Injection molding is usually the first choice when it comes to producing high-quality plastic components. It entails heating plastic material and injecting it into a mold for cooling and solidification. Injection molding comes with high precision and is a repeatable way to produce identical plastic parts. However, there are many myths surrounding injection molding. These misconceptions can cause misunderstandings and misinformed decisions.
As a seasoned manufacturer or someone new to injection molding, it is essential to separate fact from fiction. This article will debunk ten common injection molding myths and unlock the full potential of this manufacturing process.
10 Common Myths and Facts About Injection Molding
There are many misconceptions about injection molding that are becoming the norm. They can lead to poor decisions when choosing a manufacturing process. Below is an extensive discussion of the common myths about injection molding and the facts behind them.
Myth 1: Injection molding is only for high-volume production.
Fact: From prototyping to large-scale manufacturing, the injection molding process is ideal for projects with different quantities of parts.
Reasons: Modern tooling technology advancements make injection molding feasible for low-production runs. One of the most significant concerns in injection molding is the lengthy setup process and the time it takes to produce the molds. With the introduction of rapid tooling, it is possible to create molds in days. This reduces lead time and set-up costs.
Myth 2: Injection molds are too expensive for small businesses.
Fact: Injection molding is an affordable fabrication option for small and medium-scale businesses.
Reasons: A key factor that affects the cost of injection molding is the mold itself, which is usually made of steel. Steel molds are expensive, and small businesses cannot afford them. However, aluminum molds are becoming the mainstay, costing about 30-50% of the steel type. Furthermore, 3D-printed molds are less expensive to produce compared to traditional ones. Many third-party manufacturers now offer low-volume injection molding services with no strict minimum order quantity.
Myth 3: Plastic injection molded parts are weak and low-quality.
Fact: The injection molding process produces durable, high-quality parts with tolerances as low as +/- 0.001 inches.
Reasons: The molded part’s strength depends on the starting material’s mechanical properties. Modern injection molding operation is compatible with high-grade plastics such as polycarbonate, nylon, and acrylonitrile butadiene styrene. You can further reinforce these materials with additives like carbon fiber to increase strength and durability. Furthermore, this technique produces repeatable parts with consistent quality across thousands and millions of cycles.
Myth 4: Injection molding can’t produce complex geometries.
Fact: Injection molding can create complex shaped parts with detailed features compared to other fabrication techniques.
Reasons: The recent advancements in mold design, such as side actions and slides, allow one to produce undercuts, internal channels, and delicate textures. Additionally, over-molding or insert molding operations make using more than one material for a single part possible. Furthermore, the design for manufacturability (DFM) approach helps you to optimize your designs. You are sure you can easily mold the features before making heavy investments. You can also use modern simulation tools to design molds that will accommodate complex shapes.
Myth 5: Recycled materials can’t be used in injection molding.
Fact: With proper selection and processing, it is possible to reuse recycled material during injection molding.
Reasons: It is possible to reprocess plastics and polymers to ensure they retain their properties. Technological advancements have provided methods that break down plastics into their original monomers. The recycled products are free of impurities, and you can mold them to the same quality as new plastic. Furthermore, you can mix recycled plastics with virgin materials to ensure consistent quality with top-notch mechanical properties. For instance, blending 20% recycled plastic with 80% fresh one gives a product that performs like 100% virgin plastic.
Myth 6: Injection molding always leaves visible defects.
Fact: Proper design, material selection, and process control minimize defects in injection molding.
Reasons: The defects such as warping and sink marks that arise from injection molding are not peculiar to the operation. It occurs when you don’t design properly or use incorrect molding parameters. For example, sink marks happen when there is uneven cooling. Additionally, you would also see flow lines from improper melt flow rates. Adding essential features like ribs or gussets reduces warping in thin-walled parts. Furthermore, the use of hot runner systems in injection molding has streamlined the process. This technology provides uniform operating temperature and reduces visible runner marks.
Myth 7: Cooling time cannot be optimized without sacrificing quality.
Fact: With advanced technology, it is possible to optimize cooling time without compromising the quality of the molded part.
Reasons: Modern injection molds come with channels that make cooling faster and uniform. This feature reduces cycle time by up to 30% while maintaining quality. Furthermore, using materials like beryllium, copper, and aluminum has improved things in many ways. These mold materials have high thermal conductivity, enabling faster heat transfer during cooling.
Myth 8: It is challenging to change designs after mold creation.
Fact: It is possible to modify mold designs to accommodate changes efficiently and cost effectively.
Reasons: The use of computer aided design and computer aided manufacturing software makes it easy to update mold designs. You can easily modify the mold’s geometry and implement changes with minimal error. Furthermore, many molds are designed with removable inserts and modular components. As a result, you can replace or adjust specific sections of the mold without remaking it as a whole. So, if a shell feature like logo or text needs to be replaced, you can easily swap the insert in question.
Myth 9: Injection molding is unsuitable for sustainable manufacturing.
Fact: There are many eco-friendly practices that make injection molding adaptable for sustainable manufacturing.
Reasons: A well-planned injection molding operation produces near zero material waste. Compared to other methods like machining, injection molding is more material efficient. The use of hot runner systems makes everything better. The material remains molten throughout, and you do not have to regrind solidified runners. Additionally, you can incorporate closed-loop recycling systems to reuse scrap metal generated during molding.
Myth 10: Injection molding machines require constant manual supervision.
Fact: Injection molding machines are highly automated and require minimal manual intervention.
Reasons: Modern injection molding machines have robotic systems that automate everything. You do not have to handle tasks like part removal and gate trimming. This feature allows the machine to run independently for extended periods. Additionally, some machines come with real-time sensors. Hence, one can monitor parameters like pressure, temperature, and cycle time. These automated machines are essential in high-volume production. They operate round the clock and produce defect-free parts.
Conclusion
Injection molding is an efficient manufacturing process. However, misconceptions about its capabilities have limited and prevented manufacturers from leveraging its full potential. Understanding the facts behind these myths will allow you to optimize production processes and improve product quality. This article has addressed ten popular injection molding myths. It has highlighted how modern technological advancements have transformed injection molding into a sustainable plastic fabrication solution in industries worldwide.