Can PLA Plastic Be Injection Molded?

1. Introduction

As more and more people are becoming conscious of the environmental impact of plastic, PLA (polylactic acid) plastic is gaining popularity as an eco-friendly alternative to traditional plastic. However, many people are still unaware of the capabilities of PLA plastic and whether it can be injection molded like other plastics. In this article, we’ll explore whether PLA plastic can indeed be injection molded.

2. What is PLA Plastic?

PLA plastic is derived from renewable resources such as corn starch or sugarcane. This makes it a sustainable and eco-friendly alternative to traditional plastics made from petroleum-based resources. PLA plastic can be composted in industrial composting facilities, making it an even more environmentally sustainable option.

3. Can PLA Plastic be Injection Molded?

The short answer is yes, PLA plastic can be injection molded. However, there are some considerations to keep in mind before you decide to use PLA plastic for plastic injection molding.

PLA plastic has a lower melting point than other plastics used for plastic injection molding, such as ABS (Acrylonitrile Butadiene Styrene) and PET (Polyethylene Terephthalate). This means that the temperature and pressure settings used for PLA plastic will be different from those used for other plastics.

Additionally, PLA plastic has a lower viscosity than traditional plastics, which means it’s not as easy to flow into intricate molds or thin-walled parts. You may need to adjust your injection mold design to accommodate the lower viscosity of PLA plastic.

Despite these considerations, PLA plastic can still be successfully injection molded with the right equipment and settings. Moreover, it has a number of advantages over traditional plastics, such as being biodegradable and compostable.

4. Advantages of Plastic Injection Molding PLA Plastic

A. Sustainability

As mentioned earlier, PLA plastic is derived from renewable resources and can be composted in industrial facilities. This makes it a much more sustainable alternative to traditional petroleum-based plastics, which can take hundreds of years to decompose.

B. Lower Carbon Footprint

The production of PLA plastic also has a lower carbon footprint than traditional plastic production. A 2019 study found that producing PLA plastic resulted in 25% fewer greenhouse gas emissions than producing traditional plastics.

C. Versatility

PLA plastic can also be used for a wide range of products, from disposable cups and utensils to medical implants. Its versatility makes it a great option for businesses looking for sustainable alternatives to traditional plastic products.

5. Challenges of Plastic Injection Molding PLA Plastic

A. Low Mold Temperature

As PLA plastic has a lower melting point than other plastics used in plastic injection molding, it requires a lower mold temperature during manufacturing. A mold temperature between 50 - 60 °C is typically recommended to prevent the PLA plastic from degrading. This requires specialized equipment and careful temperature control to maintain consistency and prevent defects in the finished product.

B. Lower Viscosity

PLA plastic has a lower viscosity than other plastics used in plastic injection molding. This makes it less suitable for complex geometries and intricate injection mold designs. The flowability of the PLA plastic must be carefully considered when designing the mold to ensure successful plastic injection molding.

C. High Moisture Sensitivity

PLA plastic is highly sensitive to moisture, and even small amounts of moisture can affect its characteristics and properties. One of the key ways to combat this is by ensuring that the PLA plastic is properly stored and dried before use. Moisture can also be introduced during the manufacturing process and must be carefully controlled to prevent defects in the finished product.

6. Considerations for Injection Molding PLA Plastic

A. Injection Mold Design

The injection mold design for plastic injection molding PLA plastic needs to take the material's lower viscosity into account. Wall thicknesses need to be consistent, and intricate designs may need to be avoided. It’s imperative to optimize the injection mold design for consistent flow and complete cavity filling, to ensure that the end-products have high-quality surface finishes.

B. Drying and Handling

Due to the high moisture sensitivity of PLA plastic, it’s important to use a dryer to drive off moisture before processing. Moreover, the equipment used for plastic injection molding PLA plastic must also be meticulously cleaned and the areas around the molding machines must be clean and dry. Operators must wear gloves to prevent natural oils that can contaminate the PLA plastic from adhering to molds.

C. Processing Parameters

PLA plastic has different processing parameters than traditional plastic materials. It’s important to adjust the injection speed, mold fill rate, and mold temperature to suit the material’s lower melting point and lower viscous flow rates. Process parameters such as melting temperature and injection pressure must also be carefully monitored and adjusted during the process to prevent any defects.

7. Conclusion

PLA plastic can indeed be injection molded, but with some considerations. While it may require some adjustments to injection mold design and temperature settings, PLA plastic offers a sustainable and eco-friendly alternative to traditional plastics. Its lower carbon footprint and biodegradability make it an attractive option for businesses looking to reduce their environmental impact. By using PLA plastic for injection molding, we can take an important step towards a more sustainable future.