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. 

Above article from www.appropedia.org

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A Quick Overlook of – Your Cheatsheet

A Guide for Purchasing Locks and Gun Safes

Investing in a gun always cost you a lot of money and that is why it is important to ensure that you take care of it by all means possible and also to avoid hurting people that are not your focus.You can always protect your gun by locking it in a gun safe. It is true that the buying process can be a great experience but also stressful but if you have more info, you can always make the right decision. Read this article to understand different considerations you can make when purchasing gun safes and locks.

The most important thing is to be fully informed when it comes to purchasing the gun safes and locks and the best thing is that you can browse for more info. The Internet is full of such information because there is always a helpful article describing different aspects of the gun safes and locks. You also have to stress around you will you can ask for more information especially those that you continue to site when it comes to using gun safes and locks.

The most important thing to realize is that the gun safes and locks will come in different sizes. This is you choose to buy will depend on the number of guns you have and also their sizes.As you continue reading more about the guns, you realize that many people recommend buying bigger capacity use it even for other purposes.

As you visit this website for more details, you realize that a gun safe and a lock can come in different styles. As you continuously refer to this page for more details, you can look at the different designs that are there so that you can purchase the one that pleases your heart.

As you follow this link on gun safes and locks, you realize that there are types of locks that you can invest in. This great site has different explanations of the different types of gun safes and locks and the level of security they can offer. The best thing you can do therefore is read this article more until you are fully satisfied with which type to choose.

You can never lock a company that is known for durable and fire and waterproof gun safes and locks and you can find such a company from great read articles or even original article from the company itself and if you like this company, you can buy from them. Before you can buy a gun safe and lock from a specific company, see here for the explanation to help you understand how to handle it and you can also see page that can explain more if you don’t understand fully.Get more than one estimates from different companies and also you can visit this website to get more info on prices.

If You Read One Article About , Read This One

Tips to Put Into Consideration When Choosing Ultrasonic Sensors.
This means that with the technological growth sensing tech has different features for presenting in different fields. Having some sensing tech that is affected by certain things like the photoelectric sensor they may fail in delivering its signals due to some factors. The ultrasonic sensors are among the best because it is not affected by any obstacle because sound can travel even in dirty environments. The ultrasonic sensor has a unique way of presenting the sensory results by the distance covered from the sound waves making it important to be keen when selecting it as it comes in a wide range of variety. This means that there are very many productions that use the ultrasonic sensors that include the food and beverage, agriculture and packaging. This means that hints mentioned below are vital for an individual to consider when choosing ultrasonic sensors.
A primary aspect to consider is the sensing distance of the ultrasonic sensor. This means the distance between the sensor and the object to be sensed. Having a wide range of variety of sensors it is important for an individual to identify the one that will serve their purpose according to the distance they can cover. It is important to place the sensors at a far distance from the targeted object so that you can avoid some instances of causing damages to it that will require regular repairs. Therefore the use of extended distance ultrasonic sensors will help cover longer distances and the sensor will be placed well helping you in achieving the results that you need.
It is important to factor in the type of ultrasonic sensors that you will use for your application. The analogue and adjustable are the main types of ultrasonic sensor. This therefore means that the analog sensor has a high voltage signals that are equivalent to the distance measured. Therefore, the switch point is the advisable ultrasonic sensor to get because of its advantage of adjusting that can be set for distances.
Lastly it is important to consider the environmental placement. It is therefore important to consider the environment before settling for the sensor so that you can choose the one that will be compatible with the surrounding fitting well and providing quality results. Having the ultrasonic sensor placed in the right angle in cylindrical housing have various benefits that include mounting it and adjusting in proper places that will help in achieving quality result for your application. Having the best quality that you need in ultrasonic sensor will be achieved by considering the hints above.

Study: My Understanding of

Things You Need To Know When Starting A New Business

Every person who wants to start a business usually wants the business to succeed. One thing that you should know is that if you want to Latin American Trade start a business in places like Latin America, you ought to first do a thorough research when it comes to getting to know the strengths, weaknesses, opportunities, and threats that are there. You ought to know that there are so many fundamental principles that tend to help someone to be able to lay a strong foundation for a new business so that it can grow and flourish.

It is usually advisable for you to Doing Business Latin America choose a business venture that will be exciting to you and you love doing it. You should not choose ventures by focusing on its financial possibilities. It can never be fun building something which you do not enjoy doing at all. If you usually do not like what you are doing, And you only think about the better possibilities and growth then Entrepreneurship Latin America keep in mind that even if it ends up succeeding you will still end up being unfulfilled.

You should make sure that you develop a business plan as it is quite important because if you fail to do so, then the whole business will not succeed. When you ensure that you develop a business plan, you will be forced to think through the logistics of starting the business, and it becomes something that you will always think about through ahead. marketing your goods and services is one of the most important things, and you should start doing it from the beginning. You ought to know that there are so many ways that you can market your goods and services. You can always research on the internet or even read books when it comes to different ideas that you can use to market your business. This information is usually important, and if you use it well you Trade and Investment can be certain that your products will definitely Business Expansion be bought by clients. New businesses end up making the mistake of promising the client’s many things that they cannot be able to deliver. Someone should never oversell their products or services by promising their clients things that they cannot be able to deliver Latin American Business as it can be really disappointing. It is advisable for someone to beat the expectation by making sure that they provide products and services better than what our customers would have expected Startups to Watch instead of handling International Expansion disappointed customers who expect more than what you can deliver. You ought to make sure that at all the times you are truthful about your products and true to your buyers.

