NYLON VS ABS INJECTION MOLDING

The plastic industry has seen a lot of growth over several decades. The direction of growth might shift towards one form of plastic or the other in different years. But the general effect is the increasing options for plastics. Product designers and manufacturers today have a myriad of choices in material selection. Nylon and ABS are two very well used plastics in the manufacturing of plastic products. They are particularly attractive to injection molders as they offer some peculiar advantages. Several nylon products will do just as well if they got made with ABS and vice versa. There are also some products where one might prove better than the other. So if you are in the business of injection molding, you might at some point have to choose between them. Whichever way you involve in injection molding. Knowledge of the difference between certain plastics is valuable. In this article, I’ll take you through the fundamental differences between Nylon and ABS. In particular how these differences play out in injection molding. 

To choose between both plastics, it is important to know a little about each one. So first we begin with the description and properties of each type. Then we look at specific instances where one might be better suited over the other.

ABS gives you all the performance you need in engineering plastic. Just don’t turn up the heat.

Acrylonitrile Butadiene Styrene is an engineering grade plastic with quite some impressive properties. This is even more impressive considering that it is inexpensive. It can stand toe to toe with nylon when it comes to strength and abrasion resistance. The only downside to ABS is that it melts at a much lower temperature than most engineering plastic. Limit the application to room temperature and watch ABS perform!. Just look at the list of properties in the table below. For a low-cost plastic, it gives impact strength of engineering plastic. It also has good scratch resistance. Think, lego pieces and Rubik’s cube. You will find it getting used for electronic plastic parts. Examples are casing for adaptors and sockets. You’ll also find ABS in desktop and laptop keyboards. If you consider the heat input required to injection mold higher melting plastics. Then the low melting point of ABS is an advantage in injection molding. You’ll need less energy hence fuel to heat the plastic to the working viscosity for injection molding. So when the product you are producing only gets used at room temperature, ABS would do just fine. This is why you will find ABS in consumer products that are low cost but must perform. Their abrasion resistance also contributes to their usefulness in such products.

Table comparing some properties of ABS with that of Nylon.

NYLON, the heat resistant plastic that is also temperature sensitive

Nylon has an interesting history. It got discovered by Wallace Carothers in 1935. An American scientist who worked at the Dupont lab. At the time of the second world war products like rubber and silk fell in supply. This was because they get sourced from natural resources. There was a need for a substitute that gets synthesized in the laboratory. There were a few years between the first lab production and industrial manufacturing. The chemistry is still the same. But the process for the production of nylon has improved over the years. Also known as polyamide, nylon is of different types. Most commonly used in commodity and engineering application is nylon 66 and nylon 6. These are also referred to as PA 66 and PA 6. 

The numbers after the nylon refer to the number of carbons. These are in the amide and the carboxyl side of the repeating unit. Where there is only one structural unit that forms the repeating unit. The nylon carries only one number. For example, nylon 6 gets made up of a monomer of six carbon with an anode end and a carboxylic acid end. Nylon 6,6 gets made from two structural units. One has amide groups at both ends while the other has carboxylic acid groups at both ends. Other forms of nylon-like nylon 6, 8, and nylon 6, 10 also exist. 

As for performance, you can call nylon the thermal upgrade of ABS. It does most of all what ABS does. Except it can also do these even when the temperature is a little higher. Nylon is also an engineering plastic. Although it falls at the high end of engineering plastics. Its mechanical strength is close to those of some high-performance plastics. You’ll find nylon in applications like seat belts and baggage buckles. You’ll also find nylon in one of its early and still existing applications as nylon stockings. Their high tensile strength makes them very good for forming strong fibers and ropes. Its chemical and wear resistance makes it great for wearables like diving suits. At the higher end of its application, you’ll find nylon used in gears, bearing,s and other mechanical parts. Its great tensile strength combined with its smooth surface and abrasion resistance. Makes it great in such applications. For example gear parts will glide in and out of the bearings and the teeth will not get worn. They will also not release tiny pieces of nylon which can cause problems in machines. Nylon serves as a replacement for metals with low strength. This is due to its strength as well as heat and chemical resistance.

Image compare Nylon and ABS with other plastics used in injection molding.

