Injection Molding | Plastic Injection Molding| Aero-Plastics Inc.

Aero-Plastics specializes in injection molding projects such as insert molding and other value-added services. We offer injection molding PEEK, Ultem and other high-performance engineered resins, plus commodity resins such as polypropylene, polyethylene, polystyrene, ABS, and nylons.

As veterans in high-performance polymers and engineered resins, you can rely on us to provide expert guidance on materials. All of our tooling is built to Class 103, 102, and 101 industry standards.

What is Injection Molding and How Does It Work?

Injection molding is a manufacturing method in which molten material – commonly a thermoplastic or polymer – is injected into a mold in order to produce a part.

A heated barrel mixes the desired material and injects it into a mold cavity. Through the cooling process, it hardens to the shape of the cavity, creating the desired product. Molds are usually designed by an engineer or industrial designer, who then further refines the mold with precision machining.

Use cases for injection molding vary widely; it can be used to manufacture molds and parts from tiny components to large automotive parts.

Injection Molding Machines

Injection molding machines consist of two units: a clamping unit and an injection unit.

Use cases for injection molding vary widely; it can be used to manufacture molds and parts from tiny components to large automotive parts.

Plastic Injection Molding Process

The plastic injection molding process begins with the melting of raw material in a heated barrel, used to mix the desired material prior to injection.

This molten plastic is then injected at high pressure into a mold cavity and cooled to form the desired shape. Molds are usually designed by an engineer or industrial designer, who then further refines the mold with precision machining.

The high injection pressure means that the molten material fills all of the mold’s cavities and forms a solid part. Through the cooling process, it hardens to the shape of the cavity, creating the desired product.

After cooling, the parts are ejected from the molds and can be further processed or assembled as required.

When the part is ejected, it can be post-processed if needed (e.g., painting, finishing) before being shipped out for use.

Injection Molding Machine

Injection molding machines consist of two units: a clamping unit and an injection unit.

The clamping unit of injection molding machines is used to open and close a die in the machine, and to eject the final product.

The two methods for the injection unit are a straight-hydraulic or a toggle.

Straight Hydraulic

A straight-hydraulic injection molding machine uses a hydraulic cylinder to open and close the mold, and then inject plastic through a nozzle in the machine. This type of injection molding machine produces parts with high repeatability and accuracy.

Toggle

Toggle clamping uses the injection unit to melt the material, then inject it into a mold. In a process called metering, a screw then rotates to gather melted material from the hopper, until enough is accumulated to begin the injection process. The injection molding machine controls the injection speed via the rotation of the screw.

Injection Molding Machine | Aero-Plastics

The Advantages of Injection Molding

Manufacturers typically turn to the plastic injection molding process to produce a large volume of a particular part, for several main reasons:

Consistent & Repeatable

The molds used for injection molding offer one of the strongest guarantees that parts will match the original. This lends to brand-consistent quality and part reliability and reduces the amount of plastic material waste.

Injection molded products are also incredibly durable and resistant to wear and tear.

Easily Scalable Production

Injection molding is a perfect solution for scaling large volume or mass production due to the simplicity and consistency of the process. Standardized injection molds allow manufacturers to dial in the specific requirements of their product and reproduce them quickly and accurately.

Low Price Per Unit

After setup costs are paid off, the price per unit of products manufactured via injection modeling drops steeply and remains extremely low. The more parts produced, the lower the individual cost, making plastic injection molding especially suitable for high volume production.

What Plastics & Resins Are Used in Injection Molding?

Aero-Plastics has the ability to mold nearly all engineered resigns, including:

Polypropylene
Polyethylene
Acrylonitrile Butadiene Styrene (ABS)
Polycarbonates
Nylon
PEEK
Ultem

Depending on your application, certain materials may be more suitable than others. For example, if you need a high-strength but flexible material to fill your mold tool, thermoplastic materials like ABS might be best. High-density polyethylene, on the other hand, features a high chemical resistance, making it suitable for products or components that will be exposed to moisture or chemicals.

