Manufacturing Processes: Injection Molding and 3D Printing

Manufacturing Processes: Injection Molding and 3D Printing

Manufacturing Processes: Learn the Basics about Injection Molding and 3D Printing

Injection molding or 3D printing? Which manufacturing process will achieve your desired fit, form, and function? Turns out, you may not have to choose one over the other.

As these processes continue to advance, product designers have more options. They can leverage the benefits of both processes to produce higher-quality parts.

So the question is no longer limited to which manufacturing process will you choose. But rather, when and how can they be used together?

Engineers are building road maps to create viable paths to bring their products to market on time and on budget. However, many of these paths are based on using one process. Therefore, they may not be fully optimized for success.

Manufacturing Processes: Injection Molding and 3D Printing

No matter what new processes and technologies are introduced, there is always room for recalling fundamentals. In fact, revisiting the the basics will help you to make more informed decisions when choosing between injection molding and additive manufacturing.

Know Your Part: How the part is used can determine which manufacturing process you choose

How will the part be used? This is the most important question you can ask yourself. Whether you choose injection molding or 3D printing, understanding how the part will be used can help to mitigate risk.

Concept or Final Production

One end of the continuum demands that you are in pilot mode manufacturing multiple prototypes to determine the best design. On the other end of the continuum, the demand is for  efficient manufacturability and alignment with the intent to flawlessly go-to-market. Materials testing, form-fit-function, tolerances, design iterations, production part quantity all take on a different meaning based on which end of the continuum defines your scope.

Simple or Complex Parts

Regardless of which end of this continuum defines your part, there are many manufacturability compromises that could derail your intended design. One way to help mititage risk is to apply specific measures based on whether the part is simple or complex.

Simple Does Not Mean Easy

A simple part is designed using one type of material and requires little to no special considerations during production. Just because it is a simple part doesn’t mean it will be easy to manufcture.

Therefore, build a list of non-negotiables that the manufactgurer must follow to help achieve your design intent.

Complex Part Designs

In contrast, a complex part design may require overmolding to add a soft grip to your part. Or it could include undercuts which require special accommodations during production to assist with ejection from the mold.

Whether using plastic injection molding or 3D printing, involve your manufacturer early when producing complex parts. This will help to improve your design’s manufacturability. Also, it can help mitigate risk and eliminate unnecessary production costs.

Optimize the Product Development Cycle, Mitigate Risk when Choosing a Manufacturing Process

The process for launching a product that includes manufacturing processes like injection molding and 3D printing has been continuously developed for decades. The time, energy, and cost required to make changes increases as you progress through the process. At the very least, factors to consider when optimizing your desing for production should include time-to-market and process integration.


Understand where you have the most leniency and where there is little to no compromise. Once you know your strategy, you can leverage key constituents such as the right manufacturing process and manufacturer to achieve your design intent.

For example, Microsoft develops a strategy to introduce products to market knowing that “version 1.0” will be swiftly iterated and followed by the launch of “version 1.1.”  The question you need to answer is, “What’s my project’s strategy?”.

Process Integration

It is becoming more and more clear that reliance on one manufacturing process may not always be ideal. As an example, reaching an aggressive time-to-market with a new product introduction containing complex parts requiring iterative testing as to form-fit-function is a reality for many engineers. This requires inexpensive prototype testing providing the most speed prior to moving into a mid-volume production environment.

Beginning with a 3D printed part to validate your design while you are tooling-up for mid-volume injection molding runs may be the best time-to-market solution to reduce your risk and predict your outcome. This approach also suggests that you involve yourself earlier in the design process with a manufacturer who will understand your strategy and align processes to fit.

Know the basics of the 3D printing and injection molding manufacturing processes

When designing plastic parts, think of 3D printing and injection molding as manufacturing processes that are on the same team with different roles. They each provide unique value, but can also complement each other to produce your product.

Here is an overview the 3D printing and plastic injection molding processes.

3D Printing Manufacturing Process

Consider the following 3D printing technologies and how they could apply to your project. While this is not the full comprehensive list of technologies available, it does represent the majority.

3D Printing Technologies

Stereolithography (SLA) – Available since 1989, SLA uses an ultraviolet laser to cure parts one layer at a time in photo-reactive epoxy resin. It is one of the most accurate 3D printing technologies and ideal for fine detailed, small featured parts as fine as .002” layer thickness. SLA is capable of producing large parts as well.

Fused Deposition Modeling (FDM) – FDM extrudes thermoplastics layer by layer, with a variety of thicknesses as fine as .005” per layer. FDM uses real engineering grade thermoplastics, functional parts that can withstand rigorous testing, and creates end-use production parts with a variety of color options. It has excellent tensile strength, flexibility, high melting points and chemical resistance, and UV resistance.

