Industrial cleaning methods typically involve either solvent or aqueous cleaning. Solvents are effective at dissolving lubricants and tough soils but come with environmental and health risks, leading to strict regulations. Aqueous cleaning, particularly in metal cleaning, is the focus here, with more details available in our blog on Aqueous Cleaning Fundamentals.
WHAT THE NECESSARY PROCESS IS
Consideration of the entire workpiece preparation process is crucial in addition to cleaning. This may entail rinsing, drying, and even cooling. For instance, a part cleaned for laser welding needs cleaning to remove contaminants, rinsing to eliminate chemical residues, and drying to ensure quality welding. Parts washers can be configured to accommodate these stages. The workpiece’s geometry and required cleanliness level determine the equipment and method. Immersion aids in cleaning complex geometries, while ultrasonics enhance it further. Power flushing may be needed for internal cavities. The production rate also influences equipment choice, with batch washers suitable for small-series production and continuous washers, like conveyor-style washers, for high-production programs.
PART FIXING AND AUTOMATIC LOADING
While manual part loading is often sufficient, growing automation demands can necessitate automatic loading and unloading in parts washers. Understanding the loading process early on is crucial, and certain washer designs are more compatible with automation. Implementing a PLC and HMI is essential for comprehensive process control and interfacing with upstream and downstream automation. Fixturing is commonly employed to optimize workpiece orientation, drainage, and precision positioning for pick-and-place automation or critical feature targeting. Effective fixture design minimizes contact with the workpiece to prevent interference with cleaning and avoid marking machined surfaces.
CHOOSING THE CORRECT FILTRATION
When cleaning processes have gravimetric or particle-size requirements, solution filtration is vital to capture and prevent particle adhesion on workpieces. Proper filtration selection is crucial for desired cleaning results, considering that finer filtration (mesh size) raises equipment and operating costs. Aqueous cleaning primarily employs two filter media types: bags for less stringent applications and cartridges for the most demanding. Ensuring the entire pump flow is filtered to maintain contaminant-free contact with workpieces is essential, but higher flow rates can impact filtration equipment costs. Different micron ratings can be used for cleanliness compliance, but smaller ratings clog faster, especially with cartridge filters. Using larger micron bag filters upstream can extend cartridge filter life. High-production settings may utilize parallel filter housings with diverter valves for uninterrupted filter changeovers.
A ESSENTIAL STEP TO FINISH THE CLEANING PROCESS IS RINSING
Rinsing is a crucial cleaning step, varying in effectiveness from slight cleaner removal to complete elimination for downstream process integrity. Many washers offer freshwater rinse fed by plant water supply via low-flow hollow-cone spray nozzles. The efficacy depends on cycle length and water disposal considerations. Recirculating rinses are more efficient and ecological, reusing water with higher flow and pressure, particularly in continuous processes where water conservation is essential.
For more information on rinsing, refer to the following blog posts:
- Recirculated Rinse: An Option Worth Considering for Turntable Parts Washers
- Going Green in Metal Finishing
- The Importance of Rinsing in Metal Cleaning and Surface Treatment
THE SIGNIFICANCE OF DRYING FOR THE COMPLETION OF PRODUCTS OR EFFICIENT OUTPUT
Aqueous cleaning typically occurs between 120˚F to 185˚F (49°C to 85°C), and workpieces can flash dry given sufficient time. Compressed air is used to blow off excess liquid, particularly effective for drying blind holes or cavities despite continuous operating costs. Centrifugal blowers and air knives assist in excess liquid removal and drying. Regenerative blowers are common, offering sufficient volume and air temperature elevation. Convection dryers employ heated air for quick, even drying within temperatures of 120˚F to 250˚F (49°C to 121°C), efficiently recirculating air, provided there’s no entrapped liquid.
Vacuum drying in metal cleaning efficiently and gently dries workpieces by evaporating entrapped liquid through pressure reduction. It is particularly useful for electric motor and generator cleaning. Vacuum drying can also prepare thoroughly dry parts for downstream operations while cooling workpieces during the process. For more details on drying after cleaning, read our white paper. In aqueous cleaning, choosing the right parts washer depends on factors like rinsing, drying, cooling needs, manual or automatic loading, fixturing, and filtration.