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 skeleton can help you understand the nesting process more accurately and can be used as a launch pad for the game plan to achieve the desired result.
After looking at the “skeletons” of the nesting process, you may find that you can generate more efficient nesting. But please know whether the result that needs to be considered is the actual result obtained after the change is made. 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 yield with the workflow of the entire workshop.
If you work in a large workshop that handles a large amount 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.
Expanding the combination of parts may increase nesting efficiency, and it may also increase the time the operator spends on machine setup downstream, which is caused by frequent material and tool changes. In addition to preventing auxiliary operations, the 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 the color changes .
When considering the entire workflow of the shop, make sure to investigate the actual time it takes 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 required to find creative 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 the 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.
Batch nesting is one of the latest nesting improvements. Batch nesting needs to be nested on multiple sheets at a time to achieve the best overall material utilization. This paves the way for higher yields, because a wider range of parts can be effectively nested 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 time, material output or manpower.
That is, in terms of maximizing materials, using the ideal paper size may also be a factor. 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, leaking all your production secrets to someone who can listen. Is the framework in good shape, or does it indicate that your process can be fine-tuned? Are you so fascinated by nested parts that the paper is dumped into the machine, or is there an annoying collision? How much material is left?
Although you have worked hard to read all the clues available, sometimes our best plan simply fails to work in practice. For example, by diligently producing the best nests, a high material utilization rate can be achieved, but when these nests are actually cut, the grinding wheel is out of the entire operation.
In order for the nesting to work normally, 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 accumulate bones under the punch or to 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 skeleton 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 yield by nesting between fixtures. Perform common wire cutting without sacrificing the stability of the printed sheet, and use the largest part group size to create a subset of the common 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 residuals 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 retrieving them 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 bit of material, but it will simplify the logistics, for example in the previous example, the result is a 48 x 36 inch residue.
In addition to reading the skeleton used for drawing utilization, the bones left after nesting can also tell you the nesting and part quality challenges related to roll paper 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 machinery 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, the 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 material utilization in a way that meets the needs of your workshop. 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. Through this integration, your business software can tell you which parts you need to cut and when, so that timely parts can be easily moved downstream for secondary operations without forcing the operator to spend a lot of time managing the parts stack. Ideal settings might include part disassembly and stacking automation, which can reduce errors and give operators more time to focus on other tasks.
Everything that is read and understood at a glance is beneficial to the workshop. Strategic part identification (for example, color-coded nested reports) can simplify classification and achieve error prevention. And add part identification during the nesting process, such as an etched part number or a printed label that can be manually or automatically applied, to identify the part before it leaves the nest.
Although not every shop has the resources needed to achieve the ideal settings immediately, especially without interrupting processes that normally work well, 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-14-2020