PT Blog

How to Know When Your Process is Ready to Make Acceptable Parts

When do you know that your press, process, and mold are at a steady state and making acceptable parts? This is a simple question with no simple answer. Consider—as I often have—the hundreds of variables involved in injection molding. Think about processing variables such as melt temperature, screw design, check-valve design and repeatability, injection speed, cushion repeatability, etc. Then consider machine issues like calibrations for pressures, speeds, consistency, wear, etc. Now add in mold variables such as wear, water-line hook-up, flow consistency, and temperature fluctuations.  Given all this, it’s hard to tell when you have reached the point of feeling comfortable to start collecting parts for the production order.  

Perhaps newer computer-driven machines make it easier for a processor or quality-control technician to watch many of these variables. But how many do you pick, which are pertinent to this part, and what are the tolerances? Some shops try doing this, but they find out rather quickly that one of those variables soon goes out of whack.  Depending on how this variable was set up, it may reject the part or shut the process down. 

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Processing Medical Plastics? Here's How to Minimize Risk

In plastics processing for the medical and pharmaceutical industry, it’s all about risk. Or, better yet, about minimizing risk. Manufacturers of medical devices and pharmaceutical packaging, along with their customers, need to make sure there’s no chance a patient might have an adverse experience caused by some defect or oversight. Therefore, the companies supplying component parts also need to be vigilant to make sure actions they take don’t compromise the performance or safety of the final product.

Plastics used in healthcare provide vital functions such as enabling speedy diagnosis, minimal invasive surgery, self-medication, and reducing transmission of bacteria, as well as protecting drugs from moisture and oxygen. These materials must deliver consistent performance, including resistance to sterilization, chemicals and lipids. They often must also meet standards for biocompatibility and toxicity, where even slight changes in the ingredients in the plastics used could affect the acceptability of the finished device. For these reasons, regulatory authorities such as the U.S. FDA and relevant authorities in Europe require that the plastics are “well-characterized” with detailed information on the material ingredients and formulation, manufacturing processes, and extensive supporting data with respect to physical and mechanical properties, biocompatibility and toxicity.

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‘Game Changing’ Flat Die Lives Up to Its Billing

A new flat die and control package billed by its developers as “revolutionary” and “game changing” is proving to be just that. After some three years in development, the Reflex die for cast film and coating/laminating was officially unveiled at last October’s K 2019 show in Düsseldorf by Cloeren Incorporated, which has sold nearly 100 of the dies worldwide, including about 30 units teamed with Windmoeller & Hoelscher’s Die Control Wizard (DCW) operating in what’s called “touchless” mode.

One such die and control package has been in operation since March 2019 at the Searcy, Ark., plant of extrusion laminator Bryce Corporation. The Reflex-DCW combination, retrofitted on an existing line, has thus far resulted in a 50% reduction in total yield loss, 80% reduction in belled/soft edges (Fig. 1), and a more than 50% reduction in setup time (Fig. 2), remarks Andy Pratt, Bryce’s v.p. of operations support. Bryce was so impressed with the new die and control package that it has since ordered two more systems for its Memphis, Tenn., operation.

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Prices Up for Nearly All Major Volume Resins--For Now

As the third quarter was coming to an end, prices of nearly all volume resins were higher or heading that way. Going into the fourth quarter, with the exception of PE, the trajectory was largely projected to be flat, and in some cases downward. Although contributing factors varied, they included supply tightness due to planned and unplanned production disruptions, higher feedstock costs, and incremental recovery in domestic demand. Also at play was the wild card of the hurricane season.

While precautionary shutdowns as Hurricane Laura made landfall in the U.S. Gulf Coast did cause some blips in production and, some force majeure actions, nearly all were very short-term. Particularly in the case of polyolefins, the production disruption added to upward pricing pressures. Rising prices were putting a damper on exports, which were quite strong earlier in the summer—particularly for PE and PVC—though a general trend toward more stable or lower prices is considered likely to recapture some of that business.

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Plastics Processors Report Quickening Expansion

The Gardner Business Index (GBI) for plastics processing—based on monthly surveys of Plastics Technology subscribers—expanded for the second straight month in August, ending at 53.4. Custom processors fared even better, with a 56.3 August reading (Fig 1). Among the components of the Plastics Processing Index, new orders (Fig. 2) and production both showed quickening expansion for a second straight month and were joined by employment, which expanded for the first time since the outbreak of the Coronavirus. All index components reported higher readings in absolute terms for the month. (Index values over 50 indicate expansion, below 50 indicate contraction.)

Unlike the textbook example of a recession, the economic impact of COVID-19 on the plastics processing market has been unprecedented because of its shock to both demand and supply. While in a classic recession there is a reduction in the demand for goods, which lowers sales; the pandemic also has reduced sales because even when there is willing demand for a product, disruptions in the supply chain meant there may not be product to sell. Whether lost sales are due to a shift in demand or a lack of available supply, the impact to the economy is the same. As supplier delivery readings continue to normalize and new orders continue to move higher, it appears that the industry is taking the right and necessary steps for a successful near-term recovery.

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