Prototyping Material: A Guide to Choosing the Right Material for Your Project

Prototyping material selection is an important part of product development. Developing a prototype is crucial to guarantee that a product is functional, efficient, and effective. Before beginning mass production, a prototype allows you to test and validate your design and detect any possible issues. However, selecting the right prototyping material might be a big challenge. 

This article will cover the different types of prototyping materials, the factors to consider when choosing a material, the processes for prototyping with different materials, and the advantages and disadvantages of different prototyping materials. This way, you could better choose the suitable material for your project.

Types of Prototyping Materials

Plastics, metals, and silicone rubber are examples of prototype materials. Let’s take a closer look at them all.

Plastics 

Plastics are a common prototyping material because they can be used in many sectors and have many benefits, such as being durable, flexible, and cheap. They are synthetic polymers that can be molded into different shapes and sizes. This makes them perfect for making parts with complicated geometries.

Plastics can be prototyped using a variety of processes, including injection molding, 3D printing, and CNC machining. For prototyping, a wide range of plastics are accessible. Among the most prevalent types are:

Acrylonitrile Butadiene Styrene (ABS): ABS is a type of plastic made from three main ingredients: acrylonitrile, butadiene, and styrene. It is a strong and durable plastic material often used to make things like toys, appliances, and car parts. It is known for being strong, long-lasting, and resistant to heat and impact. ABS plastic is low-cost and easy to mold and process, making it a popular choice for 3D printing and injection molding.

Polycarbonate (PC):  PC is a thermoplastic polymer with excellent strength, durability, and transparency. It is frequently used to fabricate automobile parts, electronic components, safety equipment, bulletproof glass, and other protective materials. Polycarbonate is also used to manufacture 3D printing filaments because it easily molds and shapes into intricate forms. It is a very adaptable material that is impact and heat-resistant, making it a popular choice for various applications such as automotive and aerospace.

Polypropylene (PP): Like polyethylene (PE) and polybutene(PB), PP is a polyolefin or saturated polymer. PP is one of the most useful polymers with excellent chemical resistance, fatigue resistance, temperature resistance, and lower density than HDPE. PP is a lightweight and flexible plastic often used for packaging, buckets, bowls, crates, toys, medical parts, auto parts, washing machine drums, battery cases, and bottle caps. PP can be elastomer modified to make bumpers and talc-filled to make it stiffer at high temperatures.

Polyethylene (PE): PE is a kind of plastic noted for its durability, flexibility, and chemical and impact resistance. It is extensively used in manufacturing items like packing materials, containers, and pipelines, as well as creating toys and other consumer goods. Polyethylene is a versatile material that is easy to shape and process, making it a preferred material for injection molding and other manufacturing processes. Because of its capacity to be readily molded into complicated forms, it is also extensively used to manufacture 3D printing filaments.

PE is classified into several classes based on density. Examples include low-density polyethylene (or LDPE), medium-density polyethylene (MDPE), high-density polyethylene (HDPE), and ultra-high molecular weight polyethylene (UHMWPE or UHMW). The surface hardness, tensile and flexural strength, and resistance to chemicals and wear are all better when the density increases.

Polyoxymethylene (POM): POM, often known as Delrin® or Acetal, is a thermoplastic-engineered material used to create parts with improved stiffness, low friction versatility, and superior dimensional stability. POM is robust and durable, with high tensile strength, wear, creep, warp resistance, toughness, and endurance. POM is widely used to produce automobile parts, sporting equipment, gears, bearings, conveyor parts, electrical components, sliding and guiding parts, etc.

Polyamide (PA)/Nylon: Polyamide, often known as PA or nylon, is a synthetic polymer with great strength, durability, and wear and tear resistance. It is widely used to produce gears, bearings, automotive parts, textiles, and other industrial materials. Because it can be easily molded and shaped into complicated forms, PA is also extensively utilized to create 3D printing filaments. It is a versatile, durable, and flexible material frequently used as an affordable silk, rubber, and latex alternative.

