Reliable Partner for Gas Assist Injection Molding

Professional Gas Assist Injection Mold Manufacturer

Gas assist injection molding is conventional injection molding with the addition of a compressed gas (nitrogen) that is injected into the part, forming a hollow core. It can Improve polymer flow, product stiffness, and reduce internal stress & warpage. Kemal with a professional team to design the mold and adapt your design to suit gas. So that the gas will go along the right path, Then the molds can reach the optimal function to achieve the ideal product. If you need a quote and support, let us show you what are we capable of.

Gas Assist Injection Molding Parts

The gas injection must wait until the plastic passes through the position of the gas pin for a period of time. If the gas delay time is too short, the gas will blow through, and the analysis will stop. If the time is too long, the gas penetration will not be enough. Kemal designers take every detail into consideration to ensure product quality. and provide incredible strength to plastic parts. and meet your request perfectly.

Why Choose Kemal Make Gas Assist Injection Molding

Gas-assisted molding was used to fill the mold cavity with quantitative plasticized plastics. The gas injection pressure must be greater than the injection pressure to achieve the hollow state of the product. After the finished product is filled with gas, the pressure of the gas acting on the hollow part of the finished product becomes the holding pressure, which can greatly reduce the shrinkage and deformation rate of the finished product

Kemal team professional in the optimization of gas-assisted product structure, the optimization of mold structure designing and manufacturing, so that make a feasibility analysis for projects correctly and provide you with a High Cost-Effective program.

There is no doubt that Kemal’s experience and ability in the gas-assisted injection molding industry to meet your requirements.

welcome any inquiry for Gas Assist Injection Molding.

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Kemal Your reliable Gas Assist Injection Molding Manufacturer

Kemal has been using gas-assisted molding in plastic injection molding for over 20 years, providing custom gas-assisted molded parts to customers around the world. Gas-assisted injection molding is a great option that has allowed many large, heterogeneous parts to be made in less time and cost without sacrificing quality or design choices

Kemal has rich experience in design engineer, mold making team, and injection molding technology team to provide professional design, production, and testing services for your gas-assisted injection molding mold

We have not only precise mold making equipment, but also gas-assisted injection molding equipment, such as nitrogen generator, air pressure control regulator, etc. our company also has 60-2000 ton injection molding machine to provide professional services for your gas-assisted injection molding.

Gas-assisted injection molding is mainly used in automotive, medical, home appliances, engineering products, and other industries.

If you need gas-assisted injection molding project information or quotation, please contact us immediately,  we will reply to you within 4 hours!

More Questions You May Ask

What is gas assist injection molding?

Gas-assisted injection molding systems inject an inert gas (usually nitrogen) directly into the plasticizing plastic in the mold cavity through a segmented pressure control system, causing the part to expand and create a hollow space, while still maintaining the shape of the product surface.

What’s the APPLICATIONS of gas assist injection molding ?
  1. Tubular and rod-shaped parts such as door handles, swivel chair supports, hooks, handrails, rails, hangers.
  2. Large flat parts, such as door panels, copier housings, dashboards, etc.
  3. Complex parts such as bumpers, appliance housings, car bodies, etc.with complex shapes, uneven thicknesses, and defects such as shrink marks and stains caused by conventional injection techniques.
What is the Principle for gas assist injection molding?

   Please below image.

 

Gas Assist injection molding process

What's the advantages of the gas assist injection molding ?
  1. It is capable of forming plastic parts with uneven wall thicknesses and complex three-dimensional hollow plastic parts.
  2. The continuous flow of gas from the gate to the end of the flow, with no pressure loss, enables low-pressure injection molding, resulting in molded parts with low residual stress, low warping, and dimensional stability.
  3. The gas-assisted injection helps to reduce the weight of thin-walled parts by improving the molding performance of the part due to the airflow assisted filling of the mold.
  4. Due to the lower injection molding pressure, it is possible to mold larger parts on injection machines with lower clamping forces.

