Somtimes, we have received some quotations where a customer needs a flame retardant plastics, and/or with determinated homologated brand, due to several reasons. Nevertheless It is necessary to take account the type of flame retardant as you can see below, based on depeding on thickness.
An example, one request for quotation where we must us the homologated raw material “x”. But if we inject this thermoplastic we cannot meet the customer’s requirements due to the part had about 1,5 mm of thickness and the mentioned raw material was flame retardant grade V0 based on a test piece of about 3 mm of thickness. By these reasons, we consider necessary to talk about this additive used in several sectors like electronic, electrical or household appliances. We are talking about the flame retardant plastics.
According to UL94 classification (Underwriters Laboratory in EEUU, with their known yellow datasheets) and based on test where the test tube is burned in vertical by flame analyzing up to the fire is self-extinguishing. Therefore the different grades of flame retardant are as follow:
- V2, the combustion of sample is stopped in 30 seconds and there are dropping of particles in flames
- V1, the combustion of sample is stopped in 30 seconds but there are not dropping of particles in flames.
- V0, the combustion is stopped in 10 seconds and there are not dropping of burning particles, like previous case.
There are other nomenclatures such as 5VA, 5VB with vertical test tube, too. In these cases a burn can produce a hole or not. These cases are not so common than three mentioned nomenclatures before. The lower UL94 classification is for HB grade, where the sample is placed in horizontal. It is known like self-extinguished although this type burn like wood (to understand the simile).
Below you can see a good video from youtube (source:Filoalfa 3D) with different behaviours in final parts (ABS in this case), alhtought obviously there are more flame retardant engineering plastics like Polyamide (PA),Polycarbonate (PC)…
The flame retardant agentes more common to get some grades that we are talking about it are: antimony trioxide, red phosphor (common for dark colors), halogens (fluor, chlorine, bromine, iodine, astatine)… for example. But, sometime these elements can produce harmful smoke for human beings during combustion. By this reason each time is more usual to use flame retardants halogens free, from biological raw materials sustainably manufactured, decreasing the fossil resources besides of carbon emissions to atmosphere.
If you need technical support to chose the adequate enginnering plastic based on your application, we are glad to help you working together from initial design (bearing in mind our injection molding process) up to serial plastic part