Low-Volume Injection Molding: Tailored for Your Small Batch Needs

Transitioning Trends in the Rapid Manufacturing Sector: Unveiling the Potential of Low Volume Injection Molding

The rapid manufacturing industry is currently undergoing a significant transformation, and within this landscape, low volume injection molding stands out as a pivotal technique. This method empowers plastic part manufacturers to effectively meet market demands by facilitating the production of small quantities of plastic components without compromising on consistency or quality.

Understanding the intricacies of low volume injection molding is paramount for manufacturers seeking to gain a competitive edge in today’s dynamic markets. To navigate this evolving terrain, we present an exhaustive guide covering all aspects of low volume injection molding.

Exploring On-Demand Manufacturing in Injection Molding

On-demand low volume manufacturing represents a paradigm shift in the manufacturing domain, introducing profound changes in the dynamics between engineers, suppliers, and manufacturers. This shift is particularly pronounced in the realm of custom plastic fabrication.

The proliferation of advanced technologies continues to reshape the manufacturing landscape, offering avenues to streamline quoting processes, enhance prototype manufacturing, and optimize supply chain visibility. Additionally, the advent of convenient platforms enables customers to manage their orders seamlessly from any location, further driving efficiency and accessibility in the manufacturing ecosystem.

BOYI, for instance, leverages cutting-edge Big Data analytics, software, and hardware to facilitate seamless integration into Industry 4.0. This strategic approach ensures the adoption of innovative methodologies and adherence to industry best practices. Consequently, it optimizes production processes, leading to enhanced efficiency and cost-effectiveness in the manufacturing of low-volume plastic parts.

In contrast to traditional manufacturing, which focused on mass-producing standardized products, on-demand manufacturing caters to the production of low-volume, customized items such as small-scale plastic injection molded parts. This methodology capitalizes on cloud-based technologies and self-service models, empowering customers with real-time quoting and order tracking capabilities.

Through on-demand manufacturing, customers gain access to precise small series injection molding parts tailored to their specific requirements. This streamlined approach addresses various challenges, including lead time reduction, improved communication, enhanced design for manufacturability (DFM), and cost optimization. As digital technologies continue to evolve, on-demand manufacturing emerges as a pivotal driver of transformation within the industry.

Key Benefits of Low-Volume Injection Molding

Low volume plastic injection molding offers several advantages that make it the manufacturing choice for several plastic parts over the traditional injection molding process. Here are some of its advantages.

Uses Softer Aluminum Tooling

Small batches do not require the hardened steel mold tooling typical of the traditional molding method. Instead, it utilizes softer aluminum material for mold fabrication. Aluminum, being considerably softer than steel, facilitates quicker and more efficient mold production.

Additionally, aluminum tooling eliminates the need for extra annealing steps required for steel, simplifying the heat treatment process. Moreover, aluminum molds support a wide range of surface treatments comparable to those used for steel.

Quality Parts Manufacturing

Despite employing softer tooling material, low volume plastic injection molding yields highly durable and functional parts.

Aluminum’s superior heat transfer rate over steel reduces the complexity of cooling line placement, allowing for more mold components and enhancing design flexibility. Consequently, this manufacturing process bridges the gap between prototyping and high-volume production, ensuring quality results.

Cost Savings

Low volume plastic molding enables manufacturers to produce parts without imposing minimum order requirements. Consequently, this approach proves advantageous for small batch plastic manufacturing, eliminating the need to contend with outdated inventory and resulting in significant cost savings.

Shorter Lead Times

The low volume injection molding process results in shorter lead times. Aluminum’s soft nature simplifies and expedites mold manufacturing, accelerating the overall production process.

With injection molds reaching manufacturing facilities more swiftly and low production volumes involved, production speeds up significantly. This expedites time-to-market, making low-volume injection molding a valuable technique for both small and large product teams.

Flexibility in Design

Low volume production involves manufacturing smaller quantities in the small run. Therefore, there will not be any major impact if a company decides to modify or alter the design. That way, the product can be perfected before it reaches the consumer.

