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Low-Volume Injection Molding: Understand Your Production Options

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    The rapid manufacturing industry is in a massive transition state. This fast-paced market requires getting products into the market as quickly as possible. At the same time, designers, engineers, and manufacturers have to ensure that they maintain quality products. Low-volume injection molding is one aspect of manufacturing that caters to clients’ needs.

    This production method enables manufacturers to create identical low-volume plastic parts with consistent characteristics and qualities. Manufacturers now adopt new operation techniques to gain an advantage in the evolving markets. This extensive guide takes you through everything you need to know about low-volume injection molding.

    On-Demand Manufacturing as the Next Industrial Trend

    On-demand, low volume manufacturing is a relatively new concept in the manufacturing world. It brings about a number of dramatic changes to how engineers interact with suppliers and manufacturers. This is even more so when it comes to custom plastic fabrication. The rise of various advanced technologies continues to evolve the manufacturing space.

    low volume injection molding for on demand manufacturing

    In so doing, there is an increased potential to eliminate quoting delays and improve prototype manufacturing techniques. The visibility of orders within the supply chain becomes a lot more straightforward. Also, customers are able to manage their orders from anywhere via a convenient platform.

    RapidDirect, for example, now combines the latest Big Data analytics, software, and hardware to enable Industry 4.0 integration. This way, there is a guarantee for innovative approaches and best practices. It, in turn, results in smarter production and ensures the cost-efficiency of low-volume plastic parts production.

    Traditional manufacturing involved the mass production of large-scale similar products. However, on-demand manufacturing enables low-volume, customized products such as small-scale plastic injection molding. It takes advantage of cloud-based technologies and self-service models. This allows customers to get quotes in real-time and keep tabs on their orders throughout manufacture.

    With on-demand manufacturing, customers can order precise small series injection molding parts. The quantity on order will satisfy immediate production requirements. This will address several pain points regarding lead time, communication, design for manufacturability (DFM), and cost. With digital technology becoming central to the industry, on-demand manufacturing is leading a decent revolution.

    Key Benefits of Low-Volume Injection Molding

    Plastic injection molding is one of the major processes in rapid manufacturing. It is a rapidly evolving model enabling faster production to market times. However, the traditional process is not as fast as you would like it.

    an injection molded prototype

    The plastic market demands, in some ways, contradict the nature of production. The complexity of mold design may further increase the time needed to make the parts. However, low-volume injection molding helps to address these problems effectively. Here are some of its advantages.

    Uses Softer Aluminum Tooling

    Low volume injection molding doesn’t require the hardened steel mold tooling typical of the traditional molding method. Rather, it uses the softer aluminum material for making the molds. Aluminum is a considerably softer material than steel. Thus, it is much easier and faster to work with. 

    Furthermore, aluminum tooling allows for easier heat treatment because there is no need for the extra annealing step. There is often the need to anneal steel tooling to reduce any internal stress and to toughen the metal sufficiently. Moreover, aluminum molds support most surface treatments that you would normally use for steel.

    Quality Parts Manufacturing 

    Despite using a softer tooling material, low-volume injection molding produces highly durable and functional parts. It is a practical manufacturing technique for producing several types of products. Furthermore, aluminum has a better heat transfer rate than steel. The better conductivity makes the positioning of cooling lines less critical. That way, there is room for more mold components. Thus, low volume injection molding ensures better design flexibility, closing the gap between prototyping and high-volume production.

    Save Costs

    There is this popular belief that buying products often saves money. This is not always true in some cases. Where it may be the case for household items, it may not be the same for construction items. In terms of manufacturing, the cost per unit depends highly on the materials used in the production. In some cases, high-volume injection molding companies may impose some minimum order requirements. They do this to offset large production investments and cover costs.

    On the other hand, low-volume injection molding often comes with much lower overheads. In this case, manufacturers can make products without demanding minimum orders. Therefore, if you’re looking to get small-batch plastic manufacturing, this can really be helpful. You will also avoid getting products from an outdated inventory. All of these translate to effective cost-saving.

    Shorter Lead Times

    Asides from the affordable cost, the manufacturing technique also helps to improve the efficiency of plastic part production. It works with a system that helps in a faster quotation of orders. The software also reviews the part design to ensure accurate and quick output.

    Moreover, the soft nature of aluminum makes mold creation far easier and quicker. You also do not need hardening to enhance durability. So, the mold gets to the manufacturing facility a lot quicker, and production can start in earnest. In many cases, this significantly accelerates time to market, making this technique beneficial for both small and large product teams.

    Flexibility in Design

    Small-scale injection molding involves manufacturing smaller quantities in the short run. Therefore, there won’t be any major impact if a company decides to modify or alter the design. That way, the product can be perfect before it gets to the consumer.

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

    Bridge for Scale

    If a company plans to have a mass-produced product, small scale plastic manufacturing is the way to start. It helps to bridge the production gap between prototyping and production. This method brings a feasible prototype to production without requiring too much commitment. It also helps to fine-tune the product and the process.

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    Design Considerations for Low-Volume Injection Molding Parts

    There are some key design considerations that you must keep in mind for effective manufacturing. They include:

    Choose the Right Material for Your Injection Molded Part

    There are several commercial-grade plastic materials available for manufacturing. The first step in designing for low-volume injection molding is the selection of material. Thermoplastic resins come in different additive filler and color options.

    materials for low volume injection molding

    Features such as strength, thermal and chemical resistance, durability, and others will vary by the chosen material. Some materials will require fewer drafts due to their flexibility. You should consider the intended application of your products and their possible level of exposure before choosing the material.

