Inox Plastic Injection Molding

If you are looking for a trusted plastic injection molding provider, Inox Casting is one of the recommended that can satisfy your needs. Inox casting will bring your business to a higher level. We have 20 years of existence in this industry and as of that, we obtain rich experience in the plastic injection molding industry.

 Inox Casting plastic injection molding is one of the most popular and commonly used processes of producing identical plastic products in high volumes. It will bring a lot of benefits and advantages including the following:

• Fast production and highly efficient
• Low labor costs
• Design flexibility
• High-output production
• Large material choice
• Ability to include inserts

With Inox Casting plastic injection molding, it is possible to use fillers in the molding material. These fillers reduce the density of the plastic whilst it is being molded, and can help add greater strength to the completed part.

We offer comprehensive custom plastic injection molding services to a wide range of industries.  From low volume work to high volume production runs, we have the expertise and facilities to meet our customers’ contract manufacturing needs. 

Inox Casting has a full capability to source and to mold any grade of material from typical commodity-grade plastics to engineering, functional, and structural grade materials in a variety of colors and formulations. 

For any inquiries, you can email us!

Plastic Injection Molding: The Ultimate Guide

Let’s look at some fundamental factors you should know about plastic injection molding process.

Take a look:

1.  What Is Plastic Injection Molding?

Plastic injection molding is the process of making different shapes and sizes of plastic materials using molten plastic.

It uses thermoplastic polymers or thermosetting that are injected into mold cavities that solidifies to form the final product.

plastic injection molding

2.  Plastic Injection Molding Process

The plastic injection molding process involves a number of steps that you must take into account.

Despite sounding easy from the definition, you have to make sure that all the parameters are under control.

plastic injection molding process

To ensure that the overall quality of plastic molds is adhered to, here are the main steps you have to follow.

Step One: Selection of the Right Mold And Thermoplastic

First, you have to select the right type of thermoplastic that will fit the right type of mold design.

There are specific types of thermoplastics that do not fit particular mold designs.

You have to be careful with the selection process to ensure that the mold design fits the thermoplastics.

Additionally, you must know the design that you intend to create before designing the mold.

The most common types of thermoplastics that you can opt for include:

i. Acrylonitrile-Butadiene-Styrene (ABS)

ii. Polycarbonates (PCC)

iii. Nylons (PA)

iv. Polypropylene (PP)

You must also note that the final characteristics that you want on your product will influence your thermoplastic choice.

Step Two: Feeding And Melting Plastic Materials

As soon as the plastic injection process begins, you will proceed with feeding the thermoplastic materials to the machine.

You will feed the thermoplastic materials through the hopper or feeder and it will be guided into the cylindrical heated barrel.

The cylindrical heated barrel has a screw that turns and continues with the plastic material feeding process.

As it turns, the cylindrical heated barrel melts the thermoplastic materials by maintaining the right temperature.

Step Three: Injecting Molten Plastic To The Mold

As soon as the molten plastic flows to the end of the barrel, the gate at the exit of the barrel closes.

After that, the screw moves back to allow more thermoplastic materials to flow from the hopper into the barrel.

As that happens, pressure inside the barrel builds up, ready to release the molten plastic into the mold.

At that point in time, the molds come together to create the shape required of the final product.

Once the pressure inside the cylindrical heated barrel builds up, the gates open and release the molten plastic into the mold.

Step Four: Molding And Cooling

Once the molten plastic is in the mold, it remains under pressure for some time or through the holding time.

The holding time will vary ranging from milliseconds to minutes depending on the type of plastic materials.

Apart from that, the complexity of the mold design will also affect the overall holding time.

The holding time will ensure that the mold forms correctly and the plastic packs out of the tool.

Finally, the mold will open up to release the final product and leave it to cool down through the cooling time.

As soon as the parts are cool enough, you will release them from the molding machine and proceed with secondary processes.

The secondary processes that you can work on are polishing, cleaning, and dying before sorting and packaging.

3.  Types Of Injection Molding For Plastic Material

There are many plastic injection molding technologies that you can explore to bring prototypes to life.

Here are some of the technologies that you can choose to assist in the plastic injection molding process.

Thin Wall Plastic Injection Molding

You will use the thin wall injection molding technology to make thin-walled plastic materials.

It is the most suitable technology that you can use to make electronics, test apparatus, vessels, tubes, among other enclosures.

thin wall plastic injection mold

You must be careful with every aspect of the design, and processing to ensure you produce high quality materials.

The thin wall geometry must be of high quality to ensure that it holds up well.

Gas-Assisted Injection Molding

You will use the gas-assisted injection molding process to manufacture thick plastic molds.

Gas-assisted injection molding shoots gas into plastic material-filled injection mold.

It allows the plastic on the outer part of the mold to have a finished smooth appearance.

The inner part of the mold remains hollow or porous with minimal risk of cracking the mold.

gas assisted injection molding

It not only minimises the risk of breaking, but also reduces the overall cost of production.

You will use fewer plastic materials in the gas-assisted injection molding process thus saving on cost.

Liquid Silicone Injection Molding

You can opt for the liquid silicone injection molding process to make very hard plastic molds.