A quality plastic injection molding process provides immediate feedback to improve manufacturability. It enables the testing of new concepts across various industries before mass production begins.

Bridge for Scale

If a company plans to mass-produce a product, low volume injection plastic molding is the ideal starting point. It serves as a bridge between prototyping and full-scale production, facilitating the transition from prototype to production quickly and with minimal commitment. Additionally, it allows for the refinement of both the product and the manufacturing process.

Designing Low-Volume Plastic Parts: Essential Considerations

In the realm of manufacturing low-volume plastic parts, meticulous attention to design is paramount. Below are critical considerations that demand your attention:

Selecting Optimal Material for Injection Molding

The cornerstone of successful low-volume injection molding lies in the judicious selection of materials. With a plethora of commercial-grade plastic options available, discerning the right thermoplastic resin is pivotal. Variables such as additive fillers, color variations, and performance attributes including strength, thermal conductivity, chemical resistance, and durability must be meticulously evaluated. The material chosen should align harmoniously with the intended application and operational milieu of the plastic parts.

Refining Surface Finish

Achieving the ideal surface finish necessitates a delicate balance. While it may be tempting to pursue a flawless exterior, it’s imperative to refrain from over-engineering surface smoothness. Excessive polishing, such as hand-polishing mold cavity surfaces to attain an ultra-smooth finish, can significantly inflate manufacturing costs and lead times. Opting for a more pragmatic approach, such as an as-milled surface with visible tool marks or employing alternatives like 600 gritstone or bead blasting for a textured finish, ensures a judicious balance between cost-effectiveness and functional integrity. The selected finish should seamlessly complement the operational requirements of the part.

Balancing Wall Thickness

In the realm of rapid injection molding, the significance of uniform wall thickness cannot be overstated. Deviating from the recommended thickness range for plastic families can precipitate a litany of molding defects, including sinking and warping. Adhering to the general guideline of maintaining wall thickness between 0.04 to 0.14 inches consistently throughout the part is imperative for ensuring structural integrity and mitigating potential manufacturing challenges.

Improving Product Integrity through Radii Implementation

Aluminum mold machining typically employs end mills, posing a potential issue with sharp internal corners. The presence of sharp corners in injection molded parts often induces stress and compromises the integrity of the product. To mitigate this concern, prioritizing the utilization of vertices or rounded edges (radii) in plastic part design is recommended. This strategic approach ensures the creation of sturdier products while enhancing moldability.

Enhancing Mold Ejection Efficiency with Draft Angles

Incorporating draft angles into the design facilitates the production of plastic parts with tapered edges, particularly beneficial for low volume production. This design feature reduces friction during demolding, thus minimizing the risk of mold or part damage and streamlining the part removal process. Adhering to a general guideline of integrating draft angles ranging from 1 to 2 degrees in injection molding practices optimizes ejection efficiency.

Maximizing Efficiency with Multi-Cavity Molds

For applications necessitating the simultaneous production of multiple identical parts, the adoption of multi-cavity molds proves advantageous. These molds enable the concurrent creation of two or more designs with minor variations, expediting the evaluation of different product iterations. Beyond initial sampling, multi-cavity molds offer cost-effective solutions by optimizing production volumes and reducing per-unit costs.

Understanding the Process of Low-Volume Plastic Molding

The low-volume plastic molding process encompasses various intricate steps aimed at achieving precise results. Below delineates the core stages involved:

Tooling and Mold Design

The initial phase entails meticulous scrutiny of the final plastic part specifications and judicious selection of appropriate materials. Subsequently, the mold design is meticulously crafted, typically leveraging metals like aluminum for injection mold fabrication.


This pivotal stage entails the utilization of cutting-edge 3D printing technology to fabricate prototypes of the injection molds, commonly referred to as 3D printed molds. Engineers rigorously assess these prototypes for design flaws and functionality discrepancies, subsequently refining the mold through advanced manufacturing techniques such as 3D printing or CNC machining.

