Vacuum Recirculation Milling Technology

Motivation:  Hockmeyer developed and patented a new concept for a recirculation media mill to fill a performance void that exists with traditional mills in this classification.
Problem: Hockmeyer’s traditional Immersion Mill provides superior performance, but cannot be easily installed in many existing production facilities due to inadequate head space required for the hydraulic lifts needed to raise the mill.
Approach: This new technology combines immersion milling design with a diaphragm pump to pull vacuum on this system.  The flow of the material is from the bottom of a supply tank, through the milling chamber and back into the tank.
Result: The new recirculation mill has several technological advantages:

  • Separate control of spindle and pump speeds.
  • Measure flow through the milling chamber.
  • Design provides very effective cooling to control batch temperature.
  • Smaller plant footprint.
  • Rapid batch turnover.  Up to 50 gallons a minute through our 2.5 liter prototype mill.
  • Better quality products: smaller particle distributions, increased color, transparency and gloss.

Conclusion:  This advancement in milling technology will fit in much tighter locations in plants, reduce media loading, increase batch turnovers, reduce grind time, replace existing milling equipment without major plant renovations and reduce overall milling cost.


Barry Cullens has been with Hockmeyer Equipment Co. for about 30 years. Barry was employed early as a machinist before becoming the Laboratory Manager. Over the last 10 years Barry has been in charge of Research and Development for the company. As Director of Research and Development many improvements to existing equipment have been made to increase the capability and efficiency of the equipment. New equipment has also been developed including equipment for milling high viscosity formulations, particle analysis equipment, and equipment for improving pre dispersions of formulas to reduce milling time. All engineering, simulation, manufacturing, prototyping, and testing of new equipment and improvements of existing equipment have been the primary focus of this position. Graduated from Collage of the Albemarle. Associates degree in Metallurgical Science, Drafting, Machining, and Welding.