Our knowledgeable team can help you determine the best plastic materials and process for your specific application and unique needs.

Important Factors to Consider for Injection Molding

Injection molded products may be better suited for some projects over others, and understanding more about the plastic injection molding process can help you make an informed decision.

Before deciding on injection molding for your manufacturing process, it’s essential to consider a few key factors, including:

Quantity

Before selecting plastic injection molding as your production method, it’s important to first determine how many parts need to be produced in order to make the process (and initial investment) cost-effective. You may do this by figuring out how many parts it will take to break even on the project, and building in a conservative margin.

Budget

Injection mold production requires a significant up-front cost, in order to prepare the mold and manufacturing setup. However, this subsequently ensures a low production cost after that initial investment is paid off.

Part and Tool Design

If a part is to be produced by injection molding, this must be considered in its design — this includes simplifying its geometry and number of components as much as possible. The mold should be designed with a goal of minimizing the risk of defects during the production process.

Designs that are well-suited for plastic injection molding should ideally have a uniform wall thickness, as well as avoid sharp corners, undercuts, and other features that could increase manufacturing time or, in some cases, require additional molding processes for an individual injection molded part.

Production

For injection molding, it’s prudent to minimize cycle time as much as possible. The more time you can cut from the cycle, the more money you’ll save.

Simplifying production times often comes down to finding ways that can reduce the number of steps or tooling changes during the injection molding process. This could involve combining parts into a single section or reducing gate locations on the product.

It also helps to keep assembly simple – the more parts required in the setup, the higher the cost, so it’s often beneficial to keep injection molded parts as self-contained as possible.

Aero-Plastics’ Injection Molding Tolerance Objectives

Injection molding tolerances, listed below, are directly related to the material to be molded; part size and part geometry. We review parts and tolerances on a case-by-case basis during quoting, and use a Design for Manufacture process to align your project goal to our manufacturing methods.

We want you to achieve the best value possible — so our experts work with you on these tolerance objectives. Over-specified tolerances can increase project costs, and we understand how to minimize them without sacrificing product quality.

At Aero-Plastics, we strive to provide the highest quality plastic injection molding with the following tolerance objectives, which relate directly to the material to be molded.

Assess All Factors That Influence Applicable Tolerances

Our team of experts will assess physical factors that can influence tolerances, namely the material being used as well as the size and shape of the part being manufactured.

Material

The molding material affects all applicable tolerance objectives, from shrinkage rate to physical properties and cost.

Part Size

Larger parts require a larger tool set and will have greater variation in wall thickness, which can often create an increase in available
tolerances.

Part Geometry

The more complex a part’s geometry is, the higher the tolerance objective has to be in order to maintain quality and consistency. Complex features with tight tolerances may require substantial design revisions or additional tooling.

Review All Injection Molded Quotes

Our team is sure to review parts and tolerances on a case-by-case basis for all plastic injection molding quotes to ensure that we can deliver on all objections and achieve optimal part quality.

Follow Our Design for Manufacture Process

We use a Design for Manufacture process to align your project goal to our manufacturing methods. This process allows us to evaluate the design of a part and molding process before production begins – which ensures that we can successfully meet your requirements and attain part quality.

Provide Post-Molding Machining Processes As Needed

For tight tolerance parts, we can combine molding with post-mold machining operations. We’re on the Boeing QPL for all types and classes of molded parts, and an approved molder on the D1-4426 for BAC 5321 class II injection molded parts.

Manufactured Parts Suited for the Injection Molding Process

Aero-Plastics offers injection molding services for a variety of applications including medical, consumer goods, industrial equipment, automotive components and more. We have the capabilities to provide you with a custom solution that meets your needs.

Products that are well-suited for injection molding include:

Medical Devices (like syringes, surgical devices, or implant parts)
Home Appliances
Automotive Parts
Circuit Boards
Ejector Pins
Toys (like plastic bricks)
Bottle Caps
Air Vents

Unsure if your part is suited for the injection molding process? Our experienced engineers are happy to answer any questions you have and will work with you to determine if plastic injection molding is right for your project.

