Thermoplastics as a substitute for metal additive manufacturing?

In the last few years, metal additive manufacturing has become increasingly popular. And rightly so: a variety of products can be made with it, be it prototypes, miniatures, jewelry, functional parts or even kitchenware.

Metal additive manufacturing technology enables the production of highly complex geometries due to the fact that is not constrained by the same rules associated with subtractive machining and other traditional manufacturing techniques. In fact, some 3D printed parts are already just as good, if not better. But there are more benefits. In this article we will first have a look at the other advantages that this relatively new technology brings. Then we will explain why 3D printing thermoplastics can be an even better and cheaper substitute. More and more companies are using 3D printing thermoplastics for crafting metal (like) objects as this has a lot of extra advantages compared to the standard process of metal additive manufacturing.

The benefits of metal additive manufacturing

You can produce complex geometries such as lattice structures and conformal channels to improve performance.
You can merge multiple parts into single or fewer components to improve reliability and reduce inventory.
It is a complementary tool that can be integrated into current manufacturing processes to reduce steps, time to market and cost.
You can create fully bespoke or customized components to improve performance.
Light weight – only build material where it is needed, reducing waste.
Reduced tooling costs – parts can be manufactured directly without the need for tooling.
Rapid design iterations right up to manufacture.

Thermoplastics as a replacement for metal additive manufacturing?

Many industries, such as the aerospace, medical, energy and automotive industry are realizing the potential of replacing metal additive manufacturing by 3D printing thermoplastics. Large scale, interior, or enclosure metal parts can easily be manufactured by 3D printing thermoplastics. Thermoplastic products can perform as well as and in some cases even outperform metal in ratios such as strength-to-weight and strength-to-stiffness.

An example of a thermoplastic that is a great replacement for metal is PEEK. It is a perfect material for mechanical engineers and manufacturers as it can be used for creating metal-like prototypes that can be tested as well as concepts and the final, finished products, which are ready for use. Metals like Carbon Steel, Stainless Steel, Titanium, Aluminum, Magnesium, Brass and Bronze can all be replaced by PEEK.

There are a lot of thermoplastic materials with PEEK and PEI/ULTEM™ being the most popular high performance materials. It depends on the requirements you have with regard to the material which one you can choose best. This concerns, for example, resistance to heat, corrosion protection, electrical conductivity and many other things. The big difference between metal and plastic is in the chemical structure of the two materials. However, we will not deal with macromolecules and atoms in any detail but briefly explain the main differences.

The advantages of thermoplastics

1. Enhanced performance

Enhanced performance benefits include everything from extending lifetime by eliminating corrosion, increasing fuel efficiency with lower friction, and handling higher loads/speeds to operating in more extreme chemical environments.

2. Weight reductions of up to 80%

With 3D printing thermoplastics you can create lightweight objects that are still strong. The inherent low specific gravity of PEEK (1.3 g/cm3) is less than half that of aluminum and one sixth that of steel. Maintenance costs, logistics, installation – all see significant cost reductions in tandem with a decreased part weight. If you were to take a part made from steel made by metal additive manufacturing and compare it to the same part made from thermoplastic, the plastic part could be more than 6 times lighter.

3. Less waste

It creates minimal waste. Because, compared to metal additive manufacturing, 3D printing thermoplastic helps increase material efficiency it is used a lot in product development. Thermoplastic materials can be melted, cured (cooled down such that they become solid), melted again, cured again, and so forth. Therefor manufacturing waste can be reused (thus preventing it from becoming “waste” in the first place).

4. Greater design freedom

Greater design freedom comes from PEEK’s amazing processing versatility which allows complex geometries to be molded-in without labor intensive post-machining steps. This, in turn, helps engineers improve on performance while reducing total system cost. Simply said, you can make objects that can’t be made with metal additive manufacturing. Even with today’s technology, metal’s inherent characteristics prohibit complex part designs or shapes, such as compound curves or fluid designs from either a material capability or cost limitation.

The disadvantages of thermoplastics

1. Design changes needed

Finding the right parameters for metal (like) 3D printing while designing takes some practice. Most 3D designs can’t be 3D printed without additional design changes. So you can’t take a part that was designed for plastic 3D printing (like PLA or ABS) and start printing away. Trying to make a plastic material fit a metal design would almost be like trying to fit a square peg into a round hole.
Most 3D objects designed for CNC milling aren’t compatible with 3D printing. CNC objects have more volume – if you just 3D print this object, it would be very costly. Every thermoplastic has certain properties you have to consider of in the designing process. You can get the specifications from the manufacturer or ask us.

