Blown Film Extrusion Introduction

Blown Film Extrusion Introduction
Blown film extrusion is a technology that is the most common method to make plastic films, especially for the packaging industry. The process involves extruding a tube of molten polymer through a die and inflating to several times its initial diameter to form a thin film bubble. This bubble is then collapsed and used as a lay-flat film or can be made into bags. Usually polyethylene is used with this process, and other materials can be used as blends with these polymers. A diagram of a polyethylene chain is shown in Figure 1 to the right.
Background Theory on Polymers

In the cooling step of blown film extrusion, the amorphous, transparent melt crystallizes to form a translucent, hazy, or opaque film. The point where opacity begins in the bubble is known as the frost line. 
Fig 1: Model of polytheylene chain frompolyethylene Wikipedia article.The frost line height is controlled by several parameters: the air flow, film speed, and temperature difference between the film and the surroundings. Properties of the film, such as tensile strength, flexural strength, toughness, and optical properties, drastically change depending on the orientation of the molecules. As the transverse or hoop direction properties increase, the machine or longitudinal direction properties decrease. For instance, if all the molecules were aligned in the machine direction, it would be easy to tear the film in that direction, and very difficult in the transverse direction.

The Film Blowing machine Process

Fig 2: Schematic of set-up from User:J.Chiang.

Typically, blown film extrusion is carried out vertically upwards, however horizontal and downward extrusion processes are now becoming more common. Figure 2 shows a schematic of the set-up for blown film extrusion. This procedure consists of four main steps: The polymer material starts in a pellet form, which are successively compacted and melted to form a continuous, viscous liquid. This molten plastic is then forced, or extruded, through an annular die. Air is injected through a hole in the center of the die, and the pressure causes the extruded melt to expand into a bubble. The air entering the bubble replaces air leaving it, so that even and constant pressure is maintained to ensure uniform thickness of the film. The bubble is pulled continually upwards from the die and a cooling ring blows air onto the film. The film can also be cooled from the inside using internal bubble cooling. This reduces the temperature inside the bubble, while maintaining the bubble diameter. After solidification at the frost line, the film moves into a set of nip rollers which collapse the bubble and flatten it into two flat film layers. The puller rolls pull the film onto windup rollers. The film passes through idler rolls during this process to ensure that there is uniform tension in the film. Between the nip rollers and the windup rollers, the film may pass through a treatment centre, depending on the application. During this stage, the film may be slit to form one or two films, or surface treated. Advantages Blown film generally has a better balance of mechanical properties than cast or extruded films because it is drawn in both the transverse and machine directions. Mechanical properties of the thin film include tensile and flexural strength, and toughness. The nearly uniform properties in both directions allow for maximum toughness in the film.
Blown film extrusion can be used to make one large film, two smaller ones, or tubes that can be made into bags. Also, one die can make many different widths and sizes without significant trimming. This high level of flexibility in the process leads to less scrap material and higher productivity. Blown films also require lower melting temperatures than cast extrusion. Measured at the die opening, the temperature of cast film is about 220 C, where as the temperature of blown film is about 135 C. Furthermore, the cost of the equipment is approximately 50% of a cast line.

Blown Film Extrusion Disadvantages Blown film has a less effective cooling process than flat film. Flat film cooling is done by means of chill rolls or water, which have significantly higher specific heat capacities than the air that is used in the blown film cooling process. The higher specific heat capacity allows the substance to absorb more heat with less change in the substance temperature. Compared to cast film, blown film has a more complicated and less accurate method to control film thickness; cast film has a thickness variation of 1 to 2% versus the 3 to 4% for blown film. The resins used for casting typically have a lower melt flow index, which is the amount of polymer that can be forced through a standard die in 10 minutes according to a standard procedure. The melt flow index for cast film is about 5.0 g/10 min where as for blown film it is about 1.0 g/10 min. Consequently, the production rates for cast film are higher: cast film lines can reach production rates of up to 300m/min where as blown film lines are usually less than half this value. And finally, cast film has better optical properties, including transparency, haze, and gloss.

