OVERCOMING CONTRADICTIONS (NO MORE
The first tutorial contained three problems
that readers were encouraged to solve by applying the described
Now letís discuss solutions.
Problem 2: Unloading
Unloading loose, frozen material by first
defrosting it can be an expensive procedure. What other method would you
Because we are talking about frozen
material, psychological inertia impels us to look for various ways to thaw
the material. But consider the principle of inversion, which
recommends doing the opposite of what would usually be
attempted. The opposite of heating is freezing -- and indeed, if the
temperature of the material is lowered even further (using liquid
nitrogen, for example) the material becomes brittle and can be easily
loosened for unloading.
Problem 3: Bullet-proof windows
Initially, bullet-proof glass windows
used on fighter aircraft had a serious defect: When a bullet hit the
window, a "network" of cracks would form in the glass and
obstruct the pilotís vision. How might this damage be reduced?
The segmentation principle can help
here. This principle recommends that the window be made of smaller panes
of glass that are cemented to an acrylic plastic sheet using a transparent
adhesive. When a bullet hits the window, the pane that took the hit -- and that pane alone
-- fills with cracks (see figure).
Problem 1: Removing
layers of insulation
Certain metallic surfaces must be coated
with a thick layer of insulating material. Removing this coating later is
difficult, however. How might this be accomplished?
Remember the prior action principle
in last monthís tutorial? This principal can be applied by placing a
steel wire on the metal surface prior to applying the insulation. The
insulation layer can be cut by
pulling the wire. Itís a good
approach -- but the problem is not yet completely solved.
|The next step is to select a wire of
appropriate diameter. To withstand the pulling force, a relatively
thick wire must be used. There are disadvantages to using a thicker wire,
however. First, it increases the consumption of material; second, a thicker
wire means a heavier wire, which in turn means that more force will be
required to cut the insulation. Itís a paradox.
In TRIZ, this type of
situation -- i.e., where two mutually opposite requirements exist -- is
called a physical contradiction. In this case, the physical
contradiction can be expressed as follows: the wire must be thick in order to withstand the
pulling force and the wire must be thin to minimize the cutting
force and reduce material consumption.
Most of us do not like dealing with
paradoxes. Instead, we try to overcome the situation by compromising,
making a trade-off, finding an optimal solution, etc. And in many situations this
will work. But often contradictions are "sharp" and compromise
is not possible.
Paradoxes produce frustration in humans -- and even animals
-- due to the uncertainty that they engender. Ivan Pavlov, the noted
physiologist, conducted a group of
experiments to study the reactions of dogs to
contradictory situations. A dog was trained to expect a positive outcome
(food) when viewing a circle, and a negative outcome (mild electroshock)
when viewing an ellipse. Because it knew exactly what to expect in each
case, the dog was able to handle each situation adequately. Then the
experimental conditions were changed: the dog was shown a circle that
began to flatten until it looked more and more like an ellipse. Eventually it became impossible to recognize
whether the image was a
circle or an ellipse -- at which point the frustrated dog suffered a
In TRIZ, there is a special tool to handle
Invention 11. Coating metal workpieces
Metal surfaces are chemically coated as
follows: the metal workpiece is placed in a bath filled with a metal
salt solution (e.g. nickel, cobalt, etc.). During the ensuing reduction
reaction, metal from the solution precipitates onto the surface of the
workpiece. The higher the temperature, the faster the process takes
place; however, at high temperatures the solution decomposes, and up to
75% of the chemicals are lost by settling on the bottom and sides
of the bath. Adding stabilizers is not effective, and conducting the
process at a low temperature sharply decreases production.
Letís see how we can use TRIZ to address
this problem. The physical contradiction is as follows: The temperature
should be high to increase productivity, and it should
be low to avoid waste. To resolve physical contradictions, the following separation
principles are recommended:
- Separation in space
- Separation in time
- Separation between the whole system and
- Separation based on different conditions
To apply the principle of separation
in space, for example, we should ask ourselves the following question:
Do we need
this parameter -- temperature, in this case -- to be high (and low)
everywhere, or is it necessary in certain places only? If the temperature
need not be both high and low everywhere, we can try to
separate these opposite requirements in space.
In this case, we need the temperature to be
high only near the parts rather than everywhere in the bath. How
can this be achieved?
The answer is as follows:
The workpiece is heated to a high
temperature before it is immersed in the solution, and the process
itself is conducted at a low temperature. The solution is therefore hot
near the workpiece but cold everywhere else. (One way to accomplish this
is to apply an electric current to the workpiece during the coating
A potato can rot due to naturally-occurring
bacteria on its surface. Heat kills the bacteria, but too much heat will cook
the potato as well.
If the potatoes are exposed to a flame at
500-850 degrees C for a short duration (4 to 8 seconds), the surface bacteria
will be destroyed while the inside of the potato is unaffected.
