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The Foundry Industry is heavily tied to automotiveproduction and in 1998 the average light vehicle,of w hich 52 million were built, contained 80 kg ofAluminium. In 2001 the average weight ofAluminium in a light vehicle reached 100 kg and by2009 the average light vehicle will contain 120 kgof Aluminium and the number of vehicles producedwill be above 70 million. The amount of Aluminiumcastings produced globally will therefore continue

to increase, they will also become thinner in wallsection and lighter in weight.

Another important factor is that castings will beused for more sophisticated applications and allthis will lead to ever greater demands for majorimprovements in metal quality.

In addition, to remain competit ive foundries willhave to become ever more cost conscious andcontinually investigate means of reducingproduction costs. This will necessitate the industryexamining every facit of production andconsidering techniques thought inappropriate, ortoo revolutionary in the past, to maintain theprogress made in recent years by the aluminiumcasting industry. One such technique is the use ofDIRECT POURING.

There has been considerable research conductedin the recent past into the running and gating ofaluminium castings and there is a much clearerunderstanding of the flow effects needed to createingate velocities to produce good quality castings.

As castings become thinner in section, the dieneeds to be filled quickly and smoothly, thealuminium needs to be introduced as low aspossible in the casting and risers to remain hot andeffective in feeding.

Running systems have to be designed to ensureyields are high and keep sawing and dressing coststo a minimum, hence methods engineers are facingcompromises continually.

DIRECT POURING is a concept introduced some16 years ago to the industry where metal is poured

directly into the casting cavity through a ceramicfoam filter. This regulates and controls the flow ofmetal into the die or mould and has led to manybenefits for many foundries as can be seen in thefollowing examples.

Direct Pouring An aid to efficiency

Example 1A gravity die cast radiator top tank (figure 1) is castby gravity die in eutectic Aluminium - Silicon alloy.This sizable, thin-walled component was prone tocold shuts as well as pressure test failures. Bychanging to a simple running system where thecasting was top poured through a 50 mm diameterfoam filter the cold shut problem was completelycured while the filtered metal ensured the casting no

longer suffered from oxide inclusions and pressuretest failures. The 3.44 kg casting saw direct netsavings of 2.5 per casting as a result of this change.

Figure 1: Radiator t op tank

Example 2In gravity die casting, the filter is printed directly intothe die but in sand casting the foundry has theadditional option of using a KALPUR* unit where thefilter is contained inside an insulated sleeve to offereven better feeding characteristics. An engine sump(figure 2) is sand cast and is poured through a KALPURunit placed on the top of the casting. This replaced the

old running system which introduced metal through aseries of ingates into the bottom flange. The pouredweight was reduced from 11.5 kg to 7.5 kg, a savingof 4 kg and an overall saving in manufacturing cost tothe foundry of over 5.00 per casting.

1Figure 2: Sand cast engine sump

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Many sand foundries have utilised this methodof producing castings and seen that there is noneed for complicated running systems andlengthy method development where jobbingwork is involved.

Example 3This 6 cylinder manifold (figure 3) is 17kg as castand is poured through two KALPUR units. It hasbeen sectioned to show the thin inner walls and thecasting is subjected to pressure testing aftermachining. Being cast in eutectic Aluminium -Silicon alloy with Sodium modification this type ofcasting can be prone to pressure test failure but thisparticular method produces a very sound castingbeing free of both shrinkage and oxides.

Example 4Small and large castings can easily be poured withKALPUR and this further example (figures 4 & 5) iscast through 3 KALPUR units. The casting formsthe chassis for a silicon wafer manipulatingmachine. There are 10 cores involved and thefinished weight is 15.5 kg. There are some quitedrastic changes in wall thickness requiring feedingof the heavy sections.

The casting is now poured through three KALPURunits and compared to the old traditional runningsystem a saving of over 10 kg of feed metal ismade. Taking into account the saving in melting

cost, metal loss, sand binder usage, fettling , sawingand cleaning this would result in a reduction inmanufacturing cost of over 15.00 per casting.

KALMIN* 1000As part of the continuing improvementprogramme, FOSECO has now developed a newproduct KALMIN 1000.

This insulating material can be supplied innumerous shapes and has the advantage of beingformed and hardened in accurate tooling thusbeing a very dimensionally accurate andconsistent product.

KALMIN 1000 is also free from organic materials

and is therefore relatively fume free during casting.

When used in conjunction with ceramic foam filtersthe KALMIN 1000 sleeve can be formed around thefilters during manufacture giving a precise fit andeliminating the possibility of metal by-pass.

Examples of these units can be seen in Figures 6and 7.

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Figure 3: A six cylinder manifold

Figure 4: Chassis casting immediately after pouring,showing three KALPUR units

Figure 5: Chassis casting after knock out

Figure 6: A range of KALPUR unit s in KALMIN 1000

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In direct pour applications this feature is of greatvalue in ensuring maximum performance in flowcontrol. A reduction in flow rate of up to 30% canbe experienced w ith the new KALPUR units offeringeven better flow control characteristics.

A range of pouring sleeves are also produced wherethe filter is a separate item, this enables the foundryto mould the cup in place and insert the filter later.Other sleeves are designed for inserting aftermoulding having the filter formed in situ.

ConclusionsThe use of DIRECT POURING therefore offers thefoundry:

Simple running system design.

Excellent yield.

Limited temperature loss.

Good directional solidif ication.

Smaller moulds.

Reduced sawing and cleaning.

Faster processing of castings.

Filtered quality Aluminium at reduced cost.

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Figure 7: Further pouring unit s in KALMIN 1000

Resulting in:Ease of methoding design.

Improved metal utilisation.

Shrinkage free castings.

Reduced binder spend.

Lower finishing costs.

Better casting quality with fewer rejects andless repairs.

DIRECT POURING can be carried out in sand castingthrough an insulating KALPUR unit or in gravity diethrough a SIVEX filter printed into the die. TheKALMIN 1000 route also offers a moredimensionally accurate product which further

reduces the flow rate through the pouring device.

Foundries are continuously searching for methodsof improving casting consistency while controllingtheir production costs. DIRECT POURING is oneproven method of achieving this aim.

ReferenceCase study 282.; Use of molten metal filters in NonFerrous Foundries: Department of the Environment sEnergy Efficiency Best Practice Programme.

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COMM ENT

Edit orial poli cy is to high lig ht t he latest Foseco pro ducts and t echnical development s.However, because of t heir n ewness, some developm ents may not be imm ediately available in your area.

Your local Foseco company or agent will be pleased to advise.

All rights reserved. No part of thispublication may be reproduced, storedin a retrieval system of any nature ortransmitted in any form or by anymeans, including photocopying andrecording, without the writtenpermission of the copyright holder.

All statements, information and datacontained herein are published as aguide and although believed to beaccurate and reliable (having regard tothe manufacturers practical experience)neither the manufacturer, licensor,seller nor publisher represents orwarrants, expressly or impliedly:

(1) their accuracy/reliability(2) that the use of the product(s) will

not infringe third party rights

(3) that no further safety measures arerequired to meet local legislation

The seller is not authorised to makerepresentations nor contract on behalfof the manufacturer/licensor. All salesby the manufacturer/seller are based ontheir respective conditions of saleavailable on request.

FOSECO the logo, ALSPEK, KALMINEX,KALPUR, POLITEC and STELEX are TradeMarks of the Foseco Group ofCompanies used under licence.

Foseco International Ltd. 2006