Calcium oxide and water are used so that the energy released by an exothermic reaction heats the beverage. All the consumer needs to do is follow the simple instructions and wait approximately six minutes for a hot beverage or soup.
Measure Phase (With TRIZ)
Much work in the seaming of a metal end to a plastic body was performed by American National Can (ANC) on the Omni-Bowl Project. The double-seams achieved were retort stable physically as well as hermetically. OnTech utilized ANC's seam geometry and "chuck and role" profiles in order to reproduce the same seam quality, but with a multi-layer blow-molded container. This container manufacturing system provides a less expensive container but loses dimensional control (the flange diameter as the body must be continuous to a certain width). In order to achieve x, at the reduced cost of blow molding (vs. injection blow molding) a TRIZ technical contradiction was used:
Analyze Phase (With TRIZ)
Here, we apply the principles (generic solutions) to the technical contradiction. Segmentation stimulates the division of a mono-step manufacturing process (blow-molding with exact flange dimension, which is impossible) into a two-step manufacturing process (blow-mold and die stamp flange to correct dimension). This ideal solution is the answer to our flange problem: we get the needed dimensional accuracy utilizing an inexpensive process and a basic secondary manufacturing step.
Visually, the OnTech seam is as robust as the Omni-Bowl seam. The overlap, cover-hook and body-hook are comparable and in certain cases superior. (See Figures 4 and 5.)
Seam quality was validated using microscopic dimensional analysis as well as immersion testing, micro-leak analysis and inoculated pack analysis. The importance of this preliminary piece of innovation becomes apparent when the container is sterilized via the retort process.
The retort process is a sterilization method by which the complete package is subjected to an elevated temperature (~250°F) for the amount of time required to stabilize the package temperature at the target temperature. The duration at this temperature is dependent on the required log reduction of bacteria in the foodstuff. A pressure vessel utilizing saturated steam is the means by which the heat is transferred to the package.
The pressure in the vessel is greater than 1 atmosphere so that T>212°F may be obtained. It is in this environment that the integrity of the double-seam is challenged. The fact that the OnTech container has three internal chambers exacerbates the problem of retort greatly. There are also four seams or sealing surfaces of the OnTech container subjected to the rigors of the retort process: two double-seams, a power-inertia weld, and a heat seal. The pressure differentials in the three chambers must be equalized in order to maintain physical structure.
As you can see from Figure X, the temperature inflections a', b', c', and d' occur at various times, t1, t2, t3, and t4, respectively. This compound inequality, t4> t3> t2> t1>tretort; yields various physical contradictions during the retort thermal profile.
As shown in Figure 8, philosopher Dr. Rudolf Carnap (1891-1970) described properties and the relation of physical things as follows: An object, or substance (Sx) as in Su-Field modeling, occupies a definite region of space at a definite instant of time, and temporal series of spatial region during the whole history of its existence. A substance occupies a region in the four-dimensional space-time continuum. A substance at a given instant of time is a cross-section of the whole space-time region occupied by the substance (a substance-moment). Carnap's insight into the ability to "slice" an event into time and space intervals is important for zone-of-conflict determination.
During the retort heating cycle, the puck water boils, the beverage boils, and the plastic body and cone soften. The headspace in the beverage compartment attempts to expand (the beverage is incompressible) and this exerts pressure on the end (A) (the location of a double-seam). The cone headspace expands exerting force on the cone wall (B). The puck headspace expands exerting force on the puck foil (C) (the water, again, is incompressible). A, B and C are positive pressures during the ramp-up cycle, where A>C>B (to the bacteriological death temperature). After the minimum hold time (at 250°F) the steam is collapsed and the pressure reduces to 1 atmosphere and the containers are cooled (water circulation in the retort vessel).
The cooling cycle, unchecked, creates vacuums, A-1, B-1 and C-1, where A-1> C-1> B-1. A-1> wall strength of the cone, thereby causing the collapse of the cone (the cone volume changes from ~325cc to ~300cc post-retort). The cone collapse increases A-1 and this vacuum A-1> wall strength of the body, thereby causing body paneling. It is these two conflicts that require the retort cooling cycle to be controlled. (See Figure 9.)
