are usedFig 19.18

For jobbing and simple moulding machine application KALPUR ram-upfilter feeders, Fig 19.19a are used by means of a centering support pattern

in combination with a protective bridge pattern Fig 19.19b

KALMINEX 2000 ZTAE KALPUR exothermic units and insulatingKALMIN STP units are available for ram-up applications

Use of the KALPUR unit eliminates the conventional gating system andcreates the ideal directional solidification condition The KALPUR filterfeeder units must be selected according to their modulus and flow rate with

a filter type appropriate to the alloy being cast

Table 19.5 The KALPUR filter feeder product range

KALMIN S KSET Insulating NF; iron, steel Horizontal insert 50, 60, 70, 80, 90, 100 KALMIN S KSE Insulating NP; iron, steel Vertical insert 60 and 90

KALMIN 70 STP Insulating NF; iron, steel Jobbing ram-up 50, 70, 90, 125 KALMINEX 2000 Exothermic- Iron and steel Jobbing ram-up 100, 120, 150, 180

*NB for aluminium, iron and steel casting KALPUR types are KALPUR AL; KALPUR FE and KALPUR ST respectively in which SIVEX; SEDEX/CELTEX and STELEX filters are integrated.

Breaker cores

Breaker cores for the reduction of the feeder-to-casting contact area enablefeeders to be broken off or knocked off from many types of castings In thecase of very tough casting alloys where it is not possible to simply break off

or knock off the feeder, the advantage of using breaker cores lies in thereduction of fettling and grinding costs for the removal of the feeder

KALPUR Fe KSET 8/11/L10

23 30

10 20

(b)

Figure 19.17 (a) KALPUR insert filter feeder units with upper filter location for horizontally parted automatic moulding lines Without breaker core for direct pouring through a side feeder With breaker core for direct pouring through a top feeder (b) KALPUR Fe Insert side feeder used for feeding two ductile iron case covers.

Figure 19.18 (a) KALPUR pouring cup filter-feeder units with lower filter position for vertically parted moulding lines (b) KALPUR pouring technique used on a DISAMATIC moulding line for casting ductile iron hydraulic arms.

Besides the conventional types of breaker cores based on silica sand(Croning) and chromite sand, special breaker cores with a very small apertureare also in use in repetition iron foundries These special breaker cores asshown in Table 19.5 are made from highly refractory ceramic.

Table 19.5 Application of breaker cores

non-ferrous metals

non-ferrous metals

Chromite sand Grey, ductile iron 200–500

Experience has shown that at least 70% of the breaker core area should be

in contact with the casting, in order to level out the temperatures of themetal and the breaker core from the superheat upon or before reachingliquidus

Some of the standard forms of breaker core available from Foseco areshown in Fig 19.20 Foseco feeder sleeves can be ordered with or withoutbreaker cores attached

Figure 19.20 Standard forms of breaker cores.

Standard Breaker core (…/11) Standard Breaker core (…/14) Ceramic Breaker core (…/11 K)

Standard Neck-down Breaker core

(…/31)

The application of feeder sleeves

Ram-up jobbing applications

(1) Manual moulding

Sleeves of the correct dimensions are set on the individual pattern in thepredetermined location and the mould is rammed around the sleeves Thebase of the sleeve should not come into direct contact with the casting but

be set on a sand step at least 10 mm thick or the sleeve should be fitted with

a breaker core

(2) On semi-automatic, cold set and slinger moulding lines

If the pattern plate is accessible to the machine operator, the feeder sleeve islocated by hand on the pattern plate To avoid damage during machinemoulding, sleeves should be supported by standing them on a pattern dummy

or peg at the correct location and having the correct shape and height.Figure 19.9 shows one such arrangement

Insert sleeves

Often on high pressure, squeeze press or air impact moulding lines, patternplates are no longer accessible Foseco recognised these changes in the late1970s and early 1980s and developed insert sleeve application systemsallowing fully automatic machine users to retain all the advantages ofemploying feeder sleeves without slowing down the moulding cycle

A prefabricated feeder sleeve with strictly controlled dimensional tolerances

is inserted into a cavity formed during the moulding operation by a sleevepattern of precise dimensions located on the pattern plate (Figs 19.10,19.11)

The insert sleeve patterns are fixed by screwing them onto the castingpattern and they provide the cavity for the insert sleeve Owing to thespecial sealing and wedging system no metal can penetrate behind theinserted sleeves and these cannot fall out from their seat during closing andhandling of the mould

The design of the insert patterns also forms highly insulating air chambersbehind the inserted sleeves This additional insulation increases the moduli

of the insert sleeve feeders as follows:

FEEDEX Insert Sleeves HDP + 5 %

KALMINEX 2000 Insert Sleeves ZP + 5 %

KALMIN S Insert Sleeves KSP + 4 %

The insert sleeve patterns have a solid aluminium core with mounting threadand a highly wear resistant resin profile Insert sleeve patterns are availablecorresponding to the various types of insert sleeves with and without breakercores Both insert sleeves and insert patterns are thus part of an integralsystem

Floating feeder sleeves

This is a relatively simple application technique with low feeder sleeveapplication cost since feeder sleeves are simply placed on the drag partingline The method is applicable for all moulding machines having a horizontalmould parting line No problems are encountered regarding strength, springback etc of the feeder sleeve On high pressure moulding lines, more economicand non-polluting insulating KALMIN sleeves can be applied