Functional thinking in production process
Ives De Saeger
P41 Industrial Services
Varendrieskouter 133, 9031 Drongen Belgium
1 Topics to cover
TRIZ, workplace, production, process, assembly, process analysis, process design,
Using only functional thinking, one of the tools within TRIZ (the theory of inventive
problem solving) the workplace can be redesigned and trimmed to a greater extent
than with traditional process analysis using time & methods study together with lay
out analysis. Functional thinking is described as a way to practice innovation and lead
to new insights than what is known in process analysis, added value and method
study. Functional thinking can easily integrate risk analysis and environmental issues
thus expanding the use to greater needs. Using an academic simplified example of a
subassembly functional thinking shows what results can be expected
1.2 TRIZ: Try Reading It in Swahili
TRIZ, the theory of inventive problem solving, has nothing to do with a theory and is
more about problem formulating than solving! TRIZ originated in Russia in 1946
through the work of Altshuller. Altshuller was a patent officer at the Russian Navy in
charge of educating his fellow officers how to invent. Because of the lack of theories
concerning inventing Altshuller developed one himself resulting today in a systematic
way to innovate. Based on patent analysis several tools were created such as
contradiction table, functional analysis, pattern of evolution, ARIZ (a step-by-step
problem analysis), ideality and resources. TRIZ contains a database on physical,
chemical and geometric effects gathered from science. TRIZ basic fundamental is
"why invent the wheel if it already exists ?". TRIZ helps to formulate your problem
in a specific and systematic way but even provides you with solution directions how
to proceed further.
1.3 The portal to process innovation: functional thinking
TRIZ offers an interesting look at functional thinking. Functional thinking is defining
the functional relations between all the objects of the system considered. In a
traditional assembly work station the following objects might appear: worktable, rack,
storage bin, power tool, operator, half products, crates, hose pressured air, electricity
cables, hoisting material, wheels of crate, litter, documents eg standard operating
procedures, terminals etc.
We are not defining the functionality of the end product, and its components as it is
normally done in TRIZ, but all the functions of the objects on the workplace and their
relations to each other and to the half products. The functions can express useful and
non-useful functions (here defined as opposites).
Useful - harmful
A crate may deliver the function of protection (useful function) , contain a number of
products and the ability to stack more products in height during transport (effective
function). This crate may also damage the product (harmful function) , limit the
operator from grasping the product out of the crate (insufficient function) and create
extra frequented work ( eg work that has to be done, but not in every product cycle)
eg the elimination of the foams, plastics and rubbers used to protect the parts. The
feedback loop of waste material causes the need of more space on the work floor.
An oven may be used to pre-heat objects but you would want to have less of this
function, expressing an excessive function. Or the oven might perform the heating
insufficiently by not heating the pieces quick enough and thus creating waiting time.
The focus of process innovation is detecting the functional relations and using this
functional analysis to
Trim (eliminating unnecessary objects or functions, one of the basic approaches in
•Invert functions (the other way around)
•Improve process time
•Deploy excessive, missing and harmful actions (safety)
•Improve process tool design
•Start a creative process
•Define the ideal system
1.4 Functional Analysis Tree, an example
•The functional analysis will be applied to the following case (figure 2). A large part
(A) situated on the left of fig 2, is lifted by use from a hoist to the worktable where the
part is placed. The operator takes a piece (B, the cylindrical object) and positions it
onto the large piece A, a bolt is screwed onto the piece (B) and the operator uses a
battery tool to fasten it. The battery tools is not visible in the picture. The assembly
is hoisted back to a roller. This assembly could be seen as a subassembly in a super
system. The crates are placed by another operator and the assembled pieces are
mounted in a larger assembly perhaps on a production line. The basic parts A, B and
bolts are brought by logistics by means of fork truck.
•Figure 1 is added to show a previous step before a process analysis. some firms still
use the step 1 lay out. The ergonomics are improved so the operator doesn't have to
bend to attach the hook to the large piece or bend to grasp piece B. A flow way, a
rack with a FIFO system, is used in figure 2 to implement a x-bin system. The
conveyor improves the distance the next operator has to take before he can assemble.
The conveyor transports the assembled piece to where the next needs it.
Figure 1: step one
Figure 2: step two
This case is purely academic, normally the number of the added pieces will be higher
and will be calculated from the cycle time.
structure (I profile, 4 poles and
A process analysis can be found in appendix A. (table 2, the time is not included since
it is not an issue here.)