Setting Up the Injection Molding Machine

Prior to commencement, essential components such as the ejector system are seamlessly integrated into the mold. Subsequently, the mold is meticulously loaded onto the injection molding machine. The engineer then meticulously calibrates crucial parameters including temperature, pressure, and injection speed. A comprehensive test run is conducted to ascertain the quality and efficacy of the production run.

Optimizing the Injection Molding Process

The injection molding process comprises several critical stages, each contributing to the overall efficiency and quality of the final product:


Efficient clamping involves the utilization of a robust clamping system capable of exerting sufficient force to secure the mold firmly in place. This action ensures the precise alignment of mold halves, minimizing disruptions during injection. Notably, in scenarios involving 3D printed injection molds shielded by a metal frame, the clamping force must be meticulously calibrated to balance stability and flexibility.


This pivotal step varies depending on the machinery employed but fundamentally involves the seamless transfer of molten plastic into the injection barrel, followed by its precise injection into the mold cavity.


Upon injection, the molten material begins its cooling and solidification process within the confines of the mold. The duration of this phase is influenced by factors such as mold composition, with plastic molds typically exhibiting slower thermal transfer rates compared to their metal counterparts. To expedite cooling, methods such as compressed air or interchangeable stacks may be deployed to optimize efficiency.


The ejection of molded parts, whether manual or assisted by ejector pins, marks the culmination of the injection molding process. Mechanically, this involves the retraction of the clamping plate and subsequent opening of the mold halves. Ejector pins then facilitate the smooth removal of the finalized part from the mold cavity, ensuring precision and minimizing production downtime.

Quality Control and Post-Processing

Quality control encompasses the meticulous inspection of low-volume plastic parts to identify and rectify any defects, ensuring strict adherence to established quality standards. Subsequently, precision trimming of the molded components is conducted, followed by meticulous secondary surface finishing operations.

Exploring the Versatility of Low-Volume Injection Molding

Low-volume injection molding stands out as a pivotal manufacturing solution, particularly advantageous for small and medium-scale enterprises. Here, we delve into the key applications of this innovative technique:

Rapid Prototyping

Low-volume injection molding emerges as an optimal avenue for prototyping plastic parts. Its merits lie in expedited and cost-efficient production, facilitating seamless testing and validation of designs prior to mass production tooling. This enables smoother refinement processes, bolstering product development cycles.

Small Batch Injection Molding

This method finds resonance in producing small batches of parts, offering an economically viable solution, notably for businesses constrained by capital for large-scale production. In contrast to conventional injection molding, it entails lower costs and supports small-run production, empowering businesses to promptly adapt to dynamic market demands.

On-Demand Injection Molding

Embracing a responsive approach, on-demand injection molding facilitates production based on immediate requirements. This mitigates the need for substantial inventories, thereby reducing storage costs. Additionally, it fosters agility in navigating demand fluctuations, rendering it particularly suited for enterprises operating within unpredictable industries.

Optimizing Selection of On-Demand Injection Molding Partners

Low-volume injection molding stands as a cornerstone of efficient, high-quality manufacturing processes. Yet, navigating the landscape to identify the ideal provider for plastic injection molding services presents its own set of challenges. Below, we delineate key considerations to guide your decision-making process:

Volume Capacity and Specialization

Begin by scrutinizing the volume capacity and specialization of prospective companies. Prioritize those equipped to handle low to moderate production volumes, typically under 10,000 parts. Such firms demonstrate agility in providing rapid prototypes crucial for testing iterations.

Specification Adherence

Select a partner committed to delivering low-volume, high-quality injection molded products without compromise on specifications. This necessitates meticulous compliance with design requirements, backed by recommendations informed by extensive experience, knowledge, and expertise. Additionally, any adjustments to the design should undergo your thorough approval process.

Flexible Service Offerings

Opt for a partner offering a comprehensive suite of prototyping services, including mold flow analysis, responsive manufacturing, and adept part design capabilities. Integration of complementary manufacturing services such as CNC machining and additional injection molding further enhances value. This holistic approach ensures a nuanced understanding of your project requirements and facilitates proactive resolution of production challenges.