Common Problems Air entrapment between film layers and rollers – this may cause film scratching or wrinkling, or processing problems when winding up the film due to reduced friction. Possible solutions to this is using a vacuum to remove entrapped air or by using winding rolls with a diamond shaped groove in the rubber cover to increase surface area and decrease amount of entrapped air in the film. Large output fluctuations from the die – this causes thickness variations, and can be prevented by keeping the extruder clean and by using more consistently shaped pellets in the extruder. Melt fractures – these appear as roughness or wavy lines on the film surface, and can be eliminated by lowering the viscosity of the polymer melt. This can be done by increasing the melting temperature or by adding an internal lubricant to the material composition. Thickness variations in the film – this can be avoided by centering the die in the extrusion line before every run, adjusting the air speed of the cooling system, or by using heated die lips. Die lines on the surface of the film – this defect reduces the aesthetic appeal of the film, reduces optical properties, and weakens mechanical properties such as tear strength. This can usually be avoided by routinely cleaning the inner surfaces of the die and by refinishing scratched or roughened flow surfaces. Gels – these defects are small, hard globules encapsulated in the film or stuck on the film surface and reduce the aesthetic appeal of the film and cause stress concentration points which may result in premature failure. These are caused by overheating to the point of polymer degradation in the die, and can therefore be avoided by cleaning the inner surfaces of the die on a regular basis. Optimization of the Process Coextrusion One way to improve the line efficiency of blown film extrusion is to implement coextrusion. This is the process of extruding two or more materials simultaneously through a single die. The orifices in the die are arranged such that the layers merge together before cooling. This process saves time because it extrudes two or more layers at the same time, and it provides a method with fewer steps to produce multilayer films. The production rate for a coextruded multilayer film of three layers is about 65m/min, and the production rate for a single layer of blown film is about 130m/min. Thus, in order to produce 10 000m of a three layer multilayer film, it would take almost 4 hours using a single layer blown film process, and only 2 and a half hours using the coextrusion process. Furthermore, the film produced from the single layer process would require an extra step to glue the layers together using some sort of adhesive. Coextrusion is the least expensive means of producing layered films and the coextrusion system is capable of quick changeovers to minimize production line down time.

Minimizing the Melt Temperature
The efficiency of blown film extrusion can be improved by minimizing the temperature of the polymer melt. Reduction of the melt temperature causes the melt to require less heating in the extruder. Normal extrusion conditions have a melting temperature at about 190 C despite the fact that the temperature of the melt only needs to be about 135 C. However, it is not always practical to decrease the melting temperature by that much. By decreasing the melt temperature 2 to 20 C, the motor load can be decreased by about 1 to 10%. Furthermore, reduction of the melt temperature causes less need for cooling, so there is a reduced use of the cooling system. Moreover, removing heat from the bubble is usually the rate-limiting factor in this extrusion process, so by having less heat in the polymer to remove, the rate of the process can be increased, thus yielding higher productivity. A way to maintain the melt temperature at a minimum is to choose an extruder that is matched to the specific processing conditions, such as the material of the melt, pressure, and throughput.

Heated Extrusion Die Lips
Typically, solutions to melt fractures involve decreasing the output or increasing the melt temperature to decrease the shear stress in the extruder. Both of these methods are not ideal because they both reduce the efficiency of the blown film line. Heated extrusion die lips can solve this problem. This targeted heating method allows for film extruders to be run at higher production rates with narrower die gaps while eliminating melt fractures. Direct heat is applied to the surface of the polymer melt as it exits the die so that viscosity is reduced. Therefore, melt fractures, which are caused when trying to extrude too much of the polymer at one time, will no longer act as a limiting factor to increasing the production rate. Furthermore, heated die lips use less energy than increasing the melting temperature because only the surface of the melt is heated and not the bulk of the liquid. Another benefit of using heated die lips is that thickness variations can be controlled by adding heat to certain areas along the die circumference to make the film at that position thinner. This would ensure that no excess material is used.
Determine how much energy each of these processes can save per given volume of material. 

