A combination of inadequate feeding and the strain rate has been qualitatively described as a cause of hot tearing. Rappaz, Drezet, and Gremaud gave a quantitative description of conditions that can cause nucleation of hot tears, usually called RDG criterion.
A study involving several hot tearing tests concluded the RDG model has the greatest potential of predicting hot tearing, but only on qualitative basis.
When tears lack important components, however, the complex film breaks down, resulting in dry spots on the cornea that can trigger a cycle of eye irritation and excessive tearing.
Left untreated, irritated and tearing eyes can lead to more serious problems such as blurry vision, cornea infections, and even an ocular surface disease called keratoconjunctivitis sicca.
Specimens for critical tearing energy tests were prepared from production power steering hose, supplied by either Preferred Technology Group or Dayco-Swan Co.
Critical tearing energies were determined using a standard method which is detailed elsewhere (ref.
There is an expected increase in the rate of reflex tearing when contact lenses are applied, especially in rigid gas permeable (RGP) lens patients during adaptation, (11) but there are few studies that have examined the long-term effects of contact lens wear on tear production.
During initial lens adaptation, proteins from the lacrimal gland (lysozyme, lactoferrin) tend to remain at the same concentration during reflex tearing, but the serum-derived proteins (albumen, transferrins, immunoglobulin G (IgG)) reduce in concentration during initial lens wear.
It also was observed that pouring at a lower superheat reduced the hot tearing
A comparison of strain rate results from the stress/strain analysis with the temperature fields from the solidification analysis can be used to find regions that may be susceptible to hot tearing. When a part of the casting is simultaneously being rapidly stretched (undergoing high rates of strain) and is at or near the solidus temperature, this is a high-risk area for hot tearing.
For this reason, the development of a criteria that combines the results of both analyses to show areas at risk of hot tearing in a single picture has been undertaken.
The low-zinc yellow brass (C85200) also was susceptible to drossing and hot tearing
, while the high-zinc yellow brass (C85800) was prone to drossing but not to hot tearing