Metal Casting Final Exam

Blowholes and Open Blows

The spherical or elongated cavities present inside the casting or on the surface

Misrun

Occurs when the molten metal is unable to fill the mold cavity completely, leaving unfilled sections of the pattern

Cold Shut

Occurs when two metal streams meeting in the mold cavity do not fuse together properly, thus causing a discontinuity or weak spot in the casting

Hot Tear

A defect that causes cracks in the surface of your casting as a result of internal cores failing to collapse.

Finite Element Analysis (FEA)

A numerical analysis procedure that can be applied to a large class of engineering problems that otherwise would be very difficult to solve using classical analytical techniques.

Rapid Prototyping (RP)

A series of processes utilizing specialized equipment, software, and materials that are capable of using 3D computer-aided design data, to directly fabricate complex objects.

Stereolithography (SLA)

Most common Rapid Prototyping technique, which builds shapes using light to selectively solidify photo-curable resins

Rapid Casting Technology (RCT)

Uses a printing method to build sand molds and cores directly from CAD files

Casting Cleaning

Process involving the removal of cores, gating and risering system elements, cleaning of the casting surface, chipping of fins along the parting line, as well as any other unnecessary projections on surfaces

Degating

Process of removing the gating and risering systems by means of hammering, chipping, mechanical cutoff, or flame or arc cutting,

Robots

Often used in high-volume casting to eliminate manual operations. Often, a robotic system is designed as a cell, in which castings are degated, ground, and moved within the operation by robots.

Dye and Fluorescent Penetrant Testing

In this test, a part, after being cleaned, is dipped or sprayed with a visible or fluorescent penetrant. Dye Penetrant Testing will produce red lines or dots, indicating defects. Fluorescent Penetrant Testing will produce glowing yellow/green dots or lines under ultraviolet light.

Mag-Particle Testing

Applicable for surface testing of only ferromagnetic materials. The casting is magnetized and then a magnetic powder is sprayed onto the casting surface. The powder naturally localizes at surface defects.

How might one be able to overcome poor permeability in their foundry sand?

use proper grain fineness (GFN) for the foundry application, use proper drafting of pattern, and do not overpack.

Cuts and Washes

Irregular lumps or clusters of metal on the casting surface, often accompanied by sand inclusions elsewhere. Caused by the turbulent pouring of molten metal into the gating system, which dislodges uneven lines or clumps of sand and thus, creates the defect.

Erosion Scab

A defect usually occurring in the drag where the loosened sand has been eroded away by the turbulent pouring of molten metal, and has left a solid junction between the casting and the defect.