AFS美鑄協(xié)缺陷圖譜及分析

1、Phone: (800 537-4237Appendix Title PageCredits Introductionw w w .b z f xw .c om2Chapter Page1 Broken or Cracked Castings. 5 2 Crushes, Pushups and Clamp-offs. 8 3 Cuts and Washes. 12 4 Dirt, Slag and other Inclusions. (165 Drops. 256 Erosion Scabs. 307 Expansion Defects. 338 Gas Defects. 389 Gross

2、Segregation and . 46 Carbon Flotation (Kish10 Hard Spots, Hard Areas and Chilled Spots (4911 Hot Tears. 55 12 Inverse Chills. 58 13 Mass Hardness. 61 14 Metal Penetration and Fusion. 63 15 Misruns and Cold Shuts. 68 16 Off Dimensions Related to Cores (7517 Open Grain Structure . 79 18 Poured Short.

3、82 19 Ramoffs or Ramaways . (8320 Rough Surface. 85 21 Runouts and Bleeders. 88 22 Scars, Seams and Plates. 93 23 Shifts. 96 24 Shot Metal or Cold Shots. 100 25 Shrinkage Cavities and Depressions. 102 26 Stickers. 106 27 Swells, Strains, Sags and Core Fins. (10828 Veins and Fins. 113 29Warped Castin

4、gs (116w w w .b z f xw .c om3American Foundrymens Society, Inc.Des Plaines, IL 60016 Reprinted 1998The American Foundrymens Society as a body Is not responsible for the statements and opinions advanced In this publication. Nothing contained in any publication of the American Foundrymens Society is t

5、o be construed as granting any right, by implication or otherwise, for manufacture, sale or use in connection with any method, apparatus or product covered by Letters Patent, nor as insuring anyone against liability for Infringement of Letters Patent.Copyright 1972, 1984, 1997CreditsThis manual was

6、prepared by the Molding Methods and Materials Group, Special Publications Committee 80-G, Section 2, Casting Defects:George W. Anselman , Victor Rowell , Vice-Chairman Chairman Sales RepresentativeConsultant, Anselman Foundry Construction Aggregates Corp. ServicesAlbert M. Prewitt , Edwin H. PhelpsS

7、ecretary Research SupervisorCampbell, Wyant & Cannon American Cast Iron Pipe Co. Foundry Co.Joseph Cunningham LeRoy E. TaylorCunningham Patterns Sales Representative Manley BrothersRichard A. Green Charles W. Ward Foundry Sales Mgr. Foundry Consultant International Minerals & Benjamin Harris

8、 Co. Chemical Corp.James C. Lee AFS Staff Superintendent Ezra KotzinFrank Foundries Corp. Technical DirectorThis software version was prepared by:Clifford E. Couture Peter M. Wendt Vice President President Datalab, Inc. Datalab, Inc. Software & Imaging Software & Imagingw w w .b z f xw .c om

9、4IntroductionQuality control implies both prevention and cure of casting defects. This text deals with the diagnosis and correction phases of quality control in the area of rejected castings or castings that require costly repair, grinding or cleaning.Every business prefers a minimum of rejects. Int

10、elligent effort in this direction will yield excellent returns on the investment of time and energy needed to make every producing individual zero-reject conscious.There are correct and incorrect methods of approaching any problem. The steps in corrective procedure are expressed in the following out

11、line:1 Identify the defect2 Obtain the facts. The record should answer such pertinent questions as where? when? how? howoften?3 Research for missing facts 4 Verify the defect5 Try corrective action-one change at a time 6 Follow up.w w w .b z f xw .c omBroken or Cracked Castings - Chapter 1 Descripti

12、onThis refers to castings, which have been broken or cracked by mechanical action, rough handling, or thermal shock.Causes I. Casting and Pattern Design1 Irregular sections, sections, such as isolated heavy sections, light sections or projections require careful handling at shakeout, cleaning, finis

