Strategic nesting is a balancing act between sheet metal and sheet manufacturing. You want to obtain the best material yield and stability of the cutting process, but you also need to consider downstream operations. Getty Images
Although manufacturers understand that nesting is prepared for optimal efficiency, they usually learn the hard way, that implementation technology cannot replace the need for an accurate description of how the nesting process affects the shop floor workflow. Reading the clues left by the bones can help you understand the nesting process more accurately and can be used as a launch pad for game plans to achieve the desired results.
After reading the “skeletons” of the nesting process, you may find that you can generate more efficient nests. But please know whether the result you need to consider is the result you will actually get after making the change. Yes, the skeleton can tell you how to maximize the use of materials and the efficiency of machine cutting, but knowing how to deal with this information can be tricky. Nesting is the first step in a production process with many moving parts, so you need to balance the benefits of increasing material output with the workflow of the entire workshop.
If you work in a large workshop that handles large amounts of material, or often work with expensive materials, even a small increase in paper utilization can produce impressive results. Medium and small stores can also gain significant benefits through efficiency arbitrage.
No matter how much you may save, finding the right balance between higher material yield and smallest work in process (WIP) is a challenge. If the parts move smoothly downstream, the real question is whether you can send more parts downstream without shaking or sinking the ship.
Although expanding the part mix may improve nesting efficiency, it will also increase the time the operator spends on machine setup downstream, which is caused by frequent material and tooling changes. In addition to preventing auxiliary operations, the more mixed use of parts in the nest may cause your welding department to wait for the last part in the assembly before continuing the work, or make the paint line wait for the last part before changing the color.
When considering the entire workflow in the workshop, make sure to investigate how much time it actually took to load and change tools between jobs, change laser cutting gas or load different NC programs into the controller. In addition, does your CAM system allow you to edit the automatically generated nests?
It also helps to understand how much time and effort is invested in managing and tracking finished parts, especially when laser or stamping operators are asked to find novel ways to stack parts around the machine.
If you carefully consider the downstream stroke of the part, changing the nesting process can bring huge benefits. Even if machinery and personnel are added to respond to the increasing demand, efficiency can be improved. Regardless of your situation, a careful investigation of the actual needs of your store is the right starting point.
Dynamic nesting is usually the fastest and easiest way to handle various parts. The dynamic, true shape nesting illustrates the unique shape of each part and nests them on the drawing. For example, if you have a part shaped like a window frame, you can nest another part in it to make the most of the sheet. With dynamic nesting, you are unlikely to leave a lot of material on the skeleton because it is designed to automatically utilize as much material as possible.
Bulk nesting is one of the latest nesting improvements. Bulk nesting requires multiple sheets of paper to be nested at a time to achieve the best overall material utilization. This paves the way for higher yields, because it is possible to effectively nest a wider range of parts not only on one sheet, but also on several sheets.
When stores often perform the same work, static nesting is usually used, so static nesting can be reused as needed. Depending on the strengths of your CAM or nesting system, the time it takes to make changes to existing jobs may further erode the savings gained by increasing material yield.
Applying collinear cutting can help you improve cutting efficiency, especially in certain nested layouts. But in some cases, it is unlikely to create significant gains in terms of time, material output, or manpower.
In other words, using the ideal paper size may also be a factor in maximizing material savings. This does not necessarily mean that you need to prepare multiple sizes of paper, but it is a good idea to perform some experiments or test runs while allowing the nesting software to view multiple paper sizes and make the correct selection based on the part. mixing.
The question here is not whether there is a skeleton in the closet. You know that you already have a skeleton, but it is in the workshop, revealing all your production secrets to someone who can listen. Is the framework in good shape, or does it indicate that your process can be adjusted? Did you move away because of the nested parts so that the paper was dumped into the machine, or was there an annoying collision? How much material is left?
Although you have worked hard to read all the clues available, sometimes our best plan does not work at all. For example, by diligently producing the best nests, you can achieve a high material utilization rate, but when actually cutting these nests, the grinding wheel will be out of your entire operation.
In order for the nesting to work, the nesting software must be compatible with the machine, because the nesting can only be cut into the best function of the machine. The fastest way to build up the skeleton under the punch or possibly remove the laser head is to create a poor cutting path.
• Move small parts away from the clamping edge to maintain the integrity of the skeleton. This will provide your bones with the required structure to provide a strong frame for the part.
• Avoid heat accumulation to ensure parts accuracy and avoid collisions. On laser or plasma machines, cutting multiple holes or small parts in concentrated areas may deform the material. On a punch or laser machine, parts may fall off the tabs that hold them in place.
• Improve material output by nesting between fixtures. Perform normal wire cutting without destroying the stability of the paper, and use the largest part group size to create a subset of normal wire cutting.
Maximizing the remaining volume may be the key to increasing profits. To ensure consistent results over time, save the ideal residual settings in the production database. You may decide to trim the residue to simplify the handling of the remaining material. However, the caveat here is that creating too many unique remnants can become difficult to locate and manage.
A good option is to use the ideal remaining width so that they are easy to collect when retrieved from storage, and you can limit the amount of remaining size that the operator has to deal with. If you cut the worksheet after the last part of the nesting, you will usually get a unique size, such as 48 x 33.625 inches. Use the ideal width and cut the crop to 6 inches or 10 inches. You can create standard remaining dimensions. You will sacrifice a little material, but will simplify the logistics, for example, in the previous example, the rest is 48 x 36 in.
In addition to reading the skeleton used for drawing utilization, the bones left after nesting can also tell you the filling and part quality challenges related to grid spacing, excessive tabs and poor tab positions. Tracking these results is the key to assessing the quantity and quality of output. Using these results, you can build a database to help you discover best practices.
Developing the most suitable workflow for you, the nesting process of the machine and CAM software may require trial and error, but in the long run, this kind of work will reduce waste and improve the process. Your database should include successful best practices, including material type and thickness, type or style of tabs, and preferences for tab location and size.
When the nesting process is truly optimized, they should be applied consistently to maximize the material to suit your workshop needs. You can change the overall workflow and prepare for the possible influx of various parts, but before putting a potential wrench into work, consider the big picture.
In order to optimize nesting, it should ideally include Manufacturing Execution System (MES), Enterprise Resource Planning (ERP) or similar platforms integrated with CAM software. This integration allows your business software to tell you which parts to cut and when to cut, so that timely parts can be easily moved downstream for secondary operations without forcing your operators to spend a lot of time managing parts heap. Ideal settings might include part disassembly and stacking automation, which can reduce errors and give the operator more time to dedicate to other tasks.
Everything that is read and understood at a glance is beneficial to the workshop. Strategic part identification (such as color-coded nested reports) can simplify and error-proof classification. Add part identification during the nesting process, such as etched part numbers or printed labels that can be applied manually or automatically, and can even identify parts before they leave the nest.
Although not every workshop has the resources needed to achieve the ideal settings immediately, especially without interrupting the normally well-functioning processes, incremental changes can be made over time. After all, the goal is not necessarily to be a perfect store, but to be a store that suits the conditions you already work in.
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Post time: Aug-28-2020