Elastomers: what you need to know

With 3D printing came a revolution in manufacturing and industrial design, underpinned by dramatic developments in printing materials. One material that has provided proved material innovation is the elastomer, which gives users the ability to 3D print flexible parts to meet their prototyping needs.

What is elastomer?

The name elastomer comes from the term 'elastic polymer'. An elastomer is a rubbery material composed of long chainlike molecules—polymers. Elastomer is often used interchangeably with the word 'rubber' because both are similarly flexible and elastic. The key difference between elastomers and rigid polymers, though, is resilience. A rigid polymer will yield, deform, or even break if forced to stretch, bend, or compress. By contrast, an elastomer will simply stretch or compress before returning to its original shape.

How does elastomer work?

When we take a microscope to an elastomer, we can see it's made up of various crosslinks between the polymer chains. These links tell the material how much to stretch before going back to their original form.

Under normal conditions, the long molecules of the elastomer are coiled in an irregular configuration. But when the molecules are stretched, they straighten in the direction the force is being applied. When the elastomer is released, the molecules return to their original configuration straight away. This gives the material a flexible but rigid quality, allowing it to be used in a host of different ways.

What is elastomer used for?

Elastomers are all around us—the global elastomer raw material market is worth over $20 billion. And there are more than 20 different types of elastomer, including natural and synthetic varieties.

Almost half of that market is accounted for in the transportation industry. A further 14% is wheels and tires for various uses, followed by 9% in both construction and, perhaps surprisingly, footwear. That gives you a glimpse into how prevalent this material could be in your day-to-day life.

A few objects that elastomers can help manufacture include:

• Belts

• Balloons

• Floor mats

• Gloves

• Hoses and tubes

• Pencil erasers

• Rubber bands

• Seals and gaskets

• Toothbrushes

What is the best type of elastomer for 3D printing?

Elastomers are already widely used across different industries and manufacturing techniques, and they are developing all the time. One of the latest improvements is Stratasys' durable elastomer TPU 92A—a thermoplastic polyurethane with a shore value of 92A.

TPU is renowned for high elongation, superior toughness, and extreme durability. This makes TPU 92A ideal for 3D printing, working equally well across functional or ergonomic prototyping, and end-use parts.

What is 'shore value'?

Shore value is a way of describing a material's hardness or softness, ranging from rubber bands to tire treads, shoe heels and all the way to rubber casters. Around that point on the scale is where TPU 92A sits.

Parts in this range have outstanding tear resistance, fatigue resistance, memory, and recovery compared to softer shore elastomers. This makes TPU 92A especially suited to prototyping high functioning, durable elastomeric parts.

Over 30,000 hours of testing have helped create 3D printing materials that outperform expectations

Is shore value the only factor to consider?

Not quite. Material is important—and TPU 29A has tested well against the competition, ranking two times better in key properties such as size, hardness, elongation, tensile strength, and tear strength.

However, the material alone does not give you the complete picture: you will need to be equally careful in selecting a printer that makes the most of your elastomer material.

Many low-cost 3D printers can print versions of flexible materials, however they rarely do so efficiently or accurately. And forget support removal; it's a complex and hands on process. To get the complete picture, you need to interrogate performance of the printed part, the printer's ability to produce large and complex parts, and the overall cost per part once labor and accuracy have been considered.

The freedom to go large and complex

The most common complaint about systems that print elastomers is a toss-up between small build volume or slow print speeds—it can take a long time to print even the smallest and simplest of parts.

With TPU 92A and a F123 Series Stratasys printer—F170, F270 or F370 models —you can create large parts and overhangs and incorporate cavities and complex geometries. Best of all, you can do it accurately and repeatably.

The mark of a good quality printer is its ability to retain the best properties of the elastomer material in the final part. How will your part perform as it is stretched and compressed? In tests, elastomer parts produced using Stratasys printers elongate to 500%; the nearest competitor failed at 350%.

FDM TPU 92A eliminates expensive and time-consuming molding or casting methods to produce elastomer parts

Considering cost per part

It seems natural that a cheaper material would lead to a lower total cost per part. However, the reality is a little more complex, especially when it comes to removing supports that hold the material in place.

Removing supports by hand is intricate, labor-intensive work, and it sometimes results in a damaged part. It can take up to an hour to remove a simple part by hand, which means additional labor costs of around $50. For a complex part, that rises to $65.

Stratasys' printers have soluble support—which means you don't need to spend that time and money removing the support. The support simply dissolves to release your printed part, which can reduce labor costs by up to 76%—saving you money on every single part.

Elastomer: the future of design

3D printing should free you from design constraints, not add restrictions. With TPU 29A and Stratasys' printers, you can reduce your prototype-to-production cycle and print more complex parts, more reliably—all for a lower total cost-per-part. This is a new world of design freedom.

Find out more about Stratasys TPU 92A here.