Preform injection molding

Inox Cast Preform Injection Molding

Inox has been producing preform injection molding for more than 20 years. We are already providing preform injection molding across the countries in the world. Along with our highly skilled engineers, we can create preform injection molding machines depending on your technical specifications.

Our preform injection molding has cost-effectiveness, high efficiency, and energy-efficient. We engineered this amazing equipment safer to use to prevent work-related incidents. This preform injection molding is approved and certificated by ISO9001, TS 16949, and CE inspection.

Inox Cast provides custom-made preform injection molding equipment or even standard designs. You can directly send us your specific ideas for the pattern you want for your ideal preform injection molding. We will do the rest procedure to make your desires come true.

The finished preform parts are usually contained of glass fibers since they are beneficial for products with complex design features or deep mouldings. While there are numerous methods used for processing plastic preforms. Some of these methods are the plenum chamber process, the use of a water slurry system, and the directed fiber process.

However, the parts or components produced through this process can have different shades of colors as per customers` requests.

The preform injection molding has features including:

• the content of diethylene glycol
• molecular weight
• acetaldehyde content
• carboxyl group
• a glass transition point
• the degree of clear transparent limpid lucid
• the percentage of total polymer
• Melting point

Choose preform injection molding by Inox Casting for your next projects or applications. We are well-equipped with excellent technicians and advanced machines that will accomplish every request of our valued customers all over the world.

Please check out Inox Cast today to support your business!

Preform Injection Molding: The Ultimate Guide

Probably, you are wondering what preform injection molding is all about.

A reason this guide explores everything about preform injection molding incuding features, necessary conditions, techniques and characteristics, amongst others.

Let’s dive right in.

1. What Is Preform Injection Molding?

Preform injection molding

Preform injection molding is a process in which plastic parts are produced by injecting a mass of plastic called a preform into a heated mold.

The mold is cooled and ejected to eject the plastic parts in this process.

Additionally, the preform (a shaped plastic blank) is placed into the mold cavity and injected with molten resin under high pressure.

This manufacturing process allows designers and manufacturers to create products like plastic bottles uniform in shape and size.

Plastic injection mold

2. What Are The Conditions For Performing The Preform Injection Molding Process?

There are several conditions to execute the preform injection molding process. Some of them are given as follows:

Process Parameters Controlling

The various parameters controlled during the process should be in specific values; otherwise, the mold shape or structure will be affected.

Some of the parameters which are essential while preform the injection molding process is given as follows:

i. Screw Speed

Because this is a thermoforming process, screw speed plays a vital role in forming quality.

To ensure that parts are being formed at a proper rate, monitor your screw speed.

You can do this either by tracking revolutions per minute or monitoring RPM via sensor feedback could be as high as 160 rpm in heavy machines.

ii. Pressure Of Injection

Injection pressure required to perform a particular job is determined by the mold type, part design, and material used.

This injection process takes place at much higher pressures than other injection processes. Preform injection molding equipment generally runs at 100-200 bars (1,500-3,000 psi).

iii. Injection Speed

The Injection Speed condition is one of the most important conditions for preform injection molding.

It is indispensable for preforms that are larger than 1 inch thick.

iv. Mold Temperature

The temperature of the mold is essential because it influences how quickly air escapes from the mold and how quickly the material cools when injected into it.

v. Tube Temperature

A significant factor in preform injection molding is tube temperature, which should be held in the range of 90-110°C.

The inside surface of the tube should be smooth and even provide a consistent internal cavity for injection moulded parts.

vi. Temperature Of Nozzle

The higher the temperature of the nozzle, the denser the polymer becomes.

However, if it gets too hot, the melt may become pasty and not be able to flow freely through the injection molding machine.

Also, the nozzle should be kept at a temperature of 180°C or above to ensure proper melt flow.

vii. Pull Loose

Pull Loose condition is very important to the performance of the Preform Injection Molding process.

Pulling too tight in this process can cause compensation failures, leading to defects and low-quality parts.

Remember, pulling too loose will create excess slush in the mold, not allowing the operator to run features with a good surface finish.

viii.  Speed Switching Mode

Speed Switching Mode is essential for performing the Preform Injection Molding Process because it allows the mould to cool down quickly.

It prevents too much heat accumulation within the mold cavity and relieves non-uniform temperature distribution inside the mold.

Thereby, reducing shrinkage defects and skill marks on molded parts.

ix. Cooling And Cycle Time

There is a certain degree of cooling time required in Preform Injection Molding.

Again, the plastic will absorb heat quickly, and this will take the shape of the mold while at the same time the mold cools down.

This procedure needs careful consideration to ensure that there is enough cooling time.

x. Resin Compatibility With Material

The materials used must be compatible with the resin in the injection molding machine. The compound should not damage the tool.

