You know how bad it is when you get stressed out, with all the day to day challenges and issues? Well, plastics get stressed too.
The process of producing plastics into sheet, rod and tube is a stressful manufacturing process.
Stress free plastic manufacturing
The process to make a plastic sheet, plastic rod or plastic tube requires the plastic resin to be heated to temperatures of 350° – 500º to get the resin to flow through the machines.
The material is then pushed through a die at high pressure.
This heat and pressure cause many stresses to affect the plastic material.
The cooling of the plastic shape is critical
If the plastic cools to quickly, the surface cools and the center is still very hot, this is a major cause of internal stress.
Processed to quickly and voids or cold spots cause poor quality sections.
Processed to slowly and materials burn in the die and visible burn spots appear on the surfaces – bad material
Proper speed provides homogeneous material that has cooled at a uniform rate through the sheet yields a very low stress sheet
The stresses from this production can be very significant and can ruin your parts. One common prevention method is to anneal or stress relieve the raw material prior to machining, and may require stress relieving during machining if large amounts of material are being removed. The stress relieving process is a slow heat and cool process, contact us for details on your material or project.
Here is an example of a highly stressed plastic sheet, it is 1.250″ thick glass filled nylon sheet. The manufacturer sent us this sample to show the ‘quality’ of their material. We attempted to cut off a strip to do some testing, and you can see the results. This material warped so much it stopped our saw! We never did buy anything from this supplier.
Compression Molded Plastic Sheet and Brownies…
Nylon with huge amount of stress, cooled too quickly.
Yes, you read that right, brownies. I still remember the wonderful smell of my Grandma’s house when she was baking her special 2″ thick brownies. The smell was great, but I also remember the critical timing in the oven. She would open the oven and peek in, and close it quickly so as not to let the heat out. Then, when they looked about right she would open the oven and slip a toothpick into the center of the pan and pull it out again slowly. I can remember asking, “Grandma, why do you put in the toothpick into the brownie?”. The answer was, that the outside cooks quicker than the inside, and it takes a while to get the brownies to cook all the way to the center.Then, when they were all cooked, I would have to wait while they cooled. And, sometimes, if I didn’t wait quite long enough, when I would take a bit the center would burn my tongue. Ouch!
The interesting thing is, that plastics are about the same. Most plastics have a very low co-efficient of thermal conductivity (that is sure a mouth-full), which means that heat and cold don’t travel through the plastics well. This means that it takes a while to ‘cook’ the plastic all the way through, and not just the surfaces. And, just like my brownie story, the plastics take a long time to cool. If the outside of the plastic cools much faster than the inside, then large amounts of stress develop.
The process of compression molding of the plastic sheets is ideal for eliminating stress. The sheets cook slowly, so the entire sheet, including the center, is heated to a uniform temperature. The temperature is held at temperature to insure a fully cooked sheet (you can’t use a toothpick here). Then, over several hours, the temperature of the sheet and the entire compression molding press is lowered very s-l-o-w-l-y. This allows the center of the sheet to cool at the same rate as the external surfaces, and this yields a very stress free sheet. The premier manufacturer of this high quality compression molded sheet is Westlake Plastics. We have been a master supplier of the Westlake Plastic materials for over 35 years.
What should you do to eliminate stress?
If you are experiencing problems with your plastic materials, such as twisting, warping, ‘potato chipping’ or any other sign of stress, contact us. It is probably not your fault. There are dozens of manufacturers that produce engineering and mechanical plastic shapes, they are not all the same. During the production of materials, the process should include a secondary annealing step to remove stress from the newly product. By removing all stress from the sheet or rod you are insured of a ‘clean slat’ before you start machining or finishing. We only provide materials from top rated manufacturers, we truly care about the materials you receive from us.
If you have been experiencing problems with the materials you are getting from other suppliers, let us know, we can help eliminate your stress problems. E-mail us or call us at: 866-832-9315
Today’s topic is all about industrial plastic sheet materials in flat sheet or sheets. Also known as plate, slab, strip and bar.
Most plastic materials are processed into sheets or rods. Rods are round, sheet is flat, square or rectangular. These two basic shapes are both generally extruded, although sheet can also be compression molded. Almost all plastic raw materials are available in sheet, and in a huge range of sizes. Most materials are available from .063″ to over 4″ in thickness; and some as thick as 8″ (how to measure thickness accurately, use a 6-Inch Digital Caliper with Extra-Large LCD). Sheet sizes vary, but generally most plastics are produced in 48″ X 96″ sheets or larger, but once again this changes with types of materials and thickness desired. We can help with almost any plastic material.
Need Help Picking a Plastic Sheet Material?
