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CASTING DEFECTS
CASTING
DEFECTS
CASTING
DEFECTS
Basic categories of casting defects:
· Metallic projections
· Cavities
· Discontinuities
· Defective surfaces
· Incomplete casting
· Incorrect dimension
· Inclusions or structural anomalies
CASTING
DEFECTS
Metallic projections
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
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
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
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
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
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)
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
CASTING
DEFECTS
·Cavities
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.)
CASTING
DEFECTS
• Slag blowholes
• Surface or subsurface blowholes
• Corner blowholes, draws
• Surface pinholes
• Dispersed shrinkage
• Open or external shrinkage
CASTING
DEFECTS
• Corner or fillet shrinkage
• Core shrinkage
• Internal or blind shrinkage • Centerline or axial shrinkage
• Macro- or microshrinkage,
shrinkage porosity, leakers
CASTING
DEFECTS
Discontinuities
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
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
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
CASTING
DEFECTS
Defective Surface
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)
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
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
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
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
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
CASTING
DEFECTS
• Oxide scale
Adherence of oxide after annealing
• Adherent packing material
Adherence of ore after malleablizing (white heart malleable
• Scaling
Scaling after anneal
CASTING
DEFECTS
Incomplete Casting
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
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.
CASTING
DEFECTS
Incorrect Dimensions or Shape
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
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
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
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)
CASTING
DEFECTS
Inclusions
or
Structural Anomalies
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)
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)
CASTING
DEFECTS
Summary
CASTING
DEFECTS