Injection molding is an efficient manufacturing method, but it often generates significant waste, including low efficiency, work errors, injection machine damages and downtime, high scrap rates, and more. Below are 7 methods to reduce injection molding costs, helping to improve the profitability of the injection molding process.
Reduce Risk and Quality Costs
Aspects related to reducing risks and quality costs are often passive rather than proactive. The reason for this lies in the unpredictability of the injection molding process, making it challenging to anticipate issues. Unforeseen risks and expenses arise when the delivered products are non-compliant.
However, there are better ways to handle this. Start by using scientific molding principles to develop repeatable and stable processes. By incorporating sensors and molding technologies to develop the process, you can monitor common injection defects to ensure 100% quality assurance for your customers.
Frequently, we encounter situations where an injection machine has been running for weeks, and process technicians must continuously make adjustments. Despite these efforts, product defects persist, and we must modify the process and isolate suspicious items, regrind and remold them.
The worst-case scenario is when some defective products have already been sent to customers, leading to costly consequences. Without developing and documenting reliable processes based on scientific molding principles, our technicians waste precious time adjusting processes, hoping for acceptable production outcomes.
When defects occur, technicians are required to adjust the injection machine again to resolve the issue, without certainty that the problem won’t recur. Deciding how to handle defective products, such as sorting or reworking, may take several days or even weeks and is rarely 100% effective. It is a non-value-added task.
Avoiding these situations is possible if time is spent creating and documenting a process capable of consistently producing high-quality products from the outset. Using cavity pressure sensors to monitor the production process achieves a higher level of quality control. Imagine knowing whether a product is acceptable even before the mold opens and being able to automatically sort the products.
Improve Efficiency Through Automation
By leveraging molding technologies and training, various production areas can be automated, boosting labor efficiency. Three useful automation methods include product gripping, stacking, and palletizing. Process control technologies enable automatic sorting and alerting, notifying you when the process deviates from tolerances. With access to data, you can identify root causes faster, avoiding finger-pointing and further enhancing efficiency and accuracy. Troubleshooting can cease, and problem-solving can begin.
Consider the processes in a factory without automation. In a step-by-step molding manufacturing process, we need to extract products and runners from the mold, place them orderly, and then package the final products onto trays. At some point in this process, an assembly step might be required, adding additional labor, floor space, and time.
If these processes are entirely manual, the efficiency will vary. Even with the most skilled operators, time fluctuations can lead to varying cycle times, resulting in unstable product quality. Such fluctuations accumulate throughout the process.
When we start automating these processes, we eliminate these fluctuations, improve efficiency, enhance quality, and create more available space. Quality automation—through process monitoring, vision systems, or online dimension verification—ensures our customers will never receive defective products.
Reduce Scrap
By promptly identifying process changes, you can solve problems faster, resulting in reduced scrap, increased machine utilization, and lower waste costs. This goal can be achieved through process control software, cavity pressure monitoring, and training.
Inherent quality costs exist in the manufacturing process. This cost often emerges at the back end of production, just before delivering products to customers, involving valuable resources and time in inspecting products. The problem with such costs is that we never have a fixed quality cost. As production changes, the time and the number of employees required to sort products also change.
Employee turnover can lead to investing in training new employees to learn how to sort non-compliant products. Ensuring that all technicians receive standardized training proactively reduces or eliminates defective products, rather than reacting to them or preventing high scrap rates caused by low skill levels, narrow process windows, or the absence of process windows.
Another way to consider quality costs is at the front end. By building quality into the process and monitoring quality throughout the cycle, we can detect process variations. For example, if we know that a wide variation in material viscosity will lead to quality issues, we can use process monitoring tools to detect viscosity changes. At this point, the process can be adjusted back to the median to manufacture high-quality products.
Purchase Wide-Spec Resins
Resins with larger performance variations are cheaper but may pose challenges in ensuring or maintaining product dimensions for strict tolerances. However, this could be a successful venture when using DECOUPLED MOLDING® technology and cavity pressure sensors.