13、hing and heat- treating. 2 Lack of fillets 3 Lack of proper reinforcing ribs, tie bars or stress reliefingII. Pattern Equipment1 Failure to provide proper break-off notches on the gates and risers2 Flask bars that extend into deep pockets, not allowing normal collapse of thesand.III. Gating and Rise

14、ring1 Lack of adequate fillets2 Incorrectly placed or dimensioned cracking strips and tie bars3A gating system which promotes stresses or segregation due to turbulenceEarly rough shakeout of this gray iron casting broke the gates into the castings while they were hot and weak.V.Molding Sand1 Poor sa

15、nd collapsibility due to excessive hot or dry compressive strength 2 Low sintering point materials in sand3High hot compressive strength coupled with hot sand deformation5w w w .b z f xw .c omVI. Core Practice1 Poor collapsibility due to excessive hot compression strength2 Low hot deformation when c

16、oupled with poor collapsibility3 Rods or arbors that are too close to the surface of cores4 Over-reinforced coresVII. Molding Practice1Mold rammed too hard 2Rods, arbors, and gaggers which are too close to the mold surface 3Risers or sprues too close to a flask bar 4Excessive swabbing or sponging 5I

17、mproper use of chills or excessive chilling Poor design of the cracking strip increased the breakage of this malleable casting in the hard iron conditionVIII. Metal Composition1Improper metal composition for the application 2A composition having too high a shrinkage characteristicIX. Melting Practic

18、e1 Excessive carbide stabilizers which promote high shrinkage 2 Composition having too high a shrinkage characteristic 3 Gaseous or over oxidized metal 4 ContaminationCareless finning caused this casting to break in the gate area.w w w .b z f x w .c o m The protruding section of bar on the casting s

19、hown tended to break off during cleaning, milling or shake out. X. Pouring Practice1 Insufficient pouring temperature to promote proper collapsibility of sand and coresXI. Miscellaneous1 Shakeout too hot or too rough2 General carelessness in handling at shakeout 3 Improper packing in tumbling barrel

20、s or barrel blast4 Careless and rough handling in loading or tumbled with light thin section castings 5 Careless and rough handling in loading or tumbled with light thin section castings6 Improper piling or stacking7 Banding too tight on pallets 8 Any mechanical handling that drops castings any dist

21、ance into containersTight banding of pallets broke this casting. www.bzfx Crushes, Pushups and Clamp-offs - Chapter 2Careless handling of the mold during assembly caused this crush on the cope section.Description Crushes, pushups and clamp-offs are indentations in the casting surface. These de

22、fects are caused by disruption of the mold surface due to external or internal force or weight. The major cause of these defects is carelessness particularly related to flask equipment, rigging, and molding practice. CausesI. Casting and Pattern DesignNoneII. Pattern Equipment1 Worn patterns and cor

23、e boxes. A worn pattern can result in the core print being too small for the normal core. Conversely, a worn core box results it the core being too large for a normal print 2 Insufficient draft 3 Pattern not correctly mounted 4 Misalign cope and drag patterns, or plates 5 Worn pins and bushings 6 Co

24、re prints not properly marked 7 Lack of crushing strips 8 Core print too small to support the core 9 Warped or untrue pattern plate (cope and drag 10 Excessive flexibility of matchplatew w w .b z f x w .c o m Crush caused by poor pin alignment. 11 Flask landing strips too high above parting line. Th

25、is creates a condition of excessive loading at the sand-to-sand contactIII. Flask Equipment and Rigging1Misalignment of flask equipment, pins, and bushings 2Weights too heavy or uneven 3Insufficient sand bearing surface 4Warped or uneven flask joints 5Worn stripping plate on molding machine 6Imprope

26、rly fitting, dirty, or crooked jackets 7Worn pins and bushings 8Uneven, dirty or burned bottom boards 9Weak bottom boards 10Improperly barred copeIV.Gating and Risering 1 Gating and risering do not, by themselves, create a crush although mounting gate runners too close to the pattern can result in a

27、n inadequate sand bearing surface.V. Molding Sand 1 Weak sand 2 Low green tensile strength may permit the cope to sag 3 Low green deformation causes the sand to crush rather than give during closing of flask 4 Low dry strength in a dry sand mold may fail to support the normal loadVI. Core Practice1A