Deciding on the proper material for an application is the first step. Start by reviewing our Plastic Materials Selection Guide to help narrow your search. Having the key properties and needs of your project in mind will help you with this step. Also looking at both the pro’s and con’s of a material will assist in this search. Materials with the greatest property range can be extremely expensive, selecting a material that meets your needs and your budget should be considered.
Step two is researching sizes and availability – this is where we can really help. With most of the major manufacturers as partners, we are able to source your parts from many factories. While the quality from most factories is excellent, the variable is standard and custom sheet sizes. We also stock a wide variety of materials in large sheets. One of our many manufacturers is Westlake Plastics. They have been compression molding large sized sheets of many popular plastic resins; these sheets are available in 48″ X 120″ as a standard sheet size in most plastics. They produce these materials from .250″ – 3.0″ thick or thicker. Other manufacturers produce 24″ X 48″ or 48″ X 96″ sheets as standard. Please contact us for specifics on your material selection.
Mechanical Acetal Sheet
Most of our plastic resins are available as a sheet. This includes some of the most popular plastics, like: Polycarbonate Sheet, Acetal Sheet, PTFE Sheet, Ultem Sheet and dozens more. Sometimes, Plastic sheet is called: Plate, Strip, Bar, Slab, Block or Panel. Please think of these names as being synonyms with Plastic Sheet. Contact us with your special requirements.
In thicker gauges, plastics are frequently referred to as plate, slab or block. And strips or narrow pieces are called bar. A rose by any other name, call it what you will, the plastic starts as a flat sheet from the factory. We can cut them to size or shape. Blanking of sheets to useable sizes is our specialty. Narrow pieces used for long applications are normally called strip. Strip is common in wear type applications.
For a list of materials we have as standard stock materials, check our Plastic Sheets Page. These and many other plastic materials are available, and custom sizes, shapes and colors vary by base material. As a stocking distributor for dozens of major manufactures, we are the West Coasts leading plastic sheet supplier or distributor. If you are in need of some technical assistance go to our Plasticologist page for specific help.
Contact us for more information on plastic sheet materials. Email us or call 866-832-9315
Since 1975 we have provided large diameter plastic rods and thick plastic sheets, plates, slabs and blocks. One of our long time ‘secret’ sources has been Gehr Plastics. Since 1932 the Gehr family has owned and operated the Gehr Plastics company. They are a worldwide leader in semi-finished plastic shapes in thermoplastics, primarily sheet and rod. The headquarters for Gehr Plastics is in Mannheim, in south western Germany. For almost 30 years, Gehr Plastics has had production facilities in the Philadelphia area, providing the USA with the same high quality plastic shapes.When we mention large diameter rod, we mean it! Gehr can produce plastic rod up to almost 20″ diameter in several grades of plastic. They also produce sheet plastics up to 8″ thick, and make the largest materials of most manufacturers of plastic sheets and rods.
At Gehr Plastics, Quality Engineering Plastic Comes First
Our first purchases with Gehr Plastics was in the PVC rod family. Once again, they make huge cross sections in many materials, including the PVC rod. Many manufacturers struggle with large sections of PVC rod because keeping it void free throughout the large diameter is very difficult. Not for Gehr Plastics, they specialize in engineering plastic materials. We have chosen this high quality manufacture for their exceptional product quality. We know the demands of our client base, and only choose the best factories to supply our products. Gehr is definitely one of the premier plastics producers in the world. While the quality of the PVC rod is excellent, the rest of the Gehr Plastics product line is also some of the best plastic semi-finished shapes available in the market place. Here is a list of some of the many materials that Gehr Plastic produces:
14 inch Natural Polypropylene Rod produced by Gehr Plastics, the largest domestic plastic rod currently in production. 12″ diameter UHMW rod from Roechling Plastics, Industrial Plastic Supply is master distributor for both of these manufacturers.
And a new and exciting product – Clear Nylon Rod (Contact us for more information)
Many of the above items are also available in sheets, plates, slabs or blocks.
Gehr Plastics – one of our engineering plastic partners
We have been proud to offer the complete line of plastic rod, sheet, slab, plate and block from Gehr Plastics, and consider them a highly valued partner in supplying these engineering plastic materials to you, our valued client. For more information on the size range, availability and pricing on these and other plastic materials,click hereor call us at 866-832-9315
Acetal Copolymer and ABS (Acrylonitrile-Butadiene-Stryene) have some similar properties but are really very different materials. They similarities are: high impact strength, ease of machining with standard cutting tools and good mechanical properties. They are also both FDA compliant and are both good substitutes for brass. They also have great water absorption resistance and good electrical properties. Both materials are good for some of the same applications but certainly not all. Listed below are some of the major differences.
