July 9, 2021
Resin Selection In Plastic Injection Molding Services
Plastic injection molding service is a highly flexible and effective manufacturing technique that enables manufacturers to produce various products
Plastic injection molding service is a highly flexible and effective manufacturing technique that enables manufacturers to produce various products and parts from molten plastic resins. Polymers and plastics have been integrated into an increasingly diverse range of products and applications due to advancements in plastic injection molding service and material development.
Plastics are becoming the preferred material for industries ranging from consumer goods to medical equipment due to their lightweight efficiency, cosmetic appeal, and longevity.
Several different types of plastic resins on the market, each with its own set of characteristics that make it suitable for specific applications. It is essential to choose the suitable resin for your needs to achieve peak efficiency.
A resin is a plastic or polymer in a liquid or semi-solid state that can be heated, melted, and formed into plastic pieces for plastic production. The term resin in injection molding service refers to the molten thermoplastic or thermo-set materials used in the plastic injection molding process.
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Considerations for Resin Selection
New polymers and compounds are added to the market daily. The sheer number of options will make selecting plastic injection molding materials difficult for plastic injection molding companies.
Choosing the best plastic resin by the plastic injection molding companies necessitates a detailed understanding of the end product. The following questions will help you determine the suitable resin materials for your injection molding service requirements.
- What is the final part’s intended purpose?
When choosing the best material for your design, you must explicitly outline the components’ physical characteristics, including possible stressors, environmental hazards, chemical toxicity, and the product’s planned service life.
- What is the minimum strength required for the part?
- Is it necessary for the component to be flexible or rigid?
- Is the component needed to withstand unusual pressures or weights?
- Would the components be subjected to certain additives or other elements?
- Would the components be subjected to high temperatures or harsh environmental conditions?
- What is the expected life of the part?
- Are there any particular aesthetic considerations?
Choosing the right product entails selecting a material that can show the desired color, transparency, texture, and surface treatments. Consider if the resin you use would fulfill the appearance and purpose specifications of your product.
- Is certain transparency or color required?
- Is a specific texture or finish required?
- Is there a pre-existing color that must be matched?
- Should you think of embossing?
- Are there any regulatory requirements?
Regulatory criteria for the part and its intended use are essential in resin selection by plastic injection molding companies. Suppose the component will be exported overseas, used in food manufacturing, added to surgical devices, or integrated into high-performance engineering applications. In that case, the material you use must satisfy the appropriate industry specifications and regulatory criteria.
- Is it necessary for the product to be child-safe?
- Is it essential for the part to be food-safe?
Thermoset vs. Thermoplastic – A Plastic Primer
Plastics are classified into two types: thermoset plastics and thermoplastics. Consider thermosets as the name implies: they are “set” during processing to help you remember the distinction. As these plastics are heated, a chemical reaction occurs that causes the part to take on a permanent shape.
Since the chemical reaction is irreversible, thermoset sections cannot be remelted or reshaped. If a bio-based polymer is used, these components can be challenging to recycle.
To shape a component, thermoplastics are heated and then cooled in a mold. A thermoplastic’s molecular composition does not alter when heated and cooled, allowing it to be quickly remelted. As a result, thermoplastics are more easily reused and recycled. They make up the vast majority of imported polymer resins on the market today, and they are used in the injection molding service.
Fine Tuning the Resin Selection
Thermoplastics are classified according to their family and type. Commodity resins, engineering resins, and specialty or high-performance resins are the three broad groups or families. Since high-performance resins are more expensive, commodity resins are often used in many everyday applications by plastic injection molding companies.
Commodity resins, which are simple to handle and cheap, are commonly used in mass-produced products such as packaging. Engineering resins are more costly, but they have greater resilience, resistance to contaminants, and resistance to environmental contamination.
Some resins in each resin family have a distinct morphology. Morphology describes molecules’ structure in a resin and can be classified into one of two types, amorphous and semicrystalline.
Amorphous resins have the following characteristics:
- Shrink less when cooled
- Better transparency
- Work well for tight-tolerance applications
- Tend to be brittle
- Low chemical resistance
Semi-crystalline resins have the following characteristics:
- Tend to be opaque
- Excellent abrasion and chemical resistances
- Less brittle
- Higher shrinkage rates
Types of Resins That Are Available in Plastic Injection Molding
Finding the correct resin necessitates a detailed knowledge of the physical properties and beneficial characteristics of the materials available. We have compiled the injection molding material preference guide below to help you find the best plastic selection category for your plastic injection molding companies’ needs.
Amorphous
Polystyrene, or PS, is an example of an amorphous commodity resin. It is translucent and porous, like other amorphous resins, but it can be used in high-precision applications. It is one of the most common resins used in rubber cutlery, foam cups, and bowls.
Engineering resins, such as polycarbonate or PC, are higher on the amorphous scale. Since it is temperature and flame tolerant and has electrical insulating properties, it is primarily used in electronic components.
Polyetherimide is an example of a specialty or high-performance amorphous resin (PEI). It has the same strength and heat resistance as other amorphous resins. However, unlike most other amorphous compounds, it is still chemically resistant, and as a result, it is often used in the aerospace industry.