 

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GAS ASSIST INJECTION MOLDING: THE ULTIMATE FAQ GUIDE

As a professional Gas Assist Injection Molding manufacturer with 24 years of experience. Kemal pays 100% passion to serve you well.
Here is the FAQ list of the Gas Assist Injection Molding
You could check any question about the Gas Assist Injection Molding
that you would like to know. Such as:
What are the advantages of gas-assist injection molding?
What are the defects of gas-assisted injection molding?
What is the difference between the Gas assisted injection molding mold and the traditional mold?

For further communication just feel free to Contact Kemal Team.

Here is the FAQ List:

1.How does Gas Assist Injection Molding work?

2.What are the steps of the gas-assisted injection molding process?

3.What are the components of the gas-assisted injection molding system?

4.What kinds of injection methods are available for gas-assisted injection molding?

5.What are the advantages of gas-assist injection molding?

6.Compared with the traditional injection molding method, what are the advantages of gas-assist injection molding?

7.What are the disadvantages of gas-assist injection molding?

8.What are the basics of gas-assisted injection molding?

9.What should we pay attention to when gas-assist injection molding?

10.What are the defects of gas-assisted injection molding?

11.In gas-assist injection molding,how to avoid gas blowing through the product?

12.In gas-assisted injection molding, what should be done if the gas fails to reach the end of the airway?

13.In gas-assist injection molding,What should we do if the cavity exhaust is bad (bad flow line)?

14.In gas-assisted injection molding, What we can do when the streamline appears at the end of the molding?

15.How to avoid hysteresis marks in gas-assisted injection molding?

16.How to deal with depression in gas-assisted injection molding?

17. In gas-assist injection molding,When the mold is opened, what should be done if the product expands without leakage of gas pressure?

18.In gas-assist injection molding,What we should do when the surface of the product collapses?

19.How to reduce the mold cost when designing a gas-assisted injection molding tool?

20.How to reduce the forming time when using the gas-assisted injection molding ?

21.In gas-assisted injection molding, what happens when the gas enters the plastic following the direction of least resistance?

22. What can Moldflow do in gas-assisted molding technology in the application of automotive doorknobs?

23.What are the characteristics of gas-assisted injection molds?

24.What product production does Gas-assisted injection molding technology generally used in?

25.What product production does Gas-assisted injection molding technology generally used in?

26.What is the difference between the Gas assisted injection molding mold and the traditional mold?

27.What are the basic design principles of Gas assisted injection molding parts and Gas assisted injection molding molds?

 

1.How does Gas Assist Injection Molding work?

The Gas Assist Injection Molding working process is as below:
When Gas Assisted Injection Molding works, an accurately measured melt is injected into the cavity first, and then a gas (usually nitrogen) is injected into the melt through a special nozzle, gas diffusion pushes the melt into the cavity.
After that, the pressure of the gas in the melt remains constant or increases to a certain extent for the pressure holding filler, After cooling, remove the gas in the plastic parts can be demoulded.

2.What are the steps of the gas-assisted injection molding process?

The steps of the gas-assisted injection molding process are as below:
The first stage of Gas Assist Injection Molding: Plastic injection, the melt enters the cavity,a thinner solidification layer is formed when a cooler wall is encountered.

The second stage of gas-assisted injection molding: Gas incident, inert gas enters the molten plastic, Push the center of the unsolidified plastic into the unfilled cavity.

The third stage of Gas-Assisted Plastic Injection Molding: At the end of the gas incident, the gas continues to push the plastic to melt until it fills the cavity.

The Forth stage of Gas-assisted injection molding: the gas hold pressure, In the holding pressure state, the gas in the air passage compresses the melt to fill the material to ensure the appearance of the parts.

3.What are the components of the gas-assisted injection molding system?

The components of the gas-assisted injection molding system are as below.
(1) Ordinary injection molding machine(The accuracy of material calculation is generally quite high).
(2) The Nitrogen control system, Including self – enclosed gas auxiliary nozzle.
(3) High-pressure nitrogen generator.
(4) Industrial nitrogen cylinders and air compressors that provide supercharging power.
(5) The mold which design for gas-assisted injection molding.
(6) Gas-assisted nozzles

4.What kinds of injection methods are available for gas-assisted injection molding?