Polyethylene Terephthalate (PET): PET is a semi-crystalline resin with an outstanding balance of strength, stiffness, and toughness, a natural high gloss finish, strong chemical resistance, and excellent dielectric properties. PET is safe for contact with foods and drinks.

PET is frequently used to make plastic components in electrical products, electrical encapsulation or insulation, electrical insulation polymers, electrical connectors, packaging or containers for food and consumables, and appliances. It is a tough and long-lasting substance that is also resistant to moisture and chemicals, which makes it a popular choice for many uses. PET is another plastic type often used in 3D printing filaments due to its moldability and ability to hold shape when heated. Also, PET is the most recycled plastic and is fully recyclable.

Polymethyl Methacrylate (PMMA)/ Acrylic: PMMA, also known as acrylic or acrylic glass, is a transparent, lightweight, and durable plastic widely used to produce items, including signs, displays, and protective materials. It is renowned for its resistance to impact and ultraviolet light and its ability to be easily molded into intricate shapes. Acrylic material is frequently utilized in 3D printing filaments due to its versatility and ease of processing.

Acrylic(PMMA) is a very adaptable material utilized in various applications, from consumer goods to industrial materials, such as food storage containers, refrigerator drawers, and automotive and consumer items. Moreover, acrylics are suitable for over-molding and other specialty injection molding techniques.

Polytetrafluoroethylene (PTFE): PTFE, also called Teflon®, is synthetic tetrafluoroethylene with many uses. PTFE has excellent thermal stability, chemical resistance, and high-temperature resistance.

PTFE products have good sliding properties, are electrically resistant, and have a nonstick surface. PTFE can be reinforced with glass fiber, carbon, or bronze additives to increase mechanical properties. PTFE is typically molded into semi-finished goods by compression molding and subsequently processed with cutting/machining tools.

Polyether Ether Ketone (PEEK): PEEK is a colorless organic thermoplastic polymer. It is an engineering plastic that is utilized in various applications where strength and toughness are required. PEEK is chemically resistant and can endure temperatures of up to 260°C.

PEEK offers exceptional mechanical properties, making it ideal for medical implants, automotive components, and even aeronautical parts. PEEK is also utilized in electronic components as connectors and insulators.

Pros and Cons of Plastics 

Plastics have several pros and cons when it comes to prototyping. Let us have a deep understanding of them:

Pros:

Versatility: Polymers may be molded into various forms and sizes, making them excellent for producing parts with complicated geometries.

Durability: Plastics are often long-lasting and resistant to environmental conditions such as temperature and moisture.

Low Cost: Because plastics are frequently less expensive than other materials, such as metals, they are an appealing alternative for prototyping.

Lightweight: Plastics are often lightweight, which might be advantageous in applications where weight is a concern.

Availability: Polymers are commonly available and may be obtained from vendors.

Cons:

Harm Environmental: Polymers harm the environment since they are not biodegradable and can take hundreds of years to degrade.

Limited Strength: Plastics are often not as strong as other materials, such as metals, and may not be suitable for applications requiring significant strength.

Limited Heat Resistance: When subjected to high temperatures, plastics can melt or distort, which can be problematic for specific applications.

Limited Dimensional Stability: Plastics can warp or change shape over time, which can be problematic in particular applications.

Limited Chemical Resistance: Certain plastics may be sensitive to specific chemicals, which might limit their usage in certain applications.

Metals

Metals are a group of materials known for their strength, durability, and high melting points. They are widely used in prototyping due to their excellent mechanical properties and resistance to wear and tear. Here are some common metals used in prototyping:

Alloy Steel: Alloy steel does not contain carbon as its main alloying element. It has small amounts of alloying elements like manganese, silicon, nickel, titanium, copper, chromium, and aluminum. Alloy steel is more corrosion-resistant, weldable, heat-resistant, and ductile than carbon steel. But carbon steel is stronger than alloy steel. Due to its low cost, wide availability, ease of processing, and superior mechanical rates, alloy steel is commonly utilized in industrial applications, appliances, silverware, cooking utensils, and automobiles. 

