Damaged Trough from a Shaftless Screw Conveyor

Damaged Trough from a Shaftless Screw Conveyor

Damaged Trough is repaired using UHMW-PE Sheet

Damaged Trough is repaired using UHMW-PE Sheet

These pictures were taken at a Fertilizer Plant. One picture shows what happens to a Stainless Steel Trough that didn’t use a UHMW Liner to reduce the wear and friction and the other picture illustrates a novel way to Repair and Seal a damaged trough due to a Shaftless Screw wearing through the unprotected Stainless Steel surface. Many Wastewater Treatment Plants would experience similar problems if a Trough Liner isn’t used.

Every month the Plastics Network gets a variety of misc. questions.  Starting this month, I am going to start posting and answering as many as I can,  even though some may appear to be elementary in nature.

*Vapor Polishingof all the topics, I get a lot enquiries daily on the subject of Vapor Polishing. Many have wanted information on how to purchase vapor polishing equipment. I have researched this several times and know of no company that actually produces vapor polishing equipment. Most companies in the business already, pretty much have designed and built their own equipment to fit their specific needs. If anyone out there knows of any companies that manufacture vapor polishing equipment, please post their contact information here.

*Can you melt Acetal? ….Yes. It’s crystalline melting temperature is 329F for Copolymer Acetal and 344F  for Homopolymer Acetal.

*What to expect when machining Acetal?…it is easy and very free machining. Use plenty of clearance and rake on your Turning, Boring and Cutoff tools. Good grade of carbide is all you need. See my post on “Machining Characteristics of Acetal” for more detailed information regarding machined, molded and extruded in stresses and how to deal with them. I have a lot of hands-on plastic machining experience so, feel free to ask me questions not covered on our posts.
*Difference between Injection Molding and Extruding Plastics?…as far as physical properties go, when extruding plastics a material with a higher molecular weight is preferred and when molding the opposite is true in order to get material to flow through the small gates and runners under high pressure.  Injection molded plastics are typicallly packed in the mold under considerable pressure which will typically give injection molded plastics a little higher physical properties. When extruding a  material, it is conveyed through the barrel via a screw which goes through a Feed Zone followed by a Compression and then a Metering zone prior to exiting the die. And, when processed correctly good properties are achieved but typically a little less than a part that has been molded. Most applications will never know the difference in it’s actual application.Also, Good mixing is accomplished through both processes, which is important when processing filled materials. This is a topic that could be easily expanded on..if there are any remaining questions regarding this topic, please ask.
*Plastic”Manufacturers Representative”…several enquiries have come to The Plastics Network regarding Manufacturers Representative in the Plastic Industry. Reps in the plastics industry are typlically segemented as to their expertise so, it is important to ask some questions. One segment calls on only OEM’s and even within that group there are subgroups depending on market focus ie: Automotive, Medical, General Industial, Aerospace etc. Another segment only calls on Plastics Distributors with commodity oriented products ie: Stock Shapes, Sheet and related products and most of these Reps come from a variety of Industrial Backgrounds and not just the Plastics Industry. Another segment calls on the Plastics Processors such as Injection Molders, Extruders, Blown Film, Thermoformers etc. …selling Raw material, mold bases, tooling and other support equipment for the plastic process industry.

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Profile Extrusions-Engineering PlasticsWith the explosion of new material options now available, the design engineer has some exciting options for their profile extrusion requirements.

From “Wood Composites”, “Biodegradable Plastics”, “Flame Retardant”, “Green Plastics”, “Nanotechnology”, “Antimicrobial Plastics” to “Thermotropic”,  “Glow-In-The-Dark Plastic Materials”, “Soft Touch TPE’s” plus many others! 