The injection methods are available for gas-assisted injection molding are as below.
(1) Sealed Injection Gas
The gas directly inject into a mold cavity to make the finished plastic hollow,
There is no need to use a live valve, just through the simple mold processing,
the gas auxiliary nozzle installed in the mold.
There may be one or more places on the same mold where gas is injected
(2) IN-GAS NOZZLE
A special closed air injection nozzle can be installed on the injection machine.

5.What are the advantages of gas-assist injection molding?

The advantages of gas-assist injection molding are as below:

(1) Design freedom.

Plastic parts with complex functions can be integrated into a single component.
Thick wall and thin wall parts can be combined on the same part.
The strength of the product can be increased by using a hollow “stiffener” section.
Improve the quality of the parts.
By reducing the micro-shrinkage, product distortion and deformation are reduced.
Eliminate shrinkage marks.
As the number of injection points decreases, so do the ripples and weld lines.

(2) Reduce production cost.

As the wall thickness is reduced, the total weight of the finished parts is reduced.
The cooling time and cycling time are shortened due to the smaller wall thickness.
As a result of reducing the clamping force and injection molding pressure, energy consumption cost is reduced.
Because of the integration of parts, the assembly cost is reduced.

(3) Reduce Investment Costs.

Because the injection pressure is low, the clamping pressure of the injection molding machine can be reduced, and the injection molding machine with smaller tonnage can be used.
Because of the low injection pressure, the manufacturing cost of the mold is reduced.
The low injection pressure reduces the loss of the mold, thus reducing the maintenance cost.

6.Compared with the traditional injection molding method, what are the advantages of gas-assist injection molding?

The advantages of gas-assist injection molding are as below.
(1) It can produce plastic parts with uneven wall thickness and complex three-dimensional hollow plastic parts.

(2) When the gas forms a continuous airflow channel from the gate to the flow end, there is no pressure loss. So low-pressure injection molding can be realized.
At the same time, the plastic parts with residual stress have small warping deformation and stable size.

(3) With the assistance of airflow, the forming performance of the plastic parts is improved. Therefore, gas-assisted injection is helpful for forming thin-wall plastic parts and reducing the weight of the plastic parts.

(4) Because the injection molding pressure is low, it can produce the parts on an injection machine with less clamping force.

7.What are the disadvantages of gas-assist injection molding?

The disadvantages of gas-assist injection molding are as below.
(1) It is necessary to add an air supply device and filling nozzle, which increases the cost of equipment.

(2) The precision and control system of the injection machines is required when using gas-assisted injection molding technology.

(3) A different gloss is produced on the surface of the injected and uninjected gas.

8.What are the basics of gas-assisted injection molding?

The basics of gas-assisted injection molding are as below:

(1) At the point of entry, when the pressure of the gas is greater than the pressure of the plastic, the gas is injected into the plastic.

(2) Gas injected into the plastic must be prevented from escaping from the point of entry.

(3) The gas in the plastic will flow from high pressure to low pressure.

(4)When plastic is cooled and shaped, the pressure is controlled by a gas, not a molding machine.

(5) In a continuous air passage, the pressure of the gas is the same at the inlet and the end.

(6) In order for a uniform pressure to be applied throughout the mold, the high-pressure gas will flow through very small holes very quickly.

(7) The gas in the plastic must be discharged before the mold is opened, discharged into the atmosphere by way of drainage, or returned to its original source through a filter for recycling.

(8) Compared with gas, plastic is incompressible. Therefore, increasing gas pressure cannot achieve the filling effect.

(9) The shrinkage of plastics during cooling can be compensated by the expansion of gases.

 

9.What should we pay attention to when gas-assist injection molding?

The things that we pay attention to when gas-assist injection molding are as below:

(1) The flow of gas and plastic should be consistent.

(2) If there is no blocking valve in the nozzle of the injection machine, the time of filling the material pipe (the screw moves backward) should be extended as far as possible, so as to avoid the high-pressure plastic and gas in the mold backflow into the material pipe.

(3) After the molding machine injection plastic, the gas supply plastic during the molding and cooling required pressure.

(4)The gas will follow the path of least resistance and enter the middle of the thicker section. So this part of the plastic is still in a molten state, at the same time the minimum viscosity. In addition, gas flows from high to low pressure or from low temperature to high temperature.