28、 core too large for the core print will fail to seat properly and cause a crush 2A misaligned assembly will cause incorrect contact when the flask is closed 3Core sagged out of shape may be the result of: a. Rough handling while green b. Soft ram c. Low green strength d. Excessive water in the core

29、mix e. Warped driers f. Low warm strength such as from excessive solvent g. Improper cure h. Reinforcement i.e.: rods, wires, or arbors 4 Warped cores (including shell 5 Excessive core wash can result in an oversized core VII. Molding Practice1Careless closing of the molds 2Uneven clamping of the mo

30、lds w w w .b z f x w .c o m3Faulty bedding of molds on bottom boards or plates 4Improper setting of the jackets 5Careless core setting 6Use of wrong chaplets or failure to use chaplets 7Setting dirty jackets A lump of sand on bottom caused this pushup.Crush on camshaft gear blank; finished casting o

31、n left.8Stem chaplets not properly wedged or seated 9Unshaved core prints and joints 10Failure to wedge flask joints 11Careless handling of molds during carry-out or on the conveyor 12Dropping of the weightsVIII. Metal Composition NoneIX. Melting PracticeNone X. Pouring Practice 1Resting ladles or h

32、eavy objects on molds XI. Miscellaneous1Rough handling during any part of the molding process can break or crush a mold 2 Resting heavy objects on the moldw w w .b z f x w .c o m Uneven clamping of the small mold crushed one side of the mold face. www.b zfx w.c o mCuts and Washes - Chapter 3 Descrip

33、tion Cuts or washes are rough spots and areas of excess metal caused by erosion of the mold or core surface by metal flow. This definition differentiates between a cut and an erosion scab, in spite of the fact that the two defects are often similar or identical in general appearance. It is necessary

34、 to make such a distinction because the cure for the two defects may be diametrically opposed.CausesI.Casting and Pattern Design1 A design that promotes excessive metal flow over any given area of the mold surface 2 A design which includes unavoidable nozzle effects within the castingII. Pattern Equ

35、ipment1 Pattern layouts which prevent correct gating. Equalized flow is essential if excessive localized heating of sand in mold or core is to be avoided.III. Flask Equipment and Rigging1 Flask too small to permit proper gating2 Flask bars too close to patternIV.Gating and Risering1 A gate which for

36、ces metal to impinge on a mold or core surface as in the case of gating into a thin wall of a castingw w w .b z f x w .c o m Drag view of cuts or washes caused by low strength sand. 2 A downsprue which does not provide a pool or well of metal ahead of the gating system 3 Too much metal across any mo

37、ld surface will eventually redissolve the metal skin which is formed during early stages of pouring 4 Excessive metal velocity across a given mold surface 5 Unequal distribution of metal through the gating systemw w w .b z f x w .c o m Inclusions caused by the cuts and washes on drag side. V. Moldin

38、g Sand1 Inadequate hot strength2 Insufficient clay3 Inadequate water to properly activate the clay and improper mixing4 Excessive use of certain additives such as cellulose5 Hot molding sand6 Low hot strength self-curing bindersVI. Core Practice1 Soft core surface2 Overcuring or undercuring3 Insuffi

39、cient binder or water4 Improper mixing5 Improper application and control of core wash6 Vents or reinforcements too close to the surface7 Poorly patched cores or filled hook holes8 Nonuniformly made cores9 low density10 Damage in handling11 Soft cores (rising self-curing bindersa. Overmixingb. Improp

40、er sand temperaturec. Use beyond bench lifed. Stripping too earlye. Excessive variation of acid demand of sandVII. Molding Practice1 Soft or nonuniformly rammed molds. Hot strength varies greatly depending on the mold Hardness or moisture2 Mold edges burned by excessive drying temperatures3 Gaggers,

41、 bars or soldiers set too close to mold surfaceVIII. Metal CompositionNonew w w .b z f x w .c o mIX. Melting PracticeNoneX. Pouring Practice1 Excessive pouring temperature for molding or core materials used2 Hard pouringXI. Miscellaneous1 Excessive parting or solvent such as kerosene can materially

