A short shot is an incompletely filled mold cavity. This can happen for two reasons.
Unintentional: As the plastic flows through cold portions of the mold, heat is continually being drawn from the melt. Plastic adjacent to the cold mold walls will freeze almost immediately. The thickness of the frozen layer is dependent on the balance between heat lost to the mold through conduction and heat gained from shear. If the injection rate into a mold for the material is too slow, the thickness of the frozen layer builds up to a point where material can no longer be fed into the cavity, thus creating a short shot. This can happen as a result of inappropriate filling conditions or excessively long flow channels.
Intentional: A processor can intentionally create a short shot to diagnose how a mold is filling and how the parts are forming. By taking a short shot as seen in the figure below to the left, one can diagnose that there is a filling imbalance and therefore will create variations in the shrinkage and warpage of these parts.
“Of all the training seminars that I have attended over the past 10 years, this one ranks at the top! The explanations of clamp tonnage, cooling strategies, viscosity, and key mold design components are just a few of the takeaways that will be very useful in my job function.”
THOGUS®
Russ Wolff, Business Development Manager
“I was amazed at the amount of expertise and knowledge presented in just two days. Many myths were debunked, numerous scientific explanations for the way we should be thinking about plastic flow were given, and various real-world examples were used to show how plastic flows.”
CAPLUGS®
Don Makowski, Design Engineer
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“Of all the training seminars that I have attended over the past 10 years, this one ranks at the top! The explanations of clamp tonnage, cooling strategies, viscosity, and key mold design components are just a few of the takeaways that will be very useful in my job function.”
THOGUS®
Russ Wolff, Business Development Manager
“I was amazed at the amount of expertise and knowledge presented in just two days. Many myths were debunked, numerous scientific explanations for the way we should be thinking about plastic flow were given, and various real-world examples were used to show how plastic flows.”
CAPLUGS®
Don Makowski, Design Engineer
Social
Connect with us on social media to stay updated on the latest from Beaumont.
