The Replacement of CFCs in Manufacturing. by James McEachen

Transcription

1 The Replacement of CFCs in Manufacturing by James McEachen The Conversion from Vapor Degreasing and Solvent Cleaning to Aqueous Cleaning The phase-out of CFCs is an event and not a trend. It s less influential than the four major trends driving manufacturing in general (and aqueous parts cleaning specifically). l,l,l Trichloroethane U.S. Phase-out Schedule Four Primary Trends Which Are Influencing Manufacturing Today Quality emphasis Automation New manufacturing technologies Mass customization All of these are intertwined and greatly influence the future of manufacturing. Scenario for l,l,l Tri Replacement in Cleaning Other chlorinated Aqueous Cleaning is Proven to be Equal and Superior to Vapor Degreasing and Solvent Cleaning Precision Cleaning 95 Proceedings 237

2 Confusion, Doubt & Uncertainty Aqueous? Semi-aqueous? Ultrasonics? Spray? Costs? What s the best alternative? Possible re-layout or expansion of your manufacturing facility. Changes in your manufacturing process. Wastewater management review. Cleaner Parts Less expensive cleaning Environmentally safe Aqueous Cleaning Basics Water based chemistry - Low concentration ( 1-4% typical ) - Caustic, alkaline, mildly acidic Resource commitment to a thorough process analysis effort. A capitol investment ranging from $20,000 to $1,000,000. An analysis/acquisition time frame of 2 or 3 months to 2 years. Aqueous Cleaning Basics Mechanical action is always required - Spray - Immersion/agitation - Ultrasonics - Solution turbulation - Part motion 238 Precision Cleaning 95 Proceedings

3 Aqueous Cleaning Basics Beware of confusion between parts cleaning and parts finishing - The processes are getting fuzzy - Potential for unfilled or misaligned expectations 1) 2) 3) 4) 5) 6) 7) 8) Cleaning Process Objective Part Analysis Soil Analysis Part Orientation/Material Handling Production Volume Requirements Plant Layout/Floor Space Requirements Chemistry/Additives Wastewater Management Cleaning Equipment Type is the Result of the Selection Process Not the Starting Point 1) 2) 3) 4) 5) 6) 7) 8) Cleaning Process Objective Part Analysis Soil Analysis Part Orientation/Material Handling Production Volume Requirements Plant Layout/Floor Space Requirements Chemistry/Additives Wastewater Management Any change in one element will affect the whole process. Each variable will affect the solution. No solution is possible without thorough analysis of each process segment. Step 1 Cleaning Process Objectives Is cleaning required? How clean is clean? - As clean as they are now? - Is it measurable - Is it really acceptable? Visually clean? - Subjective Clean to a specification - Particulate measurement - Oil, grease, film measurement - Are equipment and resources available to measure cleanliness? Precision Cleaning 95 Proceedings 239

4 Step 1 Cleaning Process Objectives (con t) How dry is dry? Does the part need to be totally dry? -Must this be measured? -How would hot parts effect the next process step? The next manufacturing process step determines the necessary level of part dryness Step 2 Parts Analysis Material composition -Steel, cast iron, brass, aluminum, plastic... Variations in part population Part geometry and surface condition -Holes -Blind holes -Contours -Machined or polished -Part-on-part contact sensitive Physical size & mass Step 1 Cleaning Process Objectives (con t) Final part appearance/condition -Spotting - Rust or corrosion - Part finish -Part temperature Step 3 Soil Analysis Soil Level- Light, Medium, Heavy Soil A - Particulate, Metal Chips, Shop Dirt, Grinding Swarf Soil B - Oil, Grease, Drawing Compound, Coolant, etc. 240 Precision Cleaning 95 Proceedings

5 Step 4 Orientation and Material Handling (con t) Material Handling -What is the current method of material handling? Conveyor Bins Baskets Overhead Pallets Other -Must process lot integrity be maintained? Step 4 Orientation and Material Handling Load/Unload Part orientation Part presentation Fixtures This is a critical area of concern when making the switch from vapor degreasing/solvent cleaning to aqueous cleaning. Step 4 Orientation and Material Handling (con't) What is the impact of changing material handling to meet the new challenges of aqueous cleaning? Manual or automated loading? Flow-through or return-tooperator? Step 4 Orientation and Material Handling (con't) Material handling Part orientation Part presentation Fixturing - Equipment Selection Precision Cleaning 95 Proceedings 241

