Pump casting

Terms of delivery:

1. Definition and scope

1.1Investmentcastingisaprocessby which a high surface quality can bemanufacturedthroughtheformationof dimensionally accurate casting.Thepatternsproduced byinjection
mouldingare heat disposable and aremelted outaftermanufacture of the ceramicmoulds. The ceramic mouldsaredestroyedafter casting. For this reason,both the pattern andthemoulds aredesignated lost using this method.Casting usuallytakesplace into hotmoulds.

1.2 Metals and nickel-based alloys can be used for investment casting.

1.3Thistechnicalmemorandumdoesnot apply precious metals cast using thedewaxingmethod,toproductsof thejewellery industry,dentallaboratories or toart casting.

2. Purpose

2.1Thistechnicalmemorandumdefinesdimensional tolerances, specifiesmachiningallowances andsurfaceroughness corresponding to the start ofthe art inthe field ofinvestmentcasting. It serves as a basis foroptimumeconomic cooperationbetweeninvestment casting suppliers andbuyers.

2.2Thespecificationsmentionedherereferto sand blasted preserved or pickledsurfaces intheirdeliveredcondition. Exception must be agreedwhere work processesareinvolved
which alter the dimensional tolerances.

2.3Unlessotherwiseagreed,initialsamplesare supplied for first-timeorders.These are usedto permitconcretemutual agreement betweensupplier andpurchaser.Initial samplesmust beappraised by thebuyer,followed by awritten release to thefoundry forseriesproduction.Deviationacknowledged by the releaseorwithpositiveappraisal of theinitialsamples are binding for theproductionprocessand must beenteredintothe (casting) drawing.

3. Dimensional accuracy

3.1 Contraction and shrinkage
Duringthesolidificationandcoolingof cast metals, a contraction ofthevolumenaturally occurs asaresult ofshrinkage. Otherfactorsinfluencing the production ofinstrument
castingscanresultfromtheshrinkage of the lost patternand the expansion ofmouldsduringheating. The sum of these influencingfactorsistakenintoconsideration in the shrinkage
allowanceduringthemanufacture ofinjection moulds. The shrinkage allowance isbasedonexperiencevalues,depending on the contour of the casting,theceramicshell andthe casting materials, as well as thecastingtechniques usedin theindividual foundries.

3.2 Reference planes and reference points
Drawingusedinthemanufacture of casting must be gaugedsystematicallyusingreferenceorlocating points in order to ensure thatdimensionalchecksandsubsequentmachining are in agreement. Referencepoints mustbedeterminedright fromthe early design stageand coordinatedbetweenthezero positionof thereference planes isprecisely defined bymeans ofthe referencepointdimensions. All referencepoints must bearranged insuch a way thattheyare not removed or alteredduring thesubsequentmachiningprocess.Reference points should bepositioned onthe outsidesurfaces oftheinvestment casting.They may takethe form ofraised orreferencepointsare beneficial when dealing withcastingswithrestricted shapeandposition tolerances. When determiningthereferencepoints, attentionshould be paid to ensuring that they donotfall inthe area of asprue.In case of complex shaping,it is possibleinthisway to position thecasting precisely by(pre-)machiningthelocatingpoints.

3.3 Over definition
According to DIN 406, overde finition must be avoided. Wall thicknesses must always be specified.

3.4 Mould and draught angles
Mould and draught angles are not necessary as a general
rule.Exceptionstothisforreason of mould making or casting necessity must beagreedbetweentheinvestment casting supplier and the buyer.

4. Dimensional tolerances

4.1 Linear dimensional tolerances
Achievable dimensional tolerances on investment casting are dependent on the following factors:
Casting material
Dimensions and shape of the casting
Validity of the accuracy grade

4.1.2. Dimensions and shape of the casting
Theachievableaccuracylevelofthe rated dimensions of an investmentcasting dependson thegreatestdimension and the shape of thecasting.If therateddimension(GTA)exceedsthe rated dimension rangeindicated foracertainaccuracy level,theoverall tolerance of thecasting must betolerancedat the accuracy level(greatest tolerancefield). Deviationoutside theaccuracy level must beagreed between thesupplier andthebuyer.

Note: The technical info above are incomplete. Please contact us for more information.

Our Precision Investment Casting Technology has been applied in theproduction of:

A high standard of surface quality

Low material allowance on surfacesto be machined

Facility for complex shaped innercontours due to the use of ceramic cores

A high degree of dimensional accuracy due to elimination of the mould parting line usually responsible forcasting imprecision

Hardly any restrictions in terms of materials

Almost unlimited scope for the shaping of castings

The investment casting technique is characterized by

Summary

Generallyspeaking,theinvestmentcastingtechnique is used for small pieceweights of between1g and 10kg.Largerwork-pieces up to 150 kg are alsopossible.

Piece weights

Thecastingareproducedwithout any trace of flash, and with anexcellentsurfacefinish.In manycases-expect for producing the requiredseatdimensionsthere isno needfor a follow-on machining process.

Surface quality

Allcastablematerialscanbe processed using this method. Investmentcastingisparticularlysuitable for use with materials unsuited tomachining.

Material selection

Fullservicemanufacturing of investment castings, including machining,heattreating,passivation, plating, polishing,and painting.

We offer stainless steel, carbon or alloy steel casting made by investment casting in accordance with customer's design(OEM).

Pump casting

Pump casting made by investment casting according to customer's design(OEM).