What is PEEK 3D printing?
With the advent of Additive Manufacturing technology, the world got the chance to see how many things can be printed. New materials become available every year and novel innovations are developed to meet the needs of all industries.
Among the most successful materials in the last years there is PEEK - polyetheretherketone.
PEEK is a semi-crystalline technopolymer that has the distinction of being the most famous member of the PAEK (polyaryletherketones) polymer family due to its high mechanical properties, high thermal characteristics, and high chemical resistance.
This material is revealing its capabilities to the world, especially when you combine its properties with the flexibility of 3D printing.
What are the Pros of 3D Printing PEEK?
3D printing PEEK is not an easy job. Why try it then?
3D printing PEEK with FFF (Fused Filament Fabrication) technology has many advantages: here’s 8 reasons why you should 3D print PEEK:
- Complex geometries
The more complex the geometry, the higher it would cost to produce with traditional technologies. 3D printing instead allows the manufacture of complex geometries without affecting the cost: it is dependent almost exclusively on the quantity of material that is extruded. Moreover, some technologies, like CNC machining and injection moulding, have strong limits on the geometries to be manufactured: AM design freedom gives room for more flexibility.
- Customization
Personalizing components is a key factor in Additive Manufacturing: the flexibility of 3D printing allows the design of a part to be changed with ease as many times as needed, in order to achieve a customers’ needs. - Cost savings
Being PEEK a high-performance material, its cost is not low. Saving material therefore leads to saving costs.
When machined, material is removed from stock shapes until the final geometry is achieved, and the wasted material is paid for by the customer. By contrast, additive manufacturing is a better option for manufacturing PEEK because only the material needed is used to make the part and paid for. - Rapid prototyping
Additive Manufacturing is very convenient for prototyping. The quick and easy production of functional PEEK prototypes is possible with 3D printing, allowing extensive testing before mass production with other technologies. - Small batches
Injection moulding is not a convenient technology for small batches because of the high initial cost of moulds and tools. When more parts are to be manufactured, the fixed costs are split according to the quantity. One would more likely prefer CNC machining when the number of components to produce is low. But, when too much material is removed, CNC machining is not advantageous due to PEEK’s high cost. That is why additive manufacturing is the most convenient technology for small batches of PEEK parts. - Process optimization
In some cases, customers must buy large amounts of material to have more components available in the warehouse, in case of maintenance or damage to equipment and machinery. This involves high initial costs and no certainty of use. Imagine producing what you want, just when you need it, thanks to a digital warehouse. This is now possible with 3D Printing technology: what is needed is only a digital file and a printer. - Risk reduction
Sometimes businesses have a supplier that stops producing certain components. When these components break, the costs and times necessary to replace them are enormously high. In some cases, new moulds must be manufactured for one or a few components. Having the possibility to 3D print the necessary parts simplifies the supply and reduces the cost dramatically, reducing the risk of not being able to replace a part because it is too expensive to make. - Weight reduction
PEEK is a high-performance material, meaning it has excellent chemical resistance, great thermal performance, and high mechanical properties. For these reasons, it is the perfect candidate for metal replacement applications, where it can lead to massive weight reductions. The lightest metal alloys have a minimum density of roughly 2.5 g/cm3 while PEEK’s density is 1.29 g/cm3. This means that one can almost halve the weight of the printed parts, only by switching to this polymer.