Semi-crystalline
Polypropylene, or PP, is a low-cost semi-crystalline commodity resin. It is versatile and chemically resistant, as are most semi-crystalline polymers. Because of its low cost, this resin is ideal for various applications such as bottles, packaging, and pipes.
Polyamide is a common semi-crystalline engineering resin (PA or Nylon). PA is chemical and abrasion resistant, with low shrinkage and warp. Bio-based versions are available, making this material a more environmentally friendly option for many plastic injection molding companies. The material’s hardness makes it a lightweight alternative to metal in automobile applications.
PEEK, or polyetheretherketone is a semicrystalline high-performance resin that is commonly used. This resin is used in challenging conditions such as bearings, pumps, and surgical implants because it provides strength, heat, and chemical resistance.
Amorphous Resins
ABS combines the flexibility of polybutadiene rubber with resilience. And has the rigidity of acrylonitrile and styrene polymers. ABS is easily molded and has a high-quality surface finish with a colorfast, glossy effect. The melting point of this plastic polymer is unknown.
HIPS: High-impact polystyrene (HIPS) has high impact resistance, excellent machinability, good dimensional stability, excellent aesthetic characteristics, and highly customizable surfaces. HIPS is conveniently printed, glued, bonded, and decorated. It is also very cost-effective.
Polyetherimide (PEI): A specialty or high-performance amorphous resin, PEI is a good example. PEI, like other amorphous resins, has power and heat resistance. However, unlike most other amorphous compounds, it is also chemically resistant, making it particularly useful in the aerospace industry.
Polycarbonate (PC) is a type of plastic. Engineering resins, such as polycarbonate, are at the top of the amorphous scale. PC is a temperature and flame-resistant material with electrical insulating properties often used in electronic components by injection molding companies.
Polystyrene (PS) is an example of an amorphous product resin. PS is translucent and porous, like other amorphous resins, but it can be used in high-precision applications. It is a popular resin that can be used in plastic cutlery, foam cups, and dishes.
Semicrystalline resins
PEEK (polyetheretherketone): PEEK is a semicrystalline high-performance resin that is commonly used. This resin provides resilience, heat resistance, and chemical resistance and is often used in high-stress environments such as bearings, pumps, and medical implants.
Polyamide (PA)/Nylon: Polyamide, also known as nylon, is a semicrystalline manufacturing resin. PA is chemical and abrasion resistant, with low shrinkage and warp. For applications that need an environmentally sustainable approach, bio-based models are possible. The material’s hardness makes it a lightweight alternative to metal in many vehicle applications.
Polypropylene (PP) is a type of plastic. PP is a low-cost semicrystalline bulk resin. It is versatile and chemically resistant, as are most semicrystalline polymers. This resin is a popular option for injection molding companies for many applications such as bottles, packaging, and pipes because of its low cost.
Celcon: Acetal, also known as polyoxymethylene (POM), polyacetal, or polyformaldehyde, is a generic brand name for acetal. This thermoplastic has excellent hardness, wear resistance, creep resistance, chemical solvent resistance, fast colorization, good heat distortion, and low moisture absorption. Celcon also has a high hardness and dimensional flexibility.
Low-density polyethylene (LDPE) is the most versatile form of polyethylene, with superior moisture tolerance, high impact efficiency, strong chemical resistance, and translucence. LDPE is a low-cost solution that is also weatherproof and can be processed using a variety of methods.
Finding the right resin
Making a plastic material selection can be difficult for many injection molding companies, but it can be broken down into a few easy measures. Begin by selecting the material family that will provide you with the majority of the desired properties. If this has been decided, choose the required grade of material resin.
Improve Characteristics with Plastic Additives
Various resins are known for their distinct properties. As we’ve seen, one of the three resin families (commodity, engineering, and high-performance/specialty) includes both amorphous and semicrystalline options. However, the better the efficiency, the higher the cost. Often producers use additives or fillers to impart extra properties to low-cost components to keep prices low.
These additives may increase efficiency or impart additional properties to the finished product in injection molding service. Some of the most common additive applications are as follows:
- Antimicrobial – Additives used in food-related applications or high-contact consumer products.
- Anti-statics – Additives that decrease static electricity conduction, often used in sensitive electronics.
- Plasticizers and fibers – Plasticizers make a resin more pliable, whereas fibers add strength and stiffness.
- Flame retardants – These additives make products resistant to combustion.
- Optical brighteners – Additives used to improve whiteness.
- Colorants – Additives that add color or special effects, such as fluorescence or pearlescence.
The Final Choice
One of the most important aspects of making ideal plastic pieces with injection molding service is selecting the best material for a project. Polymer technology advancements have led to the creation of a diverse range of resins from which to pick. It is essential to collaborate with an injection molder familiar with a wide range of resins and applications.
Makenica has established strategic relationships with the best resin suppliers in the world over the years. We have over a decade of experience using accredited commodity and engineering resins that follow our exacting manufacturing requirements in the injection molding service. You can still check with your injection molder unless you are well-versed in resin selection to determine the best material for a particular project.
Makenica is dedicated to offering the best quality plastic injection molded products in the industry to our clients. We appreciate the complex obstacles that product makers and suppliers face in all sectors. We are more than just manufacturers; we are also innovators. We make it our mission to provide you with the best material options for any use.
Contact our experts today to learn more about our broad collection of resin materials and plastic injection molding services.