Mild Steel /Low Carbon Steel: Mild steel is carbon steel with low carbon content. It is often referred to as “low carbon steel.” Low carbon has less tensile strength than high carbon and alloy steels because they have less carbon and other alloying elements to prevent dislocations in their crystal structure. Mild steel is a common choice for consumer items due to its high weldability and machinability.

Tool Steel: Tool steel is one kind of carbon alloy steel. It is often used to make hand tools, and machine dies, modify them, or fix them. Tool steel is known for being hard, resistant to wear, and hard to bend. Tool steel often shapes other materials by cutting, pressing, coining, or extruding. This is because steel can keep its cutting edge at very high temperatures. Tool steel is often used for stamping or extruding dies, cutting, making molds, and impact applications like hammers.

Stainless Steel: Stainless steel is a steel alloy that is more corrosion-resistant than carbon/alloy steel. 304, 316, 416, and 17-4 PH stainless steel grades are commonly used for CNC machining. Stainless steels are strong materials with a naturally occurring, protective oxide layer that makes them appropriate for difficult situations. The alloying ingredients that make up stainless steel grades cause them to differ. For instance, adding molybdenum to 316 stainless steel makes it less likely to corrode. The presence of sulfur in 303 stainless steel increases its machinability.

Stainless steel alloys are used in various applications, including consumer goods, industrial applications, heavy machinery, surgical equipment, kitchenware/appliances, aerospace, military, and automotive. Shafts, gears, bolts, nuts, and fittings are examples of stainless steel components that need excellent strength and dependability.

Copper: Copper alloys are one of the most useful metals because they are corrosion-resistant, have high thermal conductivity, and conduct electricity well. Copper alloys are great for many electrical, building, transportation, and consumer goods industries. Copper is used to making building parts, coins, condenser/heat exchangers, plumbing, radiator cores, musical instruments, locks, fasteners, hinges, components for ammunition, and electrical connectors.

Brass: Brass, an alloy of copper and zinc, has some of the same properties as copper. Brass is a durable, machinable metal. This alloy is also resistant to corrosion, electrically conductive, and has a low coefficient of friction. Brass is a versatile metal used in various applications such as plumbing, electrical, artistic, and medicinal.

360 Brass is the most machinable brass alloy, so much so that it is also known as free-machining brass. It has high corrosion resistance and strength. This heavy, strong material is best used for screw machine parts, heavy industrial parts, consumer goods, musical instruments, electrical parts, and plumbing fittings.

Aluminum: Aluminum is a silvery, low-density metal that is employed in a variety of commercial applications. Most of the time, unalloyed aluminum is ductile, has moderate strength, and is extremely corrosion-resistant. Using the proper alloying elements (Cu, Mg, Mn, Si, etc.) and subsequent heat/work treatments, aluminum’s properties may be greatly strengthened. Aluminum is widely utilized in aircraft, transportation, architecture, food, and chemical handling because of its low density and corrosion resistance.

Titanium: Titanium is regarded as the noblest metal and performs well in aggressive situations when other metals may fail. Titanium alloys are alloys made up of titanium and other chemical elements. Titanium alloys are lightweight, have exceptionally high tensile strength and toughness, are corrosion resistant, and can survive severe temperatures.

Titanium alloys are frequently utilized in bicycles, medical devices, jewelry, military applications, airplanes, spacecraft, high-stress components like connecting rods on high-end sports vehicles, and certain premium sports equipment and consumer electronics.

Pros and Cons of Metals 

Here are some of the pros and cons of using metals in prototyping:

Pros:

Strength and Durability: Metals are well-known for their exceptional strength and durability, making them the material of choice for parts that must maintain stability and reliability over time.

