Casting Defects
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CASTING DEFECTS
CASTING
DEFECTS
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CASTING
DEFECTS
Basic categories of casting defects:
· Metallic projections
· Cavities
· Discontinuities
· Defective surfaces
· Incomplete casting
· Incorrect dimension
· Inclusions or structural anomalies
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CASTING
DEFECTS
Metallic projections
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CASTING
DEFECTS
• 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
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CASTING
DEFECTS
•Veining or finning
Projections in the form of veins on the casting surface
• Heat-checked die
Network of projections on the surface of die castings
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CASTING
DEFECTS
• Fillet scab
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
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CASTING
DEFECTS
• Cracked or broken mold
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
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CASTING
DEFECTS
• Crush
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
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CASTING
DEFECTS
• Raised core or mold element cutoff
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)
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CASTING
DEFECTS
• Mold drop
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
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CASTING
DEFECTS
·Cavities
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CASTING
DEFECTS
• 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.)
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CASTING
DEFECTS
• Slag blowholes
• Surface or subsurface blowholes
• Corner blowholes, draws
• Surface pinholes
• Dispersed shrinkage
• Open or external shrinkage
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CASTING
DEFECTS
• Corner or fillet shrinkage
• Core shrinkage
• Internal or blind shrinkage • Centerline or axial shrinkage
• Macro- or microshrinkage,
shrinkage porosity, leakers
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CASTING
DEFECTS
Discontinuities
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CASTING
DEFECTS
• Breakage (cold)
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
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CASTING
DEFECTS
• Hot tearing
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
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CASTING
DEFECTS
•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
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CASTING
DEFECTS
Defective Surface
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CASTING
DEFECTS
• Surface folds, gas runs
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)
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CASTING
DEFECTS
• Rough casting surface
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
• Buckle
Grooves of various lengths, often branched, with smooth
bottoms and edges
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CASTING
DEFECTS
• Rat tail
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
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CASTING
DEFECTS
• Soldering, die erosion
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
• Slag inclusions
Small, superficial cavities in the form of droplets of shallow spots, generally gray-
green in color
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CASTING
DEFECTS
• Push-up, clamp-off
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
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CASTING
DEFECTS
• Scabs, expansion scabs
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
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CASTING
DEFECTS
• Oxide scale
Adherence of oxide after annealing
• Adherent packing material
Adherence of ore after malleablizing (white heart malleable
• Scaling
Scaling after anneal
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CASTING
DEFECTS
Incomplete Casting
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CASTING
DEFECTS
• Misrun
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
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CASTING
DEFECTS
• 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.
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CASTING
DEFECTS
Incorrect Dimensions or Shape
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CASTING
DEFECTS
• Improper shrinkage allowance
All casting dimensions incorrect in the same proportions
• Hindered contraction
Distance too great between extended projections
• Irregular contraction
Certain dimensions inexact
• Excess rapping of pattern
Dimensions too great in the direction of rapping of pattern
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CASTING
DEFECTS
• 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
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CASTING
DEFECTS
• Shift
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
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CASTING
DEFECTS
• Deformed pattern
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
Casting deformed with respect to drawing; pattern and mold conform to drawing(c)
•Warped casting
Casting deformed with respect to drawing after storage, annealing, machining(d)
(a) (b) (c)
(d)
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CASTING
DEFECTS
Inclusions
or
Structural Anomalies
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CASTING
DEFECTS
• Metallic inclusions (a)
• Cold shot (b)
• Internal sweating, phosphide sweat (c)
• Slag, dross or flux inclusions, ceroxides (d)
• Slag blowhole defect (e)
(a)
(b)
(c) (d) (e)
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CASTING
DEFECTS
• Sand inclusions (a)
• Blacking or refractory coating inclusions (b)
• Black spots (c)
• Oxide inclusion or skins, seams (d)
• Lustrous carbon films, or kish tracks (e)
• Hard spots (f)
(a)
(c)
(b)
(d) (e) (f)
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CASTING
DEFECTS
Summary
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CASTING
DEFECTS