Foreword: The rapidly growing and highly competitive injection molding industry is valued in the hundreds of billions of dollars, driving manufacturers to seek more efficient and cost-effective ways to maintain a competitive edge.

3D printing, also referred to as additive manufacturing, enables these companies to produce superior injection molding molds and tooling faster and more affordably than traditional methods. It can be argued that 3D printed molds are revolutionizing the mold manufacturing industry.

According to Intelligent Manufacturing Network News, 3D printing is considered one of the cutting-edge technologies with vast development potential and extensive application possibilities, nearly ubiquitous worldwide.

As of now, the utilization of 3D printing in education, healthcare, automotive, aerospace, and other sectors is progressively deepening, showcasing its value in commercial implementation. Hence, what is the reality behind 3D printed injection molds?

In this article, we will introduce you to the truth about 3D printing injection molds.

1. Brief Overview of 3D Printing Technology

3D printing (3DP) is a type of rapid prototyping technology, also known as additive manufacturing. It is based on digital model files and uses adhesive materials such as powdered metal or plastic to construct structures through layer-by-layer printing.

It is usually achieved using digital technology material printers and is commonly used to create models in fields such as mold manufacturing and industrial design. It is gradually being employed in the direct manufacturing of some products, with parts already being successfully printed using this technology.

3D printing is typically accomplished using digital technology material printers. It is commonly utilized for creating models in mold manufacturing, industrial design, and other fields, and is increasingly employed in directly manufacturing certain products. Some parts have already been printed using this technology

2. Injection Molding

The technique known as injection molding involves injecting heated and melted plastic materials into the mold cavity at high pressure, allowing them to cool and solidify. This method is primarily employed for mass production purposes. Central to this process is the injection mold, which swiftly and accurately produces full structures and precise dimensions for plastic products.

The current mold manufacturing process, commonly referred to as mold opening, typically involves mechanical processing. The process can be outlined as follows: Initially, a digital mold is generated using software based on the 3D model of the final product. This includes defining the cavity numbers, gate locations, and necessary runner systems for the injection molding process.

The mold components are machined using tools such as CNC, milling machines, and lathes. To achieve better injection molded products, the mold often needs finishing and final polishing to enhance surface quality. This process is laborious, and the typical production cycle for precision injection molds is approximately 20-25 days.

3. 3D Printing Plastic Mold

By combining strong and temperature-resistant materials with a plastic (or polymer) 3D printer, companies can produce their own injection molds in-house or promptly order them from a service provider. 3D printed plastic molds are suitable for producing small quantities of parts (ranging from 100 to 10,000, depending on the material) and are significantly more cost-effective, priced at 90% less than metal molds.

If the budget is limited and the lead time is short, then plastic 3D printing is the preferred mold manufacturing method. It is also widely used for prototyping, enabling companies to test and iterate more quickly before transitioning to traditional tools for mass production with greater confidence.

Technologies and Materials Used

Technology 1: Fused Deposition Modeling (FDM) is the most economical 3D printing solution for plastic mold making. However, visible layering may occur with this method. To achieve the desired accuracy, the layers need to be removed through post-grinding or chemical treatment. Additionally, these molds can be machined to tighter tolerances.

Technology 2: Resin 3D printing, including stereolithography (SLA) and digital light processing (DLP), are the more popular technologies because they produce molds with a finer surface finish that require less post-processing.

Technology Three: Selective Laser Sintering (SLS) is a technology that uses powdered polymer materials and a laser to provide molds with high surface quality and strength, often made from reinforced nylon.

When it comes to 3D printing, there’s a wide range of plastics to choose from. However, not all materials can handle the high pressures and temperatures involved in injection molding. The choice of material depends on factors such as the plastic’s melting temperature, the machine’s injection pressure, and the volume of parts needed.

The most commonly used materials include PETG, polypropylene (PP), mold resin, nylon (PA), carbon fiber nylon, etc. However, they typically can only withstand tens to hundreds of injection molding cycles. For high-volume production runs requiring thousands of parts, metal is still favored over plastic in most cases.

