The Problem:

A large blow molder was experiencing high scrap rates processing TiO2 filled HDPE on a standard chrome plated feed screw. They wanted to reduce carbonized material that resulted from sticking, charring and eventual release into the product. Screws are pulled every four months to be cleaned (sooner if necessary) and then reinstalled into whichever machine is next in rotation. Various screw designs are used depending on the polymer being processed. They have over 100 machines at this site and a total of eight manufacturing locations.

Previous chrome plated OEM screws required surface repolishing at six months and again at nine months. TiO2 attack and frequent cleaning roughened the screw surface which lead to stripping and re-chrome plating at about ten months.

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The Problem:

A major feed screw manufacturer asked Extreme Coatings to help solve a severe abrasion issue with a large injection molding customer. This is dedicated equipment processing an engineered nylon with 15% glass fiber and 20% glass bead filler. Previous CPM-9V screws experienced as much as .035” (0,87 mm) wear in two months or less. They process with a reverse temperature profile and recommended polymer residence times. The customer wanted to maintain screw design across all equipment so a specific screw design change was not contemplated for this process.

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The Problem:

This customer approached us at a trade show looking for help to solve a severe abrasion problem coupled with product contamination. The process is proprietary and details are confidential.

This is a Powder Injection Molding process and, as is common to this process, parts are sintered after molding to achieve final size and part density. Clarity of the finished part was extremely important and any contaminants in the process usually showed up as a darkening of the sintered part.

These are small parts being processed on small 30 ton machines. Past wear protection consisted of a surface hardening treatment to infuse an elemental material into the screw surface resulting in a hard layer. High temperatures were required to achieve this layer and post heat treat straightening was difficult. The result was a screw and barrel with a large initial clearance of about .009”, which accelerated wear and shortened component life. Hard surfaced screws lasted about 3 months and 300,000 shots until product contamination lead to too much scrap and the screw was replaced.

As this hard layer wears, the softer substrate is exposed, which accelerates wear. More importantly, wear increases the amount of contaminants in the finished product causing a loss of clarity. Scrap goes up.

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The Problem

A large custom compounder makes a thermally conductive material designed to dissipate heat quickly and effectively. This product is highly filled with a proprietary material that causes their customers severe abrasive wear. This has actually limited the product’s acceptance even though the resin is less expensive than other materials and very effective.

This compounder was approached by their customer asking for a solution to rapid wear. They in turn asked Extreme Coatings to contact this processor to offer help.

This customer makes parts for the home appliance market, in this case, washing machines. This thermally conductive material was specified by the manufacturer for an inlet flume that incorporated temperature sensors to control and mix incoming hot and cold water.

Standard molding equipment was used to process the first batch of parts. The Maintenance Manager commented that “the feed screw looked like a broom stick in one week running that stuff!” CPM-9V feed screws lasted 20,000 shots with .030” total OD wear in 1-1/2 months. These parts are batch produced in a campaign every four months throughout the year.

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The Problem:

This customer makes consumer products for the Lawn and Garden industry. Economics of operation has lead to much of their production activity being moved to lower cost countries. This plant countered the trend by making better quality finished products (longer life) at a lower cost than the offshore site.

They process a 33% glass filled nylon material making structural engine housings. These parts require strength and heat resistance. This is a large part approximately 2-1/2 to 3 lbs shot size on an 80 mm 18:1 feed screw. Cycle times are about 1 minute which means polymer residence time is very short and with a nylon material this can contribute to more rapid wear.

Past 80 mm GP screws were hard faced with Colmonoy 56 and hard chrome plating. At six months of 24/7 operation these screws had as much as .030” of OD wear. Root wear and flight side erosion were also evident which made screw rebuilds uneconomical.

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