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How to Achieve Maximum Success with

Tips to Help You Find the Best Sneakers in the Market

It is crucial that you know the importance of purchasing a shoe rather than walking with it. A large percentage of people wear shoes that are trending. You can find that you are comfortable with a particular shoe but its way back on fashion. You should know that the shoe that goes fast in the market is the sneakers. Therefore, you should know that choosing it to be your fashion shoe will be the best idea. The experts will guide you when you are choosing the top sneakers in the market. You should read more here to know the tips to help you find the best sneakers in the market.

You are supposed to know what you need before deciding on what to purchase. Sneakers that are designed to last for a long time are the ones that you should buy for running. If you are planning to wear the sneakers for a long time then they will wear out quickly. You should strive to know more about the sneakers that will serve a longer period.

You should know the number of time that you will require to wear the sneaker before you decide on buying them. You will, therefore, know how many sneakers you are to buy. It is important that you know if the sneakers are used for work then you are required to have many of them.

You should know that the other factor that will guide you when you are buying the top sneaker in the market is buying the one that matches with your clothes. Those that choose to match the clothes that they wear with the same color of sneakers, then they always look fabulous. Sometimes it is difficult to find the types of sneakers with the same color of your clothes. You should now know that there are colors that match with all colors that you can choose from.

It will be a good idea if you choose to buy sneakers from many different brands. By this, you will be able to know the brand that will offer the top sneakers for you. It will also be fun to line up the sneakers in your wardrobe from different firms. You should, therefore, try to learn more about a company that offers good shoes so that you can have several companies that supply sneakers to you.

By using the above information you will be able to get the best sneakers in the market that will beat all the fashion.

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Figuring Out

Advantages of Using the Pay per Click Services for Your Business
This kind of marketing program makes the business owner account for the many times that clients get into contact with their website is known as the pay per click. If you are not using the pay per click marketing you are missing out on quite a lot for it is efficient in various ways. To be enlightened on the application and benefits associated with the pay per click service, discover more here.

Incorporating the pay per click program makes the enterprise realize its goals. Identification of the business trademark is best made through the pay per click service. The pay per click marketing program is incorporated with features such that when the audience visits the page, it is easy to refer others who have an interest in the details. It is always necessary that the user applies some details concerning the service and how to benefit from it. It is of relevance for the business owner making use of the best words to describe the services as well as other relevant information concerning the business.

The pay per click is relevant since it makes the audience have the results concerning the service within a short time. With the business audience being linked to some social media pages, it is more useful for it helps the business generate more clients. The pay per click advertising strategy is helpful for it calls upon individuals who know about your service as well as those who do not. The activity makes it convenient to the new clients as well as the existing ones for they can have a good track on your services. New ideas are brought about by the program for the clients have the best exposure to the service.

The pay per click program makes the business to be in control of its marketing strategy. It is done by choosing the service with the much finances you have. For a small business, you can always start small as you can afford. With the business owner being equipped with the details on how to go about it, relating to the service becomes easier. When the business experiences a positive impact through the program, they can choose to stick to it or opt for other forms of marketing. With content marketing has overtaken other forms of advertising, the pay per click program is considered essential for it to produces the exact and genuine information that the clients require.

This program should include one of the most helpful things that every business should practice in the activities related to the business. This is out of the above-highlighted recommendations. It is relevant for the user to studies the programs details before deciding on engaging with it.

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The Beginner’s Guide to Houses

Guidelines On How To Sell Your House Fast

People have different reasons as to why they might need to sell their house after staying in it for a long or short period. Some of the reasons why a person might decide to sell their house quickly are retirement, after a divorce, when relocating to a new region or when in need of cash urgently due to an unavoidable crisis. Discussed in this article are some of the pointers to put in mind if you are looking to sell your house fast. First, if you need to sell your house fast you have to add value to it. Adding value to your house means making renovations and making your house pleasant to the potential buyers.

