Deciding Between Metal and Plastic: Factors to Consider

The decision between metal and plastic is typically based on some of the following criteria:

• Design requirements
• Industry standards
• Environmental factors (e.g., where and how the product will be used)
• Manufacturing costs
• Sustainability goals

Each material’s properties, manufacturing processes, relative strength and ultimate application will help determine which is a better fit for your product.

Properties and Characteristics

Metal is a great fit for some applications. Its properties include:

• Heat resistance: Its higher melting point makes it suitable for high-temperature environments.
• Strength: Durable metal is a good choice for structural parts and weight-bearing applications.
• Variety: Choose from conductive copper as well as its alloys (brass, bronze, etc.), steel, aluminum and more.
• Finishing customization: Metal has many finishing options (anodizing, powder coating, etc.).

While there are some potential benefits to using metal for product material, you will find that many of the same benefits can be realized with plastic if designed and engineered properly, including:

• Heat and fire resistance: Additives such as brominated flame retardant (BFR) can be used to make plastics heat or fire resistant.
• Strength: Additives such as fiberglass can increase strength, making it similar to or even stronger than the same metal part design.
• Variety: Plastic offers thousands of available material options. Select the one that is ideal for your specific product and needs.
• Color and finishing customization: This ability to customize plastic offers branding and aesthetic advantages. Most plastics start out clear, and then your manufacturer can add colorant to the material, compared with metal parts, which can be only coated or plated. You can also choose from dozens of different textures and finishes for your plastic part.

Manufacturing and Production Processes

Both plastic and metal undergo various processing methods. Plastic, commonly injection molded, can also be thermoformed, extruded and machined. Metals, commonly machined, can be die-cast, stamped and extruded. Large-volume production of metal parts is typically done using casting or forging.

Applications and Industries

Nearly every industry uses metal and plastic. Metal parts are most often found in transportation, aerospace, construction and the energy sector. Plastic parts are ubiquitous in pharmaceuticals, food and beverage , automotive interiors, packaging and sporting goods. The medical device industry uses both metal and plastic.

Strength and Durability

While metal is often considered stronger for structural and weight-bearing applications, certain plastics, such as PEEK and PEI, now compare similarly or even surpass metals in strength. The durability of each material depends on the specific type, intended application and environmental conditions under which the product will ultimately be used. Metals, particularly alloys, are known for their high strength, wear resistance and temperature resistance. Plastics offer lightweight options, corrosion resistance, chemical resistance and impact resistance.

Material Availability and Sourcing

Both metal and plastic availability may be affected by external factors. Because most virgin plastics depend on fossil fuels, they are subject to price fluctuations and supply chain vulnerabilities. Metals, on the other hand, rely on global mining operations, which are influenced by geopolitical factors, market demands and regulatory changes. Resource depletion and supply chain disruptions pose challenges. The United States generally has more supply and processing capabilities for plastics than metals. Reclaimed ocean plastic material can now be reliably procured from certified suppliers.

Environmental Impact of Metal and Plastic

Metals, especially aluminum and steel, are highly recyclable, with lower energy requirements for recycling. Mining for raw materials is a major environmental factor.

Plastics can be recycled, but rates vary depending on the material used and the availability of local recycling programs. Manufacturing plastics from fossil fuels is energy intensive, while advancements in bio-based plastics and recycling technologies aim to reduce environmental impact. Using recycled plastic, such as ocean plastic, gives companies the opportunity to take advantage of plastic’s many benefits while offering their customers more sustainable options.

Cost-Effectiveness

Plastics are often less expensive in terms of material costs, with injection molding providing advantages for high-volume production. If made in large volume, metal products can also be manufactured cost effectively. But metal parts often require post processes, which occur after the initial production process. A part may need to be milled, honed or ground after casting. This is because some features may not be able to be cast. These additional processes can add cost, which may be problematic for your overall budget.

Depending on which metal you choose, metal may be more expensive than a comparable plastic material for a given application. Metal products are also often heavier than their plastic counterparts, which could affect the assembly process and freight costs for the final product.

Design Flexibility

Because of their methods of manufacture (such as thermoforming and injection molding), plastics excel in design flexibility, accommodating complex shapes, intricate designs and various finishes. Metals, known for strength and durability, may lack some finishing options available in plastics, imposing some design limitations.

