Friday, November 26, 2010

Learning About Plastic Profile Extrusion Is Great!




Ever wonder where the dependable and long lasting plastic products come from? Or more specifically where they are manufactured? Most every plastic used in our daily lives is a product of Plastic Profile Extrusion. It's an interesting process that simply starts with the melting of small raw plastic beads. The plastic needs to be in bead form for easier melting and profile forming. Plastic Extrusion companies manufacturer recognizable products such as piping, window frames, and even adhesive tape! Wire insulation and Plastic sheeting are also big examples of manufactured products. Well for all the knowledge craving minds let's begin with the first step in Plastic extrusion!

As we begin the plastic beads are fed into a heated cavity or cylinder. In most cases the plastic is mixed with colorants or UV inhibitors. As all the plastic and anything mixed in is inside the cavity it's forced through a screw mechanism.

The screw mechanism forces the plastic and any remaining material out the extruder cavity. While the plastic is inside the heater it is a toasty 400 degrees. This is a cool fact! Most extrusion companies have three different heaters inside the cavity.

This is due to overheating being a quite troubling problem for plastic extrusion experts. SO if the plastic is gradually brought to its melting point by three heaters it's not one source of heat at one time. This allows for no overheating. Burnt plastic isn't necessary and does not smell good!

Through the cavity the friction and pressure can sometimes be so great there is no need for the heaters. Plastic Manufacturing Companies shut off the heaters and allow the friction and pressure to keep the plastic at the desired temperature. That's pretty interesting friction and pressure can keep plastic at that high of a temperature.

After the heating is complete cooling fans are then used to keep the cavity at the correct temperature. As the molten plastic reaches the front of the barrel and is complete in the cavity, it's time for the plastic to go through a specially designed screen.

This screen allows for the plastic to become separated from any remaining contaminants whether it is types of food or clay. Following the screen it's time for the die, which gives the plastic its specific profile. After the die is added it must be cooled most cases in a sealed water bath.

Plastics and Rubber Products have become a common feature in homes. For that matter even Industries have fallen hook, line and sinker for the two. Two major factors like credibility and versatility have been driving their demand. Considering the soaring demand for plastic and rubber products, we have come up with a common platform for all plastic and rubber manufacturers, suppliers, exporters and buyers, to trade with each other at the click of a mouse. A few years back, transactions used to take place ‘on –field’, with both parties sitting face-to-face, before closing the deal. Here, the major plus point is the transaction is taking place ‘on-line’ and you can strike a profitable deal right away. Sitting face-to-face can be done anytime.

Wednesday, November 17, 2010

The Real Facts of Plastic Injection Molding



Plastic injection molding is often thought to be a hard process which is a wrong notion of the people. A variety of parts are manufactured using Injection molding process which varies from the smallest component to an entire body component of a car.

The machinery involved in plastic injection molding is costlier and very sensitive and complex equipment. These machines are called as injection molding machines. The machines used are also heavy and some even weigh up to tons of kilograms. But only when these kind of machines are used the final product turns out to be a quality product. This is so because the plastics are fed into these machines and they are heated until they become fluid. This shows that the machines should withstand high temperature and hence the need for a complex equipment.

Plastic materials used for the injection moulding process are thermoplastics or thermosetting plastics. Both the thermoplastic and thermosetting plastics are polymers. Some widely used thermoplastics are nylon, polyethylene, and polystyrene while bakelite, vulcanized rubber are the widely used thermosetting plastic. Sometimes a polymer with a very high elasticity is also used. Such a polymer is called elastomer.

The plastic takes the shape of the cavity or the mold used and get solidified or settled in it. After being solidified it is ejected out After some time molded material is ejected out from the cavity. The same cavity can be used to make any number of molds. The mold is of any desired shape.

The injection molding machine has two components namely the injection unit, the mold and the clamping unit. One should not forget that the process involved in plastic injection molding is not as tough as the size of the machinery. It is a very simple and a systematic process. Initially the injection molding process starts with the injection of the plastic resins or polymers into the injection barrel. The resins are heated to melting point and now the fluid is poured into the mold which is of the desired shape needed. The mold has two components namely the injection mold and the ejector mold. The melted plastic resin in poured into the mold using a sprue the injection mold. And the ejector mold helps in ejecting the plastic part after it is solidified in the mold without any damage using ejecting pins.

The next step is the application of hudraulic or mechanical pressure. This is done in order to allow the trapped air in the mold to escape. This is called the dwelling process. After the pressure is applied the air cavities move to one corner of the mold. Then the fluid is allowed to solidify and the mold is cooled. Finally the solidified plastic part is ejected from the mold either manually or automatically.