3. What Are The Features Of Preform Injection Molding?

Preform injection molding is a plastic molding process that uses preforms as the raw material to manufacture the final product.

The various  features of this process are given as follows:

Preform injection molding

       i. Automatic Monitoring And Diagnostic System

It helps operation personnel to monitor the operating state of the equipment and detect unexpected malfunctioning of mould and related equipment in time.

This significantly improves the production efficiency and control capability.

     ii. High Productivity

High productivity is an essential feature of preform injection molding.

A preform can be molded quickly, in less than 20 seconds, and require little training to operate the equipment.

    iii. Higher Surface Detail And Accuracy

Preform injection molding is a critical manufacturing process for manufacturers looking for higher surface detail and accuracy.

It is beneficial when parts need to be created with complex geometries.

The process adds a level of dimension, surface contour, and texture unattainable with traditional molding methods.

    iv. Complex Shapes

Creating complex shapes by preform injection molding is essential for firms that sell parts and products that require intricate designs.

When making a preform, you can make it from metal, rubber, or plastic and then inject the preform into a mold to create the product.

By preform injection molding, you can quickly produce several identical parts.

This is by injecting the resin directly into your mold chamber without having the need to create expensive tooling or making multiple molds from different patterns

     v. Maximum Plasticizing Efficiency

Preform injection molding helps produce efficient parts by maximum plasticizing the material.

This process uses a small volume of plastic injected into a heated cavity of the mold.

As the plastic cools, it shrinks, forcing out any air pockets and creating an efficient part in less time than it would take if injection molding were used.

4. What Is The Processing Method To Preform Injection Molding?

Preform Injection molding Process

The processing method of preform injection molding depends on the production quality and size of the manufacturing company.

Again, the process consists of various steps, which are given as follows:

       i. Pre-Drying

Pre-drying is the first step in preform injection molding where the moisture is dried out of the raw material.

In this process, the raw material (like polystyrene beads) will be dried to about 0.05% moisture content at 180°C for four hours before entering the injection molding machine.

This process reduces the amount of moisture in each preform and helps create better quality parts with a smoother finish.

     ii. Compression And Melting

In the compression and melting process step of preform injection molding, the compressed plastic preform is heated.

It allows it to flow more freely as it is introduced into the mold cavity.

Due to thermal conductivity and viscosity, the molten material filling the mold cavity rises above its solidification temperature.

    iii. Injection Molding

The process begins by first creating a preform, or small low-pressure plastic part that is then injected into a mold cavity by a rotating screw.

As the screw is rotated, it pushes plastic that has been fed into the barrel through several orifices around its perimeter and into the die cavity of the mold.

    iv. Cooling

The plastic then cools and hardens as both the screw and the dies compress it until it has reached its final shape.

The cooling step in preform injection molding follows the injection step, and it occurs when the plastic is still in the cavity of the mold.

The preform is cooled before and during this step, preventing shrinkage from maintaining constant dimensions.

     v. Ejection

The final step in the preform injection molding process is to remove the molded part from the mold, which is done by cutting it apart.

The details are inspected, trimmed, cleaned, and packaged for shipping.

5. Explain The Characteristics That A Preform Mold Manufacturer Should Follow?

A preform injection mold manufacturer should follow the following characteristics associated with product quality:

      i. Molecular Weight

The molecular weight of the polymer materials is an important consideration by the preform injection molding manufacturers.

They will directly impact the physical and mechanical properties of the preforms, which can affect the quality of their final products.

     ii. Melting Point

Melting point affects the chemical composition of each polymer, which can be slightly different in preforms, depending on each polymer’s melting point.

Depending on your end product application and target market, using preforms with a lower melting point may be more beneficial than higher melting point preforms.

    iii. Acetaldehyde Content

Acetaldehyde Content is one of the essential characteristics of preform injection molding manufacturers.

It must be checked before beginning production. It determines both the technical performance of the preform and its toxicity.

    iv. Crystallinity

Before injection moulding, the properties of plastics, such as gloss and colour, may be altered. Crystallinity is a characteristic that gives this plastic its strength, rigidity, transparency, and resistance to heat.

      v. Copolymer Percentage

The copolymer percentage is essential for a preform injection molding manufacturer to consider when designing their molds.

Again, the percentage of the copolymer resin is almost always affected by the raw material supply.

Depending on which supplier provides the raw materials, it can vary from one order to another.

    vi. Experienced in plastic molding

Preform injection molding is a low-volume process for making complex shapes and customized plastic parts.

The preform is heated, injected into a mold, set, removed from the mold, and trimmed to produce a finished amount.

Experienced in plastic molding helps you achieve your product’s best quality and performance even at shallow volumes.

  vii. High-Quality Control Standards

These standards help ensure the high quality of your products and the repeatability of production.