I will be discuss some of these exciting material options below;

“Wood Composites” -  the use of wood in thermoplastic extrusion is a relatively new technology with extensive market growth over the last decade or so. Wood Composite Profiles are extruded using Wood Plastics Composite (WPC) resins. WPC’s are compounded using 30-60% wood filler in the form of Wood Flour or Wood Fiber both of which are available from recycled sources. These Wood Fillers are combined with plastic resins such as HDPE, Polypropylene, PVC or ABS and are processed by extrusion into a variety of shaped profiles (both hollow and solid) that retain many of the favorable qualities and aesthetics of wood but offer enhanced properties provided by the thermoplastic. “Wood Composite” profiles offer good strength to weight ratio, are durable with good dimensional stability, and are relatively inexpensive. Major Markets for “Wood Composites” include the Building Industry (Decking, Roofing Shingles, and Molding) as well as a growing market for Door/Window Profiles, Mini-Blinds, Furniture and Fencing Applications plus many others….

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“Composite Bearings” can be the ideal choice for many Self-Lubricating Heavy Duty Applicaions.

These Composite Bearing Materials are Laminated Plastic Materials made by impregnating fabric with thermosetting resins. The physical and mechanical properties of these select bearing grades make them excellent bearing materials.

Composites offer design engineers an attractive, low cost alternative to the traditional materials used throughout industry for bearings, wear pads and other components.

Applications for “Composite Bearings” include:

Composite Bearings in Hydro Electric Plants

Composite Bearings in Hydro Electric Plants

Hydro Electric Plants: Butterfly Vlave Seats, Bridge Pivot Wear Pads, Control Gate Bearings, Counter Weight Guide Blocks, Fish Screen Bearings, Lock Gate Bearings, Operating Ring Wear Pads, Running Blade Adjuster Bearings, Trash Rake Bearing & Wear Pads, Trunnion Bearings, Vertical Pump Shaft Bearings, Wicket Gate Linkage Bearings, Wicket Gate Bearings, Wicket Gate Thrust washers, Floating Mooring Bitt Roller Bearings, Chain Guide/Slides, Servo Wear Rings.

 

Composite Chain and Wear Guides

Composite Chain and Wear Guides

 

Composite bearing Materials make excellent Chain and Wear Guides especially for harsh and demanding environments.

 

 

Composite Bearings in Forestry Equipment

Composite Bearings in Forestry Equipment

 

Composite Bearing materials are ideal in forestry equipment applications as well as other mobile equipment.

 

 

Composite Bearings used In Ship Rudder bearings

Composite Bearings used In Ship Rudder bearings

Composite Bearing materials used in Oil & Gas Applications

Composite Bearing materials used in Oil & Gas Applications

If you would like more information or literature on this topic, don’t hesitate to contact me.

Over the weekend, I read a good article from Michael Sepe, Analyst and Author for Injection Molding Magazine that discussed and illustrates the impact Crystallinity (of Acetals & PBT Thermoplastic Polyesters in this case) has on dimensional stability. It also, provides a better understanding of the fundemental changes in behaviour when processing an Amorphous Thermoplastic over a Crystalline Thermoplastic. (more…)

Often,  just knowing where to find information on the Plastics Industry is a great help. Whether you need Industry information to get a feel for Trends, Current Industry Status, opinions on what the future may bring , Technical Information on Materials, Process, Design or where just simply, where can I buy what I need.

On my “Industry Links” page you will find a large listing of Companies, Industry Agencies, Magazines, Industry Specific Links, Industry Organizations and other useful information.

To Highlight some of what you will find on our large “Industry Links” page are as follows:

The Global Plastics Newsletter – by Mel Ettenson, a very informative Newsletter written by people that have been in the industry for many years with lots of good articles, industry interviews , Market Trends and much more…

IAPD-International Association of Plastics Distributors, a good Association to be a part of especially if you are a manufacturer that wishes to sell through distribution channels. Also, a great resource for information in all catagories

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 plasticsrollerbearing.jpg

“Engineering Plastic Roller Bearing” - A Case Study

Application: Conveyor Roller Bearing for a Food Processing Company

Design Criteria: Needed a self lubricating conveyor roll bearing to withstand repeated wash downs and have a load carrying capability of 300#/bearing under low speed conditions.

Construction: Acetal Copolymer Inner & Outer Rings, 16 ea. Rollers 3/8″ dia. x 3/8″ lg. (alternating 8ea. 302SS &  8ea.  Acetal Copolymer)

Size: 2  1/2″ O.D.  x   3/4″ Hex Bore  x 1  1/2″ Length  x   2  3/4″ Flange Dia.

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