Find Solutions with RSP

The choice between plastic and metal depends on your specific application, industry requirements and sustainability goals. While metal may be the right choice for some applications, be sure to consider plastic for its versatility, cost benefits and potential for sustainable sourcing before deciding how to manufacture your product.

Interested in learning more about different types of plastic? Check out our posts on bioplastics and the plastic injection molding process.

Still not sure which material to choose? Contact us today, and one of our experienced team members can discuss your options and provide a quote.

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What Is Overmolding?

Overmolding is a unique injection-molding process that results in a seamless combination of multiple materials into a single part or product. Typically the manufacturer will mold a harder thermoplastic such as polycarbonate, polypropylene or ABS. Then that rigid part will get a softer thermoplastic like TPE, TPU or TPR molded onto it, adding a soft material to the more rigid plastic, and providing that seamless combination of soft and rigid materials.

Why Should You Consider Overmolding in Your Product?

Overmolding gives your product a certain high-quality design aspect that is both desirable and functional, offering the structure of a rigid backbone with the less flexible plastic and the tactility of softer thermoplastic. A product such as a handle on a piece of fitness equipment could have rigidity in the handle, but also have a soft grip molded onto that part.

Overmolding also involves less labor and more efficiency. Using our fitness equipment example, if you had a handle and did not overmold it, you would need to mold the rigid plastic part, then separately mold a silicone grip. Then, once you molded those two items, you would need to have an assembly team put the two parts together. Whereas if you overmold the product, all the assembly is done within the injection mold.

Aesthetics may also be a good reason to choose overmolding. The process enables you to have multiple colors on a product, since the rigid and overmolded materials can be different colors and also have different finishes because they are molded in separate steps.

One potential drawback to overmolding is the up-front costs associated with the tooling needed to make an overmolded product. Overmold tooling can be complex and require multiple sets of injection tools, thus increasing the start-up costs. Typically, cycle times on overmolded products are also longer and often require additional time to dial in the injection molding machines and tooling to optimally mold your overmolded product.

Examples of Overmolded Products

Aside from handles on fitness equipment, there are many products that implement overmolding. Many handheld products that have a soft grip on them are overmolded, such as toothbrushes and cleaning implements. Less visible are products like enclosures that have a gasket. Rather than manually assembling a gasket to the enclosure using either a mechanical fit or glue, the manufacturer overmolds the gasket onto the enclosure, forming a more permanent seal.

Types of Overmolding Processes – Traditional vs. Two-Shot

There are two types of processes for overmolding a product.

The first is standard overmolding, where there is an injection mold for the rigid plastic part and a separate mold for the overmolded softer plastic. In this process, the manufacturer molds the rigid plastic parts first. Once those parts are molded, then the manufacturer inserts those parts into the overmold injection tooling to have the soft plastic overmolded onto the rigid part.

The second method of overmolding is using a multi-shot injection mold, where multiple materials are molded on the same machine. Those machines first inject the rigid plastic, allow some time for cooling that part, and then inject the softer material. So when that tool opens up, there is a finished overmolded product. Unlike standard overmolding, there is no need to take the part out of the mold and put it into another mold.

If overmolding is a good fit for your part or product, or if you would like to learn more about how RSP can help manufacture it, reach out to our sales team, who will be happy to provide you with a quote and feedback on the design. Our experience and capability with overmolding can help make your product a reality.

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Choosing the right manufacturing partner in the plastic injection molding industry can involve evaluating a lot of criteria. Who is the manufacturer and where is it located? How long has it been in business? What types of products does it usually manufacture, and are they similar to what I need made? Can the manufacturer keep up with my demand in a timely manner?

These are all great questions to ask when choosing a plastic molding manufacturer, and there is a lot more to consider. So we have summarized the top five most important things to keep in mind when evaluating a plastic injection molding partner.

1. Location

It’s important to be able to communicate with your molding project team during local hours.  RSP has engineering and support in the US and China giving you access to our team almost 24 hours per day!

Where the plastic molding is performed is also important to consider. Local molders might help you save on freight, reduce shipping times and allow you to visit on-site easily. And if you use an offshore plastic molder, you may save on labor expenses, but freight costs are higher, shipping times are longer and tariff charges may be introduced.

However, there are also some important benefits of molding offshore with a US-based company like RSP.

