The Short Story
CO2 Composite Spray Technology Development
CO2 Composite Spray™ technology can claim its beginnings going back to the late 1970’s with the introduction of Fong’s pellet blasting innovations when he was working for Lockheed Aircraft. CO2 pellet blasting employs a mixture of small (sublimable) solid CO2 pellets (used almost exclusively for food packing refrigeration) introduced into a compressed air stream to blast contaminated surfaces free of gross contamination.
As a new engineer at Hughes Aircraft in 1988, I was introduced to another CO2 spray cleaning innovation developed by Dr. Stuart Hoenig, University of Arizona (Hughes Aircraft R&D affiliate) – later called the SnoGun™. The SnoGun expanded a saturated liquid carbon dioxide into a solid-gas aerosol (aka “Snow”) to precision clean a surface. Interestingly, Dr. Hoenig, who would serve as an expert witness on my behalf many years later in a CO2 Composite Spray patent infringement lawsuit, “invented” the idea of using a CO2 aerosol as a precision cleaning spray. He observed cleaning effects within an environmental test chamber (ETC) using liquid CO2 as an atmospheric spray coolant. The surface of the chamber wall directly opposite the liquid CO2 injection valve was “cleaner” than other surfaces within the test chamber. Eureka! This observation was exemplary of the innovation process at work!
Since then, and over the past 30+ years, I have had many opportunities to witness and study numerous related (and unrelated) innovations that would be the basis for the initial development of the CO2 Composite Spray and its subsequent evolutionary development. Critical to CO2 Composite Spray technology development have been the many early adopters. For example, Mr. Lynn Liebschutz, IBM (later HGST) who purchased and used my early commercial products (Warts and All) in numerous precision cleaning applications. These early adopters (and their applications) provided invaluable insights that have driven the technological and product improvements discussed herein and continue today.
A CO2 Composite Spray is a lean and green (clean) manufacturing technology for performing dry cleaning during precision assembly operations or for providing cooling and lubrication functions during challenging thermal spray and hard machining applications, respectively. A CO2 Composite Spray process uniquely combines characteristics of conventional pellet blast, snow spray, microabrasive blast treatment, high-pressure liquid spray, and ultrasonic immersion processes. CO2 exhibits solvent-like chemistry, and the spray process delivers a powerful (and high-frequency impact) shear stress to surfaces. A dilute (lean) CO2 particle-air aerosol spray composition produces both mechanical scouring and chemical cleaning actions. These cleaning actions are made vis-à-vis phase-change (solidàliquid phase) and high-frequency cavitation impacts at the particle-surface interface. Gas, solid and liquid phases combine to remove particulates and thin film contaminants from the most complex topography. CO2 Composite Spray technology provides precise control of key process variables (KPVs) including spray pressure, particle hardness, and particle velocity, uniquely providing variable and controlled compositions which optimize process performance without physical damage to substrate surfaces.
The latest generation CO2 Composite Spray technology, Vector Pro™, produces powerful micronized particle sprays exhibiting increased performance and economy. Co-developed with this third-generation CO2 Composite Spray process is a laser-based photometric spray monitoring and control technology called LightSPEC™, which provides quality control metrics for a CO2 Composite Spray.
Finally, new hybrid CO2 Composite Spray innovations have been recently developed, overcoming surface cleaning and treatment constraints and limitations of using a CO2 Composite Spray alone. These include Particle-Plasma™ and Clean Laser processing technology.
Today, CO2 Composite Spray technology is a cost- and performance-effective clean manufacturing solution for many precision cleaning applications and contamination challenges. However, arguably more importantly, the CO2 Composite Spray technology development story is beneficial for teaching the CO2 innovation process, which I call “CO2 Mechanics”. Herein I attempt to weave a story starting from the concept (the Eureka moment), through its evolution, addressing limitations and constraints of the technology while solving significant customer application problems, and finally, to the state-of-the-art for CO2 Composite Spray technology.