Co-authored with George Hank from The Company alber in Germany
Sunkist has collaborated again with Albert Germany to discuss the density of polyurethane foam, why and when it matters, and the rule of thumb when combining foam with bandsaw.
The first and most important thing to know is that Density does not equal hardness, We have covered this in the previous article. High-density foam is not necessarily a rigid foam, and foam that feels hard to the touch is not necessarily high-density.
That being said, higher density foams generally have a higher shelf-life. This is because low-density foams have more surface area in contact with air as well as less material in general. Low density foam, of course, is easier to produce. High-density foam, however, is harder and longer-lasting, so when given the choice, Sunkist always recommends high-density foam for the longevity of the product.
Low Density Foam Cutting
Toothless blade is the best choice for cutting low density foam. They provide the best yield in terms of product quality and blade lifetime.
Most prominently, toothless blades provide a clean and smooth material surface after the cut. This is why most Sunkist customers opt for a toothless blade on their continuous foaming line block cutters. With a seamless cut, there’s no need to re-trim that side during the conversion, saving you both time and material costs.
As bandknife experts, Albert also stresses the importance of bow, which is the angle of the blade as sharpened on either side. A precise and symmetrical bevel delivers a straight cut without deviation, ideal for minimizing material loss from further trimming.
High Density Foam Cutting
Toothed blades have higher cutting power and are a better choice for materials with higher resistance – ie high-density foams. This also applies to foams containing hard skin or abrasive chemical materials (for example carbon as a flame retardant and rebonded foam).
Here’s the breakdown of the Elber: The smaller teeth on the serrated blade give a finer, smoother cut with less dust buildup. Larger teeth allow faster cutting speeds and can increase the life of the bandknife in the case of abrasive foam. In some cases sharpening is used, which reduces the height of the teeth to a certain point. The different tooth sizes and shapes allow for customization based on each material type. ask our experts To recommend the right blade for your machine.
Foam density does not equal foam stiffness. Smooth blades are generally the best choice for low-density foams, while serrated blades are a good choice for high-density foams.
When you send a quotation request to Sunkist, our sales department asks you to fill out a questionnaire about production. Foam density is one of the most important questions you must answer. This allows our engineers to design the best option for you.