PU Rigid 650 Resin View larger

PU Rigid 650 Resin

RS-FL-RG-650

Formlabs

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135,00 €
135,00 €

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Resin for tough, resistant and pliable prints. For commercial and research uses only.

Formlabs is an American 3D printing equipment and materials manufacturer, with offices all over the world. Formlabs was founded in 2011 by 3 MIT students and soon afterwards they launched their first product. Formlabs are best known for their 3D resin printers and resins. Their catalog keeps evolving with the needs of the market and new cutting edge materials are being added to the Formlabs portfolio, such as the PU Rigid 1000 resin and the PU Rigid 650 resin.

Normally, polyurethane parts are made by casting or reaction injection molding. Formlabs now makes it possible for businesses and research centers to 3D print polyurethane in house on the Formlabs 3D printers. The PU Rigid resins are made with the help of hybrid chemistry, after many years of research. Their composition is a custom combination of high quality acrylate and urethane. This composition, combined with moisture curing gives the pieces 3D printed with the PU Rigid resins the final and enhanced polyurethane state.

Parts 3D printed with the Formlabs PU Rigid 650 resinParts 3D printed with the Formlabs PU Rigid 650 resin

Image 1: Parts 3D printed with the Formlabs PU Rigid 650 resin. Source: Formlabs.

The PU Rigid 650 resin is a semirigid polyurethane photopolymer designed for making high performance long lasting parts that can withstand prolonged exposure to light, heat and chemicals, as well as tolerate impact, loads, and shock, and dampen noise in the most demanding environments, without losing shape and mechanical properties.

The resins from the PU Rigid family are also stable when exposed to ultraviolet radiation and humidity. They also have flame retardancy properties and are sterilisable. Due to their hybrid chemical composition, the Formlabs Polyurethane resins are stronger and more durable than other SLA resins, which has been proven in accelerated aging tests.

Video 1: The PU Rigid 650 resin subjected to an elongation at break test. Source: Formlabs.

As it can be seen in the video above, the PU Rigid 650 resin is characterized by much more flexibility and double the elongation at break compared with the PU Rigid 1000 resin (170 % vs. 80 % respectively). This makes it perfect for applications where flexibility is as important as strength.

 A comparison of the PU Rigid 650 and 1000 mechanical properties

Image 2: A comparison of the PU Rigid 650 and 1000 mechanical properties. Source: Formlabs.

The PU Rigid 650 resin can be worked with in many different ways, depending on the user’s needs and resources. It can be printed with a dry cabinet or in ambient conditions, with automatic or manual resin dispensing.

WorkflowMethodAdvantagesConsiderationsWhen to use
Recommended Automatic filling + dry cabinet Best results + easy workflow Requires dry cabinet Frequent printing
Low cost Automatic filling + ambient conditions Low cost + simple Shorter pot life Printing in ambient conditions
Modified Manual filling + dry cabinet Extended pot life Requires dry cabinet + fine tuning Printing intermittently / repeated printing of the same part
Table 1: An overview of the workflow possibilities with the PU Rigid 650 resin. Source: Formlabs.

The PU Rigid 650 resin 3D printing workflow is explained in detail in a video from the manufacturer:

Video 2: Polyurethane 3D printing workflow. Source: Formlabs.

The Formlabs PU Rigid resins have a longer workflow than other types of resin. They require additional equipment, such as a dry cabinet for the 3D printer, a PGDA solvent for rinsing the parts and, optionally, a compressed air gun for removing any resin leftovers, as well as a humidity cure oven for post-curing. These steps should be followed for optimal results with the PU Rigid 650 resin. A full list of the recommended post processing tools can be found on the manufacturer’s website.

Pouring the PU Rigid resin into a cartridge

Image 3: Pouring the PU Rigid resin into a cartridge. Source: Formlabs.

The pack includes a 1 l bottle of the PU Rigid 650 Resin, an empty cartridge, and a funnel to help pour the resin into the cartridge for printing.

The PU Rigid 650 resin is the perfect material for manufacturing prototypes (except for same-day prototypes, since the resin requires lengthy post processing) as well as end-use pieces for multiple applications, for example in the automotive, aerospace and machine industries. Some example applications include:

  • Impact-resistant components
  • Pliable mechanical components
  • Shock absorbing bumpers and dampeners
  • Noise-dampening components
  • Flexible mechanical connectors, such as flexible and cup hinges or clip fastenings
  • Wheels
  • Calipers and other effectors

The PU Rigid 650 resin supports the 100 µm and 50 µm printing resolutions. It is compatible with the Form 3, Form 3+, Form 3B, Form 3B+ and Form 2 printers. It is compatible with the Form 2 LT and Form 3/3B V2.1 resin tanks, and with the Form 3, Form 2, and the Form 3 Stainless Steel build platform.

For more detailed technical and safety information about the Formlabs PU Rigid 650 resin, please consult the datasheets available in the Downloads section for this product.

The Formlabs PU Rigid 650 resin is the perfect material for engineers, designers or other professionals who want to 3D print strong, durable and resistant pieces in house, without the need to resort to traditional manufacturing methods and third parties’ services. It should be kept in mind that the PU Rigid 650 resin is meant for commercial and research use only, and it should not be used outside of commercial or research facilities or institutions.