It mixes the thermoplastic materials with liquid silicone to make hard plastic to withstand very high temperatures.

liquid sillicone injection molding

Apart from that, the process is suitable for making plastic materials that can withstand chemical agent erosion.

Micro Injection Molding

You can use micro injection molding to make plastic molds with shot weights such as 1 to 0.1 grams.

It is also suitable for making plastic materials with a tolerance ranging between 10 to 100 microns.

micro injection molding

You can use it to manufacture small and complicated geometries with the greatest precision and accuracy.

Reaction Injection Molding

You will use the reaction injection molding process to make plastic or polymer molds through direct polymerization.

You will use highly reactive plastic liquids mixed under high pressure before injecting into a mold.

It requires a curing reaction to occur in the mold, thus making it stronger than other types of molds.

reaction injection molding

It is suitable for machining plastic molds such as air spoilers, automotive bumpers, and fenders among others.

4.  Design Guideline In Plastic Injection Molding

One of the most important aspects to consider in plastic injection molding process is the design of the mold.

The design of the mold plays an important role in considering the type of plastic mold outcome.

There are numerous factors that you have to consider during the designing process of the plastic molds.

Here are the main factors to consider during the designing process of plastic molds.

Size Of The Plastic Part

You must consider the size of the plastic part you intend to make before coming up with the right mold.

You will look at the size, volume, depth, as well as the projected mold area during the designing process.

Tolerance Of The Plastic Part

You should also consider the resin tolerance depending on the material you select and the machining process.

For instance, you can have a machine with a machining tolerance of +/- 0.05mm to produce a resin tolerance of 0.002mm/mm.

Type Of Materials

You must also look at the type of materials that you will need to make the final product during the designing process.

You can choose from different materials including acrylonitrile-butadiene-styrene (ABS), polycarbonates (PCC), nylons (PA), and polypropylene (PP) among others.

Surface Finishes

You should also look at the most suitable type of surface finish that will fit your part specifications.

The main types of surface finishes you can opt for are PM-F0, PM-F1, SPI-C1, PM-T1, PM-T2, and SPI-B1 among others.

Draft

You should also consider having a draft of what you expect of the plastic molding process.

The main factors that you should look at are:

i. VERTICAL FACES such as 0.5°

ii. MOST SITUATIONS such as 2°

iii. MINIMUM FOR SHUT OFF such as 3°

iv. MINIMUM FOR LIGHT TEXTURE (PM-T1) such as 3°

v. MINIMUM FOR MEDIUM TEXTURE (PM-T2) such as 5

Undercuts

The designing process must also consider the undercuts on the plastic parts to produce through plastic injection molding process.

You will consider the undercuts in terms of height, width, and pull in millimetres.

Wall Thickness

You will also look at the intended thickness of the wall that you would like to have.

In this case, you must consider the types of material and the most convenient wall thickness.

Radii

Some of the materials have rounded corners rather than sharp corners thus the need to look at the radius.

It is important to identify the radii of the parts before the milling process begins.

5.  Raw Material For Plastic Injection Molding

Well, all the plastic injection molding processes begin with the assembly of all the materials.

You must have the machine or the plastic injection molding machine that will facilitate the molding process.

Apart from the machine, you must have a mold, which will shape the molten plastic accordingly.

You will have to design the mold to suit the shape of the parts that you intend to make.

Additionally, you should have the plastic materials or the thermoplastic suitable for injection molding.

Here is a list of the plastic materials that you can use in the plastic injection molding process.

Acrylonitrile-Butadiene-Styrene (ABS)

These materials have a smooth, tough, and rigid finish suitable for parts with great tensile strength and stability.

Polycarbonates (PCC)

This is a light weight, high performance plastic material, with high impact strength and stability.

Apart from that, it also has great electrical properties for parts that conduct electric current.

Nylons (PA)

You can choose from the wide range of nylon materials which have various properties to suit your application requirements.

Additionally, they have great chemical and temperature resistance with the ability to absorb moisture.

Polypropylene (PP)

You can opt for the translucent, semi-rigid and tough polypropylene with good heat resistance and fatigue.

Apart from the above categories, there are also other types of plastic materials that you can opt for.

6.  Choosing Mold For Plastic Injection Molding

The mold is the tool that you will use to produce the shape or design of the plastic parts.

You have to be careful when choosing or designing the right type of mold because it is expensive.

After making a mold, you can use it in multiple production or injection molding of other plastic parts.

You can produce the mold through electrical discharge machining processes or CNC machining.

Additionally, there are a few factors that you have to consider when choosing the mold such as:

Mold Design

The mold is made of two main parts known as the injection mold plate (moulder) and the ejector mold plate (mouldmaker).

• Multi-shot Moulding

You can also opt for the multi-shot mold which are designed to overmould within one cycle through special molding machines.

Mold Storage

You should store the original mold in the right conditions such as humidity and temperature to maintains its originality.

It is significant to store the mold in perfect conditions due to the high original cost of manufacturing.

7.  Choosing Plastic Injection Molding Machine

You can choose from the two main types of plastic injection molding machines for your molding project.