Selective Laser Sintering (SLS) – SLS uses engineering and high-performance, powder-based materials activated by thermal energy of a laser in the Z axis to build one layer at a time. SLS uses real thermoplastic base materials producing robust parts, end-use aerospace applications. Accurate fine features and complex geometries, and fire retardant plastic materials, UL 94 V0 are standard. Popular uses also include living hinges and high-flex snaps.

PolyJet – This technology is similar to inkjet printers where jets layer a liquid photopolymer that is instantly cured with UV lights attached to print heads. It produces fine layer high resolution parts. PolyJet is high speed, fine detail and smooth surfaces directly off the machine, and can print at 16 microns. Uses include living hinges, overhangs, and complicated geometries without needing to be assembled. There are multiple color options, multiple materials, and durometers in one print.

Injection Molding Manufacturing process

Injection molding offers a predictable and scalable process for both rapid prototyping and production. Its ability to produce parts from multiple materials with a high degree of consistency and tight tolerance makes it a proven approach to manufacture parts.

Here are a few popular plastic injection molding procesess to consider.

There are a number of best practices to consider including material selection, wall thickness, draft, runners and gates, ribs, bosses, corners and transitions.

Beyond best practices, injection molding offers several key features that can transform your design including overmolding, insert molding, and undercuts. Tolerances are ± .005” and can reach ± .001” with tooling. 


Injection molding processes

Overmolding  is a 2-part plastic injection molding process. It uses hard and soft plastic resins to optimize the function and structure of a part. Overmolding is often used to create a soft grip, add rubber-like grips to clips designed to grab inanimate objects, and achieve better color contrast.

Insert Molding is the process of injection molding molten thermoplastic around pieces placed in the injection molding cavity. Doing so results in a strong bond between integral pieces of your final part. Accurate mold design and construction is essential to insert molding to not only maintain part tolerances but also assure the tooling reliability.

Undercuts – An undercut is any indentation or protrusion that prohibits the ejection of a part from a mold. Undercuts can be used to carry out complex forms of molding such as the overmolding process and insert molding process. Undercuts are used to create interlocking or snap and latch features, allowing for clamshell or housing designs to come together for quick and easy assembly, or capturing holes or ports for wiring, button features or assembly, and vertical threads and barb fittings typically used in medical device products.


Relying on the fundamentals of manufacturing processes like 3D printing and injection molding can help to mitigate risk. Thinking through how your part will be used and what non-negotiables drive your design cycle will lead to the most successful project outcome.

Also, consider whether you are best served by a single process type, integrating processes, or integrating manufacturers to reach a viable conclusion to your project. Regardless one fact remains – thinking about manufacturability earlier in the design cycle to properly select and leverage the 3D Printing and Injection Molding processes is essential to your success.

Interested in obtaining more advice? Reach an Application Engineer at, or call (586) 589-4636

Working on a project?

Let us help you get that first prototype underway and have that part in your hands in as few as five days. Our engineers help you through the design process. Get your project started now!

Medical Plastic Parts: 3D Printing and Injection Molding

Medical Plastic Parts: 3D Printing and Injection Molding

Manufacturing Medical Plastic Parts: 3D Printing and Injection Molding

COVID-19 created uncertainty in product development timelines producing medical plastic parts. Future demand for your products or services is more in doubt now than ever before. And, you are likely re-thinking plans for 2021.

All of this impacts the supply chain. Which means organizations must be more agile and constantly reassess each step in the product development process.

Still, organizations are likely to return to a normal planning modus where they can look into the future to commit to product volumes and launch timelines.

In this blog we discuss:

  • Manufacturing during a crisis
  • Product development and prototype processes
  • When to use 3D printing
  • When to use plastic injection molding
  • How both processes can complement each other

Manufacturing medical components during a crisis

Product demand uncertainty

The crisis of 2020 revealed the fragility of the global supply chain. As a result, many industries were left scrambling to find distribution channels.

However, the medical industry faced different issues. For one, confirming product quantities. And second, finding capacity to fulfill product demand.

For example, consider a medical device company that pre-pandemic secured contracts to supply equipment to 1,000 hospitals in North America. Post-pandemic those hospitals’ budgets are in disarray. Which means the medical company is likely unsure of the product volume needed. Or, if any will be needed at all.

U.S. Food and Drug Administration (FDA) Testing

Producing medical components can be trickier than for other industries. On one hand, you still have to achieve fit, form, and function. On the other, you consider more stringent criteria for some healthcare applications and FDA testing.

