Lucas Noah Thermoplastics are the production material of the future and are undoubtedly here to stay. With its use becoming more widespread and applicable to any industry, from medical equipment and supplies to construction. It is an extremely versatile material that boasts many ‘green’ accolades, such as being highly recyclable. But what is a thermoplastic, and how is it any different from the plastics we commonly know?
The Thermoplastics Theory
Thermoplastics are a polymer material. This material becomes pliable and moldable when heated and hardens when cooled down, much like metal. The magic of thermoplastics (in opposition to other plastics) is that they can be reheated and re-molded again and again and again… Yes, you read that right.
Think about plastics as an egg (this specifically applies to thermoset plastics). These plastics can be heated, melted, and set to create any product. However, once the setting reaction has been completed, this product cannot be melted again. An egg, once fried, cannot be returned to its liquid state.
The opposite is true for thermoplastics. Thermoplastics are like butter: they can be heated, which causes the ‘melting,’ cooled down, which we experience as setting, otherwise referred to as solidifying and reheated to melt again and so forth and so forth.
“How?” might you wonder. When thermoset plastics are melted and set, it is not simply a liquid solidifying; a whole chemical process occurs. The setting, a.k.a solidifying of the plastic, is not a hardening of a liquid but rather a chemical reaction that occurs that changes the chemical composition of the liquid to transform it into a solid. This chemical reaction cannot be reversed. The heating and cooling of thermoplastics entail no chemical reaction, and therefore these processes do not alter the chemical composition from that with which you started.
The allure of this capability to be reset and remelted lies in the regenerative properties that arise as a result. Entire product lines can be redesigned and reproduced with no loss of materials. Standard products can be customized on-site for specific needs.
Think about pipe fittings, for example. Many industries have moved away from using metal pipes to transport whichever fluid they work with. With the assembly of pipelines, when using metals, one would be able to heat the metal to clamp it over another pipe to form an airtight seal or melt the end of two pipes to join two pieces as one. Applications and customization like these are possible with thermoplastics.
The melting point of thermoplastics is lower than that of metals. This holds its pros and cons. Pro: melting of thermoplastics is not as energy-intensive, or as dangerous a process as that of melting metals. Con: because of a low melting point, thermoplastics are unsuitable to be used within certain industries or environments.
Thermoplastics are highly customizable. There is a wide variety of thermoplastic materials available like polycarbonate, acrylic, and ABS. Each material has its own mechanical and thermal properties as well as aesthetics. You can therefore choose a material that caters to the specific functions you will need your product to perform. Colors, patterns, and images can also be designed into your product. Many thermoplastic manufacturers have designlab services to aid and facilitate these design customizations.
Furthermore, thermoplastics are lightweight, which has a great effect on the transportation and shipping of products. The production process from thermoplastic sheet to product is also fast compared to other materials such as metal.
Winning Characteristics of Thermoplastics:
Durability
Thermoplastics do not chip, fray, splinter, crack or dent. They are ductile and impact resistant. Fittings, parts, or components made of thermoplastics will remain the same shape throughout the product’s lifetime. You, therefore, do not have fitting stretching out or parts loosening over time. Practically this means lower maintenance frequency and replacement rates.
Being Chemical and Stain Resistant
Thermoplastics do not discolor, and other chemicals like cleaners or solvents do not react with the material to cause staining or corrosion. Thermoplastics also do not allow the binding of paints or finishes. This makes your product or surface resistant to things like graffiti, and even spilled paint can safely be removed from the surface.
Fully Integrated Color and Finishing
The color and finish you choose to design your products in are produced on demand by using the thermoplastic material of your choice. Having the color be part of the production of your thermoplastic and not an after-the-fact add-on results in consistent color throughout the entire material. Why is this relevant? If you need slabs of thermoplastic material, for example, that you wish to cut and build something with, your cross-sections (where you have cut) will not look different from any other side/surface of your slab.
Extremely Environmentally Friendly
Thermoplastics can be recycled as many times as they can be melted down. The great thing about recycling thermoplastics is that once you have melted down an old thermoplastic product, you do not end up with a sub-par material. The melted down, recycled thermoplastic is the same in quality and all properties as the new and original thermoplastic material the first product was made from.
Thermoplastics in Product Manufacturing
Thermoplastics can be shaped by several processes. Processes available to shape thermoplastics are injection molding, blow molding, and thermoforming. Under the category of thermoforming several distinct processes exist, each with its respective best applications and uses.
Thermoforming Theory
Thermoforming is a process that always involves a heated sheet of thermoplastic material and the creation of a vacuum between the thermoplastic sheet and mold to be used.
The thermoplastic material to be used should be rolled into a sheet of the exact thickness and finishing that is required on the finished product. This sheet is heated to make the material malleable. This sheet can then be formed into any shape.
The mold provides the shape the thermoplastic sheet will be formed into. A distinction is made between male and female molds, each serving a different purpose in respectively relevant forming processes.
The thermoplastic sheet is pulled into the mold by a vacuum created between the mold and the sheet. A vacuum is the absence of air. Once the air between the sheet and the mold is removed (sucked out), the sheet takes the space of this air. This results in the sheet lining the mold, taking on its shape.
In all thermoforming processes, the sheet must cool down and harden before it can be removed from the mold for it to hold its new shape.
Thermoforming Processes
All different kinds of thermoforming processes hold their own benefits. The thermoforming process that should be used is determined by the product being formed and its specifications like shape, detail, and size.
Thermoforming processes result in consistent and uniform production of products with high finish specifications. The same production quality can be expected from injection molding.
Vacuum Forming
This process entails a thermoplastic sheet being heated and then being pulled against a male or female mold. This pulling is achieved by creating a vacuum between the mold and the sheet.
This process should be used for:
- Fine Surface Details
- Intricate Shapes
- Tight Tolerances
Pressure Forming
This is a dual action process. Here a thermoplastic sheet is heated and pressed into a female mold. Pressure is applied from above to press the sheet into the mold while a vacuum is being pulled between the sheet and the mold.
This process should be used for:
- Sharp Details
- Texture that presents in the mold
- Tight Tolerances
- Undercuts
Twin Sheet Forming
Two thermoplastic sheets are bonded together.
This process should be used for:
- Increasing rigidity of a component
- Surface details
- Ribbing
- Improving Structural Support
- Integrated hardware
- Undercuts
- The elimination of secondary assembly
Membrane Pressing
This is a method of encasing surfaces in thermoplastics. A thermoplastic sheet is vacuum formed over the surface after being heated.
Injection Molding
Injection molding makes use of full cast molds. These are molds that are fully enclosed except for a small area where the materials the product will be made from can be poured or, in this case, injected into.
The thermoplastic with the color and material specifications you desire is produced. In its liquid state, this thermoplastic is then injected into the product mold at a very high pressure. This injection happens at a singular point/cavity in the mold. This high pressure ensures that all areas and cavities of the mold are filled.
The thermoplastic then hardens as it cools down, the mold is produced, and you are left with a finished product.
Thermoplastic Wrap-Up
Thermoplastics are incredibly versatile and durable. This durability ensures less waste due to broken parts as well as less downtime of hardware or infrastructure needed for maintenance.
Product manufacturing using thermoplastics also seems to be the lesser evil amongst plastics when looking at its impacts on the environment.
It is accessible, fast manufacturing with a smart material, and should be considered if you are looking to get quality products on the market or in your home.