42、change the hot and dry strength2 Hard pouringCut caused by low strength sand. www.b zfx w .c o mDirt, Slag and Other Inclusions - Chapter 4 Typical surface imperfections (Inclusions.DescriptionInclusions are surface or subsurface particles of sand, slag, dross, oxides or other materials imbedded in

43、the metal. They may originate from the molds, cores, metal, ladles or careless practices. CausesI. Casting and Pattern Design1 Those design factors which contribute to scabs, cuts, washes and erosion will intensify the tendency toward inclusions in a castingII. Pattern Equipment1 Improper coating fo

44、r materials involved. Some pattern coatings produce a tendency towards sticking of the sand2 Insufficient clearance for setting cores and closing3 Lack of fillets4 Insufficient draft5 Loosely mounted pattern or gating system6 Worn flask landing areas can create a crush or disrupt sand gains7 Inaccur

45、ate partingsw w w .b z f x w .c o m Use of excessive liquid parting material on the pattern left these kish tracks (classified as inclusions. III. Flask Equipment and Rigging1 Any factor in the rigging which creates a rubbing or gouging effect during the closing of the mold, or setting of cores2 War

46、ped or dirty flasks3 Worn or crooked pins or bushings4 Inaccurate core setting assembly or inspection jigs5 Dirty pins and bushings6 Inadequate locatorsIV. Gating and Risering1 Factors causing scabs, cuts and washes2 Gating systems that create slow pouring can cause scabs particularly on cope surfac

47、es3 Gating systems which create a non-filled runner should be avoided since the cope of such runners will eventually scab and drop sand into the gating systemIneffective slag trap permitted ladle slag to locate at top of the boss.4 Gating which promotes high velocity metal flow 5 The choke or the ar

48、ea of the choke core in the gating system may be inadequate to stop the flow of slag or dross 6 Exothermic materials if used in such a way as to permit the by-product of the reaction to enter the mold or castingw w w .b z f x w .c o m Defect caused by contaminant (boric acid in molding sand.V. Moldi

49、ng Sand1Sands with low physical properties, such as low green, dry and hot compressive strength 2Mold gas-metal reaction 3Low fusion point materials 4Coatings too heavy, not dried, or wrong for the purposeVI. Core Practice1 Improperly bonded or cured cores2 Excessive core gas-metal reaction3 Imprope

50、rly cleaned cores4 Premature collapse of cores in molds and gating system5 Core wash too heavy, not dried, or wrong for the application6 Broken coresResult of broken core . VII. Molding Practice 1Any molding factor which contributes to displaced or loose sand in the mold cavity 2Sloppy or careless m

51、olding 3Excessive use of liquid parting 4Loose sand from cores or molds 5Loose sand from molds left open too longw w w .b z f x w .c o m Result of coarse seacoal in molding sand. Broken edge of mold caused by low strength sand, which permitted sand grains to wash into other sections of the casting.L

52、oose sand left in the mold caused these sand inclusions on the drag face. www.b zfxw.c o m Inclusions of aluminum in a copper alloy caused by contamination during melting.VIII. Metal Composition1 In many metals, it is possible for off-analysis to create a separation of slag or slag-like materials 2

53、In cast irons, a high sulfur may lead to sulfide slag, which could separate during cooling 3 Oxides and intermetallic compounds in steel, copperbase or light alloysIX. Melting Practice1Undissolved alloy addition, inoculant, or deoxidizer 2Dross resulting from alloy addition or inadequate fluxing 3To

54、o low a melting temperature may result in the inability of the slag or dross to separate 4Insufficient slag cover during melting to maintain metal cleanliness 5Thin watery slag 6Refractory-metal reaction can easily release impurities into the metal 7Excessive fluxes or deoxidizersX. Pouring Practice1 A wet or boiling lip on a ladle can promote, or interfere with proper separation of slag2 Careless skimming of the ladle can result in excess slag