Choosing the Best Resin for Your Molded Parts

Choosing the best resin plays a crucial part in about every facet of the plastic injection molding process. There are thousands of different injection molded thermoplastics to choose from with widely varying properties. With the rising popularity of plastics, they are being used in more applications than ever before because of their reputable characteristics: strength, endurance, and resistance. This article will help guide you towards a resin that would be the best match for your molded parts.  

5 Requirements to Keep in Mind

The polymers you use plays a role in the end function and performance of your products’ life. By choosing the wrong polymer, your product may not work properly. A flexible resin isn’t suitable where rigidity and strength are required. Also, non-medical grade or non-food grade resins can present real health hazards and risks if used in medical or food functions.

Refer to our article Most Common Thermoplastics Used in Injection Molding to see how the different properties of the most common polymers can affect your final molded part. Understanding the needs of your product is the best way to understand which resin to use:

1. Part Appearance: It is crucial to determine the final appearance, including surface texture, color requirements, and transparency when picking your resin.
2. Resistance: How well the part can defend itself from chemical and environmental properties.
3. Regulatory Requirements: Parts being created, depending on industry or intended use, may have to meet strict regulations and standards including, FDA, RoHS, REACH, and NSF.
4. Product Life: The life expectancy of the part heavily depends on the resin being used in the process.
5. Resin Properties: This includes the part strength, rigidity, flexibility.

Different Resin, Different Costs

Thermoplastics are categorized by family and type that fall into three main categories; commodity resins, engineering resins, and specialty or high-performance resins.

1. Commodity Resins: These polymers are easy to process and are inexpensive, so they are used for many everyday applications and mass-produced items like packaging.
2. Engineering Resins: More expensive than commodity resins, but these polymers offer better strength and resistance to chemicals and environmental exposure.
3. Specialty/High-Performance Resins: Highest cost compared to the other two categories. However, these polymers offer the highest strength, and chemical, heat, and corrosion resistance.

The key is understanding the performance requirements that the parts must meet. These requirements will direct the part designer, plastic injection molding manufacturer and resin supplier to recommend the best polymer suited to the application. In the end, it is beneficial to work closely with your manufacturer from the beginning to determine the best resin for your next project. At Midstate, our team of injection molding professionals can help you make the proper selection. Contact us today!