California Glass Expert Performs a Failure Analysis of Sparkling Liquor Bottle Failures

A bottling line for sparkling drinks was suffering from a high rate of  bottle failures on the bottling line. In addition, several bottles failed on the shelf after bottling. Read Consulting was asked to perform a glass failure analysis to determine the cause of failure of three bottles that had failed "on the shelf". Two of the three bottles were from the same mold cavity, and both failed at the exact same height from the base (2 1/4"). The third bottle failed at 2 1/2" above the base. All three failure origins were the same. All three failures started on the outside of the bottle. All three had "crack arrest lines " near the origin. In addition, All three had no visible mechanical damage to the bottle exterior at the origin.  The presence of the crack arrest line confirms a delayed failure. These factors indicate that the failures are caused by defects caused by the bottle manufacturing process. This is a manufacturing defect that must be corrected by the bottle manufacturer.

Glass Fracture, Califirnia Glass ExpertPerforms Bottle Failure Analysis

California failure analysis expert witness was asked to perform a detailed failure analysis of a broken wine bottle. Glass fractography was used to determine the root cause failure mode. The failure originated at damage caused by the prop on the cork screw. The fact that there were two damage sites on opposite sides of the bottle and that the cork was only partially removed, indicates that the force to remove the cork was excessive. The donward force on the prongs crushed the top of the bottle at two places and initiated a crack that was driven by the force needed to move the cork. This failure was not the result of a bottle manufacturing defect; it was caused by the high forces needed to move the cork and the type of cork screw used. Upper left is a photograph of the two pieces of the bottle neck. Upper right is a 20X photomicrograph of the failure origin and the initial part of the crack. The arrows show the initial travel direction of the crack. Also, visible is the "crush point" at the beginning of the failure.

Failure Analysis Expert Examines Bottle Failure

Glass failure analysis expert witness prepared numerous bottle failures of "off the shelf" 12 oz beer bottles by over pressuring them with a hydraulic pump. These tests were needed to generate bottle failures of a known origin in order to examine the crack patterns, the fracture surfaces and the failure origins. Numerous bottles were broken, and even though the locations of the failure origins varied (i.e. some were on the body and others on the heel), they all had identical characteristics. They initiated as a single crack parallel to the bottle axis. Also, the origin was always on the outer surface of the bottle and located at a minor external glass defect. In addition, the failure initiated as a fracture mirror. The fracture mirror was surrounded by mist hackle. The failure shown here initiated at the heel of the bottle. an overview of the failed bottle is shown in the two upper left photographs. The initial crack is parallel to the bottle axis, and it wraps around the heel. At both ends of the initial straight crack the crack fans out. On the upper right is a 40X photomicrograph of the failure origin. The mirror fracture and mist hackle border are clearly visible. The minor defect at the origin is just the weakest part of thisstandard bottle. This bottle failed at 410 psi. This was not a defective bottle. This would not be a product liability case.

High Pressure Bottle Failure Analysis Tests

Glass failure analysis requires looking at failed bottles and determining the cause of failure. The failure analysis procedure includes carefully examining the crack pattern and the failure origin. It also helps to have failures with known causes to confirm the conclusions. In this case bottles were purposly broken using hydraulic pressure. Their performance was documented for future use. Numerous bottles were tested, and all showed similar failure characteristics. All bottle failures were caused by "hoop stress"; thus they started as a straight crack parallel to the axis of the bottle and then branched out. Microscopically, all the over pressure glass bottle failures originated as a slow growing crack and formed a distinct fracture mirror surrounded by mist hackle. Upper left is a photograph of a representative over pressure failure. This particular failure originated on the body of the bottle. Others originated on the heel, but all had the same characteristics. Upper right is a 40X photomicrograph the origin of the failure. It consists of a slow growth fracture mirror surrounded by mist hackle. The small arrows indicate the crack travel direction. During falure analysis, a glass failure analysis expert can compare the unknown glass failure to this example to aid in determining the cause of the failure.

Glass Bottle Damage; GLass Bottle Failure Analysis

Glass expert illustrates wine bottle damage that occured during corking. This product defect occured during cork insertion. The "push rod" was off center, and it impacted the top of the bottle. As a result, there was a crush point that would have resulted in a crack during cork removal by the user. Glass failure analysis of broken bottles would have shown the origin at the top of the bottle.

Glass Expert Performs a Wine Bottle Failure Analysis

California glass expert performs a failure analysis on a wine bottle failure. In this case the root cause of the failure was due to an impact on the top of the bottle finish. it is apparent that this bottle was hit on the top. This is shown by the photomicrograph.

Glass Failure Expert Witness Analyzes Failed Wine Bottle

Glass expert performed a root cause failure analysis of a broken wine bottle. The bottle had broken at the neck into three pieces (Upper left photograph). One piece still contained the cork with the cork screw still in place. In this case the the cork screw was off center and had exited the cork when it was being "screwed" in. The side of the cork screw crushed the interior wall of the bottle neck, and this initiated the failure. The upper right photograph is of the re-assembled top of the bottle. In it one can see the exposed edge of the cork screw and the "crush" defect on the interior of the bottle neck. With this type of cork screw the cork is pried out with a lever force. In this case, this force was sufficient to cause failure and injuryto the person opening the bottle. With this type of cork screw the user must be careful to center it, or he could be injured.

This glass failure analysis showed that the failure was a result of operator error. There was no manufacturing defect.

Glass Bottle Failure Analysis

Glass failure analysis expert performed a root cause failure analysis on a bottle failure. The cap on this bottle had not been removed. The failure analysis revealed a manufacturing defect on the bottle interior. On the upper left photo is a 30X photomicrograph of a portion of the origin on the fracture surface. The arrows show the travel direction of the crack exiting the origin. On the upper right is a 30X photonicrograph of the origin as it appears on the interior surface of the bottle. There is a "chip" associated with the origin; therefore, this is a product defect on the bottle interior.

Glass Expert Performs Sauce Bottle Glass Failure Analysis

Glass expert peformed a bottle failure analysis on a broken bottle of steak sauce . Intitally it was stated that this was a new and unopened bottle; however, examination revealed that there was sauce on the bottle threads. In addition, the "band" below the plastic lid was not connected. From this it was concluded that the bottle had been opened in the past. The fracture surface was examined and the root cause failure analysis showed the origin to be located on the bottle "shoulder ring" which is just below the plastic lid band. Upper left is a photomicrograph of the a portion of the fracture surface that includes the origin (indicated by the arrow). Upper right is a higher power photomicrograph using Nomarski optics of the failure origin. In this case the failure originated at the site of chipping damage to the bottle (arrows indicate the initial crack direction). This is not a manufacturing defect.

Glass Expert Analyzes Wine Bottle Defect

A glass expert was asked to examine poor quality bottles received by a winery. The issue was whether this product defect would significantly lower the strength of the bottle and would present a product liability problem. The photo on the upper left is a photograph of the manufacturing defect. It is a 4 inch horizontal "gash". The center picture is a photo-micrograph of the defect cross-section. The cross-section shows that the edges of the defect are rounded. This is a molding defect that occured when the glass was at or above the its softening point. The edges of the defect are rounded; therefore, in the opinion of a manufacturing engineer, they are unlikely to cause a low stress bottle failure. The picture on the upper right is a photo-micrograph of the top of the defect. There is a thin sheet of glass over the center mound of the defect. It is believed that this defect was formed in the blow molding step of the bottle manufacturing process.