Nylon can withstand high-temperature applications. This of course means it needs high heat input to be injection molded. Not only that, but it also has a short glass transition temperature. This means that you need to keep a close eye on the temperature when processing. (And by close eye I mean accurate temperature control system/strategy. (There’s no point close watching the temperature only for it to overshoot). Thermoplastics in general when heated will show a temperature rise. This until they reach their glass transition temperature. This is the part where they transition from a hard solid-state to a liquid. What’s unique about plastic is that they have a state between hard solid and liquid. Here they keep a viscous dough-like state. This allows them to get molded into different shapes. When cooled they become hard and rigid again. Injection molding of thermoplastics gets based on this property of plastics. Injection molding generally occurs when the plastic is in this vicious state. Getting too close to the liquid state risks exceeding the degradation temperature. Unlike compounds like metal and water, plastic does not exist in the gaseous state. Take a look at the molecular weight of even the simplest of plastics and you can see why. They are way too heavy to have a gaseous state. Although the soft rubbery state is general to all plastics, the profile varies. Some plastics will have a wide glass transition temperature. This means they absorb heat at a wide range of temperatures. They become less viscous as more heat gets applied until the final liquid state. Some plastics behave almost like candle wax. Once they reach their glass transition temperature. The melting into liquid is not too far off. They would become viscous. But over a shorter temperature range before they become liquid. This means the degradation temperature is not too far off. The gradation occurs as the liquid gets so hot it should boil. But plastics don’t have a boiling point (The point liquids become gaseous). This means you only have a short range of melt temperature to work within. This is what we mean by the nylon being high melting but is temperature-sensitive. It can withstand high temperatures during its application. But during processing, you must stay within a short melt temperature range.

Comparing ABS and Nylon

Let us now place both plastics side by side and see how they compare. The table below lists different attributes of the two plastics. 

We see that both have quite impressive attributes. It is thus not a case of one being better than the other. Rather it is a case of which is best suited to your purpose. There would be no point bearing the added cost of heating with nylon injection molding. If all you need is the mechanical strength of ABS. The tensile property of nylon gives it an excellent fiber-forming property. It also makes it a good plastic for forming into complex parts. ABS has a much higher impact strength than nylon. The graph in the image below compares the impact strengths of some common plastics.

So there are many differences and similarities between ABS and nylon. The one you go for depends a lot on your product and machinery. You might even choose to do some rapid prototyping with ABS. Then test the strength of the material using CNC machined nylon. There are of course the applications where you can use either with no-fault. The main limitation there would be a service temperature. 

Our Industry Experience with ABS and nylon

Cavity mold offers injection molding services as well as mold making services. We have helped companies to produce parts from various types of plastics. These include ABS and nylon. You can gain from our experience in plastic injection molding and mold manufacturing. Contact us today to discuss your injection molding project. 

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The plastic industry has seen a lot of growth over several decades. The direction of growth might shift towards one form of plastic or the other in different years. But the general effect is the increasing options for plastics. Product designers and manufacturers today have a myriad of choices in material selection. Nylon and ABS are two very well used plastics in the manufacturing of plastic products. They are particularly attractive to injection molders as they offer some peculiar advantages. Several nylon products will do just as well if they got made with ABS and vice versa. There are also some products where one might prove better than the other. So if you are in the business of injection molding, you might at some point have to choose between them. Whichever way you involve in injection molding. Knowledge of the difference between certain plastics is valuable. In this article, I’ll take you through the fundamental differences between Nylon and ABS. In particular how these differences play out in injection molding. 

To choose between both plastics, it is important to know a little about each one. So first we begin with the description and properties of each type. Then we look at specific instances where one might be better suited over the other.

ABS gives you all the performance you need in engineering plastic. Just don’t turn up the heat.

Acrylonitrile Butadiene Styrene is an engineering grade plastic with quite some impressive properties. This is even more impressive considering that it is inexpensive. It can stand toe to toe with nylon when it comes to strength and abrasion resistance. The only downside to ABS is that it melts at a much lower temperature than most engineering plastic. Limit the application to room temperature and watch ABS perform!. Just look at the list of properties in the table below. For a low-cost plastic, it gives impact strength of engineering plastic. It also has good scratch resistance. Think, lego pieces and Rubik’s cube. You will find it getting used for electronic plastic parts. Examples are casing for adaptors and sockets. You’ll also find ABS in desktop and laptop keyboards. If you consider the heat input required to injection mold higher melting plastics. Then the low melting point of ABS is an advantage in injection molding. You’ll need less energy hence fuel to heat the plastic to the working viscosity for injection molding. So when the product you are producing only gets used at room temperature, ABS would do just fine. This is why you will find ABS in consumer products that are low cost but must perform. Their abrasion resistance also contributes to their usefulness in such products.

Table comparing some properties of ABS with that of Nylon.