Impact strength (KJ/m2) 44
Elongation at break (%) 170
Tensile strength (MPa) 34
Tensile modulus (MPa) 670
Flexural strength (MPa) 22
Flexural modulus (MPa) 570
Surface hardness 6
Flexibility Flexibility
UV resistance UV resistance
Chemical resistance Chemical resistance

The shelf life of the PU Rigid 650 resin is 12 months (from the manufacturing date) in the unopened aluminum bottle and the pot life is about 1 month once the bottle has been opened. The pot life can vary from 4 to 7 weeks depending on the ambient humidity and the temperature outside the cartridge.

The PU Rigid 650 and PU Rigid 1000 resins are different than other Formlabs resins in terms of printing and post processing, which is why the following usage tips should be read thoroughly.

Elevated moisture and temperature reduce the Formlabs PU Rigid resins’ pot life. Exposure to these conditions during storing or printing will result in the resin curing, increasing its viscosity and eventually becoming non viable. This is why the PU Rigid 650 and 1000 resins should be stored in a controlled humidity cabin (dry cabinet) before, during and after use. The dry cabinets recommended by the manufacturer can be seen here.

Viable and non viable PU Rigid 650 resinViable and non viable PU Rigid 650 resin

Image 1: Viable (left) and non viable (right) PU Rigid 650 resin. Source: Formlabs.

The manufacturer recommends changing the resin in the tank or mixing in fresh resin when the resin viscosity exceeds 2000 cPs. The resin viscosity can be checked with a Zahn cup #5 viscometer or with a blunt, flat object, as shown in the picture above. If the resin flows easily and fills in the gap left by the tool, the viscosity is low enough to continue printing.

Washing and cleaning of parts 3D printed with the PU Rigid 650 resinWashing and cleaning of parts 3D printed with the PU Rigid 650 resin

Image 2: Washing and cleaning of parts 3D printed with the PU Rigid 650 resin. Source: Formlabs

For washing, the FormWash should be used for 2 minutes in combination with a Propylene Glycol Diacetate (PGDA) solvent. The evaporation of the PGDA solvent can be sped up by dipping the pieces in an n-Butyl solvent for 15 seconds or by using an air compressor. Do not wash parts printed in a PU Rigid resin with isopropyl alcohol (IPA) as it can cause degradation in material properties.

In case the user does not have the FormWash machine, the Formlabs Finish kit can be used as well. The finish kit comes with various useful tools for removing parts from the build plate or removing supports.

Parts 3D printed with the PU Rigid 650 resin should be removed carefully and dried in ambient temperatureParts 3D printed with the PU Rigid 650 resin should be removed carefully and dried in ambient temperature

Image 3: Parts 3D printed with the PU Rigid 650 resin should be removed carefully and dried in ambient temperature. Source: Formlabs.

Both PU resins are characterized by very strong adhesion to the build platform. Therefore, the manufacturer recommends printing all parts on supports to make removal from the build platform easier and to reduce accidental damage to the part during removal. It is recommended to use a sharp tip spatula for part removal to reduce the pressure as much as possible.

Next, the pieces 3D printed with the PU Rigid 650 resin should dry completely in ambient temperature for at least 24 hours. As far as curing, the PU Rigid 650 resin should be cured in a humidity cure oven at 46 º Celsius and at 70 % relative humidity. No other curing device will work since the resins need specific levels of humidity for the PU to finish its reaction. The humidity cure ovens recommended by the manufacturer can be found here.

Before curing the parts 3D printed with the PU Rigid resin, remove the supportsBefore curing the parts 3D printed with the PU Rigid resin, remove the supports

Image 4: Before curing the parts 3D printed with the PU Rigid resin, remove the supports. Source: Formlabs.

The curing time ranges from 3 to 14 days and largely depends on the part thickness. It is highly recommended to cure the parts without the supports as they are more difficult to remove if they are post-cured.

quick start guide and more detailed instructions on using PU Rigid 650 Resin can be found on the manufacturer’s website.

General information
Manufacturer FormLabs (Massachusetts, EEUU)
 Technology SLA / LFS
Material Photopolymer
 Wavelength UV 405 nm
Format 1 litre
Compatible 3D printers Form 3, Form 3+, Form 3B, Form 3B+, Form 2
Compatible resin tanks Form 2 LT, Form 3/3B V2.1
Printing properties
Layer height 100-50 microns
Layer exposure time There is no need to configure the print parameters on Formlabs printers. The chip embedded in the resin cartridges detects the type of material and sets the print automatically.
Layer cooling time
Lifting height
Exposure of the lower layers
Number of lower layers
Curing and washing properties 
Wash time (FormWash) 2 min in PGDA
Curing time (full cure in FormCure) Humidity Cure Chamber, according to indications
Mechanical properties (cured)
Izod impact resistance (ASTM D256-10) 375 J/m (notched)
Charpy impact resistance (ISO 179-1:2010(E)) 44 kJ/m2 (notched)
Elongation at break (ASTM D638) 170 %
Tensile strength (ASTM D638) 34 MPa
Tensile modulus (ASTM D638) 670 MPa
Flexural strength (ASTM D 790-15) 22 MPa
Flexural Modulus (ASTM D 790-15) 570 MPa
Surface hardness  (ASTM 2240) Shore 64 D
Thermal properties (cured)
Softening temperature -
Electrical properties (cured)
Volume resistivity (ASTM D257-14) 4.7 x 1011 Ohm/cm
Further information
Flammability rating  HB UL 94
Lifetime (from manufacture)  24 months
HS Code 2916.1

* The typical values detailed in this table should be considered as a reference. Actual values may vary depending on the 3D printer model used, part design and printing conditions. We recommend that you confirm the results and final properties with your own test. For further information, please refer to the product data sheet.

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