PEEK 3D printing Roboze: precision, accuracy and repeatability
3D Printing is very often still connected to hobbyists and scarce dimensional tolerances. This is true, unless you have a very good printer like Argo by Roboze. Listed below are some of the features that result in a reliable and repeatable printing process for the manufacturing of functional parts:
- Beltless system
Roboze Beltless system aligns 3D printers with CNC machines, substituting the traditional movement system of belts with a pinion-rack mechanism and ensuring a position accuracy of as low as 10 μm. Not only does this reduce issues like deformation, wear, and loss of calibration, but it also lowers the amount of maintenance needed by the printer. Maintenance of industrial 3D printers with belts must be done by a trained technician with dedicated tools and may require a whole day of downtime. Roboze printers only need some Teflon grease to be applied once a month with no skills, no tools and low downtime. - Heated chamber
The high temperature required to process PEEK, added to its semi-crystalline nature, create a material with a high shrink rate of about 2%. When a material with a high shrinkage is extruded, it may detach from the build plate with a defect called warpage. Argo’s heated chamber has the aim to solve this issue, reaching a homogeneous temperature of 180°C in just 2 hours, that allows PEEK to solidify in its semi-crystalline state. The bi-directional air flow inside the chamber avoids possible shielding phenomena that would occur with a unidirectional flow. Without a heated chamber, PEEK would be printed with a lower crystallinity rate and the shrinkage would be high, resulting in lower tolerances and an accentuated anisotropy of the part. - HVP extruder
Designed by Roboze’s R&D Department, the HVP extruder solves the need of extruding PEEK. This high-performance material has a high viscosity and the higher the viscosity, the greater the difficulties that might be faced while printing. Thanks to the internal ceramic channels specifically designed to reduce friction and to influence the shape memory of the material, PEEK’s extrusion is facilitated. - Buildplate
It is fundamental to ensure excellent adhesion between the printed part and the build plate, so that no movement or deformation occurs during the extrusion process. Roboze systems use polymeric films that are fixed to the build plate through a vacuum system. Once the part is firmly fixed on the build plate, maintaining a perfect parallelism between the extruder carriage and the plate itself is crucial. With the automatic build plate levelling implemented on the printers, it is possible to adjust the plate inclined through three actuators, correcting for any thermal expansion and mechanical deformation.
To achieve good prints, it is mandatory to have a constant distance between the extruder head and the build plate. If this distance is too short, there would not be enough space for the filament to come out, resulting in a clogged extruder. On the other hand, if the distance is too great, the extruded material will not adhere firmly, leading to possible detachments of the parts from the build plate.
With the automatic calibration of the Z-axis, the identification and set of the machine zero, the absolute position of the extruder with respect to the build plate, is possible. This probing system does not depend on the type of extruder or its wear or the wear of the polymeric film, making it a repeatable process. - High temperature Dryer (HT Dryer)
A typical property of many plastics used in 3D printing is that they are hygroscopic, i.e., they absorb moisture from the surrounding environment. When the water molecules in the air condense on the surface of the polymer, they penetrate inside it, interacting with the polymer chains and breaking the covalent bonds to form new hydrogen bonds. This type of depolymerization, called hydrolysis, leads to the degradation of the mechanical, chemical, and aesthetic characteristics. Using a so called “wet” filament in a 3D printer causes the water inside the filament to vaporize, creating air bubbles in the extruded material. This results in low adhesion between layers, a worsening of the surface finish, oozing, stringing, warping and continuous clogging of the extruder. Thankfully, there is a solution to this problem: hydrolysis is reversible and Roboze developed a device for drying, conditioning, and managing the filaments inside the machines: the HT Dryer.
It is a galvanized steel device completely integrated in the printers, enabling them to load the filament coil automatically.
Its function is divided into 3 phases:
- Heat source application: heat breaks the hydrogen bonds between polar groups of the polymer chains and water molecules, leaving them free to move along the filament.
- Migration of water molecules: from the core to the surface of the filament, guided by the concentration gradient.
- Removal of water molecules: once on the surface, the water molecules are removed from the filament with the help of a stream of dry air.
- Print log System
An additive manufacturing process can be defined as repeatable when the characteristics and tolerances of similar parts are kept constant over time. The Print Log System has been introduced to monitor and analyse the operations performed by the printer during the production phase. In this way, all the operations performed by the machine are traced, with the aim to identify any anomalies and be able to guarantee a product compliant with the purpose of use over time.
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