The controlled cooling cycle was the result of the following physical contradiction: You need the steam collapsed to end the thermal cycle, but you do not need the steam collapse because of the physical detriments. Therefore, utilizing the separation in time principle it is possible that the cooling process may be stepped (at precise t and P intervals) in order to allow the wall strength to recover before the vacuums, A-1, A-1, B-1 and C-1 are maximized.
The loss of cone volume post-retort occurred with pronounced variability and unpredictability. Rather than oppose this deformity (using principle 22 "convert harm into benefit") we designed to predict and control the deformity (see Figures 10-14). The control of the deformity allows us to minimize and control the vacuum, A-1, so that A-1 wall strength of the body wall. Controlling the cone deformity also allows us to insure enough unrestricted CaO expansion during hydration. The thermodynamic life-cycle of CaO is interesting in its elegance and beauty: it reverts to the form it was mined; therefore, no net loss to earth as an open system.
Improve Phase (With TRIZ): Oxygen Ingress
The retort process forces retort water into the plastic of the body. This saturation of the polypropylene expedites the oxygen ingress problem (O2 ingress to the beverage through the package that degrades the beverage flavor and allows bacteriological growth).
The low thermal conductivity of the cone (its primary constituent is polypropylene) causes various undesirable conditions. The design of the OnTech container includes a solid and liquid reactant which are co-mingled, when desired, in order to evolve energy (generated from a basic exothermic reaction) to heat the beverage. The container utilizes Fourier's Law of Heat Conduction (named for French mathematician and physicist Joseph Fourier (1768-1830)) to heat the beverage. This physical law states that two areas with different temperatures sharing a common non-insulated wall will reach equilibrium over time. At reaction initiation, heating begins and the temperature inside the cone becomes greater than the temperature of the beverage. In accordance with Fourier's Law the temperatures begin the equalization process by the transferal of heat through the cone to the beverage. The insulating properties of the cone (its primary constituent being a polypropylene homo-polymer) and the rate of heat absorption of the beverage, cause an inequality (transient heat transfer) in the dynamics of the heat transfer system (rate of energy created by the reaction is greater than the transfer rate through the plastic).
The reaction is spontaneous and independent from the thermo-physical properties of the other elements of the system.
For this particular experimental case the internal cone temperature reaches its maximum at 4 minutes and 40 seconds. The beverage, however, reaches its maximum temperature at ~8 minutes. The time difference (4:40 versus 8:00) is indicative of the thermal resistances between the energy source and the beverage. During the time interval at which the energy release rate of the cone core is maximized (~2:40-4:40) the rate at which the beverage is being heated is approaching its maximum. It is precisely these thermal resistances and the thermodynamic inequalities described that present the possibility of experiencing POMD (post operational maintenance drop) under certain conditions.
An effect of the thermodynamic inequalities is the thermal over-saturation of the polypropylene homo-polymer that comprises the cone wall. This thermal over-saturation, under certain conditions, could result in a cone breach.
The application of principle 40 yielded the inclusion of ceramics and pitch-based carbon fibers to the standard polypropylene. The thermal conductivity of the composite polymers greatly increased the slope of heat generation and alleviated many of the failures associated with the previous configuration.
The Finished Product
The integration of The Theory of Inventive Problem Solving (TRIZ) with Six Sigma is absolutely necessary. The ability to solve problems in a closed-system and an open-system are vital to the optimum resolution of each problem. TRIZ and Six Sigma present the practitioner with the required capabilities to search for solutions in both domains.
Michael S. Slocum, Ph.D., is the principal and chief executive officer of The Inventioneering Company. Contact Michael S. Slocum at michael (at) inventioneeringco.com or visit http://www.inventioneeringco.com.
Amir H.M. Kermani is an Industrial Engineer from Tehran Polytechnic. He has researched quality management techniques, particularly Six Sigma, DFFS, QFD and TRIZ. Kermani is among the few people who have tried to develop TRIZ knowledge and establish a TRIZ base in different industries (including chemical and petrochemical) in Iran. Contact Amir H.M. Kermani at Kermani (at) iiits.org.
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