Heat Resistance: Since many metals have high melting points, they are heat-resistant, making them an excellent choice for applications operating in high temperatures.

Conductivity: Many metals are appropriate for constructing electrical and electronic components since they are good heat and electricity conductors.

Machinability: Metals are generally easy to machine and can be rapidly shaped into complex geometries.

Corrosion Resistance: Because of their strong corrosion resistance, certain metals, such as stainless steel and aluminum, are suited for applications that need exposure to damp environments or corrosive chemicals.

Cons:

Cost: Metals can be more expensive than other materials, such as plastics or composites, which makes them less suited for applications that require low-cost prototyping because of the cost factor.

Weight: Because of their potential to be heavier than other materials, metals aren’t always the best choice for applications that call for lightweight parts.

Conductivity: Conductivity may be both a benefit and a disadvantage for metals. In some applications, electrical conductivity is not something that is wanted, then the conductivity of metals can be a drawback.

Machinability: Machinability is a property of metals that describes the ease with which they may be machined; nevertheless, certain metals, such as titanium, can be difficult to machine and need specific equipment and expertise.

Corrosion: While certain metals have great corrosion resistance, others, such as copper, have a high susceptibility to corrosion, which limits the usability of these metals in certain applications.

Silicone Rubber

Silicone rubber is a versatile and well-known material in the elastomer sector. This material may be cured in various ways, including catalyzed, thermal, or UV curing. Silicone rubber is widely used in various sectors, from consumer goods to medical devices.

Pros and Cons of Silicone Rubber

Here are some of the pros and cons of using silicone rubber in prototyping:

Pros:

Flexibility: Silicone rubber is a flexible material readily molded into complicated forms and geometries, making it excellent for prototype applications requiring flexibility.

Heat Resistance: Silicone rubber has outstanding heat resistance properties, making it appropriate for high-temperature applications.

Chemical Resistance: Silicone rubber is extremely chemically resistant, making it perfect for applications requiring exposure to caustic substances.

Biocompatibility: Silicone rubber is biocompatible, making it perfect for medical and healthcare applications.

Electrical Insulation: Silicone rubber is a great insulator, perfect for electrical and electronic components.

Cons:

Cost: Since silicone rubber is more expensive than other materials, such as plastics or metals, it is less appropriate for low-cost prototype applications.

Durability: Because silicone rubber is a flexible material, it may not be as durable as other materials, such as metals, limiting its utility in some applications.

Shrinkage: Silicone rubber can shrink throughout the curing process, causing modifications to the prototype’s final dimensions.

Surface Finish: Silicone rubber can have a rough surface finish, making it unsuitable for applications requiring a smooth surface.

Contamination Sensitivity: Silicone rubber is susceptible to contamination, impairing its properties and performance.

Factors to Consider when Choosing Prototyping Materials

When selecting prototyping materials, several factors should be taken into consideration, including the following:

Cost: Because the costs of the parts might range quite a bit, it is essential to consider a budget for the undertaking.

Durability: Certain products require great strength or durability. Selecting materials that can endure the stresses imposed on them is essential.

Functionality: Certain materials may be more suited for certain functions, such as insulating, absorbing shock, or conducting electricity, respectively.

Manufacturing Method: The manufacturing process that will be utilized for the final product may also impact the selection of materials used for the prototype.

Prototyping Process for Different Materials

Generally speaking, the prototyping process for different materials involves 3D printing, CNC machining, sheet metal fabrication, injection molding, and urethane casting. 

3D Printing 

3D printing, also known as additive manufacturing, is constructing a three-dimensional item layer by layer using a computer-generated design. 3D printing is an additive technique in which layers of material are built up to make a 3D part. This is the inverse of subtractive manufacturing processes, in which a finished design is cut from a bigger block of material. Because of this, 3D printing wastes less material.

CNC Machining

CNC machining is a technology that removes material from a block of material, such as aluminum or steel, using computer-controlled machinery. It has high precision and may be used to generate complex geometries. It is, however, more time-consuming and costly than other processes.