A house that is attractive will attract suitable buyers, and you will be able to sell it after a short period. Green homes have more market compared to those that do not so make sure you make your home one. Do the major repairs in the house so that it looks complete and new to the impending buyers.

Another tip is to make sure you do your marketing properly. If you do poor marketing, it will take a long time to make a successful house sale. It is not enough to simply put a signboard outside your property; you are expected to do more so that the house gets enough exposure that will make it popular thus getting more potential buyers. Social media, traditional media, and newspapers are other channels which you can use to market the property you are selling. All channels of advertising should be used to inform buyers that there is a house for sale. A quick sale is possible if you use an all-round marketing method.

you can sell your house to property managers. This will be helpful to you because these property buying companies will purchase your house without looking at the condition in which it is in when selling. This method is one of the easiest to sell your house since you are not required to renovate your house and do repairs prior to selling and also you do not need extensive marketing in order to sell your house.

The buyers can be found on the internet and simply contact them so that they can come and see the property. After a few hours or minutes of agreements, they will send you cash without any delays. It is advisable to sell your home to these property managers because the payments are made on time. Also, be keen when selling your house to these buyers to get the real value for your home.

Try to reduce the house price to a reasonable amount that is less than the real worth net of the house. It is not advisable to do that, but if you need the money urgently, then it is good to consider the idea.

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The Best Advice on Moving I’ve found

Important Aspects That Will Make Use of Known Storage Units Company as Your Source of Help Today

If you would like to expand your storage needs you should make sure that you have the perfect place that you can use at your needs. If issues are looking for the perfect kind of the place that will be able to offer the best variety of the storage it will be great to know that you can rent the best services today. You will note that if you have a great company that will be ready to work well with the needs that you have will be necessary for your storage activities. In the storage activities that you would like to have, it will be rather crucial to have one of the best companies at your help today.

A great company will have a complete package when it comes to your overall needs. If you don’t know what will make you go for the professional company services in your storage needs, here are some of the aspects that you will stand to gain from today. The pricing will be part of the top gains that the known company will be ready to help you at today. The pricing is a significant factor more so if you have a lot of products that you would like to store.

It is crucial to know that if you get better rates for your rent, then you will be able to use the facility for more items as well as for a very long time. The other significant element that a top company will have in store for you is the collection activities. If you will meet some given threshold of storage you will be sure of getting some special treatment through a free selection of the products that you would like to transport.

For your continued use of the top company services you will be sure of getting the ideal discounts that will be great to work well with the needs that you have as a person today. Seeking the very best kind of company will make sure that you have an excellent program for the discounts for your continued services use. At your storage needs, it will be great to note that use of the particular company will be ready to offer you the top access at your disposal.

Use of the high kind of the top company will have some essential services at your help. The security matters and a great company will know the necessary measures that it should put in place to make sure that the client products are safe. Getting the best kind of the storage units will help you to take care of your items.

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Smart Ideas: Money Revisited

Online Casinos And Everything You Need To Know About It

There are a lot of people who think that one can win in online casinos only when they are lucky. Yes, it is true that chance plays a big role in a lot of games, but if you are individually skilled, it would really be in your great advantage and best in your favor as well since you will be able to give balance to the games. The money at stake and the chances of a person to win should be determined in a poker game and this will take the skill of a player. Mental calculations are essential skills needed for a blackjack player in order to perfect their game. That is why the casino is the perfect source of income for players that are skillful. Spending a lot of time playing casino games will surely improve the level of skill that the player has. If you are looking for ways wherein you can practice your mastery in this craft, you may access online casino games anytime, anywhere. If you want to get a lot of money from online casinos, you should continue on reading this article since it will be able to provide you with some useful tips.