ABS Sheet and Rod Information
ABS comes as Natural (straw) and Black color in Plate, Slab, Sheets and Rods, and thin sheet (.040″ – .250″) it is available as White or Black with a textured surface one side. It can be cut from 48″ X 96″ sheets into strip, panels or pieces.
ABS is formable. ABS is a great thermo-formable material while Acetal is not. Acetal is used more for machined parts such as gears and screws. ABS is great for molding and shaping parts from vacuum to heat forming. Excellent for model building and prototype projects.
ABS is easily bondable (similar to PVC). ABS can be bonded or welded to itself. Because Acetal is self lubricating, it is not possible for anything to stick to it unless etching is done – therefor it is not bondable.
ABS is a great material for painting and silk screening. While Acetal can not be painted or silk screened unless it has undergone Corona Treating (a flame surface treatment), but if treated will nice paint or screened surface.
ABS has better chemical resistance than Acetals. Both are attacked by acids like sulfuric, but ABS has a wider range of resistance to chemicals like aqueous acids, alkaline and alcohol. Acetal will degrade when exposed to such chemicals as chlorine and alkaline.
Specialty grades of ABS are available, including: Glass Filled, Static Dissipating, and Fire Retardant Grades (like Royalite – R59)
ABS Typical Properties Table
General Property
ASTM Test
Value
Specific Gravity
D7921
1.08 – 1.25
Tensile Strength
Yield D638
4,100
Izod Impact – Notched
D256
7.7
Hardness – Rockwell
D785
R105
Deflection Temp @ 264psi
D648
177
Co. Thermal Expansion
D696
5.3X10-54.6 -5.5X10-5
Acetal Copolymer and Homopolymer Sheet and Rod Information
ABS Resin Structure
Acetal is the better machining plastic, considered the best machining plastic material. Because of its durability and wear resistance, Acetal is an excellent choice for producing a wide variety of parts that require high wear resistance over a wide period of time. When machining to tight and specific tolerances, Acetal is ideal.
Acetal has low co-efficient of friction. Due to its self lubricating properties, it is a great material for sliding and wear applications. This material provides years of maintenance free bushings and bearings.
Acetal sheet is produced from .062″ – over 6″ thick and sheet sizes of up to 48″ X 120″ as standard. The standard color for Acetal and Delrin is Natural (a deep milky white) and Black. Some colors are available as Medical Grade, and can be obtained in limited sizes. These sheet are available cut to: slabs, blocks, plates, slabs and blocks.
Acetal (Polyoxymethylene) can be both a homopolymer and a copolymer. The homopolymer acetal has a repeating chain of one atom while the Acetal copolymer has two atoms forming a repeating chain. Dupont™ Delrin® is a popular acetal homopolymer brand name and the most commonly used acetal homopolymer.
Acetal – Delrin Properties Table
General Property
ASTM Test
Typical Value Unfilled Homo-Polymer
Typical Value Unfilled Co-Polymer
Specific Gravity
D792
1.42
1.40
Tensile Strength Yield
D638
9,600 – 11,000
9,000 – 10,200
Tensile Modulus
D638
450,000
400,000
Izod Impact – Notched
D256
1.2
1.0
Hardness – Rockwell
D785
M94
M90
Deflection Temp @ 264psi
D648
257
220
Deflection Temp @ 66 psi
D648
347
335
Water Absorption @ 24 hrs
%
0.24
0.25
Co. Thermal Expansion
D696
6.83X10-5
5.4X10-5
ABS and Acetal – Similar, but very different materials
Both of these materials possess excellent qualities and have a wide range of different uses. Acetal is great for machining, while ABS is great for forming and bonding. They both can be used for machined parts and are great choices for food contact and electrical applications. These two materials are both strong and durable plastics, but one might be better than the other for a specific job. When picking the right plastic, it is important to compare plastics and their specific properties to make sure the material won’t fail and that your job will be successful.
Contact us for additional information, call us at 866-832-9315 or contact us here. Consider Industrial Plastic Supply for all your plastic needs, we want to be your go-to plastic supplier.
**Note: Delrin® is a registered Trademark of Dupont
The world is an ever changing and frequently hostile environment. Damage can be caused by a range of factors: from storms, floods, tornado to fires, hurricanes and earthquakes – all natural disasters.
This is certainly evident in the recent earthquakes and tsunami that ravaged Japan and Haiti. In addition, we have man made disasters. The nuclear concerns in Japan have captivated people’s attention throughout the globe. The Gulf Oil Spill is an example of another environmental disaster. Plastic materials are the perfect choice in prevention, preparedness and clean up from natural disasters.