• Lower tooling costs (typically 30–50% or more!)
• Lower minimum order quantities (MOQs)
• Shorter lead times: RSP has fully automated molding lines with 24/7 operations to reduce lead times and maintain extra capacity for rush orders
• Lower molding costs: take advantage of lower-cost labor, engineering and automation

2. Manufacturer Capability

When selecting a manufacturer, it is important to know whether the company you’re considering working with has the capability to make the type of product you need. There are certifications required for many sectors, such as medical, automotive and aviation products. In these industries, manufacturers must meet certain criteria, obtaining certifications such as ISO 9001, ISO 13485 and others.

RSP is certified to manufacture medical products to the ISO 13485 standard and is also registered with the FDA so we can meet a medical plastic good requirement. It is important that you know what is required for your industry and select the right partner that can manufacture your product to that standard.

3. Specialization

Some companies choose to focus on a particular specialty or sector to serve. In some cases, a manufacturer may make only automotive or medical products, or only kids’ toys. They set their entire manufacturing space up for this specialized type of product. So when you are looking for a manufacturing partner, it is wise to review whether the company is a good fit for your needs.

RSP does not specialize in one specific sector. We work across multiple sectors, including medical products, consumer goods, aftermarket automotive and cosmetics. A specialized factory can be helpful if you happen to have a product within that specialty, but having a manufacturing partner that is agile and can work across multiple industries has a lot of benefits. You just need to decide whether specialized manufacturing is necessary for your product.

4. Access to & Experience with Sustainable Material Choices

Today there is a lot of demand for materials like recycled ocean plastic, eco-friendly materials and bioplastics. If your customers are looking for more sustainable products, be sure to find out if your potential manufacturer has access to these materials and knows how to work with them.

RSP is a pioneer in the use of recycled ocean materials procured through Oceanworks (Oceanworks.co), and we know firsthand that there is a learning curve when implementing them in an existing tool or designing injection tools around the use of these materials. RSP has also tested numerous bioplastics, including bamboo, jute and hemp blends. So if you or your clientele desire a product with a bio or ocean material, a company like RSP that has the know-how and experience with these newer materials can help you navigate the options available to implement with your product.

5. Engineering

When selecting a plastic molding company, find out whether the factory you work with has a team of engineers who can offer design suggestions for and assistance with any issues you may have with the design of your product that may need to be tweaked during production. Sometimes a relatively small adjustment to a product’s design can result in easier assembly, faster molding cycle times or less fallout, which can help lower costs or make manufacturing the product much easier. It can be very beneficial to have these types of suggestions from your manufacturer. RSP has a team of mechanical and tooling engineers with over 200 years of combined experience among them, so we are able to help make engineering decisions to more efficiently and cost effectively manufacture your product.

Want more information about plastic injection molding? Contact us today.

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PET Plastic Manufacturing Services

PET plastics are commonly used in thermoforming, injection molding of plastic products, and blow molding of bottles and containers. As a PET plastic manufacturer, RSP offers engineering, tooling design and molding of many different PET products. PET plastic is a versatile material suitable for use in a variety of markets, from industrial to consumer, and is food safe. It is also fully recyclable and energy efficient, making it a more sustainable option.

What Is PET Plastic?

PET stands for polyethylene terephthalate. This material is a type of clear, strong, lightweight plastic. Unlike many other plastics, PET is not single use and is 100% recyclable, stamped 1, which is accepted by most community curbside recycling programs. Durable PET plastic products are used every day in food and beverage products, as PET is most often used in packaging, such as bottles for soft drinks, salad dressings, cooking oils, shampoos, liquid hand soap and much more.

Benefits of Manufacturing with PET Plastics

PET plastic is a relatively low-cost raw material that is readily available in the market. In its raw state, PET is a transparent semi-crystalline resin. It can easily be converted or compounded with additives to maximize its performance. Possibilities include:

• Making it more or less flexible
• Better resistance to solvents and acids
• Improved standard temperature range
• Adding color
• Reinforcing glass fibers
• Adjusting gloss finishes

PET is considered an easy-to-work-with polymer that also has high mechanical strength, impact resistance, dimensional integrity and stiffness.

Common PET Plastic Products

PET plastic is most familiar to consumers as beverage containers, but its use is by no means limited to juice or soda bottles and milk cartons. There are many more applications for pr PET plastics. These include:

• Containers for consumer packaged goods (cosmetics, food, pharmaceuticals, etc.)
• Industrial strapping
• Clothing (jackets, sleeping bags)
• Protective packaging

When it comes to containers and bottles, PET is the material of choice over glass and aluminum for several reasons. It is lighter and uses less material than glass, so it is easier to ship and less prone to ls damage in transit. When these factors are considered, PET is surprisingly more sustainable than many people realize.

