All of Milgard's extrusion equipment is custom designed and built for Milgard in Europe, an area where vinyl windows have been a standard since the fifties. Milgard's dies are more consistent and precise than those found anywhere in the world: And their processing equipment is engineered to produce uniform heat and pressure to make sure their production quality equals their design quality.
After all, processing stresses and rough surfaces can cause headaches over time. And to be sure their frame profiles continue to be the highest quality, Milgard's team of specialists maintain these dies and equipment regularly to exacting tolerances.
- Basically an elaborate "pump" in the form of a large screw.
- A dry powder (PVC) is fed into the FEED section of the extruder barrel.
- The "FLIGHTS" or wings of the extruder screw force the material forward while applying pressure and heat from the HEATING BANDS.
- As the material moves through the COMPRESSION ZONE, additional heat and pressure is applied until the PVC reaches a fusion point.
- The VACUUM PORT draws out any moisture from the material in a vapor form. If any moisture remained, it would cause bubbles (creating a weak frame for impacts) or blister during the extrusion process.
- The product then moves into the METERING ZONE where even more heat and pressure is applied - at this point, 4,000 psi of pressure at 385° forces the PVC through the die.
The die is what gives the vinyl its shape. The molten material is forced through a series of dies that gradually create the final shape. They are much wider and more complex than a "Playdough" die or pasta die, even though these are often used as a reference as to how this process is done. Milgard's dies are produced in-house at the extrusion facility's tool shop. The material flows through the die at a rate up to 1,000 lbs of vinyl per hour.
The calibrators are where the material becomes solid. The calibrators hold the material's shape until it's stable and cooled. A vacuum actually pulls the material against the calibrator "wall" to maintain the shape. A "puller" down the extrusion line is now pulling the solid shape through the calibrator at the precise speed at which the molten material leaves the die "upstream." The material is then cut to length.