2. It is not cost efficient to use for mass production

3. You can’t make very big parts (yet)

Industries where 3D printing thermoplastic is being used

Within the 3D industry, one of the top notch materials is PEEK or Carbon PEEK. This high temperature material has amazing properties, such as chemical resistance, a low moisture absorption and great durability and strength.

3D printing PEEK as a replacement for metal is used in several different markets already due to its great capabilities. It’s one of the most reliable materials to print with, so it sees its application in objects that need great accuracy and strength. Here some examples of industries that are already using PEEK to further drive innovation in its fields.

Automotive industries

PEEK is being used increasingly in the automotive industry (read more here about PEEK 3D printing). It can improve fuel economy (the relationship between the distance traveled and the amount of fuel consumed) and reduce emissions in two ways. First, by reducing energy losses due to excess weight and second, by reducing friction losses in the powertrain. A 68% weight reduction in gears, for example, results in a 78% reduction in the moment of inertia which leads to a 9% increase in efficiency. The reason: low weight – i.e. reduced moving masses – and the lower friction losses typical of plastic, both of which help considerably when optimizing response or when accelerating or decelerating masses.

The automotive industry drives for weight reduction to achieve increased fuel efficiency needed to meet aggressive government mandates. Also noise reduction and low maintenance are important design goals. For example, by using PEEK as a replacement for metal in the gear, noise, vibration, and harshness was lowered by 3 dB – this is equal to a 50% noise level reduction for the human ear.

Aerospace industries

In the aerospace industry, PEEK sees for instance its application as a material for protecting wires. It can decrease the weight of wires, thus increasing fuel efficiency.

One of the world’s leading suppliers of interconnect products has worked to replace aluminum and stainless steel in their line of wire and tubing clamps. One electrical wire bundle clamp made with PEEK is 20% lighter than the aluminum clamp it replaced.

Imagine the weight savings as there are approximately 15,000 clamps used to secure the wiring and cables on a given. This translates to $23,000 per year in fuel savings as well as a CO2 emission reduction of 80 tons for each plane using this technology. Not only can this application help save airlines money and reduce air travel’s effect on the environment, but the clamps are also much easier to install. Installation time was actually reduced by 30%. This really demonstrates how PEEK is solving multiple problems to gain acceptance versus metal in one of the world’s most conservative industries.

Dental and medical industries

Thanks to its favorable properties, PEEK can be used in many medical technology fields. For instance catheters are made from it. Due to its columnar stiffness and tight bend radius in thin walls, catheters are maneuvered more easily through a body’s pathways.

Another example is a medical device for applying dental fillings. The working parts, which are subjected to heavy mechanical stress, are no longer made of metal, but from PEEK. This reduces the weight of the device noticeably, thereby eliminating user fatigue. Furthermore, the plastic feels warmer to the touch than does the metal, thus making it more pleasant to handle when filling is applied. Furthermore PEEK lends itself better to sterilization and is more durable than titanium alloys. Its outstanding mechanical, chemical, and electrical properties make this plastic an all-purpose material for the medical industry.

Electronic industries

High performance polymer solutions offer greater versatility, reliability and design freedom for next-generation electronic devices and enable leading brands to produce cutting-edge products that are thinner, lighter and smarter. Such solutions are used in many consumer electronics and appliance components. Here, direct metal replacement is one approach, but it is also possible to integrate polymer with metal components to enhance performance and realize significant value.

From mobile device enclosures, switches, circuit boards, batteries and audio speakers to printers, sensors and connectors, polymer solutions are increasingly being specified by industry leaders to solve engineering challenges and differentiate a products’ ultimate performance and reliability. For smartphone enclosures, polymers enable designers to achieve the premium, high tech look and feel of anodized aluminum with structural integrity to handle abuse, both in the manufacturing process and in the hands of the consumer. For instance, in the appliances market, a 3.5dB (>50%) noise reduction and 2% efficiency gain are realized when polymers replace metal in refrigerator compressor valves, delivering real economic and consumer experience benefits for the consumer.

Energy industries

Durable polymer-based solutions are extending the scope of oil and gas exploration and are helping to optimize production efficiency in hot, corrosive environments. High performance thermoplastic delivers long-term reliability and reduced downtime due to its excellent resistance to sour gas and harsh fluids.