Our molding tolerance objectives:

The material used dictates the tolerances that can be maintained.
Size and part geometry influence the tolerances.
Aero-Plastics reviews all injection molded quotes to ensure the part quality and objectives can be delivered.
Aero-Plastics uses a Design for Manufacture process to attain part quality.
In cases of very tight tolerances, we can use post-molding machining processes.

Frequently Asked Questions about Injection Molding

How much does injection molding cost?

While injection molding has a significant up-front cost, it quickly turns into one of the most cost-effective methods of manufacturing parts.

We’d love to give you a quote. Use this simple form, and we’ll respond within 1 business day.

Our mantra — “Driven by Dependability” — is founded on our adherence to our quality system, and remains the leading reason our customers keep coming back.

How do I design for injection molding?

We address the most important design concerns for injection molding projects above, in the Important Factors to Consider for Injection Molding section. Below are more helpful guidelines:

Materials should be specified and acknowledged by both parties early in the design process. This allows us to purchase large quantities of specific resins at major discounts, which we pass on to clients.
Designers should avoid sink marks in injection-molded parts. The recommended maximum wall thickness at the base of a rib or boss is less than 50-60% that of the perpendicular face wall.
Designers should take care to include steel safe areas in injection-molded parts. Tight tolerances such as snap fits, alignment features, and interlocking parts increase the risk of production error, because they’re difficult to replicate. Steel safe areas are designed with enough clearance to allow a molder to easily machine away steel in order to tighten up the clearances after initial test shots are molded.
Gate location is critical and should be specified and agreed upon by the designer, molder, and manufacturer. It affects appearance, warpage, tolerances, surface finish, wall thickness, and more.

Which polymers is injection molding used for?

The most common polymers and thermoplastics used for injection molding are acrylonitrile butadiene styrene, polyethylene, polycarbonate, polyamide (nylon), high impact polystyrene, and polypropylene.

What is custom injection molding?

Your project’s level of complexity is what determines the level of “customization” it requires — in other words, the level of engineering and design support required, analysis needed, and number of process technologies required.

While cheaper methods make for a quicker time to market, custom injection molding takes more care with part design, material selection, mold design, and process control in order to achieve more consistent and accurate end products.

Can metal be injection molded?

Yes. Injection molding can be used to manufacture metal parts, by a process called metal injection molding (MIM), in which metal powder is mixed with plastic and molded. The plastic is subsequently removed, and the remaining part sintered.

MIM allows us to produce intricate parts in a wide range of metals, including steel, stainless steel, and high-temperature alloys.

Choose Aero-Plastics for Your Injection Molding Manufacturing Process

Injection molding is a precise and reliable fabrication process suited to the production of a wide range of parts.

At Aero-Plastics, we specialize in producing high-quality parts with tight tolerances, thanks to our team of experienced engineers and detail-oriented processes.

We’re here to help make your injection molding project a success.

Mold Isometric | Aero-Plastics

Mold End Elevation | Aero-Plastics

Mold Cross Section| Aero-Plastics

Mold Finished Product | Aero-Plastics

Why Choose Us?

Dependability

You can count on Aero-Plastics to deliver the most critical and complex plastic products on time and with the highest quality. We continually measure performance using our Dependometer, ensuring that your order is delivered as promised.

Expertise

We are experts in machined nonmetallic and injection molded components that meet the stringent requirements of industries requiring tight adherence to QMS principles. Our deep experience in the aerospace market—monitoring all quality and delivery metrics of each project and documenting every step along the way—enables us to take on the most demanding customers and complex parts.

Quality Process

We are AS9100D:2016 certified. Our Quality Management System establishes the processes by which we operate and the metrics by which we measure our performance to meet your requirements.

Quality Parts

Our state-of-the-art production capabilities combined with our high performing team allows Aero-Plastics to deliver the highest quality machined nonmetallic and injection molded products in the industry.