After the cooling process there is often change in the mechanical that is both physical and chemical properties of the plastic part. The thickness of the mold is one of the important design considerations of the injection molding process. Usually a mold with an uniform wall thickness is preferred. Thus it reduces the change in mechanical properties of the plastic part.

Friday, November 12, 2010

Discovery of Plastics Towards World Development



Today, plastic is considered one of the greatest inventions in our new generation. It signifies modernity and progress of humanity. Plastic has touched lives of people compared to other breakthroughs in technology. It has replaced old and usual things. Elegant heavy tables and desks have been transformed into lighter structures, with pastel color touches and made homes and offices change their theme. Indeed, plastic fits into the contemporary world. Aside from being light and strong it can be easily molded and it is durable. But have you ever asked yourself how plastics were invented? Everyday, plastics are scattered everywhere, which contributes to health, safety, and security, but have you ever tried searching the origins of plastic?

In 1862, Alexander Parkes made the first ever man made plastic for London's Great International Exhibition. This material, which was made from organic materials that came from cellulose, was first known as Parkisine. Once this material was exposed to heat it could be molded but when cooled, it would retain its shape. Alexander Parkes said that his discovery could do all that rubber can do but at a lower cost. He discovered a material that could be transparent and could also be carved into different shapes. However, it soon lost its limelight as investors had pulled out of the market because of the high value of raw materials used in producing it.

After the discovery of plastic many items were found to be more useful and efficient when made from it. Late 19th century there was a rush on finding a replacement for the ivory used in billiard balls - this was the time that Billiards was extremely popular and the elephant population was being decimated to obtain their ivory. Fortunately, an American inventor named John Wesley Hyatt found the solution using celluloid in 1869. He accidentally spilled a bottle of collodion in his workplace and he discovered that it formed a tough and flexible film. That was when he had the idea of making billiard balls using this new material named collodion, which substituted ivory. But since this material is brittle in nature, billiard balls made from collodion shattered once they hit one another. There was a solution to this problem, which came by adding camphor from laurel tree. Due to this addition, the celluloid was the first thermoplastic or substance that molds when under pressure or heat into shapes that can be retained even after being under heat or pressure.

In 1907, a man-made synthetic was first discovered by Leo Baekeland, a chemist from New York who developed Bakelite or a liquid resin. The Bakelizer, an apparatus made by Baekeland, enabled him to control volatile chemicals when heated and pressurized. This pot-like equipment used by Baekeland developed Bakelite, which hardens rapidly and takes the shape of a container. If hardened, the resin will form a replica of any container where it is placed. Bakelite can be added into any material such as softwood, to make it more effective and more durable. The United States government used Bakelite in its weaponry and war machinery where steel could not be used. It was also used for domestic use such as insulation. Through these uses Bakelite proved itself as a very effective building material. Moreover, Bakelite is resistant to electricity, chemically stable, shatter proof, resistant to heat and it does not discolor, fade or crack when exposed to sea salt or sunlight.

Plastic was later made into different varieties of usable materials like Cellophane, which was discovered by a Swiss engineer named Dr. Jacques Edwin Brandenberger. He came up with an idea for a protective and clear packaging layer during 1900. While sitting at a restaurant, he saw a customer who happened to spill a bottle of wine on the table cloth. A server removed the table cloth and replaced it with another disposing of the soiled one. The Swiss textile engineer swore to dedicate himself to discovering how to apply clear flexible films on the cloth that would keep it safe from such accidents and would make it easier to be cleaned with just a swipe of a towel. He then worked on resolving this issue by utilizing different kinds of materials in experiments up until 1913 when he hit pay dirt with Viscose - known today as Rayon. Brandenberger applied the Viscose to cloth, however the material became hardened and was to brittle for use. Despite his unsuccessful venture in applying his material to cloth he discovered another use for the Viscose. He developed new equipment that would create thin Viscose sheets which later became known as Cellophane. Minor improvements were made to Cellophane in years that followed that allowed it to be used as a clear layer for packaging of any product. Cellophane was the first completely flexible and water resistant wrap.