Is Manufacturing PET Plastic Eco-Friendly?

PET is considered a more eco-friendly and sustainable packaging material than other plastics. While like most other plastics, it is produced from petroleum, PET plastic offers a unique environmental profile over its lifetime due to its excellent strength and recyclability. When you choose PET over other plastics, your customers will be able to do their part by recycling PET-based products locally, bringing the PET material full circle.

PET is exceptional for its capacity-to-weight ratio. This means you can put more product in less packaging while also using less weight and less fuel for transportation. Even with its petroleum base, it compares very favorably when considering all factors to its common competitors aluminum and glass. Because of PET’s durability, it is also a good candidate for reuse as a storage container for kitchen or pantry use, extending its life and keeping it out of the waste stream longer.

Frequently Asked Questions About Manufacturing with PET Plastics

• Is PET plastic safe?
  • The FDA and health-safety agencies throughout the world have approved PET as safe for contact with foods and beverages. Over its 30 years in use, there have been extensive studies and testing to confirm its safety. PET does not contain bisphenol-A (BPA) or phthalates (plasticizers). In addition, PET is inert, meaning it is nonreactive to food contact and resistant to microorganisms.

• Are there dimension limits for PET plastic bottles?
  • PET bottles can vary widely in shape and form from standard round models to bear-shaped bottles for honey with thousands of varieties in between. The largest bottle RSP manufactures is five liters in size with outside dimensions of 150mm width and 350mm height. However, the same process can be used to mold much larger items like construction barrels that are over one meter tall.

• Are there differences between PP & PET plastics?
  • Yes! These two plastics are commonly used in packaging food and beverages. They are both recyclable but there are some very important differences to consider.
    • Clarity: PET is superior to PP for clarity.
    • Temperature: PP is slightly more heat tolerant, allowing for up to 80°C (176°F) of filling temperature vs. 71°C (159.8°F) for PET.
    • Impact resistance: PET has higher tensile and impact strength than PP. This means a molded cup, for example, will be stronger with more durability when made from PET.
    • Oxygen barrier: PET has superior oxygen barrier properties, which allow it to better retain taste and aroma of food placed inside. PP is an extremely poor barrier to oxygen.
    • Moisture barrier: PP is a better moisture block than PET.

• Can you laser cut PET plastic?
  • Yes! PET can be laser cut and engraved if using the proper equipment. RSP uses 25-to-150-watt CO2 lasers for cutting PET.

• How are PET bottles made?
  • PET bottles are typically made by a blow-molding process. However, before you can blow mold the bottle, you need to start by melting plastic pellets and injection molding the plastic into a parison, a small tube with a hole at one end. The parison is transferred to a blow-molding machine and clamped inside a mold. Once retained, compressed air inflates the parison like a balloon to fill the space inside the mold. The PET plastic bottle is allowed to cool and then removed from the mold.

Get a Quote for Contract PET Plastic Product Manufacturing

Want more information about PET Plastics? Contact us today.

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RSP offers both 3D plastic printing and plastic injection molding services. While these were once considered competing technologies, now many RSP clients are using both 3D printed plastic and plastic injection molding during the design phase and sometimes even in production. Each method has unique advantages, and they can even be used together synergistically to optimize production.

Cost Analysis of 3D Printing vs. Injection Molding

Cost is the main driver for most clients choosing between 3D printing and injection molding. The chart below demonstrates a typical cost curve to determine a break-even point. While every project is different, a typical break-even is between 250 and 500 parts. This is the point at which the cost per unit is the same between each technology. With 3D printing, the per-unit cost changes very little as the material cost and machine time are the same for each unit. Because injection molding requires tooling design and molds, these up-front costs can be substantial. This means, if you allocate the tooling into the cost per unit, the initial parts appear very expensive, but as the volume increases, the price per unit drops below that for 3D printing.

Other Determining Factors

Besides cost, there are other considerations when choosing between 3D printing and injection molding services for your plastic product manufacturing needs.

Projects Best Suited for 3D Printing

• Quick turnaround times: days or weeks
• Designs requiring frequent changes
• Low-volume production: 100 parts or less (this varies based on the project)
• Relatively small-sized components
• Standard materials (there are limited materials available for 3D printing)

Projects Best Suited for Injection Molding

• Longer turnaround times: 5–10 weeks for most molds
• Stable part designs that don’t require changes
• Higher-volume production runs: 1,000 parts or more
• Larger parts
• UL listed components or assemblies: more variability in flammability, ignition and electrical properties

Which Is Stronger?

