Injection Molding

Various plastic injection moldings
Injection Molding Case Study


A long time Benz customer in the plastic injection molding industry had been experiencing the formation of varnish deposits in their machines running on a standard zinc-based AW (anti-wear) hydraulic oil. The customer asked Benz to develop a hydraulic fluid that could extend the mean time between oil changes along with reducing the time to change oil. Benz took the challenge to further understand varnish potential in hydraulic oils and develop a product that would meet the
customer’s needs.

Customer Stated Goals
• Reduce overall varnish
• Increase time between oil changes
• Increase uptime performance


Increased temperatures, such as plastic injection molding hydraulic systems, accelerates oxidation (oils reaction with oxygen), but it is difficult to predict when the adverse consequences will impact mechanical operations with varnish deposits. The detection of oxidation has often been linked to varnish formation, but Benz research has shown that some fluids varnish heavily with very little oxidation detected while other fluids may be heavily oxidized and produce little or no varnish. To be predictive, a combination of test methods must be utilized before degrading consequences of viscosity increase, odor, color change, and varnish deposits become apparent.

ECLIPSE VR series is designed to minimize the varnish potential in high heat hydraulic systems, such as injection molding operations. Benz laboratory research developed testing standards that allowed the development of ECLIPSE VR series by degrading the fluid in a predictive way and testing its varnish levels via MPC (Membrane Patch Colorimetry) testing.


Customer tested ECLIPSE VR 46 in a Husky Hylectric plastic injection molding machine that was prone to varnish. ECLIPSE VR 46 has an 80% reduction in MPC value after extended run time, which was <10ΔE. The customer expects to at least double their oil change interval.

Decreases in varnish deposits will reduce machine downtime by 40 hours, due to less time needed to clean the machine and change oil. Additional savings are developed by reducing valve issues and optimizing machine speed throughout the life cycle. Increasing the time between oil changes will reduce the overall oil usage by ~50% each year all adding up to $160,000 operational savings for this facility (50 machines with 300-gallon sump average) by utilizing ECLIPSE VR 46.