Melt Diverter & Valve Retrofit

Structural Foam Melt Diverter Valve Improvement Retrofit

The diverter valve is on structural foam machines equipped with one extruder supplying plastic to two injection assemblies. This retrofit will reduce your existing diverter maintenance costs by increasing its useful life through new coating materials for the diverter bodies and rods, and by creating a two-piece assembly on specific styles of bodies.

Melt Diverter Design Factors

The Melt Diverter Valve is a hydraulically operated sliding spool valve placed either:

• In-between the melt relief valve and two fill pipes. This type of diverter has a one-piece body that cannot be modified into a two-piece body due to existing design constraints. Or,
• In-between the fill pipe and the two melt accumulators. This type of diverter has a one-piece body that can be modified into a two-piece assembly (an outer body and an inner sleeve).

Diverters are used on machines that have one extruder supplying plastic to more than one melt accumulator. This allows for filling one accumulator at a time in a pre-selected order. After the plunger in the first accumulator reaches shot size, the diverter closes the passage to that accumulator and opens the passage to the other accumulator for filling.
The Melt Diverter Valve also functions as a shut-off valve on some machines by closing the plastic passages between the extruder and the accumulators when shot size has been reached. Shutting off the plastic passages improves shot to shot repeatability and helps prevent plastic from backing up into the feed throat.

Wear is created on the inside surface of the diverter body, and the outside surface of the diverter cylinder rods due to:

• Constant movement, which occurs every cycle.
• Contamination in recycled material.
• Abrasive fillers.

To combat this wear, Uniloy Mlacron has tested and approved an Xaloy 800 coating for diverter bodies or sleeves, and an Xaloy 8000 coating for the rods. This material has proven to increase the useful lives of bodies, sleeves, and rods by more than 3 times the usual 2 year life span of the existing steel bodies and bronze rods.

Retrofit Package Description
Uniloy Milacron offers 2 different styles of retrofits to match your particular machine requirement. Package “A” is for existing diverters that cannot be modified into two-pieces, while Package “B” is the correct package for existing diverters that can be modified into two-piece bodies. Please consult your local Uniloy Milacron Parts Sales Representative if you need help in determining which style of retrofit you require.

Melt Diverter Retrofit - Package “A” Includes:

• Diverter Valve Body
• Diverter Rods (2)

This package replaces your existing steel diverter body with one coated on the inside with Xaloy 800 and replaces your existing bronze rods with Xaloy 8000 coated rods.
Melt Diverter Retrofit - Package “B” Includes:

• Diverter Body Sleeves (2)
• Diverter Rods (2)
• Sealing O-Rings (2)
• Socket Head Cap Screws (8)
• Alteration Drawing For Existing Diverter Valve Body

• The O-ring seal in place of the gasket ring provides superior sealing.
• An 8-bolt flange replaces the 4 swing bolts. This creates better force distribution and improved sealing.
• The shear pins have been eliminated, which could have caused leakage.
• The swing pivots have been eliminated, allowing for easier re-assembly.
• The melt relief body and flange are now a rugged one-piece construction.
• Head heater wattage has been increased for quicker warm up.
• Externally mounted, spring-loaded, ceramic heaters have been utilized which are easier to replace, allow for thermal expansion, and have a longer useful life.
• The rupture disc has been moved from the extruder barrel to the melt relief, which eliminates pressure spikes from the screw and allows plastic to go into the dump pan.

Melt Relief Valve Assembly includes:

Relief Valve Body
Cylinder Spacers
Cylinder
Valve Seat
Retainer For Seat
Special Barrel Flange
Rupture Disc Assembly