Plastics in disaster preparedness.
Many plastic materials are used in the prevention, control and repair management – whenever and wherever a natural disaster may occur.
One of the most visible plastics is the Polycarbonate used in hurricane window covers / shutters. Polycarbonate is a clear rigid plastic that has extremely high impact strength, and is the material most commonly known as ‘Bullet Resistant Glazing’. It is used in safety glasses, riot shields and bank theft prevention glazing. The Polycarbonate protects windows and inhabitants from flying debris and breaking glass caused by the high winds, hurricanes or tornado. Use of the Polycarbonate window coverings saves homes from damage, and helps reduce insurance premiums.
Hillsides are affected by storms and heavy rains, causing mud slides. The standard and most popular solution is to cover hillsides with Polyethylene film. This helps to prevent the rains from saturating the ground and causing the ground to move or shift. The Poly film is normally .004” – .010” thick in widths up to 20 feet and lengths of 100 feet (the same material used as painters tarps from home improvement centers). This film is then attached to the hill with spikes, stakes or sand bags; and this material sheds the water rather than letting it soak in. It can be applied with folds and used like rain gutters to direct water flow away from specific areas. Also, the current sand bags used are not the old cotton fabric bags used years ago; they are now a high strength and tear resistant woven polypropylene ‘fabric’ bag.
The recent critical issues with nuclear leaks bring up an interesting use of a plastic material. As you may recall, after the earthquake and tsunami, the Japanese energy experts were pumping water and boron into the reactors to help control the amount of nuclear energy released.
The nuclear industry uses a plastic material, High Density Polyethylene (HDPE) that has been filled with the natural mineral boron. This boron filled (typically a 5% boron fill) is used to shield neutrons and nuclear energy in many applications; nuclear submarines, nuclear power plants, hospital radiation, dental x-ray shielding and industrial radiation applications. It is normally produced in sheet, and can then be mounted in and around the radiation source as shielding. The benefit to using this boron filled HDPE is this sheet weighs significantly less than traditional lead shielding, and is therefore much easier to install.
Plastic used in clean up from disasters
It is much more difficult to clean up after natural disasters occur. Many of the methods used in the preparation limit the amount of clean up caused by natural disasters.
Depending on the severity of the natural disaster, the uses of plastics in the aftermath are almost limitless. In the cleanup and rebuild after major Earthquakes, shelter is a key component. One of the quick shelters brought in are simple wooden frames with twin-wall plastic sheets made from either Polypropylene or Polycarbonate stapled or nailed to the framework. This provides an inexpensive, easily movable and effective shelter for short term housing. The twin-wall design provides excellent insulation and energy savings. This style shelter is foldable, easy to transport and very easy to set up. Several versions can be made from small huts to larger family areas, to separate sanitary latrine units. These extruded twin-wall materials work well to protect against rain and excessive exposure to the elements. These can be used as assembled, or with a sand bag reinforced perimeter. In Haiti, there were reports of residents filling used one gallon water bottles with mud, and building shelters with these mud building blocks.
The gulf oil spill brought plastics to the front line in disaster cleanup again. Materials used to collect and dispose of excess oil from the waters were rushed to the area. Polyethylene bags are used to collect the oil covered and saturated cleaning rags and clothes, preventing additional dispersion. Many varieties of machinery were brought in to clean the waters. One style machine uses 8” UHMW rod as a squeegee roller that grabs the oil from the water surface and then collects it for later use. Oil booms and rotary wheels are common systems for collecting oil from spills. Because plastics have great surface tension, the oil ‘sticks’ to the plastic surface during the cleaning process. Then the plastic surfaces are wiped clean for reuse and capturing the oil. Plastic tubes and hoses are used to move the oil after collection.
A significant use of plastics would be in the aftermath of natural disasters, specifically in the sanitation and clean water areas. First is sanitation; plastics are used in keeping items clean and dry. Polyethylene film covers items such as medical supplies, shelters, clothing and food cartons. This film keeps the items protected during shipment and ready for use.
Water is the second area of concern. Clean water is critical during the clean up and resettling after a natural disaster. Individual use water bottles are the quick and easy way to deliver water. Larger rotationally molded tanks are brought in with the ability to store large amounts of water in the areas affected. Reverse osmosis equipment (many components are made from plastic) is brought in to convert contaminated water in the clean potable water on site.
In all of these examples, plastic is lighter in weight than the alternatives, normally less expensive that the alternatives, it lasts longer and the plastics are recyclable.
Plastics are excellent choices for material to use in natural disasters.
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