(5) At the point of entry of the gas, the injection pressure of the gas is greater than that of the plastic, and the gas will be set into the plastic.

(6) If the gas escapes, no effective pressure can be supplied. In addition, the use and cost of gas will also increase.

 

10.What are the defects of gas-assisted injection molding?

The defects of Gas-assisted injection molding are as below:
(1) Gas blowing wear.
(2) The gas failed to reach the end of the airway.
(3) Poor cavity exhaust (poor flow line).
(4) The streamline appears at the end of the product forming.
(5) Hesitation mark.
(6) Sag.
(7) When the mold is opened, the product expands because the gas pressure is not released.
(8) Poor sag or collapse of the product surface.

11.In gas-assist injection molding,how to avoid gas blowing through the product?

If we would like to avoid the gas blowing through the product, we should pay attention to that:
(1) Gas injection time is delayed (let more plastic enter the mold first).
(2) Reduce the rate at which gas pressure rises.
(3) Reduce high pressure holding time.
(4) Increase plastic injection.
(5) Reduce the pressure of the first high-pressure holding (HP1).
(6) Change the material.
(7) The crystallized material is better.

12.In gas-assisted injection molding, what should be done if the gas fails to reach the end of the airway?

When the gas fails to reach the end of the airway, we should pay attention to that:

(1) Reduce the amount of plastic emitted.
(2) Early injection time of gas.
(3) Increase the rate at which gas pressure rises.

13.In gas-assist injection molding,What should we do if the cavity exhaust is bad (bad flow line)?

When the cavity exhaust is bad (bad flow line), we should pay attention to that:
(1) Reduce the injection rate of plastic
(2) Modify the injection point of plastic (filling point),
(3) Increase the injection port

14.In gas-assisted injection molding, What we can do when the streamline appears at the end of the molding?

When the streamline appears at the end of the molding,
we should pay attention to that:

(1)Early injection time of gas.
(2)Increase the rate at which gas pressure rises.

15.How to avoid hysteresis marks in gas-assisted injection molding?

If we want to avoid hysteresis marks in gas-assisted injection molding, we should:
(1) Early injection time of gas.
(2) Reduce the injection pressure and the injection rate of the plastic so that gas can enter the plastic easily.
(3) Change the location of the gas entry to the “low-pressure plastic zone”, e.g. the downstream of the plastic entry point; Or increase the cross-section of the plastic entry point

Note: The above solution is to keep the plastic flowing until the cavity is filled with plastic and gas.

16.How to deal with depression in gas-assisted injection molding?

(1) Increase high-pressure retention.
(2) Early injection time of gas.
(3) Increase the pressure on HP1.
(4) Add airway to the concave surface.

17. In gas-assist injection molding,When the mold is opened, what should be done if the product expands without leakage of gas pressure?

(1) Reduce the total time of gas injection.
(2) Reducing Time of low pressure holding and Reducing ejection pressure.
(3) Blow away the plastic at the point of entry.
(4) Change the point at which the gas enters.

 

18.In gas-assist injection molding, What we should do when the surface of the product collapses?

(1) Cooling water is added to reduce mold temperature
(2) Reduce the firing rate of the plastic
(3) Increase the pressure of the gas
(4) Check for leaks
(5) Change the plastic

19.How to reduce the mold cost when designing a gas-assisted injection molding tool?

When designing a gas-assisted injection molding tool, we can cut down the cost like that:
(1)Reduce product wall thickness, and Reduce product weight, less job on manufacture, less cost.
(2)Use high flow index MFI materials or increase the firing rate of plastics So it could reduce the product wall thickness.
(3)Use low-cost or low-density plastics to increase flow rates.

20.How to reduce the forming time when using the gas-assisted injection molding?

When using the gas-assisted injection molding, we can reduce the forming time as below:
1)Reduce the product wall thickness, which could reduce the cooling time.
2)Lower mold temperature could reduce the cooling time.
3)Mold materials with better thermal conductivity, such as aluminum or copper.
4)After molding, cool with water.

21.In gas-assisted injection molding, what happens when the gas enters the plastic following the direction of least resistance?

1) Thicker section.
2) The part with the lowest viscosity of the plastic.