With the discovery of new plastics came the plastic craze in 1920 as the use of cellophane spread throughout the world. One of the largest companies known as Dupont became a pioneer in discovering other materials made of plastic. A young chemist from Harvard, Wallace Hume Carothers was then the head of Dupont lab. Carothers became responsible for the moisture proofing of Cellophane and during this process discovered a method for creating a new material - Fiber 66 - known commonly today as Nylon. The young chemist saw the promising value of the new discovered tough plastic. Since its discovery the material has been used in widespread fashion including use as a replacement for animal hairs in toothbrushes as well as silk stockings. Carothers demonstrated that by substitution and insertion of elements on the chemical chain, new, durable materials could be discovered and developed. By 1940, the world savored the use of materials like Nylon, Neoprene, Acrylic and other polymers which had taken the place of natural materials.

Another important innovation with plastics was the development of polyvinyl chloride or PVC or vinyl. While working for the B.F. Goodrich company an organic chemist by the name of Waldo Semon attempted to combine rubber and metal. Although its importance was not immediately recognized he later discovered the value of this material as it was inexpensive yet fire resistant, durable and could be molded easily. This material caught the attention of western families for it could last many years in an average living room.

Organic chemists at Imperial Chemical Industries Research Laboratory tested various chemicals in conditions with high pressure. In 1933, these researchers, R.O Gibson and E.W Fawcett discovered polyethylene that made a vast impact throughout the world. These researchers were attempting to discover the reaction of a benzaldehyde and ethylene mixture when suddenly the experiment's testing container leaked and the pressure inside escaped. Upon opening the tube they found a white and waxy substance that looked like a plastic. This was the discovery of polyethylene and soon after compressors were created for large scale production of the product. Since its discovery Polyethylene has been an important material in the history. During World War II, this material was used in cable coatings used underwater and for military applications like radar insulation. It can actually reduce weight of radars to only 600 pounds.

After the war, it was widely used by the general public. It was the first plastic to reach one billion pounds of production in a year in United States and is presently the largest production in the whole world. Nowadays, polyethylene is being used in making soda bottles, grocery bags and milk jugs.

Another plastic known as Silly Putty, was discovered by James Wright, an engineer working for General Electric, when he mixed boric acid and silicon oil. This rubber-like had the ability to bounce 25 percent higher compared to a normal ball made of rubber.

During roughly the same time, a Swiss engineer by the name of George de Mestral had a plastic discovery of his own. He found that when nylon was sewn under infrared light it formed very small yet tough hook-like patterns. These tiny hooks would then catch with soft material to form a very strong hold. Dubbing the new product Velcro, a cross between velour and crochet, he patented the product in 1955 and has developed it into a multi-million dollar industry today.

Since 1950's plastics have grown into a primary industry that made a huge impact in our lives providing us with improvements in packaging, creating many varieties of textiles and giving us the opportunity to produce wonderful new inventions and technologies like cars, television and computers. Since 1976, plastic was considered the most used material all over the world and was included in the best inventions of the century. Thanks to those pioneers who developed the material we are able to enjoy many luxuries of the modern era.

Thursday, November 11, 2010

Considerations in Formulating Rubber Products



Rubbers come from two distinct sources: natural rubber, which is created using latex drawn from rubber trees; and synthetic rubber, which is chemically synthesized. Regardless of origin, every rubber is characterized by its ability to withstand very large deformations and then "bounce back" essentially to its original condition. Natural rubber, while used in many products today, has mechanical, chemical and environmental resistance limitations that would make it unusable for many applications; very often synthetic rubbers can be formulated to address these short comings.

There is actually no such thing as standard rubber materials; for each use, there is a custom formulated product that is tailored to meet the precise needs of that application. Rubber is a far more complex material than other materials such as steel or plastic. Whereas steel or plastic typically is the result of melting 3 - 4 materials together, a rubber formulation often consists of 10 - 20 materials blended together. Additionally, several of these components will undergo an irreversible chemical reaction when the rubber is vulcanized during the manufacturing cycle. Because of the sheer number of ingredients and the transforming chemical reactions, there is no realistic way to reverse engineer rubber. Formulating rubber is more "art" than "science".

In formulating a rubber product, there are three types of performance challenges to consider.

  1. Dynamic. The one factor that distinguishes rubber from other materials is the very large deformations that it can endure in its applications. Rubber must maintain its properties through a lifetime of dynamic stressing. Rubber needs to be resilient enough to perform its function even after being compressed, stretched or twisted thousands, or even millions of times.
  2. Chemical. Rubber is often required to withstand a variety of chemicals. For applications in motors or generators, it must be resistant to gasoline and oils. Some industrial equipment will see a variety of harsh fluids such as cleaning solvents, acids or alkalis. Rubber tubes can have any number of harsh fluids pumped through them. Without proper formulation, a rubber compound could literally dissolve or crumble when faced with these corrosive elements.
  3. Environmental. Not only does rubber have to stay flexible for thousands of cycles and possibly withstand corrosive chemicals, but it may also be required to perform in temperature extremes. A good example of this is a car sitting out in a Minnesota winter: during the night, the sealing O-Rings in its engine will be subjected to freezing temperatures. The O-Rings need to seal just as well when that cold engine first starts as they do when the engine reaches its peak temperature.

