Dry Washing Technology

Ricoh has developed an environmentally-friendly technology that removes residue without using solvents or water. Instead, small thin films are air-blasted onto the object to be cleaned to remove the residue. This technology is applied to clean jigs used in the manufacturing process and parts during the recycling of products.

This technology is based on the principle of using airflow to blast thin resin films?each a few millimeters square?onto the object to be cleaned and removing the residue with their impact or contact (Figure 1). The thin and lightweight film, which does not damage the object to be cleaned, effectively removes residue at the edges that cannot be removed by high-speed airflow alone.

This process uses neither solvent nor water, and it also minimizes the amount of material used for the thin and lightweight film. Its capacity for removing residue does not diminish after repeated use, so the resin films can be used continuously without being replaced. Only residue removed from the object is discharged, with the resin films used repeatedly through continuous circulation (Figure 2). These properties make it possible to reduce both environmental impact and operational cost.

Drastic Improvement of Washing in Manufacturing Process

In order to recycle our products, such as copiers or printers, Ricoh has been researching and developing dry washing technology that eliminates waste liquid. Ricoh has applied this technology to the washing of jigs (pallets) used in the automated soldering process. Although pallets are generally cleaned with solvents, we have achieved solvent-free washing with this technology.

As shown in Figure3, jigs called pallets are used in the automated soldering process (flow soldering machine) to protect already-soldered parts from heat. In this soldering process, liquid flux is applied to eliminate the oxidized layer of the joining surface, but the flux gets laminated and adheres to pallets through repetitive use. The flux remaining on pallets must be cleaned off periodically.

Solvent cleaner is commonly used to remove the adhered flux, which places a burden on the environment and incurs disposal costs for the waste liquid. Also, in terms of safety and health, a solvent-free washing method is desirable.

Washing solder flux without solvent

Ricoh has been further developing dry washing technology, which was originally developed to remove toner from parts or components, and, while doing so, the company found a way to remove even adhered flux without using solvent cleaner.

Pieces of film can be easily separated from the removed residue (flux powder) because of the difference in the sizes between the film and the flux powder. Only the flux powder is collected by a dust collector and the films are used repeatedly through continuous circulation (Figure 4).

You can watch a video clip of the process of dry-washing a pallet.

Figure 5 shows the pallet before/after dry washing for 2 minutes.

Figure 5: Pallets before/after dry washing

Effect of the Reduction of Environmental Impact

This new method can reduce both environmental impact and washing costs by up to one tenth compared with the conventional method using solvent (calculated by Ricoh). Washing time (process lead time) has also reduced from more than 2 hours to less than 5 minutes.

	Conventional process	New process
Process time	More than 2 hours	3 to 5 min.
Environmental impact (waste liquid)	0.1 to 0.8L / pallet	0 (*1)
Environmental impact (CO2 emissions)	0.2 to 2kg / pallet (*2)	0.1 to 0.2kg / pallet (*3)

• (*1)The removed residue (flux powder) is collected by a dust collector.
• (*2)Solvent production and incineration
• (*3)Consumables, electrical power, washing equipment production, etc.

The range of values is attributed to the different cleaning methods, production scales and pallet sizes of the production sites.

Table 1: Comparison between the conventional and new processes

This method comes into practical use for the washing of pallets used in the automated soldering process at Ricoh Group domestic and overseas production sites.

Drastic Improvement of Washing Process for Product Recycling

Product recycling is a vital environmental protection activity for reducing the environmental impact. Regardless of how much effort we devote to recycling resources, it is not meaningful if the recycling process generates a heavy environmental impact. The washing process accounts for the highest proportion of the recycling process of copiers and printers (Figure 7). Ricoh has developed technology to improve this process.

Washing by the dry washing method

Figure 8 is a dry washing machine for removing toner from parts during the recycling of products. You can watch a video clip of the washing of parts.

Effect of the Reduction of Environmental Impact

Water has been used in the conventional washing process to reclaim parts and components covered with toner. This process requires time and energy for dewatering and drying, and moreover, wastewater generates an environmental impact and processing costs.

Ricoh has developed dry washing technology that does not require dewatering and drying. As a result, a process that used to take more than 1 hour has been shortened to about 1 minute, and wastewater has been reduced by 2.4 tons per month (Figure 9 and Table 2).

	conventional wet method	dry washing method
numbers of processes	8 (disassembly, vacuum cleaning, ultrasonic washing, rinsing, dewatering, drying, finishing, inspection)	4 (disassembly, dry washing,finishing, inspection)
washing time	10 min.	1 min.
drying time	1 hour	0 min.
amount of wastewater	300ml/unit	0

Table 2: Comparison between the conventional and new processes

This washing method is applied to the washing process for cartridges of multi-function printers at manufacturing sites worldwide.