Aluminum Extrusion Mold

Liquid Nitrogen

Cooling System

CVS’s Unique Liquid Nitrogen Cooling System

It prevents the overheating of the bearing surface of a mold during the extrusion process and maintains a constant temperature through precise extrusion temperature control.
Depending on the product, the extrusion speed is improved by 75%, even up to ≥ 300%, by improving productivity and preventing oxidation through the blocking of air with gaseous nitrogen.
The replacement cycle of extrusion mold can be extended by more than 100%, and product loss can be reduced through constant temperature control. Drawbacks and Improvements of the Existing Aluminum Extrusion Process

Drawbacks and Improvements of the Existing Aluminum Extrusion Process

    Drawback in the Existing Process

  • Billet Heating Temperature
  • Mold Preheating Temperature
  • Frictional Heat
  • Oxidation of Extruded Products
  • Loss of Products
  • Short Mold Life

    Improvements Acquired by CVS LN Cooling

  • Uniform Temperature Control
  • Temperature Control by Material
  • Automatic Cooling with Liquid Nitrogen
  • Nitrogen Barrier Against Air on the Extrusion Surface
  • Reduced Loss of Extruded Products
  • Extended Mold Life

Configuration

Storage Tank for CVS Gas-Liquid Separator

Double Cooling Unit

Vacuum Pump

Outdoor LN Storage Tank and Insulating Piping Lines

LN Flow Control Valve

Control Panel

Infrared Thermometer

Vacuum Piping

Aluminum Extrusion Process Sequence with CVS LN Cooling

01

1. Heat an aluminum billet (a lump of aluminum) at high temperature.

02

2. Put the heated aluminum billet into the extruder.

03

3. Push the heated aluminum billet out of the extruder with excessive force.

04

4. Check the temperature of the extruded product with an infrared thermometer.

05

5. Cool the bearing surface of the mold with liquid nitrogen via the installed LN inlet depending on the temperature of the extruded product.

06

6. Aluminum is extruded in the form of a mold.

07

7. Cool the extruded product with water or wind and cut it to an appropriate size.

08

8. Depending on the type of extruded product, color it by anodizing or cut it to an appropriate size.

Expected Effects of Liquid Nitrogen Cooling System for Aluminum Extrusion Mold

  • 1. Temperature control is possible even with the increased extrusion speed; extrusion can be performed at a constant temperature.

    Liquid nitrogen is supplied to the bearing surface of the mold during aluminum extrusion.
    Liquid nitrogen cools the bearing surface of the mold to control the temperature of the aluminum extruded product to the set temperature.
    Even if the extrusion speed is increased by 2 to 4 times, frictional heat is cooled with liquid nitrogen; thus producing the products at the set extrusion temperature.
    Consequently, it is possible to increase production significantly compared to the existing process.

  • 2. Loss of extruded products can be reduced.

    If the aluminum billet is heated to the extrusion temperature and then extruded, product loss in the accelerated process can be drastically decreased due to the liquid nitrogen cooling.
    Extruding heated billets allow the extrusion temperature set by liquid nitrogen cooling to be maintained, reducing losses in the accelerated process.
    The reduced product loss in the accelerated process leads to decreased total product loss and improved production.

  • 3. The surface roughness of the product is increased.

    It is possible to keep the extrusion temperature constant with liquid nitrogen cooling, no scale occurs, and none of the extrusion defects such as pick-up are formed.
    By completely preventing the occurrence of scale, the surface roughness becomes significantly higher.
    Since gaseous nitrogen is vaporized after using liquid nitrogen cooling, it serves to block the air.
    This air barrier prevents the oxidation of the extruded products.

  • 4. Extruded products at a constant temperature do not undergo changes in their mechanical and physical properties.

    In the bending strength test, the bending strength is kept constant at 500 mm and 1000 mm.
    Since uniform products can be produced in the post-processing, the defect rate is reduced, and the product quality is increased.

  • 5. Liquid nitrogen cooling drastically increases the number of billets extruded from the extrusion mold.

    Since it completely suppresses the occurrence of scale, the shelf life of the mold can be raised remarkably.
    Existing extrusion molds require reheating and finishing after producing about 30 billets, but extrusion molds using liquid nitrogen cooling increase the number of extrusions by more than 10 times compared to the conventional molds.

Bending Strength Test of Products Extruded at Constant Temperature

In the bending strength test, the bending strength is kept constant at 500 mm and 1000 mm in the products extruded and cooled by liquid nitrogen even with the higher extrusion speed.
Because the extrusion temperature is constant, the extruded products have uniform quality, leading to the uniform quality of finished products.

