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Plastic injection molding is a manufacturing process in which molten plastic is injected into a metal mold to form precise, repeatable parts. Once the plastic cools and hardens, the mold opens and ejects the finished component.
This method is ideal for producing high volumes of identical items with tight tolerances. It supports a wide range of polymers, allowing manufacturers to tailor material properties to specific product needs.
Because molds are custom-made, initial tooling costs can be high, but the per-unit cost becomes very low at scale. Injection molding is used across industries, from automotive and medical to consumer products, due to its efficiency and versatility.
Injection molding offers extremely fast cycle times once tooling is built. This allows manufacturers to produce large quantities of parts very quickly. As output increases, the per-unit cost becomes significantly lower than many alternative processes. This scalability makes injection molding well suited for production volumes ranging from thousands to millions of identical parts.
Once the mold is created, every part produced is highly consistent in shape, size, and structural properties. This makes injection molding ideal for mass production where reliability is critical. Tight tolerances can be maintained far more effectively than in many other manufacturing methods. Once tooling is validated, the same mold can be used repeatedly over long production lifecycles with minimal variation between parts.
Injection molding can create intricate shapes with fine details that would be difficult or impossible using other processes. Features such as undercuts, thin walls, and tight tolerances can be achieved with the right tooling. This capability enables advanced product designs without requiring excessive secondary operations.
Manufacturers can choose from hundreds of engineering-grade resins tailored for strength, flexibility, heat resistance, or chemical stability. Colorants and additives can be mixed directly into the raw material for consistent coloration throughout the part. This flexibility supports a broad range of industries and applications.
Excess material produced through runners or sprues can often be re-ground and reused. This reduces waste and improves overall material efficiency. Compared to processes like machining, injection molding uses far less material to achieve the same final geometry.
The upfront investment for injection molds can be substantial. Complex molds with multiple cavities or intricate features increase tooling cost even further. But per-part costs drop significantly over long production runs, making it easier to amortize the cost of the tooling.
Designing, machining, and testing a mold takes time before the first part can be produced. Any adjustments needed during mold trials can further delay production. Compared to faster-start methods like 3D printing, injection molding requires more planning upfront.
Once a mold is created, any design changes typically require costly and time-consuming mold modifications. Small alterations in geometry can lead to significant tooling rework. Injection molding is best suited for designs that have been thoroughly validated prior to tooling.
Partner with Experts Who Get It Right the First Time
Every project is reviewed by a seasoned manufacturing engineer to optimize part design, material selection, and tooling strategy — ensuring smarter decisions before steel is cut and production begins.
Injection molding is used to create housings, buttons, and internal components for products like smartphones, laptops, and remote controls. It provides the precision and consistency required for tight-fitting assemblies.
Many car parts—such as dashboards, clips, interior panels, and under-hood components—are made through injection molding. The process supports durable materials that withstand heat, vibration, and mechanical stress.
Syringes, housings, testing cartridges, and other medical-grade components are commonly injection-molded. The process supports sterile materials and high-volume production needed for healthcare applications.
Caps, lids, containers, and other rigid packaging items rely on injection molding for speed and repeatability. It enables lightweight, cost-efficient products produced in massive quantities.
Items like kitchen tools, storage bins, toys, and appliance components are frequently injection-molded. The method supports bright colors, ergonomic designs, and durable everyday use.
Gears, brackets, fasteners, and custom enclosures are produced through injection molding for industrial equipment. The process delivers strength, precision, and material customization for demanding environments.
Fathom offers multiple options for different types of injection molds based on expected production cycles and warranty. Fathom offers in-house, start-to-finish production services for plastic injection molding. Fathom will make an injection mold for a client and then use the mold to manufacture the customer’s parts.
Fathom also offers Export Molds. These molds are manufactured and shipped to the client for use in their facility or a facility of their choosing. For a complete description of all in-house and export type injection molds, please visit the Mold Types page.
Fathom injection molds are made exclusively with steel. Click here to learn more about the advantages of steel molds over aluminum molds (icomold.com/aluminum-molds/). Steel is the material of choice due to mold longevity, durability, reparability, and the ability to injection mold complex parts.
Various types of steel can be used to create plastic injection molds. While P-20 is considered the workhorse of the industry, Fathom will also use other steel types depending on the situation and requirements.
Fathom can meet all of your plastic injection molding needs. From start to finish or any step in between, we can provide the expertise and guidance to get the job done correctly, quickly, and efficiently.
Injection Molding Done with Expertise — Not Just Automation
Fast quoting is just the beginning. At Fathom, you get real engineering insight, proactive DFM guidance, and a streamlined path from prototype to full production — all backed by hands-on manufacturing experience.
