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by Nice Rapid | Oct 07,2019 | Plastic Injection Molding

Although there are now many different resins to choose from when thinking about your next injection moulding project, issues such as how flame retardant it is and whether this can be improved are not always taken into account. Due to the large amount of electronics and safety critical manufacturing that uses plastic injection moulded parts, this is something that is of paramount importance and worthy of further discussion.

Even by conservative estimates, there are over 40,000 accidental house fires in the U.K. alone, causing unnecessary loss of life and billions of Pounds worth of property destruction. This is even more sobering when looking at the developing world, whereby accidental fires and loss of life is even more prevalent, due to lack of maintenance, outdated technology and a lack of fire safety legislation and statutory firefighting capabilities.

It is always important to build fire protection and resistance into the initial design, so as to ensure that this can be demonstrated to both national and international safety bodies, when requesting type certification. Including thicker walls in the design may slow the spread of fire or can contain liquids that may be a catalyst if they are able to drip or leak onto a hot component. Likewise, thermal runaway caused by Lithium Ion batteries also needs to be contained, especially when the battery is unable to be removed, safely or not, from the device. This issue has famously troubled large manufacturers of batteries, from Samsung to Boeing, so is something that cannot be underestimated in today’s power hungry climate.

Once the basic design and construction have been agreed upon, there are two factors to consider when thinking about how to further protect plastics and their ability to resist flames and heat – these being the flame retardant properties of the material on its own and the combined benefit of adding flame retardant chemicals into the resin during moulding to increase its fire resistance.

Choosing a material that is as fire resistant as possible for the temperatures and locations it is likely to be used in is only sensible. For example, rigid PVC has a higher ignition temperature than many other plastics, with an ignition temperature 150 degrees Celsius higher than that of wood. It also releases fewer harmful elements into the atmosphere when it burns and is especially noted for not producing Chlorine gas unlike many plastics when ignited.

However, improving on the basic fire resistance of resins can only be achieved by incorporating flame retardant and resistant chemicals. Such additives protect the material in several ways:

1.) Preventing a material catching fire initially;

2.) Slowing or extinguishing an already burning material;

3.) Protecting other materials in the assembly from heat.

Each one of the above elements is very effective in ensuring that a fire cannot take hold to a sufficient degree or that if a fire does start, it is able to be kept at a low intensity until the alarm is raised or firefighting is able to commence. Environmentally, these aspects are also useful, as burning plastics are very bad both for the world we live in and our own health!

At NICE Rapid we are experts in rapid tooling, prototyping and injection moulding. We would love to hear from you when planning your next project.

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