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Home » Plastic molding » Plastic injection mold cooling system design

Plastic injection mold cooling system design

February 4, 2019 by mechanicaleng blog 3 Comments

Design injection mold cooling system is very important. Cooling time is the longest circle in injection molding process, it takes up 50~80% of molding circle. Molten plastic has high temperature, If we don’t make cooling channels, the molding circle is very long, it is cause of molded defect as bending, sink marks, weld line, short shot…

Post contents

  • I. Injection mold cooling system overview.
    • 1. Injection molding cooling method.
    • 2. Injection mold cooling process.
    • 3. Injection mold cooling system design need following remarks.
    •  4. Dimension of cooling channel.
  • II. Injection mold cooling layout.
    • 1. Core, cavity and mold base cooling.
    • 2. Cooling layout between a core and mold base construction.

I. Injection mold cooling system overview.

1. Injection molding cooling method.

1. Cooling by air: Heat radiating to air, with this method, mold cold is slowly.

2. Cooling by cooling materials.

+ Ethylene glycol and water. This is the common method for mold cooling. Cooling material will push in to the cooling channel of the mold and it makes mold cooling.

2. Injection mold cooling process.

This picture below will explain a basic cooling channel system.

Cooling channel system
Cooling channel system

A: Collection manifold.
B: Mold.
C: Supply manifold.
D: Pump.
E: Regular cooling channels.
F: Hoses.
G: Baffle.
H: Temperature Controller.

3. Injection mold cooling system design need following remarks.

+ When we design a mold, we need to make cooling channel near the biggest thickness of products.

+ Diameter of cooling channel usually is bigger than 8 mm,  It need  equal through cooling channel.

+ Adjusts the mold temperature by pouring a large amount of water having a temperature close to the temperature required for molding.

+ Increase the number of the cooling channel rather than enlarge the diameter of one cooling channel.

+ Use mold material that has high heat conductivity to improve effectiveness of cold water.

+ Make sure core insert, slider core,… can be cooling. It it can not be cold, we need to change the mold design.

+ Increase number of the cooling channel rather than increase length of cooling channel. If cooling channel is too long, Δt is bigger than 3 degree. Δt is different between input and output temperature.

 4. Dimension of cooling channel.

Cooling channel diameter should more for thicker wall thickness. This picture below will show this relation.

Dimension of cooling channel
Dimension of cooling channel
W: thickness of product (mm) 2 mm 2~4 mm 4~6 mm
d: Diameter of cooling channel (mm) 8~10 mm 10~12 mm 12~14 mm
b: Distance between two cooling channels 2~3d
a: Distance from cooling change to product 2~2.5d

II. Injection mold cooling layout.

1. Core, cavity and mold base cooling.

Because molten plastic push in to core and cavity so it is the hottest location in the injection mold. To make cooling process faster, reduce cycle time, cooling for a core and cavity are necessary.

mold base cooling channel
mold base cooling channel
plastic injection mold cooling channel around product
plastic injection mold cooling channel around product
plastic injection mold cooling channel around product with 2 level
plastic injection mold cooling channel around product with 2 level

2. Cooling layout between a core and mold base construction.

This picture below following mold base and cavity connection.

Cooling layout between a core and mold base construction
Cooling layout between a core and mold base construction

1. Mold base – cavity plate.

2. Insert cavity.

3. Cooling joint plug.

4. O-ring. It prevents cooling materials over the injection mold.

Related posts:

Cooling for slider mold injectionslider cooling channel construction in mold injection injection molding processPlastic injection molding process steps three plate mold constructionConstruction injection mold classification three plate mold constructionPlastic injection molding three plate mold

Filed Under: Plastic molding Tagged With: injection molding design, mold design, molding design

Reader Interactions

Comments

  1. Dudley Scholl says

    June 29, 2019 at 8:24 am

    Hi there, is it possible to cool a plastic injecting moulded product in a short time frame that will have some mass areas of 120mm x 70mm x 250mm in a length of 2400mm overall?

    Reply
    • mechanicaleng blog says

      June 30, 2019 at 5:13 pm

      Sorry, It is so long and I haven’t done this sample.

      Reply
  2. Jane says

    July 14, 2022 at 8:40 am

    Thank you very much for your analysis. Our company is also engaged in the plastic injection molded products and your article is very helpful to us. Our company’s website is https://zetarindustry.com
    We are looking forward to the publication of your article soon and it will inspire us more.

    Reply

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