PT Blog

Higher prices for both PE and PP are expected to be in place by end of this month, and further price increase attempts are underway for March, but how they shake out is not entirely clear. In this third week of the shortest month of the year, I checked in with senior editor David Barry at Houston-based PetroChemWire (PCW). One thing that appears to be applicable to both PE and PP is that availability of both resins is categorized as relatively tight, at least at this juncture.

PE update: Polyolefin suppliers have been intent on implementing their February 1, 5ȼ/lb increase and all indications are that this will be a full implementation. They are also out with a March 1, 6ȼ/lb price hike.

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I finally live in a neighborhood that has a curbside recycling, which to be honest, is such a relief especially given the fact that I’m the recycling beat writer for PT. It felt kind of odd not to recycle at my house when I cover the industry on a consistent basis.

Yet I still found myself having to double check a couple items…Is this material too thin to be recycled?...What’s the rule again for in-mold labels?. Thankfully though I noticed much more packaging comes with the How2Recycle Label, which let’s face it—makes it as clear as can be about what can and can’t be recycled at the curb.

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At PT’s Molding Conference 2016, held in New Orleans, we were told of the new concept of “High Definition Plastics” by Steve Verschaeve, v.p. of North American business development for RocTool Inc., Charlotte, N.C.

The HD Plastics Material Database was expressly developed to educate the market to the benefits of Heat/Cool (or “Variotherm”) injection molding using RocTool’s electromagnetic induction heating coils and its new high-performance cooling units.

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Posted by: Stephen Levy 21. February 2017

Melt Delivery Systems: Going Against Tradition

A well designed part is only as good as the melt delivery system feeding it. The goal of a properly designed melt delivery system is to create uniform melt conditions to each gate while accommodating filling pressure limitations, minimizing shear, and providing for cavity packing. 

Traditionally, melt delivery systems are sized based on estimates, similar part geometry, or poor design guidelines. However, when sizing a runner, it is important to minimize any restrictions of the material flowing through the channel. The cross-sectional area (diameter) of the melt delivery system has the biggest impact on both pressure drop and shear rate through the channel.  At a constant flow rate, both pressure and shear rate will increase with decreasing runner diameter to a point. 

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Materials and Additives are examples of the broad focus of Plastics Technology’s Molding 2017 Conference & Exhibit.


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