Have you encountered situations where you produce good products for consecutive days, only to have flash defects suddenly appear? To address this issue, process technicians lower the filling rate. After a few hours, short shots occur. Why, after everything was running well, do flash defects suddenly appear? The answer is likely viscosity.
Viscosity can fluctuate up to 30% and even with Decoupled II molding, producing compliant products can be challenging. To ensure consistent product output in every cycle (or at least as close as possible), cavity pressure sensors are used to control the process and minimize the influence of material viscosity changes.
Shorten Cycle Time
You can optimize clamp force/ejection, fill time, pack time, hold pressure, and cooling using scientific molding and DECOUPLED MOLDING® technologies. Good products can be molded with a smaller shot size.
Effective mold temperature control units or mold temperature controllers also aid in shortening cycle time. 80% of the molding cycle is devoted to cooling the product from melt temperature to demolding temperature, ensuring the product is sufficiently solid to withstand ejection force and maintain dimensional stability. If there isn’t enough cooling water flow, the ability to cool the product to the correct temperature is compromised. The only option is to leave the product in the mold for a longer time, which costs more.
Evaluating product thickness at the project’s start is the first step in determining cycle time. Questioning the product thickness and its impact on cycle time and product performance is essential. Often, we find products designed in a certain way because “that’s how it’s always been done.” You can imagine how costly this can be. Science and simulation help predict the success of a design, so we no longer need to mold products to obtain results. Ensuring proper product design is just one example of reducing cycle time.
Manufacture More Efficient Molds
In simple terms, a mold is both a pressure vessel and a heat exchanger—pressure loss always occurs in the cavity. However, in most cases, the lower the pressure loss from the gate to the end of the cavity, the less likely quality issues such as warping, sink marks, voids, short shots, or dimensional fluctuations occur.
To make plastic flow, we need to heat it, but to eject the product, we need to remove some heat. To manufacture efficient molds, ensuring the correct design of the cooling circuit is crucial. We also need to choose a metal with good heat transfer properties while resisting material wear (especially with materials containing glass or carbon fiber fillers). Finally, the process must be set up for turbulence, ensuring the mold reaches thermal stability quickly and maintains it during long-term production runs.
You can also increase mold efficiency by adding more cavities to the mold. Single-cavity molds have minimal fluctuations, but manufacturing one product at a time can be cost-prohibitive. Increasing the number of cavities allows for more products to be manufactured in the same amount of time. However, there are some limitations to how many cavities can be accommodated, including product quality, spacing between molds and injection machines, and validation requirements.
Another method to enhance mold efficiency is by creating family molds, incorporating different product geometries within the same mold. This can be challenging as four plastic variables are different within each cavity. However, with the aid of process control software and cavity pressure sensors, you can individually control each cavity using needle valve gates.
Reduce Mold Transfer Costs
Application of process development ensures you can quickly and easily transfer molds from one injection machine to another. When transferring molds, the setup conditions for the injection machine are automatically generated, allowing you to produce good products from the first mold. These settings can be used for any injection machine as long as it can provide sufficient flow, pressure, temperature, and volume. Alternatively, if simulations are not used, we can generate templates and transfer them to any capable injection machine.
By reducing the risks and costs associated with poor quality, automating production processes, minimizing scrap, selecting suitable resins, shortening cycle times, improving mold efficiency, and optimizing mold transfers, injection molding costs can be significantly reduced. These measures will not only increase profitability but also enhance customer satisfaction by delivering high-quality products consistently.
Embracing modern technologies, like scientific molding principles, DECOUPLED MOLDING® techniques, process control software, and cavity pressure sensors, can revolutionize injection molding processes, making them more efficient, reliable, and cost-effective. By adopting these strategies and staying ahead of the curve, manufacturers can thrive in a competitive market and ensure the long-term success of their injection molding operations.
In conclusion, the continuous improvement of injection molding processes will be key to unlocking greater cost savings and boosting productivity in the coming years. As new advancements in technology and manufacturing methods emerge, the injection molding industry will undoubtedly continue to evolve, offering exciting possibilities for innovation and efficiency gains. By focusing on reducing costs and optimizing operations, manufacturers can position themselves for success in a rapidly changing global market.