Make use of comps
Comps is a term that refers to a point system that can be acquired when a player earns some pre-announced number of points in every game that he is able to play but this will depend on the kind of casino service provider that they are dealing with. In order for players to return to their websites, they use comps as a marketing strategy to encourage and lure people to come to see and play the games that they are able to offer again. For them to be able to get their cash award, a certain amount of points needs to be reached so that they can redeem it. For instance, if you are able to obtain 100 comp points already, then you can get $1 or leave it be so that it will accumulate. This is one benefit that you can really enjoy since you don’t have to worry if your points will be affected with the result so your games since they will stay the same whether you win or your lose. In case you are on the losing side, you can find this to be the positive side of things since you can be bale to have your points converted into cash later on. Rewards may vary in different casinos and you have to acknowledge that some casinos are not very good at handing out cash. Instead, they will give you other rewards such as invitations to special events, dinners, tokens, liquor, voucher, and other prizes.

All type of bonuses
There are fixed bonuses and there are also random bonuses both in the form of money that players may be able to receive anytime they are playing the game.

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How I Became An Expert on Garages

A Guide in Choosing the Right Garage Door Company.

If you are looking for a company that sales or does repairs on garage doors, it is advisable you take your time so that you can choose the right one. It can be a challenge choosing a garage door company, especially with the many options to choose from. So, how do you choose the right garage door company? Your search for the right garage door company can be much easier with the tips below.

It is important you start by checking if the garage door company you are prospecting is licensed by the state. If the garage door company for whatever reason is operating without been licensed first, to protect yourself, its best you look for another alternative.

Does the company have a liability insurance cover? In case the contractors from the company injure themselves when repairing the garage door, the insurance company will cater for their medical bills.

Does the company work with contractors who have the right qualifications? Go for a company that has contractors who have been trained to install and do repairs on different types of garage door.

Does the company have experience in selling and doing repair on garage doors? It is advisable you choose a company that has been in the market for years. The company has diverse knowledge about garage doors from their many years of experience.

Getting the contact details of some of the past clients of the garage door company is important. If the garage door company is reluctant on giving you their reference list, that is a red flag and its best you look for another alternative. It is advisable you have a list of questions that you will ask the garage door company past clients once you call them. Based on the feedback you will get, decide if you want to deal with the garage door company or look for another alternative.

What kind of reputation has the garage door company built in the market over the years? It is advisable you read the testimonies that have been posted by past clients on the website of the company. From the reviews you will get unbiased opinion about the garage door company. Go for a garage door company that has the best reviews and ratings.

When choosing a garage door company, it is important you consider location. You can find garage door companies based in your area by searching on the internet.
Also, check the working hours of the garage door company.

What budget have you set aside for the services of the garage door company? There are companies that will charge you more than other to do repairs on your garage door. Although you should consider cost when choosing a garage door company, don’t choose a company charging way below the others.

If you have people who have used the services of garage door company, either to do the repairs or buy, ask them which company they used.

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The Best Advice About Sales I’ve Ever Written

Benefits of Working with the Top Best Home Buying Company in Your Locality

If you are looking to have your property on the market soon, utilizing the smartest way of getting a perfect home sale will be all that you will need to consider. You should know that selling is a process that will need a person that is ready to have only the best offer and process.

Once you go through the home sale process you will find that you will need to be happy about what you have achieved. For the home selling individuals, it can be part of the elements that they might not have a chance of getting today. Lack of the proper channels to use when they are selling their homes is part of the aspects that would affect a lot of people today when selling their homes.

It matters to know that it will be essential for a home seller to know where to sell the home for a great price and process. You should ensure that you know and also use the best of the platforms today. If you are from Houston Texas, it will be rather significant to make sure that you have the top best home buying company at your help.

Before you choose the company you should do some checks so that you can have confidence in the services that you will get from the same. To be more than sure that you have the right company will suit your home selling activities. Use of a great home buyer will help you in the following ways. For your home you will have a great chance to make the sake process quick.

Top companies will not entertain a slow process at any given day. The firm will send its representatives right away for the house valuations and following the process you will be able to get a great offer. It is crucial to note that use of the perfect home buying professionals will be ready for whatever kind of a home that you have. Therefore, you should not worry about any size of condition that the house might want.