Typical Application Cases

PepsiCo partnered with Henkel Loctite Nexa3D to create mold inserts using xPEEK147 resin material and a Nexa3D NXE 400 3D printer. These inserts are then integrated with components from traditional metal molds. The entire mold can now be manufactured in just 12 hours, with 8 hours dedicated to 3D printing and 4 hours to post-processing and curing.

Prototype mold development time has been drastically reduced from 4 weeks to just 48 hours, a significant improvement in efficiency. Furthermore, the cost of each mold set has seen a substantial decrease from $10,000 to $350. These innovative hybrid-manufactured molds have demonstrated the capability to produce over 10,000 bottles without any failures, resulting in potential cost savings of up to 96% compared to traditional metal molds.

In the realm of traditional injection molding, the primary cost driver lies in the manufacturing of the mold. The intricacies of recovering the production cost of the mold only through mass production and sale of products are highlighted. It is emphasized that for products with short life cycles or limited demand, the investment in machined tooling may not be financially viable. In such scenarios, opting for mold fabrication through 3D printing is presented as a more advantageous alternative.

This shift towards 3D printing not only provides a cost-effective solution but also allows for enhanced flexibility in product customization and small batch production. Manufacturers are encouraged to leverage this approach to broaden their product offerings within cost-effective parameters. The expedited production capabilities of 3D printed molds empower manufacturers to promptly address customer demands for new products, leading to efficient development and production of short-run products.

4. 3D Printing Metal Mold

The driving factors behind the rise in the utilization of metal 3D printed molds differ significantly from the benefits of plastic 3D printed molds. Contrary to popular belief, there are instances where metal 3D printed molds can be pricier and more time-consuming to create compared to conventional metal molds. The advantage lies not in the manufacturing of the molds but in the cost-effectiveness of producing the entire product utilizing 3D printed molds.

Technologies and Materials Used

Metal 3D printing enables the creation of molds for final product production and prototypes with intricate details, allowing manufacturers to streamline the traditional mold making process and reduce the need for skilled machinists.

A common technique is selective laser melting (SLM), a key method in additive manufacturing of metal materials. While SLM can achieve fine details, additional machining is often required. Given the current costs and processing speeds, metal 3D printing is unlikely to replace the machining of injection molding tools entirely but instead serves as a complementary tool to accelerate overall production.

Another 3D printing technology, direct energy deposition (DED), utilizes a laser to create a molten pool in the deposition area and rapidly moves it. The material, whether in powder or filament form, is fed directly into the high-temperature melting zone and deposited layer by layer after melting. This approach enables the creation of metal molds using various metal materials. For instance, a layer of stainless steel can be applied on top of a pure copper substrate to combine high thermal conductivity with wear resistance.

Required in Injection Molding Tools.

Metal 3D printed parts often require additional processing, leading to a rise in hybrid machines that combine 3D printing and CNC capabilities. The TrueShape machine, developed by Mantle, a metal 3D printing startup, exemplifies this trend.

The process begins with 3D printing a metal mold using extrudable tool steel paste. Subsequently, precision CNC machines are utilized to refine the mold to exacting tolerances prior to sintering it in a high-temperature furnace.

Typical Application Cases

3D printing is sparking a revolution in the mold manufacturing industry by enabling the creation of molds with intricate conformal cooling channels. These channels play a crucial role in metal injection molding tools by facilitating faster and more uniform cooling of parts.

Given that the cooling phase typically consumes 70% to 80% of the entire cycle time, any reduction in this phase throughout the mold’s lifespan can yield substantial cost savings for manufacturers. Furthermore, effective cooling significantly impacts the dimensional precision, surface finish, and mechanical properties of the end product.

Traditional machining techniques involve the addition of cooling channels to the mold through straight drilling. However, as the complexity of part geometry increases, achieving precise cooling along the mold contours becomes increasingly challenging. This can render the traditional production of intricate parts an arduous and costly endeavor.

Compared to traditional processes, 3D printing can create curved cooling channels within the mold that are shaped to the part geometry and deliver cooling where it is needed most to improve part quality and reduce cooling time by up to 70%.

A prime example is Yijia, a three-dimensional cupping manufacturer. Previously, cuppings produced by traditional injection molding exhibited low transparency and inefficient injection molding. This inefficiency stemmed from cupping molds crafted via traditional CNC technology, which could only process vertical cooling channels, thereby failing to adequately cool the mold.

