Let us recall the pair of technical contradictions describing the ice cube tray problem :
TC1 : If the opposite lateral faces of the compartment unit are parallel to each other, the geometry of the ice blocks is cubic, but demoulding of the ice blocks is difficult
TC2 : If the opposite lateral faces of the compartment unit are not parallel to each other, the demoulding of the ice blocks is easy, but the geometry of the blocks is not cubic
Remarks :
* it is written "ice blocks" instead of "ice cubes", for their non cubic or cubic character is a main parameter of the problem
* more exactly, TC2 describes lateral faces which make an angle > 90° with the bottom face
* more exactly, TC2 describes lateral faces which make an angle > 90° with the bottom face
* the elementary compartment C of the classical ice cube tray (see the Figure on the former post) is composed of 5 faces which form the shape of a truncated pyramid ; there are 2 pairs of opposite, non parallel, lateral faces : F1 and F2 and also F3 and F4 ; F5 is the bottom face
The problematic situation draws a physical contradiction which can be simply expressed as follows:
PC : the lateral faces must be parallel in order to obtain cubic ice blocks, and the lateral faces must be non parallel to ensure an easy demoulding
This is only a re-formulation of the pair of technical contradictions. As we have already seen on this blog, the choice of the right physical contradiction is crucial, and the physical contradiction must express the real causality of the problem.
Is it possible to separate the opposite requirements of this PC in time ? (separation in space does not mean much here since one speaks about the relationship between two parts of the technical system).
Actually the parallelism of the lateral faces is needed to produce the ice cubes during a first time T1. If the lateral faces are non parallel during a secong time T2, the demoulding is easy. Thus the opposite requirements can be naturally separated in time. Now only the embodiment of such an ice cube tray is needed.
How to create the non parallelism of the lateral faces ? If the walls are flexible, for example. This is possible with a silicone ice cube tray (see Figure below).
By experience, the ice cubes must be demoulded one by one from a silicone ice cube tray: this is not an easy job ...
There is a possible open solutions space for other types of flexible ice cube trays which all fulfil the opposite requirements.
TRIZ proposes a tool called STC (Size-Time-Cost). This tool can help removing psychological inertia* through the proposal of 6 thinking prompts where size, time and cost values are successively forced to zero and to infinity. The consideration of extreme values can lead to interesting, non obvious solutions. Actually it may be interesting to apply extreme values to any well chosen specific parameter of a technical system.
Here the property of interest is the relative position of the faces F1 and F2 (resp. F3 and F4) which controls both producing and demoulding of cubic ice blocks. Until now we have considered the parallelism character of the opposite faces. Alternatively, it is possible to consider the distance between the opposite faces in order to quantify this relative position. This has physical meaning, for an increasing of this distance makes the demoulding easy. Let us apply inifinity to the value of the parameter "distance between the opposite faces". This means that F1 and F2 belong necessarily to separated parts of the ice cube tray. F3 and F4 belong also to separated parts of the ice cube tray.
As a conclusion, for the considered compartment of the ice cube tray which fulfils the opposite requirements - and this is generalized for all compartments of the ice cube tray - a practical solution is that F1 and F3 belong to one part of the ice cube tray, and F2 and F4 belong to another part of the ice cube tray. F5 belongs to the first part, and as will be easily understood (completion of the cubic shape), it is necessary to create F6, the face opposed to F5, with F6 belonging to the second part of the ice cube tray.
This elegant solution has been patented by the cooking tools company Lékué (from Barcelona). The design of this innovative ice cube tray is seen below :
* : psychological inertia is a central TRIZ concept, which depicts an effect of the usual state of mind, where the thinking of new schemes and designs is difficult because of the former experience of the thinker, and the associated usual schemes and designs ; as an illustration, in the present example, psychological inertia is created by the one-piece design, and makes non obvious to think about the two-piece design of an ice cube tray
PC : the lateral faces must be parallel in order to obtain cubic ice blocks, and the lateral faces must be non parallel to ensure an easy demoulding
This is only a re-formulation of the pair of technical contradictions. As we have already seen on this blog, the choice of the right physical contradiction is crucial, and the physical contradiction must express the real causality of the problem.
Is it possible to separate the opposite requirements of this PC in time ? (separation in space does not mean much here since one speaks about the relationship between two parts of the technical system).
Actually the parallelism of the lateral faces is needed to produce the ice cubes during a first time T1. If the lateral faces are non parallel during a secong time T2, the demoulding is easy. Thus the opposite requirements can be naturally separated in time. Now only the embodiment of such an ice cube tray is needed.
How to create the non parallelism of the lateral faces ? If the walls are flexible, for example. This is possible with a silicone ice cube tray (see Figure below).
There is a possible open solutions space for other types of flexible ice cube trays which all fulfil the opposite requirements.
TRIZ proposes a tool called STC (Size-Time-Cost). This tool can help removing psychological inertia* through the proposal of 6 thinking prompts where size, time and cost values are successively forced to zero and to infinity. The consideration of extreme values can lead to interesting, non obvious solutions. Actually it may be interesting to apply extreme values to any well chosen specific parameter of a technical system.
Here the property of interest is the relative position of the faces F1 and F2 (resp. F3 and F4) which controls both producing and demoulding of cubic ice blocks. Until now we have considered the parallelism character of the opposite faces. Alternatively, it is possible to consider the distance between the opposite faces in order to quantify this relative position. This has physical meaning, for an increasing of this distance makes the demoulding easy. Let us apply inifinity to the value of the parameter "distance between the opposite faces". This means that F1 and F2 belong necessarily to separated parts of the ice cube tray. F3 and F4 belong also to separated parts of the ice cube tray.
As a conclusion, for the considered compartment of the ice cube tray which fulfils the opposite requirements - and this is generalized for all compartments of the ice cube tray - a practical solution is that F1 and F3 belong to one part of the ice cube tray, and F2 and F4 belong to another part of the ice cube tray. F5 belongs to the first part, and as will be easily understood (completion of the cubic shape), it is necessary to create F6, the face opposed to F5, with F6 belonging to the second part of the ice cube tray.
This elegant solution has been patented by the cooking tools company Lékué (from Barcelona). The design of this innovative ice cube tray is seen below :
* : psychological inertia is a central TRIZ concept, which depicts an effect of the usual state of mind, where the thinking of new schemes and designs is difficult because of the former experience of the thinker, and the associated usual schemes and designs ; as an illustration, in the present example, psychological inertia is created by the one-piece design, and makes non obvious to think about the two-piece design of an ice cube tray