The mechanical properties, such as tensile strength and impact strength, of materials used in 3D printing will vary considerably more than when the same materials are used in conventional injection molding methods. However, materials are constantly improving and different types of 3D printing including FDM (fused deposition modeling) and SLA (stereolithography) can produce different results. Even the orientation of the part when it is printed affects the “strength.”

Real-World Plastic Manufacturing Solution

Many clients come to RSP expecting to use 3D printing, only to find out that their project is best suited for injection molding. While the costs of 3D printing continue to decline, the technology is still best for lower-volume runs.

When you are deciding between the two production methods, RSP can give you the information you need to make the right decision for your product. Injection molding and 3D printing are complementary, and both may play a role in manufacturing your design.

Head on over to our Contract Plastic Injection Molding and 3D Printing pages to learn more about our plastic manufacturing solutions. Or contact RSP with any questions, and our client managers will be able to assist!

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Bioplastics are a type of biodegradable plastic that is derived from biological substances.

Conventional plastics are made from petroleum. Petroleum is a non-renewable resource that requires substantial energy to process and poses environmental hazards. Petroleum-based plastics also often contain BPA, which can be toxic. At end of life, conventional plastics take hundreds if not thousands of years to decompose in landfills.

Bioplastics can perform like conventional plastic in products without the negative effects, as they are made from biological materials instead of fossil fuels.

Here are several different types of bioplastic that can be used in injection-molding machines.

Hemp

Hemp is one of the strongest natural fibers. It can be used as a stand-alone material or blended with conventional plastic to reduce the amount of fossil-fuel-based plastic used. Hemp-blended plastic can be not only significatively stiffer but also stronger than conventional materials. Standard injection-molding machines can be used without any modifications.

Polylactic Acid (PLA)

PLA is usually made by fermenting corn, sugar beet, sugarcane, or potatoes. The resulting starch is mixed with acid or enzymes and heated to break down the material into dextrose. The building blocks are either lactide monomers or lactic acid depending on the desired molecular weight. PLA is the second most used biodegradable plastic in the world and can be processed by injection molding and almost any other manufacturing process that involves thermoplastic components. It is relatively expensive in comparison to plastics derived from fossil fuels. However, as a bio-based and biodegradable material, it offers some unique benefits.

Starch-Based Plastics/Thermoplastic Starch (TPS)

TPS is the most commonly used bioplastic, and is typically used for disposable items such as packaging. Products made from TPS are considered to be entirely biodegradable, and access to this raw material is easy and abundant. Starch-based plastics are generally a blend of starch and other compostable plastics, such as PLA.

Polyhydroxyalkanoates (PHAs)

PHAs can be created by the culturing of a microorganism. Vegetable oils, or corn, potatoes, and other carbs can be used as raw material for the fermentation. As a thermoplastic, PHAs can be processed on traditional equipment, and unlike PLA, they’re stable under UV light, and are ideal for food packaging as they do not easily absorb odors.

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RSP is committed to offering clients a broad range of eco-conscious plastic choices to consider for creating their molded products. They include:

• Oceanworks® Guaranteed products made with recycled ocean plastics
• Hemp and other fibers mixed with virgin or recycled plastic
• Recycled plastic from waste-stream collection
• Biodegradable lab-tested additives that help accelerate decomposition.

Recycled plastics are not a new concept, but biodegradable additives are unfamiliar to many people. What are they, and how can they be used to make your products more earth-friendly?
Quite simply, biodegradable additives are organic substances that are mixed into plastic that activate in the presence of landfill-specific microbes and enzymes. They help break down the plastic when it has reached its end-of-life destination, a landfill, not before.

The additives do not alter the durability, strength and recyclability of the plastic, and they maintain the same look as the virgin material. These types of additives are effective with a large variety of plastics, including EVA, HDPE, PET, PP, nylon, PVC, PC and more!

If you’re thinking of incorporating these additives into your product, you will want to communicate these benefits to your customers. Without testing, it isn’t possible to know exactly how long it will take for your product to break down in a landfill.

