A large portion of things we use daily contain plastic. Your smartphone, car, computer, and perhaps even your clothing is at least partially manufactured using some sort of plastic material.
But not all plastics are created equal; companies use specific types of plastic that have the necessary mechanical properties to ensure the functionality and durability of their products.
Important Properties to Consider
Plastic is almost certainly cheaper than metal or wood. It’s a great material for rapid prototyping design purposes. In fact, it’s so affordable that you can just buy a ready-to-use plastic material to 3D print your design.
But material affordability should not be an excuse for poorly-built products; not when you have several types of plastic to choose from. Each type has its physical, mechanical, electrical, thermal, and optical properties to consider.
| Properties | Description |
|---|---|
| Specific Gravity | Density of plastic compared to that of water. Denser material is indicated by a higher number. |
| Tensile Strength | The amount of force required to pull a plastic part from both ends and makes it deform or fail to function as intended. |
| Tensile Modulus of Elasticity | A measure of stiffness of elastic material that describes the material’s resistance to breakage or permanent deformation. |
| Tensile Elongation | The maximum stretch point of plastic material before failure. |
| Flexural Strength | The highest level of stress a plastic material can take at its moment of rupture. |
| Flexural Modulus of Elasticity | A measure of stiffness or the tendency of plastic material to resist bending. |
| Compressive Strength | The maximum load a plastic material can bear before compression (reduction in size). |
| Hardness | The ability of plastic material to resist indentation. |
| Izod Impact | The amount of energy required to break a plastic material. |
| Coefficient of Friction | The ability of plastic to resist sliding against another material. A lower number indicates a higher level of slipperiness. |
| Coefficient of Linear Thermal Expansion | The ability of plastic to expand under temperature elevation. A higher number indicates a greater amount of size expansion when heated. |
| Heat Deflection Temperature | The temperature at which a plastic material deforms to a specified distance under a specified load. |
| Max Continuous Service Temperature in Air | The maximum acceptable temperature above which the mechanical and electrical properties of plastic material are noticeably degrading. |
| Dielectric Strength | The amount of electric field required to puncture a plastic insulating material. |
| Water Absorption | The increase of weight of plastic materials when submerged in water for a specified amount of time. |
| Light Transmittance | The ability of plastic material to transmit light. A higher number indicates greater transparency. |
| Haze | The scattering of light as it passes through transparent plastic material. It measures the cloudiness of the material when exposed to light. |
Plastics are a synthetic material typically manufactured using a combination of petrochemicals, although the chemicals are often derived from natural products. They are versatile materials fabricated into countless products in all industries including architectural design services, automotive, household goods, electronics, toys, and hobbies.
For a lot of manufacturers, plastics offer an excellent balance between affordability and quality. Some plastics are easier to fabricate than others, so the manufacturing speed can be potentially increased using the right type of material to reduce production time and cost. Some of the most popular types of plastics are as follows.
Polymethyl Methacrylate (PMMA)
More commonly known as acrylic or acrylic glass, PMMA material is used just about everywhere in the world by prototyping design services. Chances are you have seen such material used as windows, display cases, lamps, and even car lights.
- Advantages: Besides its transparency, another selling point of PMMA is its shatter-resistant property. In other words, the material is almost like glass but is much less likely to break or crack from everyday use. PMMA is rigid so it can be easily formed, cut, or cast into various shapes. It works well at temperatures of up to 160 degrees Celsius.
- Disadvantages: When PMMA comes into constant contact with water, the material swells to a small degree because it actually absorbs water despite its hydrophobic nature. Hydrocarbons (alkyne elements) dissolve PMMA.
Thanks to its superior toughness (at least when compared to glass), PMMA is extensively used by architectural drafting services and automotive industries for things like greenhouses, canopies, façade design, car windshields, car windows, and lamps.
The water absorption property is negligible; that’s why PMMA is also widely used to build large aquariums and small fish tanks. It’s even used in the manufacturing of intraocular lenses, which are implanted in the eye as a treatment for cataracts.
Common brands include: OPTIX®, Plexiglas®, and ACRYLITE®.
Nylon
The most interesting aspect of nylon is that we can make fibers from it. The material is so flexible and strong that we can use it to make clothing.
- Advantages: There are very few other materials that match nylon in terms of flexibility and strength. It does not shatter and is very lightweight. Nylon can withstand temperatures of up to 195 degrees Celsius.
- Disadvantages: Although clothing made from nylon is pretty durable, you can dissolve the material entirely by pouring acids over it. Constant exposure to UV light will trigger the formation of molecules that weaken nylon’s microstructure. It has a high shrinkage rate, making it a poor material for the injection molding process.
Many things we have and use daily contain nylon such as clothes, napkins, backpacks, and tires, as the material is often manufactured into a fiber and used by a freelance industrial designer. It also is wear-resistant and excellent for making parts that rub against each other such as gear mechanisms or bearings.