Additionally, the same level of precision is necessary for each batch to guarantee consistent results that meet all quality standards.

It becomes essential to scale up production to maintain high quality and keep costs down as you grow your business.

6. What Are The Advantages Of Preform Injection Molding?

The advantages of this unique process preform injection molding are given as follows:

       i. Reduces Tooling Costs

Preform injection molding is beneficial because it reduces tooling costs since only one set of tools is needed to make the mold.

It is preferred over other injection molding processes such as two-shot molding because it requires less equipment and a smaller investment.

     ii. Shortens Production Times

By injection molding plastic preforms, you can shorten production time and alleviate complex assembly problems.

When parts are formed at a later stage of the manufacturing process, they are much more expensive to produce.

Preform injection molding is up to 3 times faster than other processes used in creating injection molded parts like injection molding or compression molding.

    iii. Reduces The Amount Of Scrap Generated

It is achieved because the primary forming tool, called a preform, has already been created and then injection molded into a final product.

    iv. Reusable

Preform injection molding is reusable, making it more efficient than other methods.

Preform injection molding helps minimize the cost of production.

Since you can reuse these molds repeatedly instead of purchasing new equipment every time you want something made out of plastic.

   vi. Lower Production Cost

This method of molding is cheaper and more effective compared to using production methods such as CNC machining and steel casting

  vii. Efficient And Fast Hydraulic System

Preform injection molding is a very efficient and fast hydraulic system using a steel preform as the primary material.

The main benefit of this process is that it is a flexible manufacturing process where minimal finishing operations are required, which results in quicker production time.

7. What Are The Production Equipment To Preform Injection Molding?

Preform Injection Molding Components

The various components of a preform injection molding machine are given as follows:

       i. Drying Unit

The drying unit in a preform injection molding machine is used to dry the resin.

This need is critical, and an intelligent design of the drying unit will help us save energy and avoid troubles.

     ii. Screw

The screw takes in plastic granules from the hopper and then transports them to the barrel.

Where it pushes the plastic inside it and then transfers it to the nozzle, injecting it into the mold.

    iii. Injection Unit

Here the function of the injection unit is to mix materials and molding cycles and then transfer them into the injection molding machine.

    iv. Control Unit

The purpose of the control unit in the preform injection molding machine is to manage the whole production process automatically.

It collects data from different machine parts and calculates temperatures, injection pressures, and electronic time gates.

That is, by its program before giving outdrive signals to the main components.

      v. Cooling Device

The cooling device in the preform injection molding machine is a metal part; the cooling water will enter here, so the cooling barrel wall has holes.

Besides, the water can flow into the preform cavity through these holes and heat up quickly. Therefore, it can simultaneously reduce thermal stress to improve the dimensional accuracy of products.

8. Explain The Different Applications Of The Preform Injection Molding Process?

The different applications of preform the injection molding process are given below.

       i. Cosmetic Industry

Preform injection molding is one of the essential processes in the cosmetic industry.

This process uses a preform mold base as a cavity for the primary mold.

It is used primarily for producing lipstick cups and tubes, make-up brush handles, pencil tips, etc.

     ii. Food And Beverages

Preform mold injection molding is used in the food and beverage industry for manufacturing plastic bottles, jar lids, and caps.

    iii. Oil Packaging

The preform injection molding process is used to manufacture oil industry products such as plastic pipes, joint connectors, and other oil industry products.

9. Explain The Preform Injection Molding Defects And Their Solutions?

The manufacturers have to face multiple defects if some technical or material faults are present in the machine.

These defects are given as:

        i. Burning

The burning defect is a phenomenon that affects the surface or interior of the finished product and is a result of incompletely burned out preform.

Besides, the principal reason for this is that the mold has insufficient cooling capacity.

To reduce burning in the preform injection molding process, you need to improve cooling while controlling heat transfer.

      ii. Bottom Whitening

The cause of this problem is moisture in flimsy plastic, high-speed cooling, and inadequate mold temperature.

Ensure the injection moulding cycle time does not exceed the material’s heat stability period, stabilize the injection pressure smoothness, increase injection speed using an air knife, etc.

    iii. Silver Or Yellow Streaking

The silver streaks are caused by particulate contamination of the molten polymer with silver, which is present as a dopant in the resin and catalyst system.

The most effective way to reduce it is to use a post-cure timing cycle that follows a post-cure at elevated temperature, known as a formal thermal post cycle.

    iv. Irregular Ring Grooves

Irregular ring grooves are typically caused by various non-uniform filling conditions during melt filling.

Thereby, resulting in polymers along the cavity wall not flowing as easy to fill the groove, which leads to air entrapment.

Improving the melt flow properties of polymers and optimizing venting will help eliminate these defects.

In case you have any questions or inquiries about preform injection molding, contact us now.