1.5 Using functionality in processes
1.5.1 Function finding
To identify the function of an object the question is “What it does and/or must do
rather than what it is”. A "noun verb noun" is used to identify the function. From a
process analysis viewpoint the "noun verb noun" is widely used . Using synthetic
time standards verbs such as grasp, place, release, position, walk are common in use
(look at process analysis map, appendix A). The operator uses the wrench. The verb
is the action or operation. In this case 'uses' is the verb. "Uses" is too general to be the
'functional' description. The difficulty is defining the function so it will help define
the system leading to improvements, innovation opportunities. The operator “holds”
the wrench is a better description of the function. So it is clear that the verb is too
important. The nouns used in a process analysis are the operations, a functional
analysis however will reveal other nouns such as 'holds'. The use of the worktable (=
holds a piece and provides place to work) is hardly considered by a process analyst.
The worktable will not influence the time and is therefore overlooked. However in an
extreme elimination step it should also be considered. This is the advantage of using
functional analysis, it will help you look at a process in a new manner. It will even
include potential harmful functions which are normally deduced after improving a
situation. Here it is possible to identify all functional relations (including the process
operations as other relations performed by other objects within the system.)
Looking at the process analysis table (appendix a) is it easy to make a functional
process map. Define all the objects and link them functionally. A different
representation of the ideation methodology will also be shown.
1.5.2 Applying functional thinking to the example
The functional analysis according to TRIZ (...) model is shown in figure 3. To focus
on trimming most of the functions are considered effective. A lot of functions
however could be added such as latent functions. A latent function is a function which
is present but only appears statistically. An example is that the battery tool hurts the
operator ( in fact is is the rotation of screw head which could hurt the operator), there
is a certain percentage chance that this will happen. Another latent function is that the
hoist doesn't provide its function, hoisting, because of a malfunction of the hoist.
Something is wrong and it needs to be fixed by maintenance.
Not all the objects from the object list table ??? will be added in the analysis. The
structure to hold the hoist could be added but delivers the only function of holding but
is not of interest at this moment.
The red arrow indicates non-added value, the green arrow indicates added value and
the orange is in between. Black arrows are normally not considered in process
Trying to include the relationships between the functions and the time element a
representation looking like a problem formulator model could be used.
Hook l ifts and
B Mounted on
Bolt Mounted on
lowers piece A
Walks to worktable
Get and places piece A
Hoist Lifts and lowers
P eer holds but ton
Get and place hook on piece A in crate
C rate holds
Walks to peer and hook
A time relation between the functions reveals more clearly that the hoisting material is
used to transport the main piece and needs to be done in order to assemble the pieces.
The actual process of mounting the piece B and screwing the bolt are the added value
functions of this whole representation of the process. Here you can move the
operations to change the method of assembly.
Remarks in favour of map
These representations give us a model to get insight in the system, understand the
relations between each component, leads to a better understanding of the added-value
steps and the model can be used to combine functions, eliminate functions or reverse
Remarks against map
The models also unable the process analyst is to see which function comes first. If
you take all the objects viewed in a period of time, even though they might interact as
a discrete function, the whole map is nothing more than a compression of all the
initial states as if they would all exist at the same moment. This is why at first glance
this map is not interesting from a viewpoint of processes. One conclusion could be
that this compression might exclude 'time' contradictions as this model doesn't give us
any insight in what comes first. The bolt could be placed first on the piece B and
might improve the positioning of piece B on A.
Interesting to notice is that there is clearly a difference between the operations as seen
in the table and the functions described. A process analyst will write that the operator
puts a piece on the worktable, the obvious function of the worktable (to work on and
hold the piece) is normally not an issue. It is clear that several operations are needed
to perform a function.
There is still some work to be done in the field of revealing timedependecy of the
functions. The endproduct is slowly transformed from a raw material to the final
product by adding pieces in a certain sequence.
1.5.3 Added value
Another point to consider are the features of the object. It is because a object is too
heavy (feature weight) what causes a difficulty of action. It are the features of the
objects where the problem may lay. Features such as grip, length, size, weight,
distance to get/place, ease of place are clearly better to define the problem of handling
a wrench and can be used to determine the time. It is because an object is small and
jumbled that it takes more time to take this object than if it would be free.
In describing functions one is looking at the tools and objects that produce direct
change to another object. This change may be getting and placing actions. These
actions only change the position of the object. Other actions such as welding,
screwing, cleaning change the objects visually. A process study is looking for added-
value actions. The value added action can be understood as the moment a product is
added to another thus increasing the value of the whole. One representation of added
value is the red-green model. Red applies to actions that do not contribute value,
green is the opposite. Table ??? gives insight in the operations and features of object.
