The Relative Viscosity (RV) test is often used to help identify an ideal fill speed/time for the mold. Fill speed and the resulting fill time are an indication of how fast the plastic is injected into the mold. The speed affects how much shear heating and shear thinning the plastic experiences, which in turn affects the material’s viscosity, the pressure, the temperature of the plastic inside the cavities, and the overall part quality (dimensional, aesthetics, strength, etc.). Though there are many different approaches to selecting the idea point, those who teach this method generally agree that for most parts the fill time should be located somewhere on the flatter portion of the curve (Figure 1).
REVOLUTIONIZING INJECTION MOLDING
TESTIMONIALS
“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