nesting vs point-to-point: among others, ken susnjara says that reduced scrap, higher yield and the ability to machine around defects are some of the more prominent advantages nested based manufacturing has over point-to-point machining.
The following section appears in the second chapter of susnjara\'s book, highlighting the advantages of using nested manufacturing.
Custom carpentry, especially custom cabinets, has changed dramatically over the past few years and continues to change at a fairly fast pace.
Most of this change is a product of nested manufacturing.
When 32 mmdowel buildings entered the United States for the first time from Europe, cabinet manufacturing evolved for the first time.
This construction method uses panel saw and point-to-
Point processing center.
This method uses the same basic method as the traditional method to automate processing.
First, the bulk material is sawed into a separate blank, and then the separate blank is drilled and processed into the final shape on the CNC machine, one at a time.
Point, machining and possible saw are now automated.
The cabinet design software evolves at about the same time and proposes to create programs that drive panel saws and dotsto-point.
At this point, I need to explain what I mean by \"point-to-point\".
Original CNC drilling machine bed for 32mm drilling is relatively low price
Cost machines, but also limited in functionality. To save money ,[operators]
When moving from one drill to the next, no coordinate axis movement was attempted.
Instead, they are only interested in the position of the machining head when the drilling occurs.
Since the machine is only used to locate the drilling point, it is called the point-to-point.
The shaft coordination and crash capability was then added and the manufacturer tried to change the name to the machining center.
At the same time, in order to solve the same market, drill bits have been added to the CNC router, which is also known as the machining center.
When two completely different methods and two completely different machines are called the same thing, Thingscan becomes very confusing.
So in this book I will call a machining center
Cut the blank into the final product a \"point-to-
\"I will refer to the machining center that processes parts directly from the whole sheet of paper as\" CNCrouter \".
\"It is important to recognize the difference between the two methods, because from the point-to-
Pointing to nested machining on a CNC router results in a significant increase in productivity, especially for stores that do custom work.
Let\'s take a look at the differences between the two methods in actual use.
Start with panel saw/point-to-point approach.
Basic steps required to process parts using panel saw/point-to-
The point is to transport the sheet to the panel saw first.
Then cut the paper into blank through the panel saw.
Then sort and identify blanksmust and have to separate those parts that need edge trim from the others.
These were taken to echabond and echabond.
Then all the parts are shippedto-point.
Where the parts are processed by pointto-
Point, one at a time.
When machining blanks of different sizes, it may also be necessary to adjust the position of the vacuum pod. Point-to-
The machine usually uses a separate pod. -
Some Square, some round. -
These pods have a rubber seal on top that uses a traditional vacuum at a fairly high level of vacuum.
This method produces a huge holding force and tends to keep the blank well, but this method works only when a complete seal is developed between the pod and the blank.
Therefore, it is necessary to seal the number.
Therefore, it is important that the pod is located under a blank, away from any edge to be cut, and away from any hole that may pass through the part.
If the pod position is incorrect, the machine cuts into it and not only seals, but also keeps
But the pods are often damaged or damaged.
Therefore, it is important to verify and adjust the position of the pods for each part, which takes time.
Now, let\'s compare it to nested machining based on CNCrouter.
The first step is to transport the sheet to the machine.
These complete sheets of paper are loaded onto the table of the CNC router and the parts are processed directly from the paper.
Since the paper is high-
Flow vacuum system, no adjustment is required to keep the parts in place.
Then the parts are edge.
You might notice that I did not include the steps to ship the parts to edgeband.
The reason is that most of the time, the CNC router operator can edge-seal the parts of the last piece of paper while processing the next piece of paper.
It usually takes 5 to 8 minutes for a complete machining cycle, so that there is enough free time for edge sealing. With the point-to-
Point, the pod must be adjusted, each component must be handled separately, keeping the operator fully occupied and not allowing any free time for other processes, such as edge seals.
Overall, a panel saw/point is needed for four to five people-to-
With aCNC routers and nested-based manufacturing, points can be completed with two or three people.
The first advantage of web-based manufacturing is that it requires less labor.
The next advantage of nested manufacturing is that it usually leads to better yields.
The increase in yield is mainly due to the fact that the panel saw can only cut straight lines, while the CNC router can cut in any direction.
The panel saw must cut all parts into rectangular blanks, not even rectangular ones.
The excess material produced by these parts must be ground.
The CNC router can cut the actual part shape from the paper, and soparts can be interwoven in the nest.
This can save a lot of material on some designs.
Even on rectangular parts, the panel saw requires the edges of the rectangle to be arranged in the nest along the common cutting line so that the saw can cut them.
If the width of the rectangle is different, this requirement will result in additional scrapping.