The features described here determine the actual time needed to perform this action.
This model labels operations in adding value or not. There are four colors. The
colors are explained in the table 1.
Time determining features
, distance, height, depth, size,
number of characters,...
stooping, climbing stairs,
sitting and rising, reading,
getting and placing
size (length, width, height) , surface
conditions (slippery,sticking), shape
objects not placed
at end positions:
mounting parts at its end-
The features of green are the same as
idle time: waiting for
organization of work, type of
process, tempo of operator,
The features of green are the same as orange since the only difference between green
and orange is the end-place and green has a fixed value depending on the product.
The place conditions are determined by the product designer, yet the get conditions
are determined by process designer and depend on the package, the number of
intermediate places. Some packages are placed direct on the work floor and
determine the productivity as well. Contradictions might emerge from this fact also. It
is the packaging (eg. size) which limits the operator for getting parts easily.
The blue factor is situated on a higher level of the system (the super system).
Therefore the features depend on the level of organization (planning), the type of
process or the tempo of the operator. Blue can be associated with logistic planning
systems and ideal work organization.
Applying this to the case study one might come up with an list as follows.
Object list Features for productivity &
Features for safety,
Sharpness of edges
crate A, B, Weight, length, number of parts to be Stability factor,
stacking of crates
able to carry
poses a danger,
part A, B,
size (length, width, height) , surface
Same as for
Same as for
conditions (slippery,sticking), shape
conditions (jamming, tangling,
sharpness), weight, fragility, using
both hands, ease of operation , ease
of alignment, depth of insertion,
symmetry, distance (arm reach),
Speed of motor, machine time (is
Reliability, ease Maximum load
Ease of operation, distance to walk,
ease of grasping
reaction speed of
Sharpness of edges,
distance of rolls
battery tool Ease of operation, machine time,
Reliability, ease Lifetime of battery,
Weight, length, number of parts to be Modular
able to carry
ease of operation
damage to part,
load distribution compatibility to
load distribution compatibility to
1.5.4 Method study
The sequences in process analysis are important and few software's help to chart the
possibilities because the number of permutations are too big. Analyzing the
sequences or 'work methods' as it is also called is worth the effort because it can help
innovating the process. The functional analysis helps to overcome and visualize this
problem. All the objects are equally present and the sequence can be reviewed
instantly. However some work remains to be done in defining time contradiction
within TRIZ. A time dependency is included in the Ideation terminology.
The bolt can be taken by means of battery tool (magnetic head) and thus the bolt is
screwed on the piece B. The operator doesn't need to take the bolt anymore so some
time is gained.
lowers Walks to
holds Piece A
1.6 Re-thinking the known work floor
Applying the rules as defined earlier to trim , combine, invert functions one is able to
rethink the work floor as we know it today.
Following table contains an object list and some trimming solutions, just by looking
at the functional map.
Trim the worktable and relocate it function to the conveyor:
The function of the conveyor is to bring the piece to its next intermediary
place (normally to be mounted on another piece). The roller could also
serve as a worktable and so eliminating the hoisting to the conveyor.
Use crate as worktable (see further)
1. The function of the crate is to hold the piece A. If the crate could serve
the function of the worktable all the hoisting could be eliminated. This
would mean that the crate would have to be redesigned since the other
pieces will obstruct the assembly of one piece.
2. Another possibility is that the crate provides the function of transport;
part A, part B,
Fundamental , can not be changed
For change see step 3 (packaging is changed to improve taking)
The function of the battery tool is to fasten the bolt. Up to date you
could find a battery tool that screws faster.
For instance the bolt also could be put on the battery tool and then
screwed on the piece. This will improve the productivity of process.
flow way, box,
See step 4
The function of the hoist (peer and button) is to transport the piece A (by
lifting and lowering). The lowering and lifting has no added value, in this
case it could be considered expandable. Consider that a fork truck delivers
the function lifting and lowering also on the forehand, it would be wiser to
use it in this manner.
This example clearly shows that functional analysis leads to a lean management
environment! Trimming leads to cleaner workplaces as described in 5S, but also
eliminates waste of motion, of movement (muda or waste).
Using this technique one can describe the risks involved by each remaining object to
improve further the workplace.
The functionality 'holds' is excessively present on the piece A. Piece A is held by the
crate, the hook, and the worktable and the roller. The author invites the reader to
come up with easier systems to assemble!