Specifying Cartons for Protecting a Product – Part 2
Applied Engineering: Specifying the Folding Carton
Having the actual product – the film cartridge plus the “primary package” canister – the packaging engineer can then easily weigh the two components together, take down the measurements, and then start the process of creating the carton specifications. In addition to knowing the weight and size dimensions of the end product, the engineer must also take into account its fragility and any possible environmental considerations. The plastic canister provides enough compressive strength and barrier properties to mitigate any chance of the product being damaged. While it is true that the packaging engineer places great importance on protecting the product, they also take costs into consideration and try to minimize the amount of material required.
Once all of the dimensions have been determined the engineer can start the folding carton design process. To perform this task they use sophisticated (CAD) software. The software has available choices of standard structural categories to choose when creating a structural design. Although there are an infinite number of structural design possibilities, there are a few basic styles that make up the majority of folding cartons in use. A list of some basic styles include: Standard Straight and Standard Reverse Tuck (SST & SRT); Sleeve; Full Overlap Seal End (FOSE); Economy and Partial Overlap Seal End (EOSE & POSE); Tuck Top Auto bottom (TTAB); Tuck Top Snap Lock Auto bottom; and an lots of different tray styles with varying complexities. Each basic carton style has its intended purpose. The best choice comes down again to how the product is being filled, the customer’s packing and distribution requirements, and how it is being displayed.
In designing a carton for film, knowledge that the product will be filled on an automated line guides the engineer toward choosing a structure that works well in a high-speed assembly line. A tube style carton with a full overlap seal end is ideal for this purpose. The engineer needs to enter and identify the three dimensions for the carton: length, width, and depth. The design software aids with the size dimensions for other carton components such as glue flaps, inner and outer closure panels, and dust flaps. The flaps and panels must fit together properly to function, and the graphics must line up so they register properly. The software ensures that an assembled carton meets these requirements. The decision on the choice of paperboard thickness comes down to that balance between protecting the product and minimizing the amount of material, and ultimately – the cost.
A good part of the criteria for paperboard selection comes down to marketing considerations. Bold and bright colored cartons with a critical eye toward corporate identity standards will look best on Solid Bleach Sulphate (SBS). If the customer places a greater emphasis on sustainability then recycled Clay Coated News back (CCNB) might be the desired choice. Having produced film cartons in the past, I can speak from experience that we arrived at specifying a 14 pt. thick SBS for our customer. As a basic rule of thumb, we advise going 2 pt.’s heavier (16 pt.) if a CCNB stock is chosen. This is to make up for the inherent strength advantage SBS has over CCNB.
At Impressions Inc., our package design process is done in accordance with the ISO 9001:2008 standards Once the outline or “drawing” of a carton has been completed, the file is then sent to a sample table to cut and score a prototype on the actual material, which can then be used for evaluation and testing. It is important for the engineer to verify that carton can indeed be produced within our manufacturing capabilities. Any modifications to the design are documented in great detail for future reference, as is the final customer approval. Once the structure has been approved, an “e-line” of the structure is sent as an attachment to a graphic designer who can then place the graphics with precise accuracy. Any areas that cannot be printed are clearly identified.
Testing the Carton
There are organizations that write protocol for the testing and certification of packaged containers. Two well-known such organizations are the International Safe Transit Association (ISTA) and ASTM International. I don’t have the experience to talk about the specific roles these organizations play, but in a more general sense they provide guidelines and accreditations for testing labs and the methodologies these labs perform. Their testing covers the wide range of conditions a shipper will encounter including shock, vibration, compression, and atmospheric conditions and environmental hazards. ASTM International even has a protocol for anticipated pressure reduction when a load-carrying plane flies over a mountain range. Consumer products have far reaching distribution channels and have to survive all possible sorts of hazards.
When specifying a folding carton at the single-unit level, this level of testing is usually not necessary. In addition the determination of the product’s fragility, the package engineer will make a testing evaluation requirement based on the weight, size, and cost of the original product. Film, along with many well known consumer products, is very light and not extremely expensive so the individual paperboard carton would not need to go through as much testing as the shipping cases.
To enhance the strength of the folding carton, the engineer could look at various options such as a paperboard insert or divider, some corrugate, Styrofoam, or other materials that would help buffer and hold the product in its place. Once again, the engineer wants to hold down costs and minimize the amount of materials needed to make the package.
Although earlier in this post I acknowledged the need of a plastic canister for a film carton to protect the product from outside contaminants, it is fair to point out that there are also available barriers –such as laminates and coatings- that can be applied to a paperboard roll to reduce its permeability. Each different type of laminate and coating has their own properties that provide barrier protection for the finished product. These barriers offer protection from oxygen, moisture, solvents and other potential contaminants. I am not aware of any such testing to avoiding using the canister in our film box example, but I’m sure it was at least considered at some point.