Sheet Metal Fabrication

Sheet metal fabrication is making metal parts or structures from raw metal materials. Metal parts are manufactured using various fabrication methods, including cutting, punching, bending, and welding.

Injection Molding

Injection molding is a manufacturing technology that enables the production of huge quantities of parts. It operates by injecting molten materials into a mold to make parts. It is frequently used in mass production to produce thousands of similar goods. Metals, glasses, elastomers, and confections are all injection molding materials. However, it is most typically employed with thermoplastic and thermosetting polymers.

Urethane Casting

Urethane casting, also known as vacuum casting or polyurethane casting, uses silicone molds to make plastic and rubber parts under vacuum using two-component polyurethane resins. It is a flexible manufacturing process that generates complex engineering parts in polyurethane resins and cast nylon by emulating injection molding. Urethane casting is perfect for swiftly reproducing injection molding and rapidly prototyping plastic or rubber parts.

Prototyping Material Used in the Different Prototyping Process

Here is a table that outlines the prototyping materials and corresponding manufacturing processes:

Prototyping Material and Prototyping Process
Material3D PrintingCNC MachiningSheet Metal FabricationInjection MoldingUrethane Casting
Acetal✔️✔️
HDPE✔️✔️
LDPE✔️✔️
Nylon✔️✔️✔️
PEEK✔️✔️
PET✔️✔️
PTFE✔️
PC✔️✔️✔️
PAI✔️✔️
UHMW✔️
Ultem✔️✔️
ABS✔️✔️✔️
PEI✔️✔️
PMMA✔️✔️
POM✔️✔️
PP✔️✔️✔️
Delrin✔️✔️
PPE✔️✔️
PPSU✔️
PS✔️✔️
PVC✔️
LSR✔️
TPE✔️
TPU✔️✔️✔️
Aluminum✔️✔️✔️
Alloy Steel✔️
Brass✔️✔️
Copper✔️✔️
Low Carbon Steel✔️✔️
Stainless Steel✔️✔️✔️
Titanium✔️✔️
Silicone✔️✔️

Please take note that the list shown in this table is not complete. In the processes described here, additional materials may potentially be employed. In addition, certain materials may be more suited for particular processes than others; therefore, it is essential to carefully analyze the needs of the prototype application you will be using before making a choice.

In Summary

With technological advancements, many prototyping materials are now accessible, ranging from traditional materials like metals and plastics to newer materials like silicone rubber. Selecting the right prototyping materials and manufacturing process is very important. This is because it can help designers and engineers produce high-quality prototypes that correctly represent the final product and guarantee a successful launch.

At LEADRP, we have many advanced prototyping materials to help you make your designs into real products. Our experienced engineering team has a thorough grasp of prototyping materials and will provide you with useful suggestions based on your product design. Contact us if you have any doubts about the material selection for your project! 

References

Material Properties from Material Properties Org

Material Properties from Corrosionpedia Inc.

Material Properties form The British Plastics Federation (BPF)

What Materials are Used for Prototyping (and Why)? – From PACIFIC RESEARCH LABORATORIES, INC.

Plastic Material Selection Guidelines for Injection Molding – From SMLease Design.

FAQ

ABS, acrylic, polyphenyl sulfone, polycarbonate, and nylon are just a few of the materials often utilized and provide excellent functionality, durability, and strength.

The primary advantage of prototyping is that it helps you to identify design and production issues. Early identification can avert issues later in manufacturing, reducing waste costs and manufacturing faulty products.

The prototyping process typically involves several stages: concept development,  initial prototype creation, prototype refinement based on feedback and testing, and final prototype finish.

About The Author

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LEADRP provides prototyping and on-demand manufacturing services, including CNC machining, sheet metal fabrication, custom tooling, injection molding, urethane casting, and 3D printing. With LEADRP, you can solve any challenge throughout product development and manufacturing. Click to tell us about your project or contact us for more information.

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