Complex conformal cooling channel metal molds can be produced using the Eplus3D EP-M250 SLM 3D printer. The final cupping now only requires 16.63 seconds to reach the optimal temperature for spraying. In contrast, traditional molds take 22.97 seconds, resulting in a time savings of over 6 seconds and boosting injection efficiency by approximately 26%.

The benefits of incorporating conformal cooling channels through 3D printing are evident in various sectors of mold manufacturing. Consider electronic cigarettes, for instance. Guangdong Moko states, “Over the last three years, our understanding of PCTG materials has significantly deepened, particularly in electronic cigarettes.

The utilization of this material in conjunction with 3D printing technology exemplifies a unique approach that deviates from conventional methods.” This underscores the pivotal role of 3D printing in revolutionizing the mold industry by effectively addressing challenges unattainable through traditional means.

5. Advantages of 3D Printing Injection Molds

Mold Production Cycle Shortened

3D printing of molds significantly shortens the product development cycle, driving innovation. Previously, companies have at times opted to postpone or forgo product design updates due to the substantial investment needed for manufacturing new molds. By reducing lead time for mold production and enabling swift updates to existing design tools, 3D printing allows companies to afford more frequent mold changes and enhancements. This capability ensures that the mold design cycle aligns with the product design cycle.

Moreover, some companies have invested in their own 3D printing equipment to produce molds, further expediting product development while enhancing flexibility and adaptability. This strategic approach bolsters the supply chain’s resilience against risks like prolonged deadlines and development stagnation, thus avoiding the acquisition of unsuitable molds from suppliers.

Reduced Manufacturing Costs

If the current cost of metal 3D printing is higher than the cost of traditional metal manufacturing processes, then cost reductions are easier to achieve in the field of plastic products.

Metal 3D printed molds offer economic advantages in the production of small, discontinuous series of end products (as the fixed costs of these products are challenging to amortize) or for specific geometries optimized for 3D printing, providing even greater economic benefits. This advantage becomes particularly evident when the materials used are extremely costly, and traditional mold manufacturing results in high material scrap rates, where 3D printing can offer a cost advantage.

Furthermore, the ability of 3D printing to produce precise molds within a matter of hours can significantly impact manufacturing processes and profitability, especially in scenarios where production downtime or maintaining tool inventories is costly.

At times, it frequently occurs that the mold requires modification after production commences. The adaptability of 3D printing enables engineers to test numerous iterations concurrently, thereby mitigating the initial expenses resulting from mold design alterations.

Improvements in Mold Design Add More Functionality to End Products

The unique metallurgy involved in metal 3D printing often enhances the metal microstructure, resulting in fully dense printed parts possessing mechanical and physical properties comparable to or even surpassing those of forged or cast materials (based on heat treatment and test orientation). Additive manufacturing offers engineers a plethora of possibilities to enhance mold design.

In scenarios where the intended part comprises multiple sub-components, 3D printing enables seamless integration of the design, leading to a reduction in the number of parts required. This streamlines the product assembly process and minimizes tolerances.

Moreover, it can integrate complex product functions, enabling the faster manufacture of high-functional end products with fewer defects. For instance, the overall quality of an injection molded part is influenced by the heat transfer conditions between the injected material and the cooling fluid flowing through the tooling fixture. When produced using traditional methods, the channels directing the cooling material are usually straight, resulting in a slower and uneven cooling effect on the molded part.

3D printing allows for the creation of cooling channels in any shape to facilitate conformal cooling, which is more optimized and uniform, ultimately resulting in higher quality parts and reduced scrap rates. Additionally, quicker heat dissipation significantly decreases the injection molding cycle time, as cooling period typically represents up to 70% of the entire injection molding cycle.

Optimize Tools to be More Ergonomic and Improve Minimum Performance

3D printing significantly reduces the barriers to validating new tools that cater to unmet needs in manufacturing, enabling the production of additional moving and fixed fixtures. Historically, tools and related devices have been engineered to have maximum longevity, given the substantial costs and efforts involved in their redesign and fabrication. By leveraging 3D printing technology, businesses can revamp any tool at any juncture, not limited to those deemed obsolete and inadequate for the job.