Usually, plastic injection molding machines are differentiated according to the mode of configuration.

plastic injection molding machine

Here are the two main types of plastic injection machines according to the mode of configuration.

Horizontal Plastic Injection Machine Configuration

Horizontal plastic injection machine configuration occurs on the horizontal machining center with spindles parallel to the floor.

With horizontal orientation of spindle, tools stick out of tool holders and cut across the side of the side piece.

Vertical Plastic Injection Machine Configuration

Vertical plastic injection machines occur on a vertical machining center with a spindle that faces the ground.

With the vertical orientation, tools stick downwards from the tool holders and cuts across the top of the workpieces.

8.  Benefits Of Plastic Injection Molding

Well, there are plenty of benefits that you will draw from the use of plastic injection molding.

Here are the main advantages of using the plastic injection molding process.

Scaled Up Production

All you have to do is come up with the original mold design and then continue with the production process.

With the mold design at hand, you can produce as many parts as possible at a lower cost.

Minimal Wastage

You will also reduce the quantity of waste materials produced from the machining process.

Plastic injection machining does not involve cutting off parts thus minimising waste of materials.

Part Reliability

You can produce numerous identical parts from plastic injection molding which allows for part reliability.

Additionally, it allows for consistency of parts in the injection process due to part similarities.

9.  Plastic Injection Molding Products

You can use plastic injection molding to produce different types of products.

Most of the products of plastic injection molding are suitable or useful in our daily work or living experiences.

You can use to produce products for daily use such as bottle tops, combs, toys, packaging, wire spools and chairs.

Apart from that, you can also use it to produce mechanical parts, automotive parts and storage containers among others.

10.  Reducing Cost Of Injection Molding Plastic

In any manufacturing process, you should aim at reducing the overall cost of production to maximise profits.

There are numerous factors that you can explore to reduce the overall cost of plastic injection molding.

Here are some of the factors that you should consider to reduce the cost of plastic injection molding.

• Removing unnecessary features
• Eliminating undercuts
• Using core cavity approaches
• Designing self-mating parts
• Reducing cosmetic finishes
• Considering part sizes
• Monitoring DFM analysis
• Using multicavity or family type of molding
• Modifying and reusing existing moulds

11.  Benefits Of Prototype Tooling For Injection Molding Plastics

Prototyping is the initial step in making the part ideas tangible in the plastic injection molding process.

You should consider prototyping for production efficiency, problem solving, quality assurance, material feasibility, as well as functionality.

Here are the main advantages of prototyping for plastic injection molding.

• Early discovery of the problems in the design
• Estimating the cost of production, materials requirement, and manufacturing time.
• Selection of machines required or significant with plastic injection molding process
• Prior testing to determine durability and significance of the parts
• Identifying the parts that require improvement
• Receiving feedback from clients and other end users
• Establishing the function of the final design

12.  Plastic Injection Molding Defects

Well, the plastic injection molding is usually a smooth process but may also have or face serious defects.

You can identify defects on the plastic injection molds or molding process by troubleshooting the machines.

Here are some of the defects that you can identify on the plastic injection molding process.

Flash Defects

The main causes of flash defects come from low clamp force and high injection pressure.

In this case, you can sort out the problem by increasing the clamp force and reducing injection pressure.

Warping Defects

You can experience warping defects due to non-uniformity in the rate of cooling

The best way of eliminating warping defects is by ensuring uniformity of the cooling rates.

Bubble Defects

The main cause of bubble defects is high injection temperature, high moisture content, and non-uniform cooling rates.

You can solve the problem by reducing injection temperatures, moisture content and having a uniform cooling rate.

Unfilled Sections

You can also experience defects of unfilled sections due to insufficient shot volumes and low material flow rate.

You can sort out the problem by increasing the shot volumes and material flow rate.

Sink Marks

Sink marks may also appear on the final parts due to low injection pressure and non-uniform rate of control.

You can sort out the problem by increasing the injection pressure and having a uniform cooling rate.

Ejector Marks

You may also have ejector marks due to shorter cooling times and higher ejection forces.

The best mode of solving the problem is by maintaining proper cooling times and reducing ejection forces.

13.  Tooling Considerations For Injection Molding Plastic

Well, you have to be careful and consider proper tooling for the plastic injection molding process.

There are a number of tooling considerations that you must take care of to ensure proper production.

Here are the main tooling considerations that you should note.

Financial Considerations

You have to note that the cost of production is quite high especially when considering the initial tooling cost.

The cost of machines is high, thus the need of having a proper financial backup before starting the project.

Production Quantity Considerations

You must also know the quantity of parts that you would like to manufacture before choosing the right tooling.

In this case, you should consider a flexible tooling system that allows you to produce different part quantities.

Design Factor Considerations

You should look at the design factor in terms of minimising the number of parts and simplifying geometry of items.

In such a case, you have to choose a proper tooling system that can produce different designs with minimal production defects.

Production Considerations

You must also consider proper tooling that will minimise the production time while producing perfect materials.

The tooling must be sensitive enough to various production conditions to ensure maximum flexibility on all aspects of production.

For all your plastic injection molding needs, contact us now.