Casting Defects

C A S T I N G D E F E C T S

CASTING DEFECTS

C A S T I N G D E F E C T S

Basic categories of casting defects: · Metallic projections · Cavities · Discontinuities · Defective surfaces · Incomplete casting · Incorrect dimension · Inclusions or structural anomalies

C A S T I N G D E F E C T S

Metallic projections

C A S T I N G D E F E C T S

• Metallic projections in the form of fins or flash • Metallic projections in the form of fins (or flash) without change in principal casting dimensions • Joint flash or fins Thin fins (or flash) at the parting line or at core prints

C A S T I N G

• Veining or finning Projections in the form of veins on the casting surface

• Heat-checked die

D E F E C T S

Network of projections on the surface of die castings

• Fillet scab

C A S T I N G D E F E C T S

Thin projection parallel to a casting surface, in re-entrant angles

• Fillet vein Thin metallic projection located at a re-entrant angle and dividing the angle in two parts

• Cracked or broken mold

C A S T I N G D E F E C T S

Formation of fins in planes related to direction of mold assembly (precision casting with waste pattern); principal casting dimensions change

• Erosion, cut, or wash Excess metal in the vicinity of the gate or beneath the sprue

• Crush

C A S T I N G D E F E C T S

Metal projections in the form of elongated areas in the direction of mold assembly

• Mold drop or sticker Projections with rough surfaces on the cope surface of the casting

• Raised core or mold element cutoff

C A S T I N G D E F E C T S

Projections with rough surfaces on the drag surface of the casting (massive projections)

• Raised sand Projections with rough surfaces on the drag surface of the casting (in dispersed areas)

• Mold drop

C A S T I N G D E F E C T S

Projections with rough surfaces on other parts of the casting

• Corner scab Projections with rough surfaces over extensive areas of the casting

• Broken or crushed core Projections with rough surfaces in an area formed by a core

C A S T I N G D E F E C T S

·Cavities

C A S T I N G D E F E C T S

• Blowholes, pinholes Internal, rounded cavities, usually smooth-walled, of varied size, isolated or grouped irregularly in all areas of the casting

• Blowholes, adjacent to inserts, chills, chaplets, etc. As above, but limited to the vicinity of metallic pieces placed in the mold (chills, inserts, chaplets, etc.)

• Slag blowholes

C A S T I N G D E F E C T S

• Surface or subsurface blowholes

• Corner blowholes, draws

• Surface pinholes

• Dispersed shrinkage

• Open or external shrinkage

• Corner or fillet shrinkage

C A S T I N G D E F E C T S

• Macro- or microshrinkage, shrinkage porosity, leakers • Core shrinkage

• Internal or blind shrinkage

• Centerline or axial shrinkage

C A S T I N G D E F E C T S

Discontinuities

• Breakage (cold)

C A S T I N G D E F E C T S

Normal fracture appearance, sometimes with adjacent indentation marks

• Hot cracking Fracture surface oxidized completely around edges

• Cold tearing Discontinuities with squared edges in areas susceptible to tensile stresses during cooling; surface not oxidized

• Hot tearing

C A S T I N G D E F E C T S

Irregularly shaped discontinuities in areas susceptible to tension; oxidized fracture surface showing dendritic pattern

• Quench cracking Rupture after complete solidification, either during cooling or heat treatment

• Cold shut or cold lap Complete or partial separation of casting wall, often in a vertical plane

C A S T I N G D E F E C T S

•Interrupted pour Separation of the casting in a horizontal plane

•Chaplet or insert cold shut, unfused chaplet Local discontinuity in vicinity of metallic insert

• Conchoidal or "rock candy" fracture Separation along grain boundaries of primary crystallization

• Intergranular corrosion Network of cracks over entire cross section

C A S T I N G D E F E C T S

Defective Surface

• Surface folds, gas runs

C A S T I N G D E F E C T S

Fold markings over rather large areas of the casting

• Cope defect, elephant skin, laps Surface shows a network of jagged folds or wrinkles (ductile iron)

• Seams or scars Wavy fold markings without discontinuities; edges of folds at same level, casting surface is smooth

• Flow marks Casting surface markings showing direction of liquid metal flow (light alloys)

• Rough casting surface

C A S T I N G

Depth of surface roughness is approximately that of the dimensions of the sand grains

• Severe roughness, high pressure molding defect Depth of surface roughness is greater than that of the sand grain dimensions

D E F E C T S

• Buckle Grooves of various lengths, often branched, with smooth bottoms and edges

• Rat tail

C A S T I N G D E F E C T S

Grooves up to 5.1 mm (0.2 in.) in depth, one edge forming a fold which more or less completely covers the groove