With minimal time and initial investment, 3D printing renders it more cost-effective to fine-tune tools for enhanced marginal performance. Consequently, technicians can factor in ergonomic considerations during the design phase to enhance operational comfort, diminish processing durations, and streamline usability and storage.

While these improvements may only trim a few seconds off assembly operations, the cumulative impact can be significant. Furthermore, optimizing tool design can also curtail the scrap rate of parts, contributing to overall operational efficiency.

6. Disadvantages of 3D printing injection Molds

Shrinkage Defects in Printed Molds

Like all 3D printed parts, molds can suffer from a variety of defects, such as warping caused by shrinkage during cooling. When the mold warps, issues can arise when working with products that demand high tolerances.

Structural Integrity Issues

Plastic 3D printed molds are less stable than metal molds when it comes to withstanding the high temperatures and pressures of the injection molding process. The weak structural integrity of the mold can lead to issues like degradation of mold gates and weld lines, making it unsuitable for high-volume production.

Experimentation Requires Waste

When you 3D print a mold yourself, it is typical to generate some plastic waste before achieving the desired product. Despite the versatility of 3D printing for refining designs, certain imperfections might only emerge at the final stages, leading to increased wastage. It’s essential to highlight that this waste is recyclable.

Printing Effect is Limited by Material

While high-end industries can print plastics, certain metals, or ceramics, the current challenge lies in printing materials that are both expensive and scarce. The industry as a whole requires improved stability and ease of use in materials, alongside facing bottlenecks in the research and development of new materials. Furthermore, some 3D printing equipment has yet to reach a mature level, hindering its ability to support the wide array of materials encountered in daily life.

Is the Finished Product Sturdy and Durable

While houses and cars can be “printed,” can they withstand wind and rain and run smoothly on the road? Currently, 3D printing utilizes polymer materials, each with its melting point and fluid properties. Challenges arise in combining different materials in 3D printing, leading to shortcomings like the high brittleness of the final product.

Intellectual Property Concerns

In today’s era of increasing legal consciousness, people are placing greater emphasis on safeguarding intellectual property rights in the music, film, and television sectors. The advent of 3D printing technology further complicates this matter as concerns surrounding copyright infringement and counterfeit usage loom large.

The need to establish the legitimacy of copyrights for 3D printed products and prevent unauthorized reproduction has emerged as a crucial challenge in industry advancement. The formulation of legal frameworks by pertinent authorities governing 3D printing is essential to safeguard intellectual property rights and determine the responsible use of this innovative technology.

Difficult to Overcome Environmental Factors

In the 3D printing room, issues such as insufficient air purification, gaps in the machine, and impurities mixed in metal powder materials can lead to variations in oxygen content. This can adversely affect the mechanical properties of printed parts and may even cause changes in their chemical composition. Therefore, detecting the oxygen content in the printing room is crucial.

7.Conclusion

The impact of 3D printing on the manufacturing industry has been profound. Prototype parts that previously cost hundreds of dollars and took weeks to produce can now be designed in the morning, printed overnight, and delivered to customers the next day. Some companies have already started using 3D printing processes to manufacture injection molds.

Gone are the days of waiting months for mold production or facing substantial costs for mold modifications due to design changes downstream. With 3D printing, molds can be quickly produced, whether for mold verification or small batch production of injection molded parts.

The truth about 3D printed injection molds lies in their subtle advantages and limitations. Although the mold production cycle is shortened and manufacturing costs are reduced, improvements in mold design add more functionality to the end product. Optimized tools are more ergonomic and enhance minimum performance, while customized molds help achieve a tailored final product.

However, challenges exist, such as shrinkage defects in the printing mold, structural integrity issues, wastage in experiments, limitations in printing effects due to materials, concerns about the strength and durability of the finished product, worries over intellectual property, and difficulties in addressing environmental factors.

Therefore, 3D printed injection molds can be a valuable tool in the manufacturing arsenal, particularly for rapid iterations and specialized applications, but it is not a universal solution. Each project demands careful consideration of its unique requirements and the capabilities of 3D printing technology.