Now consider all of this in the context of a pandemic like COVID-19. For one, it could mean a delay in FDA availability. Further, your in-house testing may have been halted or repurposed.

So, how can medical companies prepare for future uncertainties? First, by becoming more agile when using 3D printing and injection molding. And second, by following every step in the product development process.

Product Development And Prototype Tooling

Product Development

The product development process can be viewed as a continuum where each phase builds upon the last. Thereby enabling us to gather information necessary to bring a high-quality injection-molded product to market. This is why following each step is critical to bringing medical components to market on time and on budget.

    Prototype Tooling: Impact for medical plastic parts 

    The cost, time, and energy for making changes to your part increases as you progress through the product development process.

    In fact, this increase is about 10X that of the previous step. Which can result in costly product launch delays. And, if you produce medical plastic parts, this can impact patients’ lives as well as revenue.

    Benefits of investing time in prototype tooling

    Investing time in prototype tooling can mitigate risk when producing medical plastic parts.

    At Xcentric, we use our proprietary Process Engine software to help eliminate part defects. This allows us to continually learn and improve upon not only parts in active production, but the manufacturing process as a whole.

    The learning aspect is critical because we want to get the execution exactly right for each step in the process. In doing so, we can provide more informed suggestion to our clients about what needs to be done.

    3D Printing and Injection Molding for Medical Plastic Parts: Same Team Different Roles

    3D printing and injection molding are manufacturing processes used for producing plastic parts. They each have unique strengths and limitations. And, they also work to complement each other.

    Unfortunately, mistakes are made when producing medical plastic parts because of common misconceptions about these processes.

    3D printing: common mistakes and limitations

    Common mistakes

    One common mistake made is the failure to acknowledge that end-use criteria are radically different from those guiding a form/fit/function-type prototype. The three major differences between prototype and end-use product are:

    “For example, adding the requirement of initial function for testing purposes reduces the number of processes and materials available via the additive manufacturing process,” said Brianna Gillett, Account Executive at Xcentric.

    “Then, when you expand an end-use product’s capabilities to fit a specific application, it further reduces the number of processes and materials available to keep additive manufacturing viable. Finally, the hurdle is production rate, which naturally is related to the unit cost of the outcome.”

    Limitations of 3D printing for medical plastic parts

    Because it is so easy to use, reliable, and affordable, some organizations invest in 3D printing technologies for early-stage prototypes. 

    However, the further you progress through the development process, the more complicated projects become and the more difficult it is to achieve the desired outcomes.

    “For this and several other reasons, some may think they can skip the prototyping step of the product development cycle,” Gillett said. “But the vast majority of products have at least some changes in design or functionality. And this is when to consider injection molding as a next step.”

    Injection molding for medical plastic parts

    Simply put, the injection molding process creates plastic parts by injecting molten plastic into a mold. As the material cools, it begins to take the shape of the final product. For complete details about the process, please visit page, injection molding process.

    When to consider the injection molding process:

    • Projects at scale
    • Higher volume production runs (anything more than a few hundred parts)
    • Final part design (after prototyping)
    • Parts of any size or complexity
    • Objects that will mate together or move against one another 

    As discussed earlier, the product development process includes a series of steps. And following each step can help to stay on track for budget and time-to-market. One of the most critical steps is prototyping. 

    Prototype injection molding

    For example, consider the way a polymer fills steel or aluminum tooling. The physical act may not go the way it was simulated, following exactly the process as interpreted by an ideal situation in a lab.

    So if variations are outside the range of acceptable parameters, you will not be able to tune the process to achieve the desired outcome. Which could result in defects like warp and other aesthetic blemishes.

    These are the easy fixes that can be caught in intermediate prototyping steps. 

    3D Printing and Injection Molding for Medical Plastic Parts: Same Team, Different Roles

    Using these 2 processes together can help to bring your products to market faster.

    In the case of medical device companies, especially during the pandemic, this can literally mean the difference between life and death.

    To meet product launch objectives and ensure everything is on target, an ideal approach is to conduct initial low-cost 3D printing following simulation, then progress to pre-production and rapid injection molding tools. Learning everything you can about the processes and product can mitigate risk when moving to production.

    3D Printing and Injection Molding: Personal Protective Equipment (PPE)

    A great and very timely example of this is how 3D printing and injection molding are being applied to produce PPE. During the COVID-19 crisis, PPE includes testing swabs, ventilator components, and other items.

    These complementary processes have been able to address medical equipment needs quickly in areas where the materials were appropriate. However, the need for extremely high volumes of these items (as the pandemic response is likely to go on months longer across the globe) cannot be met by additive manufacturing alone.

    Xcentric recently partnered with ZVerse on a domestic supply chain initiative to meet the demand for PPE, especially face shields.