The CNC router allows the rectangle to be bent in the most efficient way (it\'s ca[
Real shape Led)
, Eliminating the need to arrange the parts along the cutting line, and eliminating additional scrap.
Some proponents of the panel saw pointed out that the arouter bit cut is larger than the cut of the saw blade, which reduces production.
This is rarely the case in the real world.
The only case where this is possible is that the difference in kerf width determines whether one of the two sections can be nested on a standard width sheet.
The normal cabinet depth used today allows enough dean-
On paper of standard width, there is no difference in the material around each part.
In addition to saving labor, nested-based manufacturing products are also good, in many cases compared to panel saw/point-to-
Produce points of the same work.
The next advantage of nested-based manufacturing is that it runs parts faster than panel saw/point-to-point.
The productivity of each method depends on the processing speed of the part.
Actual processing speed of CNCrouter and point-to-
The point is similar.
The processing speed is usually determined by the tools and materials being cut rather than by the machine.
Whether it\'s a router or a point-to-
Point, usually much faster than the maximum speed at which the tool cuts typical materials today. With the point-to-
However, the operator must uninstall and load each part.
The time required to do so is added to the processing time of each part, extending the overall processing time of each part.
The Point machine uses a vacuum pod to fix the parts for processing.
These steps must be adjusted according to the difference in part size, so this additional step will add more time to the whole process.
Since the point-to-
Point must process a part at a time and must clone any tool changes for each part to add additional time for the cycle.
In nested-based manufacturing, a tool is changed and then every part of the tool that needs to be processed.
This will lead to fewer tool changes and faster production.
Finally, nested-based manufacturing requires less capital investment and less overall workshop space.
CNC router and equivalent point-to-
The cost of the point processing center is similar.
However, with this --to-
Point, you also need a panel saw.
In addition, two machines require more floor space and support space than one machine.
As you know now, I am a real fan of nested manufacturing.
The nested-based process has been improved so that all the small problems and techniques are well handled.
That is, all methods based on nested manufacturing are different.
Now, let\'s take a look at these details and differences.
The first question is: where do you do nesting?
In general, it is assumed that nest and the generated CNC program are generated by the cabinet design software and then sent to the machine for cutting.
Traditionally, this is how it is done, but there are some problems with it, and there is a better way.
To understand, let\'s take a look at the work that is not typical.
The first thing about typical work is that it requires two or three different plates, probably with different thickness, and you rarely use every point of each plate.
At the end of the work, you will have two or three or more materials left.
Some of them may be half or three quarters of a piece of paper, and this material has real value.
It would be nice to be able to use it in the next job.
Once you have done about ten jobs, there are 30 to 40 parts of all kinds of materials around you.
Let\'s try to use these in a new job.
Most design software has some rules that do not use full paper.
The first thing you need to do is measure and record the actual size of a part of the paper.
Now take this information to the office and enter it into the design program.
After doing this, you will get a nest program that combines these tables with some complete tablessize sheets.
This nested program is usually sent to the machine over the network.
Before we are ready to run, we have to sort a bunch of our drawings to locate and identify the actual drawings the program wants.
This may not be easy to do, depending on how much we have and how close they are to the same size.
It is even possible that some of these flakes are used for other purposes or damaged when we program them into our work.
If so, it will be difficult for us to make choices.
We either go back and start over.
Program the work or we can use a complete table instead of a partial table.
Unfortunately, the latter will produce more parts of the paper that we have to deal.
As you can see, it becomes very complicated.
In the actual operation, it may be a bit worse than this.
Most stores find that the hassle and waste of trying to use this extra material is more expensive than any savings they may realize.
The idea sounds good, but it doesn\'t work very well in the real world.
Usually, they either let the sheets pile up and eventually ship them away or scrap them at the end of each job.
However, there is another way for nesting to work better.
What if we do actual nesting in machine control instead of office?
If we can add some improvements, it may solve many of the problems we have just discussed.
After some serious analysis, This Is Us (ThermwoodCorp. )
Decided to take it.
We are in a unique position because we have not only developed the cabinet design software, but also the software to operate CNC control.
In order to solve these problems, we can modify the two so that they can be combined seamlessly.
This approach not only solves some basic problems, but also provides many additional features and functions.
Instead of sending machine program files to CNC controls, we send instructions for the individual parts needed for the job.
Machine controls then nest these, perform CAM functions, and then perform post-processing functions to generate a program that can run.
Here are some additional features that are critical to achieving this in the real world.
In addition to nesting and creating CNC programs, controls also print part drawings that make up each nested table.
It also prints a stick.
Identifies the label on each individual part.
