Mass finishing process water in different cleaning stages.

Centrifuge Technology, Part 2 – Operational and Economic Benefits of Recycling Process Water

During mass finishing, the process water injected into the finishing machine is contaminated with the chemical ingredients of the compounds, fines from the grinding or polishing media, and metal fines from the work pieces.

In case of ball burnishing, when acidic or alkaline compounds are used, the process water can also contain dissolved metals or be alkaline or acidic. Or, for example, when the work pieces are covered with oil from machining or stamping operations, the water can even be contaminated with oil.

Rosler has developed a series of closed-loop, water circulation systems using centrifuge technology to remove these contaminants regardless of their origin and allow clean process water to be reused and/or safely discharged. In addition to offering more effective work piece processing, cleaning process water saves money and the environment through reduced consumption, compound usage, disposal costs, and regulations.

Rosler diagram of mass finishing input and output
Mass finishing input and output

Environmental Stewardship

Depending on the machine size, type, and its application, a single mass finishing machine can use between 10 and up to 250 gallons of water per hour amounting to as much as 2,000 gallons during every 8-hour shift. Considering that the average household uses approximately 140 gallons per day, this is a lot of water that is literally going down the drain.

The centrifugal cleaning process separates solids in the form of media and metal fines from the process water without removing the compound. This allows the cleaned process water to be reused in the mass finishing machine. A small amount of compound is consumed to keep the process stable and some water losses occur due to carry-out by the work pieces and evaporation. On average, centrifugal cleaning and recycling of the process water results in water and compound savings of 90 to 95%.

Reduced Municipal Regulations

Centrifuge technology does not require approval from municipal water authorities since the cleaned process water is reused rather than being discharged into a sewer. Recycling process water saves time by not having to undergo the elaborate discharge approval process.

It also eliminates the need for regular water analysis to ensure that the cleaned water going to sewage is indeed in compliance with the legal limits for hazardous materials.

Easy Operation

Contrary to conventional waste water cleaning methods, centrifuges are easy to operate and require very little operator involvement. Above all, they require no special training or specialized knowledge.

The water level in automatic centrifugal cleaning and recycling systems is automatically monitored, and any water/compound losses due to carry-out and evaporation are made up by fully automatic water/compound dosing units. For applications in conjunction with high-energy mass finishing machines that generate a lot of heat, the centrifuges can be equipped with a special cooling system for controlling the temperature of the process water.

In case of semi-automatic centrifuges, an operator must periodically remove the accumulated sludge in the centrifuge drum. This is typically done once every few hours or once per day.

In fully automatic centrifuges even the sludge removal is automated. A timer-controlled peeling knife periodically removes the sludge from the drum wall and discharges it into a waiting sludge bin. All the operator must do is empty the sludge bin every few days or, in some cases, weeks.

Diagram of a fully automatic centrifuge during the cleaning cycle and a sludge discharge peeling cycle.
At left, a fully automatic centrifuge during the cleaning cycle is shown. On the right, a sludge discharge peeling cycle is shown.

The Rosler Way

Centrifugal process water cleaning and recycling makes a significant contribution towards ecologically sustainable production and is a prime example for environmental stewardship in manufacturing. Contact Rosler today to learn how we can improve the efficiency and economic impact of your mass finishing process.

The first post in the Centrifuge Technology series was “Operational & Economic Benefits of Recycling Process Water.”

Upcoming posts in the Centrifuge Technology series will include:

  • Part 3 – “Mechanics and Limitations of Water Recycling.”
  • Part 4 – “Pre-Conditions and Consumables Enhance Process Efficiency.”
  • Part 5 – “Potential Issues and Remedies for Water Recycling.”

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