Case Study: Drying Coating on Airbags

A Carbon infrared drying system, from Heraeus Noblelight, is helping Airbags International to improve the manufacture of side impact airbags and has significantly reduced scrap levels on a coating line. Airbags International is a worldwide leader in automotive safety and manufactures both frontal airbags and inflatable curtains.

Both of these products feature a cushion which is folded in a specific way to make it unfold fast and safely in the event of a vehicle collision. The cushions for airbags are produced from Nylon 66 and an important stage in the finishing process is the silicon coating of the nylon web, after it has been washed and dried and then fixed in a Stenter. This smooth coating ensures that the cushion will unfold without sticking when deployed, at inflation times as fast as 50 thousandths of a second. Its smoothness also prevents any possible damage to facial skin.

However, as the Nylon 66 fabric is very hydroscopic, this was causing a problem at the coating stage for the heavier cloth used for inflatable curtains. Consequently, Airbags International decided to investigate ways to reduce the cloth's moisture content down to 2% to ensure the correct adhesion, drying and surface finish of the silicon coating and to reduce scrap levels.

On-site trials were carried out using carbon infrared lamps. As a result, a 120kW carbon, medium wave infrared system was installed and this proved so successful that it achieved pay-back in just ten rolls of fabric. In operation, the infrared system is controlled by an optical pyrometer, which measures the surface temperature of the fabric and then transmits a signal to regulate the power of emitters within the infrared module, which is mounted above the fabric web. The cloth is coated with silicone on both sides but the critical heating operation takes place just before the coating is applied to the bottom side. It is essential that the moisture is removed before this bottom coating is applied, otherwise it will be sealed in, potentially causing damage to the final surface finish.

The infrared module has been retrofitted very easily into the coating line, and the fast response of the carbon emitters also means that there is no damage to the coated fabric in the event of unexpected line stoppage.

Features

Drying and preheating of nylon fabric
Controllable heaters help to save energy
Decrease of rejection rate

Technical Data

medium wave Carbon infrared heaters with response times within seconds
120kW system of 64 lamps, 2kW each heating up to 120°C
line speeds of up to 30m/min
web widths of 2m and 2.4m
Controlled by an optical pyrometer

For more information...

Explore this site for application solutions employing this technology. Heraeus also offers complete systems. Please contact us to discuss your application.

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