8/30/2011· Failure Analysis
Metal Failure Analysis: Metal Food Contaminant Failure Analysis
By: Dr. Thomas Read
Materials failure analysis expert performs a failure analysis to determine the source of a metal piece found in tomato product.
By: Dr. Thomas Read
Tel: (707) 544-2374
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The fatigue failure initiated on the outside bottom where the carafe had been scratched with the abrasive scrub pad. As a result of cyclical thermal shock (between 195°C and 15°C), the cracks grew progressively till it reached a critical length. Glass thickness at the origins is approximately 3 mm. One failed after 12.
In order to simulate normal, use, coffee carafes were scratched with a chosen abrasive and thermal cycled. In this case a commercial scrub pad was used. It is a sponge with embedded 320-400 grit aluminum oxide. This scratching is to simulate both cleaning and sliding the carafe on hard counter tops. In this test, the bottom of a new borosilicate coffee carafe was scrubbed with a wet abrasive sponge and then thermal cycled numerous times till a visible crack formed. A carafe that failed after 51 cycles is examined. The progressive crack initiated at an abrasive scratch.
Figure #1: Photograph of the failed carafe bottom. The “wavy” nature of the crack indicates that it was driven by thermally generated stress.
Figure #2: Photomicrograph of the fracture origin on the fracture surface. The fracture originated at an abrasive scratch. As a result of thermal shock, the crack grew progressively till it reached a critical length. Glass thickness at the failure origin 2.8mm (Mag. 10X).
Figure #3: Higher power photomicrograph of the fracture origin on the fracture surface. The crack initiates on the outside bottom where the carafe had been scratched with the abrasive scrub pad. As a result of stresses from thermal shock, the crack grew progressively till it reached a critical length. Glass thickness at the origin 2.8mm (Mag. 40X.
Dr. Thomas L. Read, CEO of Read Consulting received his PhD. from Stanford University in 1972. He has over 25 years of manufacturing experience in electronics, metallurgy, factory safety, failure analysis, glass fracture, glass failure and bottle failure. As a member of the electronics industry, Dr. Read has earned process patents and has an extensive background in manufacturing techniques. In parallel, he has spent over twenty five years as a consultant to attorneys and engineers in the areas of failure analysis, metallurgy, glass fracture, glass failure, bottle failure, factory safety, manufacturing problems, intellectual property and patent disputes.
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8/30/2011· Failure Analysis
Metal Failure Analysis: Metal Food Contaminant Failure Analysis
By: Dr. Thomas Read
Materials failure analysis expert performs a failure analysis to determine the source of a metal piece found in tomato product.
10/24/2022· Failure Analysis
Titanium Surgical Screws Failure Analysis
By: Dr. Thomas Read
Read Consulting Failure Analysis Laboratory was engaged to determine the cause of failure of two titanium surgical screws used in corrective back surgery. These were both 6.5 mm diameter, 40mm long screws that were surgically implanted. in a patient, and they subsequently failed.
5/17/2011· Failure Analysis
Plumbing Failure Analysis: Stress Corrosion Cracking of Yellow Brass
By: Dr. Thomas Read
A plumbing failure analysis was performed to determine why a cold water supply line to a bathroom sink had failed after only one year of service.