Efficiency and Quality Assurance

The hallmark of an exemplary on-demand injection molding company lies in its unwavering commitment to efficiency and quality. Utilization of cutting-edge technologies within the manufacturing process, complemented by robust project management software, fosters seamless communication and streamlined operations. These elements collectively bolster the production of small batches of plastic parts to the highest standards of quality and precision.

BOYI Low-Volume Injection Molding Services

At BOYI, we stand as your premier partner for low-volume injection molding needs. Leveraging our extensive experience, specialized expertise, and state-of-the-art facilities, we expedite the transition of your plastic parts from production to market in record time. Our cutting-edge rapid quotation system employs the latest technologies, ensuring instantaneous quotes for your projects.

We pride ourselves on delivering swift turnarounds for our low-volume plastic injection molding services while upholding uncompromising quality standards. Opting for BOYI means gaining access to top-notch prototypes with abbreviated lead times and cost-effective pricing. Simply upload your design file, and allow us to deliver unparalleled services tailored to your requirements.

There exists a spectrum of alternative methods for low-volume plastic manufacturing, each offering unique advantages in terms of cost-effectiveness and accelerated time to market. Below, we delineate some of these alternatives:

3D Printing

Considered a high-quality manufacturing process, 3D printing stands as a viable alternative to quick turn molding for numerous product designers and manufacturers. Notably, it obviates the need for upfront investment in mold creation and boasts a significantly shorter lead time.

Engineers and designers often favor 3D printing for its capacity for rapid iteration during plastic product production. While 3D-printed parts may exhibit layered surfaces initially, these can be easily refined through sanding and painting to achieve the desired surface finish.

Precision CNC Machining: An Indispensable Manufacturing Method

Despite its historical roots, CNC machining stands as a cornerstone in contemporary manufacturing processes, particularly in the realm of small quantity plastic manufacturing. Renowned for its versatility, CNC machining transcends its plastic domain to adeptly handle various materials, including metals. Its proficiency extends to the creation of precise molds, patterns, or dies essential for diverse manufacturing processes such as molding and casting.

CNC machining, albeit a relatively pricier option, proves its mettle in facilitating swift production runs. Leveraging its capabilities, manufacturers often integrate CNC milling with complementary techniques like 3D printing to enhance production efficiency or achieve exacting tolerances.

Thermoforming: Crafting Precision with Heat

Thermoforming emerges as an alternative manufacturing technique wherein molds undergo thermal treatment, facilitating the shaping of a thin plastic sheet through mechanical force, pressure, or vacuum. This process yields components that mirror the mold’s contours, with excess material subsequently trimmed away.

Distinguished by its operation at low temperatures and pressures, thermoforming finds favor due to its compatibility with cost-effective materials. Notably, surface finish assumes paramount importance as the final product may intricately mirror the mold details. Consequently, thermoforming predominantly caters to the fabrication of relatively straightforward components such as packaging trays and vehicle door panels.

Urethane Casting: Innovating with Versatility

Urethane casting presents an innovative manufacturing avenue characterized by minimal initial investment and expedited lead times. This process commences with the creation of a master pattern via high-resolution 3D printing or CNC machining.

The master pattern serves as the linchpin in crafting a urethane mold, into which suitable resin is poured, enabling the production of multiple product replicas. Noteworthy for its longevity, a urethane mold can endure up to 20 production runs, rendering it a cost-efficient solution that empowers product designers to validate design specifications and solicit early feedback.


Injection molding presents a viable cost-effective solution for mass production. However, in instances where lower volumes are required, small and medium-scale enterprises can leverage small run injection molding to manufacture limited quantities of plastic parts. This approach facilitates expedited market entry, enhanced control over product quality, shortened lead times, among other benefits. This article serves as a comprehensive guide to small run injection molding, equipping readers with the necessary insights to make informed decisions.

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