There are four main types of investment casting defects:

hot tear or shrinkage crack
This defect occurs when the shell mold restrains the molten metal from shrinking during cooling or solidification. These defects appear as jagged cracks. Experienced foundries eliminate these defects by reducing the "strain rate" by preheating the mold, using vents, and selecting the correct type of metal for the project.

Inclusions
This question describes small, circular, or irregular craters, caused by foreign metal particles in the casting. They may also look like depressions of various shapes and sizes. A reputable metal foundry will ensure that all slag particles are removed from the molten metal before pouring it into the mold cavity.

Machine error
This defect occurs when molten metal does not completely fill the mold cavity. This is mainly due to a cold shell, slow filling or poorly designed molds. Work with a foundry known for providing quality mold making services to avoid lost time.

Porosity
Such defects include the formation of air bubbles in the investment casting during the cooling stage. Liquid materials contain dissolved gases, and these bubbles form when expelled. With the right equipment, investment foundries can prevent blowhole defects.

Defect Prevention: Using Ultrasonic Flaw Detectors
The investment casting process is complex and full of opportunities for irregularities. A reputable foundry will invest in the best equipment and technology to analyze production quality and accuracy.
Ultrasonic flaw detectors are modern mirrors used to identify defects in prototypes. It can find a variety of defects, including cracks, inclusions, voids, shrinkage cavities, porosity, spalling, and other subsurface defects.

How Defect Detection Works
The pulse echo instrument has two working modes: direct beam test and oblique beam test. The straight beam test detects defects parallel to the plane of the part. Angular beam tests provide more details. It can identify defects in angles and other areas that cannot be reached by straight beam testing. It can also spot problems in the base metal from the weld.
Defect detection is important in every industry, but it is critical for aerospace precision castings and automotive casting services.