6 Step 5 Production Volume Requirements Current Production Method Continuous Batch Cellular/FMS Production Volume Cubic feet per hour Number of hours per day/days per week Future increases expected? Pieces per hour Inaccurate assessment of production volume can dramatically effect your cleaning system acquisition cost. Chemistry/Additives Temperature/energy trade off Desired soil reaction Effect on following processes Blow-off/drying enhancements Process compatibility verification Soil removal/ waste treatment Step 6 Plant Layout and Floor Space Requirements How much floor space is available? Are necessary utilities already located onsite? - electrical, water, steam, gas, air Are service locations accessible? What are the ventilation requirements? Consider cellular or centralized placement of cleaning systems. When converting you must assume that more floor space will be required for an aqueous system. 242 Precision Cleaning 95 Proceedings

7 Closed-loop Recycling Step 8 Wastewater Management Contaminated Cleaning Solution Recycled Fluid (Changeover 5th Week) Aqueous parts cleaning creates wastewater. Aqueous parts cleaning solution is not biodegradable, and is not sewerable. However, it can be managed effectively. Contaminated Cleaning Solution (Changeover 5th Week) Step 8 Wastewater Management (con't) How is other plant wastewater currently being managed? Alternate management methods - Closed-loop recycling -Filtration (media filtration, membrane filtration, ultrafiltration, reverse osmosis) -Chemical treatment -Evaporation - Third party hauling A system can be developed for either batch or continuous operation. 4) Part OrientationMaterial Handling Step 8 Wastewater Management (con t) Closed - loop recycling advantages -Reduced usage of chemicals -Longer cleaning solution life -Reduced wastewater treatment cost -Consistent process control over part cleanliness Aqueous Cleaning Equipment Stages Pre-wash Immersion Wash Spray Rinse Combination Ultrasonics Blow-Off/Dry Regenerative/Heated Compressed Air Convection Dryer Forced Air Dryer Precision Cleaning 95 Proceedings 243

8 Other Equipment Considerations Heat Packages - Electric Oil Removal - Disk style - Belt style - Rope style - Coalescing systems - Decant/weir systems - Ultra/ membrane filtration I Particulate Filtration - Chip basket - Chip/conveyor - Bag filtration - Cartridge filtration - Media filtration Common Misconception About Rotary Drum Washers The revolving rotary drum does not create a tumbling action. The drum creates a mild part motion for effect cleaning. Tumbling action can be added as a separate feature. Other Equipment Considerations Construction - Stainless steel construction - Sloped bottom tank - Channeled solution return - Marine clean-out door - Tank access - Easy nozzle-area access - Low solution shut-off - Water and compound make-up - Manual or automated - Power exhaust - Mist collection - Insulation Aqueous Cleaning Equipment Belt Conveying System Benefits - Allows for fixturing and precision cleaning of complex parts. Opens the entire part surface to cleaning action. Excellent flexibility in terms of part orientation and material handling. Drawbacks - Poor processing of loaded shop baskets. Difficult to handle small parts. Aqueous Cleaning Equipment Rotary Drum Benefits - Continuous or batch operation. Spray only or combination spray/ immersion. Simple load/unload features. Excellent for small parts. Drawbacks - Possible part damage due to part-onpart contact. Poor performance on parts with complex geometries. Lot integrity. Aqueous Cleaning Equipment Cabinet Cleaning System Benefits - Single point load/unload. Typically smaller system footprint. Works well in low production environment. Can handle baskets and large parts. Drawbacks - Multiple stage cleaning requires sophisticated controls and tends to cross-contaminate solutions. Will not work in a continuous manufacturing environment. 244 Precision Cleaning 95 Proceedings

9 Aqueous Cleaning Equipment Immersion Cleaning System Benefits - Excellent for a variety of parts - single or in baskets Good for gross contamination which requires extended soak cycles. Drawbacks - Open tanks have potential environmental and safety hazards. Can be an eyesore in the plant. Lack of spray capability does not allow for effective impingement. Potential recontamination of parts. Cleaner Parts Less expensive cleaning Environmentally safe Aqueous Cleaning Equipment Ultrasonics Benefits - Good performance on parts with very small blind holes. Good for high precision cleaning. Handles delicate part structure. Drawbacks - Open tanks have potential environmental and safety hazards. Can be an eyesore in the plant. Lack of spray capability does not allow for effective impingement. Potential recontamination of parts. Possible re-layout or expansion of your manufacturing facility. Changes in your manufacturing process. Wastewater management review. WARNING! The conversion from vapor degreasing & solvent cleaning to aqueous cleaning is not a simple drop-in solution. Resource commitment to a thorough process analysis effort. A capitol investment ranging from $20,000 to $1,000,000. An analysis/acquisition time frame of 2 or 3 months to 2 years. Precision Cleaning 95 Proceedings 245

10 l,l,l-tri Phase Out Deadline is December 31,1995. If you need to switch to a CFC free cleaning method, you have 12 months to have it up and running. Start your selection process now! 246 Precision Cleaning 95 Proceedings