✅ 1. What is Vacuum Sizing in Extrusion?

Vacuum sizing is a method used to cool and shape extruded plastic products (such as pipes, profiles, and tubes) to their final dimensions by applying vacuum pressure inside a sizing sleeve or calibrator.

How It Works:

• The hot extrudate exits the extrusion die.

• It enters a vacuum tank, where a vacuum pump creates negative pressure inside the sizing sleeve.

• This vacuum pulls the extrudate tightly against the sizing sleeve’s inner wall, ensuring:

  • Accurate dimensions (tight tolerances)

  • Roundness and smooth surface finish

• The vacuum tank is usually filled with water for cooling.

• Water circulation keeps the temperature stable.

✅ 2. Role of Spray Nozzles in Extrusion Cooling

While the vacuum ensures proper sizing, spray nozzles are critical for efficient cooling of the extruded product inside the vacuum tank and downstream cooling tanks.

Spray Nozzle Function:

• Nozzles spray water jets or mist evenly around the extrudate.

• This increases heat transfer efficiency compared to still water.

• Fine atomization = faster and uniform cooling.

• Used in:

  • Vacuum sizing tanks

  • Spray cooling tanks (after vacuum tank)

✅ How They Work Together

• Vacuum sizing sleeve = controls dimension and shape.

• Spray nozzles = maintain cooling performance without distorting the product.

• Together, they:

  • Reduce warping and ovality.

  • Improve surface quality.

  • Allow higher production speed.

✅ Types of Spray Nozzles for Extrusion Cooling

• Flat Fan Nozzles → Wide coverage, good for spray cooling tanks.

• Full Cone Nozzles → Uniform distribution, often used for pipes.

• Hollow Cone Nozzles → Fine spray, excellent for delicate profiles.

• KB Series Nozzles (like you mentioned earlier) → Ultra-fine atomization, ideal for precision cooling.

• Feature	Vacuum Sizing	Spray Nozzle Cooling
  Primary Purpose	Dimension control & initial cooling	Secondary cooling & heat removal
  Location	First stage after die	After vacuum tank or inside tanks
  Cooling Method	Water contact + vacuum	Atomized water spray
  Advantage	High accuracy, shape stability	Fast, even cooling