• Flow marks, crow's feet Irregularly distributed depressions of various dimensions extending over the casting surface, usually along the path of metal flow (cast steel)

• Orange peel, metal mold reaction, alligator skin Casting surface entirely pitted or pock-marked

• Soldering, die erosion

C A S T I N G

Grooves and roughness in the vicinity of re-entrant angles on die castings

• Sink marks, draw or suck-in Casting surface depressions in the vicinity of a hot spot

D E F E C T S

• Slag inclusions Small, superficial cavities in the form of droplets of shallow spots, generally graygreen in color

• Push-up, clamp-off

C A S T I N G D E F E C T S

Deep indentation, often over large area of drag half of casting

• Burn on Sand layer strongly adhering to the casting surface

• Burn in Very adherent layer of partially fused sand

• Metal penetration Conglomeration of strongly adhering sand and metal at the hottest points

of the casting (re-entrant angles and cores)

• Dip coat spall, scab Fragment of mold material embedded in casting surface

• Scabs, expansion scabs

C A S T I N G D E F E C T S

Plate-like metallic projections with rough surfaces parallel to casting surface; removable by burr or chisel

• Cope spall, boil scab, erosion scab As above, but impossible to eliminate except by machining or grinding

• Blacking scab, wash scab Flat, metallic projections on the casting where mold or core washes or dressings are used

• Oxide scale

C A S T I N G D E F E C T S

Adherence of oxide after annealing

• Adherent packing material Adherence of ore after malleablizing (white heart malleable

• Scaling Scaling after anneal

C A S T I N G D E F E C T S

Incomplete Casting

• Misrun

C A S T I N G D E F E C T S

Casting is essentially complete except for more or less rounded edges and corners

• Defective coating (teardropping) or poor mold repair Deformed edges or contours due to poor mold repair or careless application of wash coatings

• Poured short Casting incomplete due to insufficient metal poured

C A S T I N G D E F E C T S

• Runout Casting incomplete due to loss of metal from mold after pouring

• Fusion or melting during heat treatment Casting partially melted or seriously deformed during annealing

• Fractured casting Casting broken, large piece missing; fractured surface not oxidized

• Broken casting (at gate, riser, or vent) Fracture dimensions correspond to those of gates, vents, etc.

C A S T I N G D E F E C T S

Incorrect Dimensions or Shape

• Improper shrinkage allowance

C A S T I N G

All casting dimensions incorrect in the same proportions

• Hindered contraction

Distance too great between extended projections

• Irregular contraction

D E F E C T S

Certain dimensions inexact

• Excess rapping of pattern Dimensions too great in the direction of rapping of pattern

C A S T I N G D E F E C T S

• Soft or insufficient ramming, mold-wall movement Excessive metal thickness at irregular locations on casting exterior(a) • Distorted casting Thin casting walls over general area, especially on horizontal surfaces(b) • Pattern error Casting does not conform to the drawing shape in some or many respects; same is true of pattern (c) • Pattern mounting error Casting shape is different from drawing in a particular area; pattern is correct(d)

a

b

c

d

• Shift

C A S T I N G D E F E C T S

Casting appears to have been subjected to a shearling action in the plane of the parting line

• Shifted core Variation in shape of an internal casting cavity along the parting line of the core

• Ramoff, ramaway Irregular projections on vertical surfaces, generally on one side only in the vicinity of the parting line

• Deformed pattern

C A S T I N G

Deformation with respect to drawing proportional for casting, mold, and pattern(a) • Deformed mold, mold creep, springback Deformation with respect to drawing proportional for casting and mold; pattern conforms to drawing (b) • Casting distortion (d) Casting deformed with respect to drawing; pattern and mold conform to drawing(c)

D E F E C T S

• Warped casting Casting deformed with respect to drawing after storage, annealing, machining(d)

(a)

(b)

(c)

C A S T I N G D E F E C T S

Inclusions or Structural Anomalies

C A S T I N G D E F E C T S

• Metallic inclusions (a) • Cold shot (b) (a)

• Internal sweating, phosphide sweat (c)

• Slag, dross or flux inclusions, ceroxides (d) • Slag blowhole defect (e)

(b)

(c)

(d)

(e)

• Sand inclusions (a)

C A S T I N G

• Blacking or refractory coating inclusions (b) • Black spots (c)

(a)

• Oxide inclusion or skins, seams (d) • Lustrous carbon films, or kish tracks (e) • Hard spots (f)

D E F E C T S

(b) (c)

(d)

(e)

(f)

Summary C A S T I N G D E F E C T S

C A S T I N G D E F E C T S