Posted by Nancy Grossbart
When my company (MDI Products) first began to work with product designers who wanted to create a foam product and had lots of plastic molding experience, it was very difficult to get them to "think differently" about how to design a product that took advantage of our
injection molded foam process. There are only some things about both processes that are similar. Both plasticize raw materials in a hot barrel. Both inject in the materials into a closed mold. Pretty much the similarity stops there.
Understanding the fundamentals is key to designing a great part. To really comprehend what is happening, you need to first know that injection molded foam is actually a foam manufacturing process which manufactures foam in the shape of your part.
The next area to understand that, unlike the single mold plastic process, the machines used in the injection molded foam process are multi-station presses, which utilize multi-molds.
Again, unlike plastic injection, the mold cavities are designed smaller than the final part size. The parts expand rather than shrink. The amount of expansion is dependant on the material softness you require.
The material remains in the heated mold during the cross-linking or cooking process. The cooking time is dependent on the thickness of the part. The mold opens very quickly when the cooking is complete. The part expands and explosively self ejects from the mold cavity. The part is removed from the mold station and set to cool.
Learn more about self-ejection, draft, corners, edges, and undercuts later.
Posted by Nancy Grossbart
Polyolefin foam is a great material for kid's products. It works well in lots of applications from padding for sporting goods to sandals (Crocs) and now, products for kids.
To begin with, it's closed-cell. That means it's waterproof and won't absorb bodily fluids. It also means it resists mold and mildew because the bacteria has no place to reside.
It's so light that it floats and can be used for bath or pool toys and has no adverse chemicals so when kids put the toy in their mouths, there is no need to worry.
Polyolefin foam has a high tear and tensile strength so it can't easily rip and won't crack or peel. This means it will not only last a long time but, when kids put it in their mouths, it will pass the bite test.
The chemistry of polyolefin foam makes it resistant to most chemicals. This allows you to clean and disinfect it with any household cleaner keeping it safe from any surface bacteria.
Parts can be also designed with lots of features and benefits including molded-in logos and graphics. And can be made in extremely bright, attractive to kids, colors.
If you're wondering if it will pass the new CPSIA standards, it will!
MDI Products' offering of formulas known as PolyCellTM are phthalate free, PVC free, AZO dye free, with insignificant metal content. In addition to all the other reasons why it is great for kid's products, you can also be confident of its safety.
I'd love to get your feedback on what other specifications might be important for kid's products.
Download 8-page white paper on
"Understanding Flexible Foam".