Static Nest vs. Dynamic Nest - The Balance Between Efficiency and Flexibility
Next, we delve into the nature of the nest itself. A static nest, one that is regularly reused. Where operators are regularly unloading the same pattern, they may be able to remember where plies are, or have a static printout for guidance. These nests are unlikely to be very efficient if they comprise of a single kit, although creating a nest with multiple instances that you’ll regularly build could be much more efficient, and the chosen method for many manufacturers. However, they lack the flexibility to accommodate a mix of parts that you may want to make at any given time, and the possibility of even greater material efficiency. This is where dynamic nesting steps in.
A dynamic nest introduces a mix of plies and kits into the layout. Although it may or may not potentially be as efficient as its static counterpart, it offers the flexibility of being able to create a range of parts, adapting to changing manufacturing requirements—all without disturbing the rhythm of the production process. For example, you could create a dynamic nest with a day’s worth of production that may also include plies scrapped from the previous day’s/week’s production.
‘Progressive Nesting’ - Balancing Efficiency with Operator Convenience
Next, we have progressive nesting. Progressive nests are created by sending each kit of plies for nesting one by one. This method, while not the most efficient in terms of material utilisation, pays dividends in another critical area; the time it takes the operator to unload and group the plies into their respective kits. This can be significantly reduced with progressive nesting, and showcases an alternative aspect of efficiency—time savings on the shop floor, which lead to a different kind of economic gain. Nests will not be as efficient as fully dynamic ones, and smaller plies from later kits may appear earlier on in the nest, impacting on the operator’s time.
Hybrid Progressive Nesting - Merges the Best of Both Worlds
Hybrid progressive nesting is a balance between material and time efficiency. By still grouping kits but allowing plies to be placed within a predetermined distance of the kit, composite manufacturers can 'bleed' or merge kits into each other during nesting, forming a more efficient nest than a strictly progressive one. Thus, a hybrid progressive nest balances material and time savings, as the operator will not have far to travel to pick up the smaller plies.
How different nesting strategies compare
In this example, we’ve created four nests:
Nest 1
Standard dynamic nest.
This is a standard mix of ten kits, with no grouping applied. It is the most efficient of the four nests, at 11.763m, but will take the longest to unload, as plies for each kit can be placed anywhere on the nest.
Nest 2
Standard progressive nest.
Each kit is sent to the nester separately, but smaller plies of later kits can be nested earlier on if space allows. This example is 447mm longer than the standard dynamic nest, and will be relatively easy to unload as most plies are grouped together, but it may cause some delays due to the nesting position of the smaller plies.
Nest 3
Fully (forced) progressive nest.
By rigidly forcing kits to be nested together, effectively forcing a boundary around them, we get the easiest to unload nest, at the expense of material consumption. It’s 1.793 metres longer than the dynamic nest, so the question is whether the speed of unloading outweighs the significant material trade-off.
Nest 4
Hybrid progressive nest.
Here, we specified that smaller plies could nest up to 1 metre within previously nested kits, and our nest was only 682mm longer than the dynamic nest, and just 235mm longer than the standard progressive nest. Yet, all plies should be within easy unloading distance from each other.
As expected, nest 1 is the shortest and nest 3 is by far the longest, but the smallest difference is between nest 2 (the progressive nest) and nest 4 (the hybrid progressive nest).
Of course, every dynamic nest will yield different results. If you’re mixing kits and maybe even adding previously scrapped plies in, you may find that one strategy delivers a better balance than another. Fortunately, with JETCAM’s Ultra Performance nesting, you can try multiple strategies without spending hours doing so – the above examples were created in under thirty minutes (that’s all four nests in 30 minutes, not 30 minutes each). In short, CrossTrack allows you to quickly generate nests that are optimised for material efficiency, optimised for best unloading, or anything in between.
Taking this a step further, if you are planning to integrate unloading technologies, a fully dynamic nest will still take an automated system longer to sort and group than its progressive counterpart, as plies will need to be placed into a buffer area until they can be sorted into their final kitting order. So, if you are looking to reduce your overall cutting to kitting time with automation, it’s the software that will help you to achieve it by making the hardware work more efficiently.
Sharing Nesting Data Up or Sideways
As a side note, also consider the potential advantages of sharing or using nesting data with third-party systems such as Enterprise Resource Planning (ERP) systems, or technologies facilitating unloading, kitting, or automatic ply placement. CrossTrack allows easy data exchange with any system using a variety of highly configurable methods. This not only minimises data entry and the possibility for error, but also helps to automatically add traceability, as each process or physical movement is logged. Examples might include getting an automated freezer to deliver the right roll of material prior to cutting, or passing kit information to an autoclave, which can then automatically inform CrossTrack when the autoclave process is complete, stopping life tracking in the process.
The data created and stored around nesting can also help with areas such as costing, as material apportionment reports could be written and automatically generated, giving you the true cost of the material and scrap associated with a composite part.