Promoting Vehicle Recycling

The world's first technology to recycle used bumper plastic for use in new vehicle bumpers

Mazda is actively engaged in recycling plastic automobile parts. We focus in particular on recycling bumpers, and have created bumper-to-bumper recycling technology for these large plastic parts. This technology is capable of recycling not only damaged bumpers, but also end-of-life vehicle bumpers to be used as material for new bumpers.is used to recycle damaged bumpers to be reused as material for new bumpers.

World-First Automated Recycling Technology*1 for End-of life Vehicle Bumpers

Mazda has developed a world-first recycling technology which enhances the process it uses to recycle used bumpers from vehicles, whose useful life has ended, into raw plastic resin for use in new vehicle bumpers. The recycled materials first started being used in 2011, in the rear bumper of the Mazda's Biante minivan.

Although Mazda had already succeeded in recycling materials from damaged bumpers to be used in bumpers for a new vehicle, using materials recycled from bumpers of end-of-life vehicles was difficult technically and financially because many of these bumpers were more than ten years old and varied in terms of paint adhesive properties and composition of their plastic. It was also costly to remove metal parts.

However, Mazda established an efficient system to collect and process end-of-life bumpers in cooperation with related companies against the backdrop of improvements in bumper scrapping technology and an increasing number of end-of-life vehicles featuring easy-to-recycle designs. As a result, Mazda was able to reduce recycling costs and succeeded in recycling materials for bumpers at a lower cost than using new materials.

*1 As of August 2011 (Mazda data)

Development of the paint removal process

Mazda collects and recycles damaged bumpers in response to environmental problems and the need to use resources more efficiently and in 1992 became the first automaker to recycle bumpers (as vehicle undercovers). In 2001, Mazda began removing the paint which causes deterioration of mechanical properties from damaged bumpers and using the recycled material to reinforce bumper plastic. However, to use the recycled material for new vehicle bumpers, it was necessary to improve the degree of paint removal in order to ensure the recycled bumpers exhibit the required surface quality. This led Mazda to develop its paint removal process.

Target paint removal ratio

The paint removal ratio for materials recycled with the conventional process is 98.50 percent, which means a 1.50 percent residual ratio. With this method, new bumpers made from 30 percent recycled material do not process sufficient surface quality to be painted. The recycled material content must be lowered to just three percent to satisfy the criteria. In order to achieve the desired 30 percent recycled material content, we first had to reduce the residual ratio from 1.50 to 0.15 percent. This led to our target paint removal ratio of 99.85.

How the paint removal ratio was improved

Mazda conducted a detailed examination of crushed bumper pellets to determine the paint removal ratio of the conventional process, and found that only a small proportion (14 percent) of the pallets still had residual paint; 86 percent were paint free.

Residual paing content of crushed bumpers treated by the conventional process

Given this, we surmised that if we could detect and remove bumper pellets with an area of residual paint over 10mm2, we would achieve a high yield of recycled material at the target paint removal ratio. (Yield is defined as: 'the number of paint-free pellets/the total number of crushed pellets x 100.)

Selection mechanism

Crushed bumper pellets are subjected to the paint stripping process, the collected in a hopper and passed through a shooter. As they exit the shooter, light is shone on them from various angles. Any paint adhered to the fragments reflects light more intensely than the (black) bumper material. Charged-coupled device (CCD) sensors detect the reflected light and an air jet immediately removes the unwanted pellets.

This mechanism to separate crushed bumper pellets successfully improves the average ratio of paint removal from 98.50 to 99.85.