Now letís consider the separation
in time principle:
Invention 13. Needle with dynamic eye
It is difficult to pass a thick thread
through the small eye of a needle. We can formulate the following physical
contradiction to represent this situation: A needle must have a large eye
to facilitate insertion of the thread, and must have a small eye for
By separating the contradiction in time
this problem can be formulated as follows: the eye must be large while the thread is inserted, and
must be small during
sewing, as follows:
||R. Pace of Britain designed a needle
made of two thin, spring-like wires of identical length. The wires are welded together at one end, twisted three quarters of a
turn, then welded at the opposite end. The resulting needle looks like an ordinary
needle, but when slightly unwound, a large slot appears through which a thread can easily pass. When released, the
needle returns to its initial shape and grips the thread.
Invention 14. Wire enameling method
In the manufacturing of a particular electronic
wire, the wire is first passed through a liquid enamel bath and then
through a die that removes any excess enamel and sizes the wire. The die
must be hot to ensure reliable calibration; however, if the wire feed is
interrupted for several minutes or more, the enamel in the hot die hardens
and firmly grips the wire. The process must then be halted while the wire
is cut and the die cleaned.
The contradictory requirements (the
enamel should be hot to ensure calibration and should be cold to avoid
hardening) are separated in time as follows:
The die should be in a hot
zone while moving and in a cold zone when it stops moving. This is
achieved by fixing the die to a spring. When the wire moves, it pulls the
die into a zone where it is heated (either by induction or by contact with
the hot chamber walls). When the wire stops, the spring pulls the die back
into the cold zone.
Invention 15. Gripping workpieces of
grip workpieces of complex shape, vice jaws must have a
corresponding shape. It is expensive to produce a unique
tool for every workpiece, however.
The principle separation between the
whole and its parts recommends that we assign one of the contradictory
requirements to the whole system and the other to its parts, as follows:
||Use a vise with
ordinary jaws, but add multiple hard bushings around the workpiece
that move horizontally to conform to the workpiece's shape.
The early stages of TRIZ development
focused on problems related to technological systems. Later, however, it became
evident that contradictions occur in many other areas of human activity --
personal interaction, etc. And what's more, the same separation
principles can also help resolve these contradictions.
If a successful company is large it will bring in high revenue, have extensive
resources, etc. At the same time, large companies often suffer from
bureaucratic problems that curtail their flexibility and can eventually
become crippling. The contradiction (a company should be both large and
small) can be resolved using the principle of
separation between the whole and its parts, as follows: Create
many relatively small, independent companies that operate under a single
Besides causing frustration, contradictions
are frequently responsible for the rejection of good ideas -- that is, ideas that have negative side effects.
Braking of an automatic welder drum
welding machines use a steel wire rolled onto a drum as an
electrode. A special motor in the welding head pulls the
wire during the welding process. When welding stops, the drum continues to rotate
due to inertia, and the wire becomes entangled as a result.
The idea of using a brake to
stop the drum from rotating freely was considered, and rejected, because it
necessitated a more powerful pulling motor and thus a heavier welding
head. This idea can be reconsidered, however, with respect to the following physical contradiction:
Drum rotation should
exist in order to unreel the wire, and should not exist to avoid
entangling the wire.
Producing pure copper
In the electrolytic process by which pure
copper is produced, a small amount of electrolyte liquid remains in the
pores on the surface of copper sheets. When the copper is stored the
electrolyte evaporates, creating oxide spots on the surface which reduces
the value of the copper and results in substantial losses. The best way to
solve the problem was to avoid producing the pores in the first place.
This approach was immediately rejected, however, because it required
substantially lowering the d-c current, which would dramatically reduce
productivity. Instead, they decided to reduce the financial losses by
washing the sheets of copper prior to storage to remove the electrolyte
from the pores. This was not only costly but inadequate, and attempts at
improving the washing process continued for over 15 years.
When TRIZ specialists addressed this
problem, they asked the copper manufacturers if there was a way to
eliminate the pores in the copper sheets. The answer: impossible. It took some effort to understand that there was a
contradiction behind this "impossible": The
current must be low to avoid creating the pores and must be high to
provide the required productivity.
Not every contradiction is resolvable
within the present confines of technology -- nonetheless, it is always worth
trying. If all known ways to resolve a contradiction fail, the
contradiction can often be circumvented altogether by changing the problem statement.
Try to apply the separation principles to
resolve the physical contradictions contained in these problems:
- The thick/thin wire contradiction in problem
1, removing layers of insulation.
- Problem 4, braking of an
automatic welder drum.
- Problem 5,
producing pure copper.
Look for examples of physical
contradictions in your work or everyday life, and note how they have been handled.
© 2004 Ideation International Inc.