Injection molding produces plastic components by shaping heated material inside a custom mold, allowing manufacturers to achieve repeatable results across large production runs.
Injection molding can produce everything from medical components and automotive parts to consumer electronics and household products. Its versatility makes it one of the most widely used plastic manufacturing methods.
Mold production typically takes 3–8 weeks, depending on complexity, size, and required precision. Timeline is influenced by factors such as part geometry, cavity count, surface finish requirements, and tooling complexity. More intricate molds or those with multiple cavities may take longer.
Most thermoplastics—including ABS, polypropylene, nylon, and polycarbonate—are commonly used. Thermosetting plastics and elastomers can also be molded depending on the application.
Injection molding offers excellent repeatability, fast cycle times, and low per-part costs for high-volume production. It also supports complex geometries and a wide range of material options.
It can be, but typically only if prototype or soft tooling options are used. Traditional steel molds are more economical for higher production volumes due to their higher upfront cost. For short runs or design validation, processes such as CNC machining or additive manufacturing are often used before injection molding is introduced for higher-volume production.
Injection molding is capable of extremely tight tolerances, often within ±0.005 inches depending on part geometry and material. This makes it suitable for precision components and assemblies.
Yes, injection molding supports both overmolding and insert molding to combine multiple materials or embed hardware. These techniques enhance functionality, durability, and design flexibility.
A molding trial sets and fine-tunes process parameters to ensure the mold fills correctly, solidifies properly at the gate, and produces quality parts at an efficient cycle time. The finalized settings are documented on a setup sheet for consistent future production runs.
Aluminum molds are generally less expensive, offer faster cycles, and are ideal for shorter runs or quicker turnaround, while steel molds cost more upfront but provide greater durability and a longer lifespan. The best choice depends on budget, production volume, and part requirements.
Our experts look for ways to reduce the cost of our plastic injection molds and price per part. Tooling cost is influenced by factors such as part size, complexity, surface finish, material choice and required production volume.
Generally speaking, our price is about 40% to 60% less than that of our competitors. The actual cost of the mold depends on factors such as size and complexity, with prices generally starting at around $5k – $10k. Check out our instant quotation system to see how much you can save with us on your next injection molding project.
We are able to accept .stp, .step, .sldprt, .x_t, .x_b, .ipt, .catpart, .prt and .sat CAD files. If you need assistance with getting your design into an acceptable file format, we can help you out with that. If you don’t have a CAD file, we have design firm partners who are skilled in creating 3D CAD files that are specifically designed for plastic injection molding.
Plastic injection molding has almost unlimited manufacturing possibilities. Examples of plastic injection molding can be found in a variety of industries including consumer electronics, car parts, medical devices, tools, toys, and packaging. Post-processing applications can be used to achieve the desired finish or texture. Plastic injection molding is an economical way to mass-produce the same or similar plastic parts.
Yes, there are a variety of secondary operations that customers can choose from to customize their product. Our experts have decades of combined experience in the injection molding field, and can lead customers through the process from design, to molding, to finishing operations. Injection molding secondary processes include painting, welding, post-mold machining, assembly, and packaging.
The best plastic for a particular injection molding project depends on your part’s geometry and the environment and application in which it will be used. The experts at Fathom will guide you through the process of choosing the right plastic for your project. Visit our Materials page for more information.
The first step is to have a 3D CAD file of your part in .STP, .STEP, .SLDPRT, .X_B, .IPT, .CATPART, .PRT, .SAT, .ZIP format. If you don’t already have one, our experienced team of engineers can help you with that. Next, upload your CAD file to our online quoting system, and you should receive your quote in about 30 seconds or less!
That depends – you have options. If you buy a production mold, we keep the mold in our production facility, maintain it, and run batches of parts for you when you need them. Alternatively, if you buy an export mold, then we will ship it to you, or to a production facility that you specify, and you are responsible for maintaining it. This flexibility allows customers to choose the tooling strategy that best aligns with their production volume, supply chain preferences, and long-term manufacturing goals.
Injection molding is designed to make hundreds, thousands or even millions of the same part or set of parts. It is an efficient and economical way to mass-produce plastic parts.
When only making a small number of parts, however, the upfront cost of a mold may not be justified. We have a wide range of manufacturing processes that can be utilized to manufacture prototype or small-batch part runs. In many cases, CNC machining or other processes are used during early development before injection molding is introduced for scalable, repeatable production.
Partner with Experts Who Get It Right the First Time
Every project is reviewed by a seasoned manufacturing engineer to optimize part design, material selection, and tooling strategy — ensuring smarter decisions before steel is cut and production begins.