When these performance challenges are combined, it can create a tremendous (if not impossible) task for the rubber formulator.

The first step in rubber formulation is to develop detailed requirements relating to conditions that the rubber will need to withstand. It is fairly straight forward to identify the mechanical/dynamic requirements; however, chemical and environmental factors are commonly misunderstood. In this case a rubber formulation chemist with a great deal of experience is necessary. The chemist has seen a large variety of applications and can help identify what conditions a product could potentially experience out in the field.

After thoroughly understanding all the requirements, a rubber formulation chemist can derive a recipe of dozens components to create the compound. Rubber formulation is extremely complex and can draw upon literally hundreds of potential variables. Because of the scale of this complexity, there are not many tools and guides to analytically determine the exact formulation that will optimize performance for a given application. Achieving optimum performance with rubber is far more of an "art" than a "science", and requires experienced and knowledgeable formulators.

It is not uncommon for a number of different mixtures to be created and tested before the ideal product is developed. Temperature stressing, fluid immersion, elongation testing, tensile strength, flex-cycling, ozone aging and weathering can be performed in a lab, and this testing provides some indication of the product's performance. However, only testing that duplicates field conditions can be trusted to determine the acceptability of the formulation.

Plastics and Rubber Products have become a common feature in homes. For that matter even Industries have fallen hook, line and sinker for the two. Two major factors like credibility and versatility have been driving their demand. Considering the soaring demand for plastic and rubber products, we have come up with a common platform for all plastic and rubber manufacturers, suppliers, exporters and buyers, to trade with each other at the click of a mouse. A few years back, transactions used to take place ‘on –field’, with both parties sitting face-to-face, before closing the deal. Here, the major plus point is the transaction is taking place ‘on-line’ and you can strike a profitable deal right away. Sitting face-to-face can be done anytime.

Wednesday, November 3, 2010

Plastic Fiber Optics



A glass or plastic fiber that diffuses light along its path is fiber optics. Light is stored in the core of the optical fiber by total internal reflection. This causes the fiber to act as a waveguide. Fiber Optics is used as light guides to conduct the stream of light source to a point of use. These guides brighten parts that are too small or too harmful to fix a light bulb. The plastic light guide and the glass light guide are the two sorts of light guides.

The general common term for a wide range of synthethic or semi synthetic organic amorphous solid materials, plastic is used in the manufacture of industrial products. Plastics are typically polymers of molecular mass, and may contain other substances to improve performance and/or to reduce costs. There are different types of plastics for different uses: cellulose-based plastics, backelite, polystyrene and PVC polystyrene, nylon, and rubber plastics. These are used for molding, plastic models, plumbing, gutters, house siding, enclosures for computers and other electronic gear, among others.

In fiber optis technology, plastic is used as plastic light guides. Fiber optic light guides consist of non-coherent bundles of optical fibers. The fibers at each end of the bundle are tightly compressed, cut perpendicular to the axis of the fibers, and polished to permit light to pass into and out of the bundle. They have a bendable outer cover and a light-conducting core. So that that the ends of the fibers spread out distinctly to lighten different points from a single light source, multi-leg devices are rip along the length of the light guide. Although flexible glass fiber optics is more flexible than plastic fiber optics, the latter is more suitable for the transmission of light in the visible and near-infrared range. Furthermore, plastic light guides have hardly any luminous loss over distance and are better suited for UV light transmission.

Choosing what guides to use requires a careful study of physical and performance specifications. Physical specifications refer to length, diameter, and termination method. Keep in mind that some light guides are terminated with a threaded or unthreaded ferrule, a tube-like mechanical fixture that confines the stripped end of a fiber bundle while others are unterminated devices. However, performance specifications refer to wavelength, acceptance angle, bend angle, and numerical aperture.

Acceptance angle is the maximum angle measured from the axis within which light is accepted or given out by the light guide and transmitted along its length, and the bend radius is the smallest bend that fibers can bear prior to fracture. Numerical aperture refers to the calculated, optical value that indicated a device's ability to collect light over a range of input angles.

When you have decided which light you need, go to a trusted provider of fiber optics and related devices to ensure that your product, be it fiber optic cables or transceiver modules, pass industry standard qualifications.