It will be an opportunity to rest the problem of real estate agent burden when it comes to your home selling needs. The commission and tedious processes will be void from the point you will meet the best home buyers. Also, you will get the right help if you have some issues that would necessitate the sale of a home quickly.

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Getting To The Point – Services

Tips to Consider When Looking For a Wedding Venue

When it comes to special and memorable life events, weddings rank at the top of the list. A wedding should be an event where all the stops are pulled to ensure that it is smooth and magical. Despite there being some factors that are essential to the success of a wedding, the choice of venue is most important. The venue can make the wedding a success or a failure. You can hardly miss at a wedding venue but what matters is which is most suitable for you. That is why you need to check out these guidelines for you to get a magnificent venue for your wedding.

One of the most vital factors that influences the choice of a wedding venue is the number of guests that you plan to invite. Regardless of whether a wedding venue is extremely popular, give it a wide berth if it is not enough for all the guests. You have to find a delicate balance with regard to the number of guests. Ensure that the venue is not too small, nor too big.

Before you settle for a wedding venue, it is imperative to investigate if it has all the necessary facilities that the wedding guests might need. It makes no sense choosing a venue with inadequate parking slots. Don’t forget to ascertain if the seating arrangement is well ordered and enough for all. Don’t overlook some critical aspects such as the availability of disabled-access facilities such as wheelchair ramps.

The price of the wedding venue is critical to the selection process. The cost of retaining the wedding venue will hugely influence the kind of venue that you will get. It is important to note that there is a wide array of venues, all at varying prices. It is only prudent to choose venues that your budget can comfortably handle without breaking the bank. Luckily enough, with a reasonable budget, you can fail to get a great venue.

Sometimes getting a wedding venue for a specific date can be trying if you don’t book in advance. There are some wedding venues that are highly exclusive and clients book very early so you have to book in advance. Even if the wedding date is not very stringent, you still need to check the calendar of the venue.

The kind of style and theme for your wedding will greatly influence the venue. Are you for a modern or traditional type of ceremony? Is it going to be formal or informal? By being knowledgeable regarding the kind of wedding you want, choosing a venue need not be an uphill task. For instance, if your dream wedding style is traditional, you can never go wrong with a castle wedding. Armed with these tips, choosing a spectacular venue will be easy.

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The Beginner’s Guide to Products

Essential Tips For Choosing Low Pressure Molding Services Provider

A viable way that you need to resort to protect electronics and develop casts to steel is through low pressure molding which is efficient and quick. It is due to the many benefits associated with this method that it has gained popularity in the manufacturing field. It is through finding the right provider for low pressure molding services that you can be certain of accessing those benefits.

It will be a big advantage for you to go for a long established low pressure molding services company as they are better placed to offer the right solutions. You will come across a large number of the firms in the market which means that you need to make your choice cautiously. You can depend on the useful information available on the web to make the decision that you will be impressed with.

The low pressure molding services firm must offer products that are of superior quality. There is the need to be familiar and satisfied with the specifications that the machines you intend to buy have. The specialist that you choose must demonstrate that they will process and deliver your order as per the given instructions.

See to it that you are going for a low pressure molding services provider that possess the required registration papers and licensure that allow them to locally undertake the business. The service provider must be affiliated to a professional body that is tasked with the responsibility of regulating the operations of business players in the field. The rating of the service provider at the Better Business Bureau is a factor that requires your careful consideration.

You must ask to be availed with references of customers that have hired the services of the low pressure molding firm. This will be a good indicator on whether you should go ahead and engage their services. You must look for excellent customer service and reliable after sales support system from the company.

It is important to find out how much you will be charged for the products and services that you will obtain from the low pressure molding firm. It is a smart move to make a comparison of the prices from different service providers. Even though you may have the inclination to go with the company that is offering you the cheapest rates, you need to be vigilant so that you do not settle for substandard services. You should therefore not use the price as the only determining factor for your final decision.

You should never complete a transaction with the low molding pressure services provider without entering into a written contract. Before you append your signature to the document ensure you understand the contents fully.

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