Cracking or fracturing is a common physical failure of a material due to low strength during a custom plastic injection molding process. It drastically reduces the quality and aesthetic appeal of the molded parts, negatively impacting the functionality and performance of the final product. While cracking is a common failure, you can easily avoid it by following some essential tips that can make the custom plastic injection molding process an effective one.
But before diving into how to avoid cracking, it’s essential to see the reasons for this cracking in the first place. Multiple factors contribute to the cracking of molded parts.
Machine
In custom plastic injection molding, the plasticizing capacity of the machine plays a crucial role in deciding whether the molded part cracks or not. If the plasticizing capacity is too small, the plastic will not thoroughly mix, leading to cracks. On the other hand, if the capacity is too large, the plastic can degrade, which in turn causes cracking.
Mold
Plastic injection mold design also directly influences the quality of the final product. Undercuts or parting line burrs can induce stress concentration points, which usually leads to crack formation. Similarly, improper ejector design exerts uneven stress on the part during ejection, increasing the likelihood of cracking. It would help if you always looked for a quality plastic injection mold supplier to get the best results.
Material
The raw material’s quality and condition significantly impact the integrity of the molded parts. Utilizing excessive reclaimed materials can compromise the consistency and strength of the plastic, leading to cracks. In addition, moisture in the material can lead to voids and defects, weakening the part and making it susceptible to cracking.
Molding Operation
In the actual molding process, factors such as cooling time and molded-in stresses can influence the frequency of cracking. Short cooling times do not allow the part to solidify completely before ejection, causing internal stresses and potential cracks. Molded-in stresses result from stress concentration points due to the design or operational aspects of the molding process.
Fortunately, cracking can be minimized or avoided altogether by applying certain best practices in the custom plastic injection molding process.
What Can You Do to Avoid Cracking?
Check and Remove the Burrs Before Injection
Before molding, ensure that the mold is clean and free of any burrs. This reduces the likelihood of stress concentration points that can lead to cracks.
Set Enough Knockout Pins to Maintain Even Stress
Design the mold to include an adequate number of knockout pins. This ensures that the ejection stress is evenly distributed, thus preventing crack formation.
Reduce the Percentage of Reclaimed Materials
While using reclaimed material can be cost-effective, it is crucial to balance this with the quality of the final product. Reducing the amount of recycled material in the mix can significantly enhance the strength and consistency of the molded parts.
Dry All Materials
Ensure all materials, especially hygroscopic ones, are thoroughly dried before use. This will help you prevent the formation of voids and defects that can weaken the part and cause cracking.
Increase Cooling Time
Allowing sufficient time for cooling ensures that the part is fully solidified before ejection, reducing internal stresses and the likelihood of cracking.
Reduce Holding Pressure
While adequate pressure is necessary to fill the mold, excessive pressure can lead to stress concentration points and, thus, cracking. Fine-tune the process parameters to find the optimal holding pressure.
The Benefits of Choosing HordRT’s Services
HordRT provides state-of-the-art custom plastic injection molding and rapid tooling services to help you in various manufacturing processes. Here are the benefits of using these services.
Rapid Plastic Injection Molding Service
HordRT’s custom plastic injection molding service stands out for its speed, quality, and professionalism. The service is characterized by a swift turnaround, ensuring that you receive high-quality plastic parts in minimum time.
HordRT’s service also guarantees the use of top-notch materials for your project. All materials are sourced directly from manufacturers or authorized agents, ensuring their quality and reliability. This approach eliminates potential issues arising from material sourcing, providing you with peace of mind and confidence in the final product.
Also, HordRT offers a variety of surface finishes after the custom plastic injection molding service, allowing you to customize the aesthetic of your molded parts. The company also provides additional molding options, such as over-molding and insert molding, to cater to your specific needs.
Rapid Tooling Service
HordRT’s rapid tooling service is a cost-effective solution that combines speed, convenience, and precision. It is particularly suitable for developing and trial producing new products, process verification, functional verification, and multi-variety and low-volume production.
One of the key advantages of HordRT’s rapid tooling service is its use of a shared mold base system, which significantly reduces tooling costs compared to traditional manufacturing processes. This makes it an ideal choice for on-demand and low-volume production.
HordRT uses superior quality materials for rapid tooling, such as the steel P20, known for its sturdiness, wear resistance, and corrosion resistance. This material contributes to a glossy surface finish, enhancing the aesthetic appeal of your products.
The rapid tooling process at HordRT is streamlined and efficient. Once the order is confirmed, a Design for Manufacturing (DFM) analysis report is provided within 24 hours. The tooling design and main steel cutting occur simultaneously after DFM approval, ensuring a swift production process.
Wrapping Up
HordRT excels in delivering rapid, high-quality custom plastic injection molding and tooling services. Their molding service ensures swift turnaround times and quality materials, while the tooling service offers cost-effective solutions for product development and low-volume production, leveraging shared mold base systems. With a streamlined process and focus on quality, speed, and customization, HordRT sets a benchmark in the industry. Contact HordRT and learn more!
