Casting Defects

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