Plastic designs vary, and products will decompose differently based on their material makeup and its thickness. And every landfill has varying solid content, temperature and moisture levels that affect the decomposition rate as well. It is possible to simply advertise the additive as an eco-conscious benefit without testing. However, in order to make any particular claims, products should be tested according to the ASTM D5511 test method. The price varies but starts at $2,000–$3,000 for a 30-day test.

Once your product is tested, a typical marketing claim might read something like this:

Best Bee Brothers quality products have been shown to biodegrade 17% in 59 weeks when tested using the ASTM D5511 test under conditions that simulate both wetter and biologically active landfills. The stated rate and extent of degradation do not mean that the product will necessarily continue to decompose or decompose completely.

California does not allow these types of claims to be made, and therefore you must include language on your packaging and website that includes “claims not valid in California.”
If you are considering a more eco-conscious approach to plastic molding, please call RSP to discuss your options and solutions with one of our experts.

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Here is a simple explanation of the difference between polymers and plastics.

Is Plastic a Polymer?

All plastics are polymers, but not all polymers are plastic. Plastic is a specific type of polymer. Plastics are synthetic and do not occur naturally.

With this in mind, we can dig a little deeper into the definitions.

Differences between polymer and plastic?

The terms polymer and plastic are not the same. Plastic is a specific type of polymer comprised of a long chain of polymers. Polymers, on the other hand, are made up of uniform molecules that are smaller than plastic molecules.

What are polymers?

Polymers can be either natural or synthetic and are created when small molecules, also known as monomers, combine chemically to form a larger network of connected molecules. The term is derived from the Greek prefix “poly-,” which means “many,” and the suffix “-mer,” which means “parts.”

What makes these networks unique is the fact each polymer creates a network of repeating units. For example, a repeating unit in the chemical structure of natural rubber is isoprene. In the image below, you can see repeating units of isoprene after isoprene is turned into a natural rubber.

The repeating units in polymers are often carbon and hydrogen and sometimes oxygen, nitrogen, sulfur, chlorine, fluorine, phosphorus and silicon.

Manufacturing with Plastics & Polymers

A lot of products now are being converted into plastic & polymer based materials due to cost-savings & efficiency benefits. If you are looking for a new manufacturing partner to help you develop your plastic product, contact us or head over to our plastic molding page for more details on our plastic molding services.

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What is polymer plastic made of?

The most familiar plastic polymers including polyethylene (PE), polypropylene (PP), epoxy and polyester (PS) are derived from petroleum hydrocarbons. These materials are used in a diverse range of applications. However, they do pose an end-of-life recycling and disposal issue as they do not break down easily. There is a big push to develop environmentally friendly polymers using biocomposites (also known as green composites) that are made up of biodegradable polymers including wood-derived polymers and non-wood fibers (straw, bast, leaf, seed, grass).

Natural Polymers Examples

The following are examples of natural polymers:

• Rubber
• Wool
• Protein
• Cotton
• DNA (deoxyribonucleic acid)

In fact, all life forms are made up of some combination of naturally occurring polymers.

What are plastics? How is Plastic Made?

Plastics are a specific type of synthetic polymer with a large molecular mass where the structure is mostly linear – they resemble spaghetti with long chains. The first synthetic plastic was created in 1909 for telephone and electrical components and was known as Bakelite.

Manufactured polymers are called thermoset polymers when they are three-dimensional networks that do not melt once formed. An example would be an epoxy resin used in two-part adhesives.

What are Manufactured / Synthetic Thermoplastic Polymers?

Manufactured polymers are called thermoplastic polymers when they are one-dimensional chains that can be melted. The majority of manufactured polymers are thermoplastic, meaning they can be heated and reformed over and over again. This is the property that allows them to be recycled and reused.

Examples of synthetic thermoplastic polymers:

• PET (polyester) bottle / water bottle
• PE (polyethylene) film / plastic bags
• PS (polystyrene) cup / foam cup

Is polymer stronger than plastic?

All plastics are polymers but not all polymers are plastics. Plastic is a polymer typically made from oil and has a wide span of durability. Polymers can range in ‘strength’ from a bowling bowl to a grocery bag. Which is stronger? The answer is, it depends! How do you define strength and how do you compare two separate items with varying chemistry.