To do this, the controls themselves are equipped with a set of printers.
If you look closely, you will find that some of these labels are printed with bar codes, while others are printed with them.
Bar codes are used to identify any parts that need to be processed on the back.
Depending on the construction method and design, some parts may need to be processed on both sides.
When this happens, we need an easy way to identify these parts and perform reverse machining.
In fact, the label is located on a part in a particular corner.
After running nest, any part with a bar code is separated and stacked to the side.
Once all the whole piece is processed, the flip operation can be performed.
There are a few things we need to do at this point.
First, we need to identify each part.
We then need to retrieve the correct CNC program needed to process the back of the part.
We then need to position and position the parts appropriately for processing.
If we can\'t find an easy way, this could be a major hassle.
Bar code labels solve this problem.
We can scan the barcode and tell the control which part we want to process.
This means that you don\'t need to keep the part in any particular order, and it\'s impossible to run the wrong program on the part.
Once the control knows the part we are going to process, it can automatically retrieve and load the correct CNC program for that part.
We will use the corner of the machine table to locate the parts.
Region set with flip
An upward stop device that can be used to locate parts.
These are then flipped down so that the machining can be done throughout the perimeter of the part without hitting the positioning rod.
When we place the label on the part in the nest, we place it in a specific corner of each part.
We will now use this tag to help us locate the flip partside machining.
Flip the part and place the label on the block in the corner.
In this way, you don\'t have to worry about the correct positioning or orientation ---
It\'s almost automatic.
Flip after pressing the start button-
Finished side processing.
This method is as simple and simple as possible.
Scan the label, locate the part and click the Start button.
The system does paperwork, identifies the part, and then finds, retrieves, and loads the correct program for that part.
This is an obvious example of the practicality of the system in practical applications.
If you\'re going to make 100, 200, or 500 parts, it\'s no big deal to look for and load program files.
If you are running a part, any time you need to find the program is a transaction. Custom carpentry has a whole new set of requirements that don\'t matter to more traditional applications, but it\'s critical if we really want to automate the custom business.
The next important advantage is that the control also prints bar code labels for the rest of the paper or paper at the end of the job.
This barcode can not only identify the size and shape of the part, but also the material of the part.
This is another feature of the real world.
If you look at the untypical scrap you will find that there is a fairly large unused surfaceuse.
What stands out from here is the fine sticks and spires, as well as a variety of almost worthless stands, which will make it painful to process and store this material.
Again, the technology came to rescue.
At the end of the cycle, after all parts are cut, the control checks the remaining materials and cuts on the outer edge of the large blank, removes the bumps, and produces a fixed blank, known dimensions that are easy to handle and store.
The next time you run the job with the same material, you can use this piece.
When you load the job for the first time, before the nested execution, the system asks if you have any paper or blanks that you want to include in the job.
Scan any paper around in the order you want to use them.
The control will first nest on these nicknames, then use the full sheet of paper and print the label for any remaining material.
Another benefit is, remember I said before that the controls know what material the part of the panel is made.
If you start a job that runs with a specific material, but try to use a panel of different materials, you will be reminded.
Again, we are trying to make the average jump process as simple and simple as possible.
As you can see, nesting in controls makes it simple and clear to use this external material, eliminating a lot of steps, fumbling and sorting tables, but it also allows you to solve another possible problem
One page or more materials may have defects that you do not want to include in the part.
That\'s a real problem when you\'re in the office.
However, when you nest on controls, you can identify bad areas and nests around controls.
You can use this paper now, otherwise you\'ll either need to discard it or spend some real effort trying to program around it.
This may be an interesting feature in the future.
We have discussed with some of the largest plate manufacturers possible ways to use surface defect plates.
In their process, they use visual systems to verify the surface quality of each material they manufacture.
Some of them have surface defects that must be rejected.
According to many factors, the number of these sheets may be quite large.
The surface defective paper may account for 5 to 6% of the production, which is a lot of scrap when you produce thousands of sheets of paper every day.
Their visual system can not only identify defects, but also identify the location of the defects.
If this information can be provided to machine control, it is possible for each material to detect defects automatically.
Therefore, the material has changed from something of little value to material actually used.
Material suppliers still need to provide this inventory at a deep discount, but not as deep as today.
This material can be easily used by Cabinetmaker and can be greatly discounted in the process.
So far, you \'ve started to see some interesting techniques that have been developed with the main purpose of making the new parts that are machined custom practical.
From this core, additional capabilities are added to provide more flexibility.
Complete copy of new furniture: how modern technology can change the furniture and cabinet industry and can be done at www through thermwood.
Wholesale woodworking. com.
Thermwoodalso also presented the book free of charge at its trade show booth.