22. What can Moldflow do in gas-assisted molding technology in the application of automotive doorknobs?

The Moldflow gas-assisted molding technology was used to optimize the design and process parameters of inlet position, inlet time, plastic injection amount, delay time, gas pressure retention curve, etc.
Reduce the blindness of the design process, reduce the number of mold tests and change, reduce the time of mold test.
Save cost and shorten the product development cycle.

 

23.What are the characteristics of gas-assisted injection molds?

1)Too large or too small will be detrimental to the penetration of the end of the airway.
There should be a large arc transition at the airway bend.
Air passages can be arranged at the root of stiffeners, self-tapping screw columns, and other structures.
In order to use the structure as a part of the airway filling shrinkage.

2)The fit clearance of the air needle shall be less than 0.02mm to prevent the melting material from entering the air needle clearance.
3)The air needle periphery and the mold seal must be good.

4)The air needle is designed to prevent nitrogen from escaping from the clearance between the air needle and the product during cooling.

5)The air needle should not be too close to the gate. Because the temperature near the gate is the highest and the viscosity is low when filling, it is easy for the molten material to enter the gap of the air needle, resulting in shrinkage marks, blow cracks, and other defects.

24.What product production does Gas-assisted injection molding technology generally used in?

Gas-assisted injection molding technology can be applied to various plastic products.
Tubular and rod-shaped parts, such as door handles, swivel chair holders, hooks, armrests, railings, hangers.
Large flat parts, such as door panel, duplicator shell, instrument panel, etc.
Complex parts with complex shapes and uneven thickness such as bumpers,
home appliance shells and car bodies, as well as defects such as shrinkage marks and stains caused by traditional injection technology.

 

25.What is the difference between the Gas assisted injection molding mold and the traditional mold?

The gas-assisted mold has an air inlet element (gas needle) and an air inlet design compared with the traditional mold.
The term “airway” can be simply understood as a passage of gas. The gas needle is a key component of a gas-assisted tool.
It directly affects the process stability and product quality.

 

26.What are the basic design principles of Gas assisted injection molding parts and Gas assisted injection molding molds?

1)First, Consider which wall thicknesses need to be hollowed out and which surface indentations need to be removed, and then consider how to connect these areas to become airways.

2)Large structural parts: overall thinning, local thickening for the airway.

3)The airway should be evenly distributed across the cavity in accordance with the main flow direction, and closed-circuit airways should be avoided.

4)The cross-section of the airway should be nearly round to allow the flow of gas smoothly, Airway section size should be appropriate. Too small an airway can cause gas penetration, Too large an airway can cause weld lines or cavitation.

5)The airway should extend to the final filling area (usually on a non-apparent surface),But it does not need to extend to the edge of the cavity.

6)The main airway should be as simple as possible, the length of the branching airway should be the same, and the end of the branching airway can be gradually reduced to prevent gas acceleration.

7)If the airway is straight, it should not be curved (the fewer bends, the better).
The corner of the airway should adopt a large rounded radius.

8)For multi-cavity molds, each cavity is supplied by an independent air nozzle.

9)The gas should be confined in the airway and penetrate to the end of the airway.

10)Accurate cavity size is very important.

11)A well-balanced cooling of the parts is very important.

Flow balance is important for uniform gas penetration when gate intake is used.

12)Accurate injection amount of glue is very important, each injection amount error should not exceed 0.5%.

13)The overflow well at the final filling can promote gas penetration, increase the air passage hollowing rate, eliminate hysteresis marks, and stabilize product quality.
A valve gate is installed between the mold cavity and the overflow well to ensure that the final filling occurs in the overflow well.

14)The small sprue prevents the backward flow of gas into the runner when the air nozzle is taken in.

15)The inlet gate can be placed on the thin wall and kept at least 30mm away from the inlet to avoid gas infiltration and backflow.

16)Air nozzles should be placed on thick walls and farthest from the final filling.

17)The air nozzle outlet direction is consistent with the material flow direction.

18)Keep the front edge of melt flow advancing at an even speed, and avoid forming the V-shaped melt flow front.

19)In the case of material shortage injection, the volume of the unfilled cavity before intake shall not exceed half of the total airway volume.