Polymer Characteristics

Each type of polymer has a very distinct characteristic, but here are some general attributes:

1. Resistant to chemicals
2. Thermal and electrical insulators
3. Lightweight and strong
4. Multiple process methods including extrusion, injection molded, blowmolded, etc.
5. Petroleum based (typically but not always)
6. Diverse and unique applications – plastics have changed the way we live, from medicine to automobiles to our homes

Negatives to Using Synthetic Polymers

While plastics have found an important role in our lives, there are several downsides:

1. Made from nonrenewable crude oil resources
2. Give off toxic fumes when burned
3. Non-recyclable materials are difficult to re-purpose and do not decompose in landfills

To combat the end-of-use dilemma with this durable material, RSP uses a number of environmentally friendlier techniques. We incorporate recycled and reclaimed plastics from the ocean and use additives such as natural fibers from hemp and rice, as well as natural substances that help plastics biodegrade in landfills.

If you have additional questions or want to learn more about choosing the right material for your product, please contact us today!

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Plastic Injection Process: From Pellet to Powder

How are plastic resins made?

1. Petroleum is drilled from the earth and transported to an oil refinery for processing.
2. The crude oil that is removed from the earth gets refined into petrochemicals such as ethane and propane.
3. Ethane and propane are then used to make the hydrocarbons ethylene and propylene in a heating process known as cracking or catalytic cracking. This process breaks down larger molecules into ethylene or propylene or other types of hydrocarbons.
4. After the material is cracked, a catalyst is added in a reactor, which creates a powder material called a polymer. This material, which the refineries call “fluff,” is combined with different additives (depending on the type of plastic desired) in a continuous blender.
5. The polymer is then put through an extruder, where it is melted and formed.
6. Once the extruded material cools it is cut and formed into the plastic pellets you can see in any plastic factory.

The pellets that all started as petroleum are used in injection and blow molding, extrusion, and other plastic manufacturing.

Where are these materials used and is RSP familiar with them?

There are thousands of different types of plastic made using the process described above. If you want to learn more about this process, head over to our Plastic Injection Molding page for more information. Different plastics are needed depending on the environment the finished product will be used in, what it will be exposed to, the desired physical characteristics, and more… For example, a plastic such as polycarbonate (PC), which is known for its strength and consistency, is generally considered a good choice for medical products. RSP is an ISO 13485 certified medical molder for plastics and rubber. Polyamide (Nylon), on the other hand, is often selected for its durability and strength in industries like automotive, sporting equipment and industrial products. Other materials are selected because of the pricing per kilogram. For example, polypropylene (PP) is often selected because of its appealing price point. However, PP isn’t an ideal material if you need the product to meet tight tolerances, as PP has a high degree of variability when it comes to tolerance.

Evaluating and selecting the right material can be daunting to do on your own, but the right contract manufacturer can help. RSP Inc. has years of experience advising customers in a wide variety of industries, including aftermarket automotive, medical devices, consumer products, industrial devices and many more. Here is a list of just some of the materials RSP Inc. has used for molded plastic parts:

• Polycarbonate (PC)
• Polypropylene (PP)
• Polyamide (Nylon)
• Acrylonitrile butadiene styrene (ABS)
• Polyoxymethylene (POM)
• Low-density polyethylene (LDPE)
• High-density polyethylene (HDPE)
• Polyvinyl chloride (PVC)
• Polyethylene terephthalate (PET)

While the process of making different blends of plastic is complicated and may be difficult to understand, know that having a partner like RSP can make your life easier when it comes to selecting the right material for your project. Contact our sales team if you have any questions or if you are looking for advice on material selection.

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RSP fully supports recycling and goes to great lengths to recycle as many materials as possible, both within our facilities in the US and China. Unfortunately, recycled plastic is not an option for our customer’s plastic products. Let’s look at the details and learn why.

As we know, using recycled plastics is both consumer-friendly and earth-friendly. It involves recovering scrap or waste product and converting it into useful products. Thus, it is common to see recycled plastic in drink jars, lawn furniture, T-shirts, jackets, carpeting, etc. Besides giving the product an earth friendly image, recycled plastic can be lower cost per ton depending on the polymer and market demand.

So, why doesn’t RSP use a lot of recycled plastics? Since recycled material must be sorted by polymer, there is often some contamination. This contamination of materials is appropriate for bottles and lawn furniture but it is not acceptable for the high quality image-conscious products RSP molds. In other words, some flaws in lawn furniture are acceptable but imperfections on a consumer product or medical product used in the hospital are not. Therefore, most of the plastic RSP uses is virgin or raw material, meaning it has never been processed or molded before.

Want to learn more about plastic material choices? Visit our plastic molding page or contact RSP today.

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