    We started off by 3D printing the face shields to meet their immediate need. Next, we used injection molding to rapidly scale the project. This enabled us to meet increasing demand for these much-needed items at a price that healthcare companies could afford.

    In the end, Zverse was extremely happy with the end results. In fact, their CEO John Carrington said, “the COVID-19 crisis has shown us the importance of establishing a strong and reliable domestic supply chain. Xcentric is an excellent partner to assist us in this important initiative.”

    To this day, we have relied on this approach to help Zverse and medical device companies produce very high quantities of PPE in a fast and reliable way.

    In Conclusion

    3D printing and injection molding are manufacturing processes that can help bring medical plastic parts to market on time and on budget. The key is to first understand the benefits and limitations of each process for your application.

    Next, follow the product development process to mitigate the risk of unnecessary costs and time delays.

    Finally, partner with a domestic supplier with the capacity to quickly scale production to meet your needs in any global climate.

    Xcentric is a premiere provider of rapid manufacturing and consultative services. Our goal is to provide a better solution from idea all the way to part, regardless of process. Contact Xcentric to learn more or to discuss current design and production challenges.

    Brianna Gillett is an Account Executive with Xcentric Mold and Engineering, providing 3D Printing and Injection Molding services to clients in the southeast region of the US. Brianna has more than 5 years experience in rapid manufacturing. Contact Brianna Gillett.

    Working on a project?

    Let us help you get that first prototype underway and have that part in your hands in as few as five days. Our engineers help you through the design process. Get your project started now!

    Xcentric Mold vs. 3D Printed Mold

    Xcentric Mold vs. 3D Printed Mold

    How do 3D printing molds match-up against Xcentric’s Advanced Mold Making and Proprietary Process Engine?

    3D printing has come a long way in recent years.  According to IBIS World, it is currently a $492.4 million market and is expected to grow by 80% over the next five years.  This sort of growth will open up all kinds of new applications for 3D printing.  In fact, NASA has already experimented with using this technology with the hope that they can begin to establish on-demand machine shops…in space.  We’ll be doing the Kessel Run in under 12 parsecs in no time.  🙂
    So, at this point, what can’t 3D printing do?

    Injection Molding Cost Analysis: Simple and Complex Parts

    Injection Molding Cost Analysis: Simple and Complex Parts

    Injection molding cost analysis is a critical exercise when choosing a manufacturing process. In fact, it’s one of the most important, especially for projects working with a tight budget.

    To help you put it all into perspective, we did a cost analysis for you.
    Below we have two part designs. One is what we consider to be fairly simple and the other is more complex.

    We’ve quoted these two parts through the quoting engines of various rapid manufacturing companies, averaged them out and compared them to our own injection molding process. This will provide you a good idea of how piece pricing will effect overall costs among the most common manufacturing methods.

    It will also provide a better sense of when to start thinking about injection molding process for your prototypes or production run. It might be a little earlier than you think.

    Injection Molding Cost Analysis: Simple and Complex Parts.

    Simple Part


      1 Unit 10 Units 25 Units 50 Units
    Process Piece Total Piece Total Piece Total Piece Total
    FDM $40.18 $40.18 $40.18 $401.80 $40.18 $1,004.50 $40.18 $2,009.00
    SLA $67.62 $67.62 $50.34 $503.40 $49.19 $1,229.75 $48.80 $2,440.00
    SLS $14.51 $14.51 $10.59 $105.90 $10.40 $260.00 $10.34 $517.00
    IM na na na na $56.00 $1,400.00 $38.06 $1,902.75

    Complex Part


      1 Units 25 Units 50 Units 100 Units
    Process Piece Total Piece Total Piece Total Piece Total
    FDM $89.19 $89.19 $89.19 $2,229.75 $89.19 $4,459.50 $89.19 $8,919.00
    SLA $95.88 $95.88 $77.09 $1,927.25 $76.70 $3,835.00 $76.70 $7,670.00
    SLS $33.99 $33.99 $24.36 $609.00 $24.22 $1,211.00 $24.08 $2,408.00
    IM na na $235.16 $5,879.00 $128.80 $6,440.00 $66.62 $6,662.00

    The injection molding process has fewer limitations than any other method for manufacturing and is still the king of thermoplastic part production. Despite SLS being less expensive, it is very limited in material selection which makes it more suitable for prototyping than anything else. Injection molding is probably more economical than you thought.

    The benefits of injection molding will allow you to select from a huge assortment of engineered grade thermoplastics, to choose many different types of surface finishes and can build some of the most complex designs. For simpler designs, the injection molding process becomes an even better choice if you need fewer than 50 pieces.