NYLON, the heat resistant plastic that is also temperature sensitive

Nylon has an interesting history. It got discovered by Wallace Carothers in 1935. An American scientist who worked at the Dupont lab. At the time of the second world war products like rubber and silk fell in supply. This was because they get sourced from natural resources. There was a need for a substitute that gets synthesized in the laboratory. There were a few years between the first lab production and industrial manufacturing. The chemistry is still the same. But the process for the production of nylon has improved over the years. Also known as polyamide, nylon is of different types. Most commonly used in commodity and engineering application is nylon 66 and nylon 6. These are also referred to as PA 66 and PA 6. 

The numbers after the nylon refer to the number of carbons. These are in the amide and the carboxyl side of the repeating unit. Where there is only one structural unit that forms the repeating unit. The nylon carries only one number. For example, nylon 6 gets made up of a monomer of six carbon with an anode end and a carboxylic acid end. Nylon 6,6 gets made from two structural units. One has amide groups at both ends while the other has carboxylic acid groups at both ends. Other forms of nylon-like nylon 6, 8, and nylon 6, 10 also exist. 

As for performance, you can call nylon the thermal upgrade of ABS. It does most of all what ABS does. Except it can also do these even when the temperature is a little higher. Nylon is also an engineering plastic. Although it falls at the high end of engineering plastics. Its mechanical strength is close to those of some high-performance plastics. You’ll find nylon in applications like seat belts and baggage buckles. You’ll also find nylon in one of its early and still existing applications as nylon stockings. Their high tensile strength makes them very good for forming strong fibers and ropes. Its chemical and wear resistance makes it great for wearables like diving suits. At the higher end of its application, you’ll find nylon used in gears, bearing,s and other mechanical parts. Its great tensile strength combined with its smooth surface and abrasion resistance. Makes it great in such applications. For example gear parts will glide in and out of the bearings and the teeth will not get worn. They will also not release tiny pieces of nylon which can cause problems in machines. Nylon serves as a replacement for metals with low strength. This is due to its strength as well as heat and chemical resistance.

Image compare Nylon and ABS with other plastics used in injection molding.

Nylon can withstand high-temperature applications. This of course means it needs high heat input to be injection molded. Not only that, but it also has a short glass transition temperature. This means that you need to keep a close eye on the temperature when processing. (And by close eye I mean accurate temperature control system/strategy. (There’s no point close watching the temperature only for it to overshoot). Thermoplastics in general when heated will show a temperature rise. This until they reach their glass transition temperature. This is the part where they transition from a hard solid-state to a liquid. What’s unique about plastic is that they have a state between hard solid and liquid. Here they keep a viscous dough-like state. This allows them to get molded into different shapes. When cooled they become hard and rigid again. Injection molding of thermoplastics gets based on this property of plastics. Injection molding generally occurs when the plastic is in this vicious state. Getting too close to the liquid state risks exceeding the degradation temperature. Unlike compounds like metal and water, plastic does not exist in the gaseous state. Take a look at the molecular weight of even the simplest of plastics and you can see why. They are way too heavy to have a gaseous state. Although the soft rubbery state is general to all plastics, the profile varies. Some plastics will have a wide glass transition temperature. This means they absorb heat at a wide range of temperatures. They become less viscous as more heat gets applied until the final liquid state. Some plastics behave almost like candle wax. Once they reach their glass transition temperature. The melting into liquid is not too far off. They would become viscous. But over a shorter temperature range before they become liquid. This means the degradation temperature is not too far off. The gradation occurs as the liquid gets so hot it should boil. But plastics don’t have a boiling point (The point liquids become gaseous). This means you only have a short range of melt temperature to work within. This is what we mean by the nylon being high melting but is temperature-sensitive. It can withstand high temperatures during its application. But during processing, you must stay within a short melt temperature range.

Comparing ABS and Nylon

Let us now place both plastics side by side and see how they compare. The table below lists different attributes of the two plastics. 

We see that both have quite impressive attributes. It is thus not a case of one being better than the other. Rather it is a case of which is best suited to your purpose. There would be no point bearing the added cost of heating with nylon injection molding. If all you need is the mechanical strength of ABS. The tensile property of nylon gives it an excellent fiber-forming property. It also makes it a good plastic for forming into complex parts. ABS has a much higher impact strength than nylon. The graph in the image below compares the impact strengths of some common plastics.

So there are many differences and similarities between ABS and nylon. The one you go for depends a lot on your product and machinery. You might even choose to do some rapid prototyping with ABS. Then test the strength of the material using CNC machined nylon. There are of course the applications where you can use either with no-fault. The main limitation there would be a service temperature. 

Our Industry Experience with ABS and nylon

Cavity mold offers injection molding services as well as mold making services. We have helped companies to produce parts from various types of plastics. These include ABS and nylon. You can gain from our experience in plastic injection molding and mold manufacturing. Contact us today to discuss your injection molding project.