UL94 is a safety standard for plastic materials. It is a preliminary indication of a component’s suitability regarding flammability in certain applications, such as: insulators in electric devices and appliances, structural parts, and various enclosures. In the US, UL94 certificates are issued by Underwriters Laboratories (UL).
UL94 rates materials according to their tendency to either extinguish or spread the flame after exposure of a specimen to a flame ignition source for a specified amount of time. In growing order of flame resistance, the main ratings are HB, V-2, V-1, V-0, 5VB, and 5VA.
- HB indicates that the material was tested horizontally and burned at a slower rate than a specified limit.
- V-2, V-1, and V-0 indicate that the specimens were in vertical position and self-extinguished within a specified time limit, with flaming or non-flaming particle drops as listed:V2: 30s/flaming, V1: 30s/non-flaming, V0: 10s/non-flaming.
- The 5VB and 5VA tests are conducted with a higher ignition source that the V-0 test.
Historically, UL issued a yellow card for plastic materials flammability testing. In 2018, UL published a study showing the inﬂuence of 3D Printing on the flammability characteristics of ABS and PEI (full report accessible here). It established that flammability is greatly influenced by the type of printer used as well as the printing parameters and build orientation.
Recently, UL introduced the UL94 blue card, which indicates the type of processing equipment and settings required to claim compliance for each material. The old yellow card system is still valid for traditional processes such as injection molding and extrusion. But yellow card ratings do not apply to 3D printing. For instance, a filament made from UL94 yellow card certified pellets is not UL recognized.
In order to speed up the UL94 certification of your device, using a 3D printed UL94 certified component, you will have to match the following conditions:
- Select a UL blue card certified resin
- Verify that the geometry of your part matches the thickness requirements
- Use printer model and printing parameters indicated on the blue card
- Perform secondary operations as specified on the blue card
As we publish this post (Nov. 14, 2019) 15 materials have a blue card including 10 materials with a rating of V-0 or better. The table below summarizes the printer model specified by UL for each V-0 or 5VA material.
The UL database contains 5 additional materials rated V-2 and HB. Notice in the table below that a given material can have different flammability classes depending on minimum allowed thickness and build orientation.
To get the details of each material including a copy of its blue card with all processing requirements, click on the following UL database link: https://iq.ulprospector.com/en/_?tt=1048/.
Specific advantages of HP MJF PA12 and PA12GB materials
Qualified3D currently offers two UL94 HB blue card certified materials: HP PA12 and HP PA12 Glass Beads, for any application not exposed to a flame hazard.
These two materials have obtained their HB certification at only 0.75mm thickness, the thinnest of all 3D printing materials. This is an advantage over all other materials when designing small enclosures and devices.
To see the UL Blue Card certificates, please visit
HP PA12 Glass Beads: http://iq.ul.com/ul/cert.aspx?ULID=103651195.
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