    Finesse a Part’s Finish

    One of the commonest mistakes you can make with plastic injection molding is choosing a better surface finish than necessary. This may badly impact the product’s functions. For example, very smooth surface finishes require hand-polishing of mold cavity surfaces. The polishing may be done with diamond buff up to 2 Ra.

    finnesse a part's finish

    This practice significantly increases mold manufacturing costs and lead time. A more cost-effective finish is an as-milled surface that probably shows some tool marks. The two other options available involve the use of 600 gritstone or bead blasting textured finish. The chosen finish must be compatible with the part’s function.

    Scale Wall Thickness in Both Directions

    Wall thickness is crucial in plastic parts production. Walls should not be thicker than the recommended range for particular plastic families. Such walls may be subject to sink, warps, and other molding defects. The general rule of thumb is to use a wall thickness between 0.04 to 0.14 inches consistently across the whole part.

    Solve Corners that Weaken Product Integrity by Using Radii

    Machining of aluminum molds occurs using end mills. Therefore, sharp internal corners may be a concern.

    using radii to improve part moldability and reduce stress

    Sharp corners on injection molded parts often create stress and compromise a part’s integrity. As such, it will be best to use vertexes or rounded edges (radii) for plastic part design. This will ensure a more substantial product and improved moldability.

    Use Draft to Enable Easier Ejection of Part from Mold

    It is beneficial to generously angle injection molded parts. This will create components with tapered edges to enable easy release from the mold.

    using draft to improve part removal in low volume injection molding

    Multi-Cavity Mold May Be a Good Option

    If you wish to form multiple identical parts in a single shot, then a multi-cavity mold will come in handy. It helps to produce two or more designs with tiny iterations at the same time. This enables the quick testing of different product designs simultaneously. Whenever there is a need for quantities beyond initial samples, they also serve as good options. At the same time, they can also help to reduce costs per unit.

    Choosing the Right Low-Volume Plastic Injection Molding Services

    Low volume injection molding is an efficient process for high-quality manufacturing. However, it finding the best partner for top-notch plastic injection molding services could be challenging. Here are a few factors to consider before choosing a plastic injection company:

    Volume Capacity and Specialization

    The first step in narrowing down your choice is to use the company’s volume capacity and specialization. Companies capable of low to moderate production (pars under 10,000) are advised. This is because they are able to offer prototypes quickly enough for testing.

    Specification Compliance

    It will be best to go for a company that can offer low volume but high-quality injection molded products without compromising the specification. That is, the low volume injection molding company must fully comply with the design specification. Recommendations are allowed based on experience, knowledge, and expertise. You must approve every adjustment to the design.

    Flexible Services

    You must opt for an injection molding partner that offers a wide range of prototyping services. These include mold flow analysis, responsive manufacturing, and part design. Offering other manufacturing services such as CNC machining and injection molding will be a quality addition. Such companies will understand your requirements better and tackle production problems early.

    Efficiency and Quality

    A good injection molding company for small scale plastic parts production must adhere to the best standards of efficiency and quality. The machines should work with the latest technologies with high-quality project management software for better communication.

    RapidDirect Low-Volume Injection Molding Services

    RapidDirect is your number one small-scale plastic injection molding partner. We effectively combine our experience, expertise, and powerful facilities to get your plastic parts from production to market within a short time. Our rapid quotation system uses the latest technologies to give you quotes within seconds.

    rapiddirect low volume injection molding services

    We boast of a fast turnaround on our low-volume injection molding services without compromising on quality. Choosing RapidDirect would mean that you get quality prototypes with short lead times and budget-friendly prices. Upload your design file, and let’s offer you our best services.

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    Alternatives to Low-Volume Plastic Injection Molding

    There are various other low volume manufacturing methods asides from injection molding. Below are some of the alternatives you can choose for cost-effectiveness and faster time to market.

    1. 3D Printing

    This is one of the latest quality manufacturing processes for low-volume productions. 3D printing does not require any upfront investment into mold creation, and it has a track record of faster lead times.

    3D printing for rapid prototyping

    Most engineers and designers prefer this method for quick iterations during plastic product production. 3D printed parts often come with layered surfaces. However, the surfaces can be easily sanded and painted for desired surface finish.

    2. CNC Machining

    Despite being one of the oldest manufacturing methods, CNC machining remains one of the most reliable low volume manufacturing methods. It is versatile and can work with different types of materials. It helps to create accurate molds, patterns, or dies for various manufacturing processes such as molding, casting, and others.

    cnc machining for rapid prototyping

    Set up costs for CNC machining may be higher than for CNC machining. However, it is well suited for low-volume production runs with quick turnarounds. Some cases may also involve CNC milling combined with other processes for effective production. For instance, manufacturers combine CNC machining with 3D printing to get tighter tolerances.

    3. Thermoforming

    This is another robust process involving creating molds over which there is the heating of a thin sheet of plastic. The heated plastic is then formed with a mechanical force, pressure, or vacuum. The plastic sheet, in this case, will take the mold’s shape with extra material being trimmed off.

    thermoforming as alternative to injection molding

    This process involves low temperatures and pressures. Therefore, making the mold will require relatively inexpensive materials. Surface finish after this process is essential because the product may pick up some details of the mold. Manufacturers limit thermoforming to the manufacturing of relatively simple components such as packaging trays, vehicle door panels, etc.

    4. Urethane Casting

    Another excellent alternative to prototype injection molding is urethane casting. A difference between them is that there is no upfront cost on increased lead times with urethane casting. It involves the creation of a master pattern of product with high-resolution 3D printing or CNC machining.

    urethane casting for prototype manufacturing

    This pattern helps to create a urethane mold where a suitable resin is poured into making several copies of the product. Since the mold can last for up to 20 runs, this method is great for cost-effective runs. It enables designers to test design requirements and gather feedback early. 

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