Category 3-point Flexural Strength (with LN Cooling) 3-point Flexural Strength (Conventional)
speed 1000mm 500mm 1000mm 500mm
3.8mm/s 116kgf 223kgf 118kgf 228kgf
4.7mm/s 116kgf 223kgf
5.0mm/s 114kgf 224kgf
5.5mm/s 116kgf 224kgf

* Source: Demo Test Report by G.S.ACE

Measurement of Dimensional Change in Extruded Products According to Ram Moving Speed

Even if the frictional heat increases by raising the extrusion speed, there is no change in the dimensions of the extruded product because it is cooled with liquid nitrogen and adjusted to the set extrusion temperature.
The table below summarizes the dimensional changes for each section according to the increase in extrusion speed when the liquid nitrogen cooling system is adopted.
With the liquid nitrogen cooling system, the product dimension can be kept constant.

Category Cavity Point Ram Moving Speed (m/min)
3.8 <Mass Production Speed> 4.7 5.5
Section1 Section2 Section3 Section1 Section2 Section3 Section1 Section2 Section3
Dimension1
(Ø27.6)
c1 p1 27.58 27.58 27.62 27.57 27.57 27.60 27.56 27.55 27.58
p2 27.65 27.68 27.70 27.67 27.67 27.71 27.68 27.68 27.71
c2 p1 27.56 27.56 27.60 27.57 27.57 27.59 27.55 27.55 27.56
p2 27.64 27.64 27.71 27.63 27.67 27.70 27.62 27.65 27.70
Avg. 27.61 27.62 27.66 27.61 27.62 27.65 27.60 27.61 27.64
Dimension2
(Ø20.3)
c1 p1 20.39 20.39 20.36 20.39 20.39 20.37 20.39 20.40 20.37
p2 20.41 20.41 20.38 20.41 20.41 20.38 20.41 20.40 20.39
c2 p1 20.41 20.41 20.38 20.39 20.40 20.39 20.38 20.40 20.37
p2 20.42 20.42 20.41 20.40 20.41 20.40 20.39 20.40 20.38
Avg. 20.41 20.41 20.38 20.40 20.40 20.39 20.39 20.40 20.38
Dimension3
(11.2)
c1 p1 11.23 11.25 11.25 11.22 11.23 11.25 11.24 11.26 11.26
p2 11.23 11.24 11.22 11.25 11.24 11.25 11.26 11.24 11.26
p3 11.24 11.26 11.26 11.24 11.24 11.25 11.26 11.24 11.23
p4 11.20 11.23 11.20 11.20 11.23 11.25 11.22 11.18 11.21
c2 p1 11.22 11.25 11.28 11.25 11.21 11.24 11.20 11.19 11.21
p2 11.22 11.21 11.23 11.21 11.24 11.22 11.20 11.19 11.20
p3 11.19 11.24 11.23 11.20 11.19 11.26 11.23 11.25 11.23
p4 11.22 11.20 11.24 11.23 11.21 11.20 11.24 11.26 11.26
Avg. 11.21 11.23 11.25 11.22 11.21 11.23 11.22 11.22 11.23
Dimension4
(12.4)
c1 p1 12.43 12.43 12.47 12.38 12.39 12.42 12.41 12.42 12.48
p2 12.40 12.41 12.46 12.42 12.43 12.46 12.40 12.41 12.45
p3 12.41 12.42 12.48 12.41 12.41 12.44 12.40 12.41 12.46
p4 12.39 12.40 12.43 12.40 12.41 12.46 12.35 12.35 12.42
c2 p1 12.40 12.40 12.46 12.39 12.40 12.45 12.32 12.31 12.39
p2 12.36 12.38 12.40 12.35 12.36 12.41 12.36 12.37 12.43
p3 12.36 12.38 12.43 12.37 12.38 12.43 12.37 12.37 12.43
p4 12.38 12.38 12.44 12.38 12.38 12.43 12.39 12.40 12.45
Avg. 12.38 12.39 12.43 12.37 12.38 12.43 12.36 12.36 12.43

* Source: Demo Test Report by G.S.ACE

Difference in Aluminum Surfaces According to Extrusion Method

Conventional Extruded Products

Rough surface; deteriorated gloss; significant defect rate; slow extrusion speed

Extruded Products with CVS LN Cooling System

Excellent anodized color; reduced loss of extruded products; decreased defect rate