INJECTION MOLDING: Easy- Cleaning Barrel Stacks for LSR Molding

Save half the usual cleaning time.

Graco Advanced Fluid Dispense (AFD), North Canton, Ohio (previously known as Fluid Automation Systems), recently launched new barrel-stack designs for Graco F-5 and F4-55 two-component LSR meter/mix/dispense systems. Available in single-pass (photo) and multi-pass versions, the new barrel stacks are said to be easy to clean and assemble and have no tapered NPT threads. Molders reportedly can save up to 50% of cleaning time versus older models. Enhancements have also been made to the regulator and mixer.

The new barrel stacks use molded plastic static mixers, which stack upon each other. These mixers are said to prevent the “side-walling” problem that may occur with older stainless-steel mixers after repeated removal and re-installation. The plastic mixer also does not suffer from installation damage due to tight tolerances between the mixer and housing. Greater clearance makes the new barrel stack easier to clean by reducing thread galling. The design also makes it easier to reach components to clean them. Users can either clean the plastic mixers or dispose of them.

The new multi-pass mixer can now run as many as 30 mixer elements, while older molds ran up to 24. Users can configure the equipment to run as few mixers as required—eight, 20, or 30. The single-pass model has 12 elements, which can be configured to use no more than are required.

Eliminating tapered NPT threads in favor of all straight threads keeps material out of the threaded areas, reducing stress on the threads as they come apart and making them easier to put together again, the company says.

Barrel stacks now come with two filter options: 1-in. diam. standard or 2.5-in. optional. The enhanced regulator is now easier to clean because it has far fewer bolts. Also, flow passages in the regulator manifold are 225% larger, reducing pressure drop through the barrel stack.