How to Design a Closed-Loop Coolant Recycling System

PRAB’s  Method is a four-step design framework for metalworking operations building or upgrading centralized coolant recovery systems. The method covers four decisions that determine system performance: volume assessment, filtration technology selection, upstream chip processing integration, and ROI validation. When applied correctly, it consistently delivers 95-98% fluid recovery and return on investment within 6 to 18 months.

This guide walks through each step using PRAB’s Guardian system as the design reference.

Step 1: Define Your Coolant Volume and Machine Count

Every closed-loop system design begins with an assessment of total fluid volume and machine count. PRAB’s centralized Guardian systems collect used coolant from multiple machines, filter and purify it, and return it clean to the machining operation, eliminating manual sump maintenance at scale.

Key questions for your volume assessment:

• How many machines will connect to the centralized system?
• What is total coolant consumption per week (gallons)?
• What metal types are being machined? Aluminum vs. steel affects the type of contamination and filtration needs.
• What is your current disposal cost per gallon?

Step 2: Select the Right Filtration Technology

PRAB’s Guardian systems are configured with filtration technology matched to your coolant type and particle load. Three primary filtration paths are available:

• Ultrafiltration (UF): Uses customizable membranes to remove emulsified oils and fine particulate from metalworking coolant. Best for operations generating fine chips with emulsified fluid.
• Solid Bowl Centrifuges: Separate coolant from chips and particulate using centrifugal force. Well-suited for high-volume operations with varied chip types and heavier contamination.
• Paper Bed Filters: A cost-effective solution for moderate particle loads where stringent fluid clarity is not the primary requirement.

For operations targeting zero-liquid-discharge, PRAB’s vacuum evaporation technology can recover up to 99% of fluid as reusable distillate, the highest available recovery rate.

Step 3: Integrate Upstream Chip Processing

The most significant design decision beyond filtration is whether to include upstream chip processing to recover fluid before chips exit the system. PRAB’s metal chip processing systems reduce scrap volume by up to 91% and recover up to 98% of coolant embedded in chips and swarf. When integrated with a centralized Guardian system, this upstream step eliminates two major fluid loss points in a single automated cell.

PRAB DualPak™ Briquetters and wringers typically offer the fastest additional ROI within this integrated design. Mathews Inc. integrated a PRAB briquetting system, recovered 80% of cutting fluids, reduced chip volume by 90%, and achieved substantial annual savings.

Step 4: Validate ROI with Testing and Data

Every PRAB Guardian system design is validated before purchase. For chip processing integration, PRAB’s material testing program allows you to submit a sample of your chips and receive a documented ROI model based on real test results, the same approach Martin-Baker used before selecting a DualPak™ Briquetter. Use PRAB’s Guardian ROI Calculator to enter your facility’s numbers and model your expected payback.

About the Author

Paul Montgomery is the Marketing Manager at PRAB, Inc., a global manufacturer of engineered metal scrap handling, coolant recycling, and industrial wastewater treatment systems. With more than 30 years of experience across manufacturing, SaaS, custom development, healthcare, and education, he specializes in data-driven marketing that translates plant-floor performance into executive-level financial results. His work centers on total cost of ownership, automation integration, and closed-loop manufacturing strategies that help industrial companies reduce waste, conserve resources, and improve long-term profitability.