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Welcome to Optimation's educational video series on nesting technology.
The purpose of this video series is to provide you with a fundamental
understanding of how nesting technology applies to your company.
whether you were considering upgrading your nesting technology, or you just want to
keep current with the latest advancements, you'll find valuable
information in this series.
Cutting regular or irregular shape parts from raw materials is a problem that has
been a part of manufacturing since its beginning.
The art of creating a plan for cutting multiple shapes from a larger raw material
is called nesting.
Often nesting is thought of as the best way to lay out parts
so that the least amount of raw material is wasted.
This is a very limited view of the problem.
In today's modern manufacturing there are many other important factors that
must be considered while material waste is being minimized.
These included
Machine Efficiency,
Scheduled Demand,
Part and Order Flow,
and of course, Unplanned Demand.
All of these components have a cost impact and must be considered in order
to find the optimal solution.
While material efficiency is often the first benefit that comes to mind
when nesting,
any of these additional factors may interact with material efficiency.
The venn diagram shows two important facts.
First there are
many factors that must be optimized to find the best possible solution,
and second,
there is a common solution set that allows all of the factors to be solved.
Inside this common solution set is where the optimal solution will be found.
Now often material cost is the largest cost factor in producing a part.
So first,
we'll concentrate on how different nesting technologies address
material efficiency.
Nesting problems are very large mathematical problems.
To get an idea of just how big these problems can get,
we'll look at nesting just thirty five parts
limited to orientations of zero and ninety degrees.
There are seventy factoral ways to nest the thirty-five parts.
Or put another way
there are over ten to the one hundredth power ways to nest just thirty five parts
limited to only two orientations.
This number is so large
even the fastest computer would take several lifetimes to create all of the
possible nests.
Clearly, it is not possible to brute force the nesting problem.
Since this problem is very old and predates computers
a solution method for parts selection was developed that a person can use
that would tend to get better solutions then just randomly cutting the parts.
The method is still in use today
and is defined as List Driven Nesting.
List Driven Nesting is simple and is used in many computer programs to approximate
a solution to the nesting problem.
Now List Driven Nesting uses the following steps:
A: Order the parts in a list.
In most cases the parts are order from largest to smallest because this generally
favors material efficiency.
B: Place the first part on the list on the raw material
and rotate it so that the center of gravity of the part is closest to a
datum point.
Often this is the lower left corner of the raw material.
C: Take the second part in the list and place it on the raw material
If it doesn't fit, go to the first part of the list that will fit on the
remaining raw material.
Rotate this part until the center of gravity is closest to the datum point.
Repeat this process until the last part on the list has been considered or the
raw material is full of parts.
The result of the above process provides one possible solution out of the over
ten to the one hundred power ways the parts could be nested.
As computers have gotten faster,
more possibilities can be considered and the number of lists and how the
list is ordered
have allowed additional solutions to be evaluated.
Some list driven systems make several ordered lists that each create
one possible nest,
and then selects the best one of the group. So for example, the list can be
sorted by largest length, or largest area,
or largest perimeter, or any other metric.
The common characteristic of List Driven Nesting systems
is that there is one or more lists that determine the order the parts
will enter the nest.
The greatest attribute of List Driven Nesting
is that it considers only a few possible solutions and therefore can run quickly.
The major disadvantage of List Driven Nesting
is that it can only embed one cost component in its list of parts.
So as an example, the list can be ordered by part size or by schedule, but not
by both.
So when considering List Driven Nesting, be sure to evaluate the impact it will
have on other cost components
that may be important to you.
A second nesting solution,
called Cost Driven Nesting, has the ability to consider multiple cost
component simultaneously.
Now this makes the problem much more complex
but provides a means to solve Real-World Problems.
To illustrate this, let's refer back to our diagram. Let's imagine that each
point in this circle represents a different possible nest.
Inside the circle there are groups of nests that satisfy a manufacturing
requirement.
There are nests that meet the material efficiency requirement,
nests that meet the production schedule as well as unplanned demand,
nests they can maximize machine throughput and nest they keep your order
flow manageable.
Where two or more of these circles overlap
multiple manufacturing requirements are being satisfied.
Now notice that the feasible range of possible optimal solutions where all
costs are optimized
is in the area where all of the circles overlap.
By considering all of these factors or costs,
Cost Driven Nesting reduces the number of possible nests down to a
manageable number.
So each cost solution considered is evaluated by applying costs so that the
lowest-cost solution can be selected.
Cost Driven Nesting also uses the mathematical technique of Fathoming.
Fathoming has the ability to search only within the narrower feasible range
of solutions,
and within that range,
look at only the best solutions.
Using these methods eliminates
trillions of bad solutions that do not need to be considered, and greatly
increases the speed
to find the optimal solution.
This technique further limits the number of nests that need to be considered
to a much smaller number of possible solutions.
Cost Driven Nesting works in the following way:
A: A cost model is developed that will allow costing of parts.
B: All costs are considered by calculating a value
for each part based upon how it is nested.
C: As a nest is built multiple costs are considered.
D: Fathoming uses the experience of the first nests to eliminate possible nests
that cannot be better than the ones already built.
This eliminates all of the poor performing nests
without having to build them.
By using fathoming only a few best possible nests are built
and the one that contains the optimal solution is selected.
The advantage of this solution
is that it considers the Real World manufacturing problem.
If your production environment has multiple critical factors to consider
when selecting which parts to cut together and on one machine, then
Cost Driven Nesting
may hold many advantages for you.
However, since this system relies on rapid input of several costing factors
Cost Driven Nesting is designed to be integrated into an existing
manufacturing environment.
Integration points such as CAD and a production schedule are common to
most manufactures.
This type of automatic system
is not recommended for companies that want to interactively produce nests.
Regardless of what type of material you're cutting,
selecting the correct parts to nest is critical to maintaining a high
material efficiency.
However there are several other factors that are also critical to effective
material usage.
We'll be covering the next two factors:
Part Placement;
and Part Quantity in our next video.
We'd like to thank you for taking the time to watch this video
and hope that you will continue to watch the rest of our series.
If you'd like more information about Optimation or any of its products, or if you
just have questions about the material presented, feel free to contact us by
either phone or email.
Optimation provides professional product with full professional grade service.
Our technologies are found nowhere else. Whether you have just one
machine or many, this technology will deliver world-class economic performance.