Common brands include SUSTAMID®, TECAMID®, and NYCAST®.
Acrylonitrile Butadiene Styrene (ABS)
The versatility and relative affordability of ABS makes additive manufacturing more accessible. In fact, it is now the main plastic material used for rapid prototyping.
- Advantages: ABS is resistant to various chemical agents—including acids and alkaline—that make most other plastics weak. The material is shock-resistant and suitable for making small objects such as a smartphone case or fashion accessories. ABS has a glossy surface that can make a product manufactured from this material look shiny.
- Disadvantages: The maximum working temperature is relatively low at 90 degrees Celsius. When used as a 3D printing material, ABS produce hot fumes that may cause irritation, headache, and nausea. It also has a high shrinkage rate.
Despite the hot fumes, ABS remains one of the most popular materials for rapid prototyping. It is used widely by manufacturing services to make cases, instrument panels, machine housings, and toys. For many people interested in rapid prototyping, ABS is the material of choice due to its affordability.
Common brands include: Royalite®, Polystone®, and TECARAN™.
Polyoxymethylene (POM)
Also known as acetal, polyacetal, and polyformaldehyde, POM is as close as a plastic material can get to metal. POM has an excellent level of stiffness and dimensional stability.
- Advantages: The material offers the strength and rigidity typically required for manufacturing high precision parts. It has low friction and works at temperatures of up to 166 degrees Celsius. POM is one of the few plastic materials that are highly resistant to moisture.
- Disadvantages: One of the worst characteristics of POM is its tendency to shrink unevenly. It can be difficult to predict how the material will turn out after being formed or cast.
Despite potential hassle during the manufacturing process, POM is an excellent material and is used extensively across various industries and by freelance DFM services.
RELATED: A Freelance Prototype Designer’s Guide to Plastics for Product Design
Common brands include: Delrin®, SUSTARIN®, and TECAFORM®.
Polycarbonate (PC)
It is a transparent plastic material with notable strength and stiffness compared to other plastics. PC offers outstanding impact resistance, much higher than PMMA. It can be tinted or made opaque to make colored glass-like material.
- Advantages: PC offers high optical clarity and functions well as an electrical insulator. It is easy to fabricate and bond with solvent cements. Working temperatures reach up to 150 degrees Celsius.
- Disadvantages: The transparency fades over time, and even quicker if exposed to UV light on a constant basis. PC is not scratch-resistant, but a special film covering should help protect its surface. The material should not be used with food or organic things.
A lot of transparent products are made of PC for examples reinforced glass, automotive lights, face shields, signs (both indoor and outdoor), and transparent manifolds. When it comes to rapid prototyping, PC is much more popular than PMMA. It’s also used by automotive design and engineering services.
Common brands include: TUFFAK® (formerly Makrolon®), Sustanat, and TECANAT®.
Polypropylene (PP)
One of the most widely used plastics in the world, PP is both reusable and recyclable for the manufacturing process of new goods. It has a semi-crystalline structure and some outstanding characteristics. SLA 3D printing uses this often.
- Advantages: PC is a low cost chemical resistant plastic. It is easy to weld using thermoplastic equipment and very durable. Since it is recyclable, PC is highly desirable across all industries in the wake of increasing environmental concerns.
- Disadvantages: A massive drawback is flammability. While most plastics are flammable, PC burns more easily compared to others, but the material comes in various grades that offer greater fire resistance. It also has poor bonding properties, so additional adhesive is necessary to apply paint.
Thanks to its chemical resistance, PC is most often fabricated into chemical and water tanks. Some propylene are in fact FDA-compliant for use as outer prosthetic sockets and body jackets.
RELATED: Selecting Materials for 3D Printing Your New Product or Prototype
Common brands include: Orthoform®, SIMOLIFE, Polystone®, and ProComp™.
Polyvinyl Chloride (PVC)
This thermoplastic is brittle, odorless, and usually white in color. PVC is lightweight and malleable, making it easy to handle and install in most applications.
- Advantages: The biggest selling point is chemical stability. It is an important characteristic to guarantee that PVC maintains its mechanical properties without changes in shape or rigidity when other chemicals are introduced.
- Disadvantages: More than half of PVC’s structure is comprised of chlorine. Carbon is often used in the material manufacturing process as well. As a result, PVC is potentially toxic when exposed to fire and as it decomposes in landfills.
PVC is widely used for piping systems, cabinets, chemical tanks, fittings, valves, and working surfaces. The material has numerous characteristics that make it suitable for both industrial and household uses. It is affordable, easy to joint using adhesives, stiff, and durable.
Common brands include: Vintec® I, Vintec® II, and Corzan® CPVC.
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