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February 2022
We would like to share with you another case study as a noteworthy example of fracture diagnosis.

Breakage of Sauce Jars

Sauce jars had broken in a filling line when the jars at 80ºF (26.7°C) were being filled with product at 190ºF (87.8°C).  There was no  preheating of the jars prior to filling.  In order to properly diagnose the cause of the breakage, it was necessary to determine whether the tensile stresses were too high or whether the glass strengths were too low.  

The fracture patterns were relatively simple with only a single crack propagating around the circumference of the bearing surface, as shown in the picture.  Based on the physical characteristics and the overall simplicity of the fracture patterns, it was concluded that the bottles failed under the influence of a low-level thermal shock load.  Thus, the lack of any preheating prior to filling did not contribute to the failures.  

Fracture origins were located on the bearing surface knurls and the absence of any visible hackle (a fracture surface marking) indicated the failures occurred at very low stress magnitudes.  

Examination of the fracture origins revealed the presence of dwell marks that were created by checks in the glass surface as shown in the picture.  These dwell marks indicated the checks had penetrated deeply into the glass which had significantly reduced the glass surface strength to abnormally low values.  

Inspection of the bearing surface knurling indicated that it was formed properly. Thus, the checks were caused by excessive heat flow from the bearing surface into an unusually cold object.  

Further microscopic examination revealed the presence of metal traces on the glass surfaces in direct association with the origin sites.  The composition of these metal traces matched the dead plates in the hot end.  Thus, a thorough inspection of the dead-plate temperatures must be performed to find the source of the checks and to make the necessary corrections to avoid this problem in the future.  

If you have questions about your glass, please don't hesitate to ASK OUR EXPERTS
We are pleased to announce the return this Spring of in-person training on our Butler, PA campus.  We begin with our most popular seminar "Fracture 1: Testing and Breakage Diagnosis of Glass Containers" on April 26-29.

We follow this in Butler with: See our  complete worldwide Training Schedule for all 2022 dates and locations for our in-person training.

If you can't travel at this time, visit our E-Seminars website to see our wide range of on-demand E-seminars along with free video trailers including our "Sand to Shelf: Essentials of Glass Containers". This eight part E-seminar offers a comprehensive overview of what you need to know about glass containers, covering the highlights of glass as a material, container manufacturing, filling, testing, design, and fracture analysis. Watch three full uncut modules as a free preview.

Or Contact Us for Private Training at your location.
American Glass Research
603 Evans City Road, Butler, PA 16001
Tel: +1 (724) 482-2163
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American Glass Research · 603 Evans City Road · Butler, PA 16001 · USA

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