The Key Elements of Great

Essential Points of Consideration When Establishing Start-Ups in Latin America

The Latin American Investment arena has a good number of businesses. The progress of these start-ups may have been facilitated by the businesses having considered the culture of the people and availed what they need. One of the organizations that have helped promote this aspect is the Biz Latin Hub, which has helps both local and foreign companies expand their businesses globally by representing them in Back Office. Another resourceful organization is Craig Dempsey. If you are considering setting up a start-up business in Latin America, there are necessary factors that you must put into an account before making the establishment. This article examines some points to be looked at by a person aiming to be involved in Latin American Business.

Determine what is required of you before you can access the market in the country. Among these requirements are those made officially by the government for Latin American Trade, while others may be by those businesses serving the market you are targeting to help as well. Finding information about these can help you access the market by having made the necessary steps required before doing so. It can also help you avoid the costs of non-compliance with set standards and regulations. Taking this step will give your business an uninterrupted continuity since you will not need to be pursuing certain conditions when you have already started. You can consider looking at the page for information on what may be required of you. You may also need Legal Services to Incorporate Company Latin America.

Think about whether the start-up you are considering has the potential for growth. This aspect may be determined by the availability of Trade and Investment that can boost your business. You must consider this aspect of expanding your business since it determines how much your business can grow in the future. Discover more about International Expansion and the possibilities your start-up can have in this area.

You can access helpful information on running a start-up effectively from those already in operation in the region. Among the ways this can be achieved is by viewing information on start-ups online to get some ideas on their business operations. You do not need to copy this, but you can surely learn a thing or two. See this page for an outline of Leading Startups you can view. You can also read more on Entrepreneurship to get you equipped with knowledge on what it takes to get a start-up running, and see if you have the potential for it. Entrepreneur Latin America can provide you with particular information about what it takes to run a start-up in the region. Find out details of related markets such as Australian Entrepreneur.

Questions About You Must Know the Answers To

How To Choose Franking Machine

This is a machine that is used to stamp an official mark on a parcel or if one is having a letter and this is always an indication that the stamp has been paid and learn. With the use of the franking machine then one is sure and advantaged since they will not be queuing at the post office and it also means that its like you are having a mini post office of your own and this link. When one has a franking machine then one is sure that the machine will not let you down at any given time and also if the stamps end one can always top up at any given time.

There are also discounts that one gets when they use the franking machines and this is an automatic 5% of every mail that you send, and it also does not cost much and thus one can always save money when they are using it and check the homepage. One is always accountable with the use of the franking machines and also one is sure that there will be no stamps that will be getting lost and also there will be no overpaying of the stamps and this service. With the use of the franking machine then one is able to control the people who will be using the machine and also one is able to control how the postage is done by each and every person. Any franked mail will always look simple though better and it also looks more professionally, the person who is receiving the mail will also take it more seriously and more about.

Promotion and also branding can always be done well when one is using the franking machine and with this one is able to add their own custom logo, their images and also the return addresses and read more now. Franking machines always come in different sizes and also they can be bought or leased depends with the needs that one has and thus the flexibility is always there and this company. When one is using the franking machine one of the advantages is that there is never an extra cost of the bags or the trays to help you organize your post and thus one is able to get a very special treatment at the post office. One will be able to save a lot of time since they will not be going to the post office more often to go and buy the stamps since the stamps can always run out at any time. When one is starting then it is always good for one to make sure that they buy a low cost franking machine and reap the benefits.

On Products: My Experience Explained

Benefits of Using Natural Cleaning Products

For you to have a clean and healthy place, be it your house, office or even a car, it is important to make sure that you are using cleaning products that are healthy and safe. The current market is full of cleaning chemicals, most of which contain chemicals that can be dangerous to your health as well as that of your family. Be a savvy cleaner by making sure that you always shop natural cleaning products that will guarantee you a clean and safe place. It doesn’t make sense to clean your place with cleaning products which are even more dangerous than dirt itself. This guide aims at giving your reasons of using the natural cleaning products and why they are the better option as compared to the chemical cleaning products.

To begin with, the natural cleaning products are on the rise, meaning that they are available in a number of options. It is now possible to use these natural cleaning products just like the chemical cleaning products out there. the good thing about these natural cleaning products is they are very friendly to the environment and they make you a great ambassador of the environment.

If you are using detergent, soap or any house cleaner that contain chemical, there is a very high probability that these harmful chemical can sip through into your skin and also affect your healthy circulatory system. Take note that skin is the largest body organ meaning a big skin surface will be exposed to these chemicals and when absorbed, it can affect various body functions or your health in general. On tops of this, if you or your loved ones have allergies, the natural cleaning products is a superb cleaning option for you. The natural cleaning products have many varieties and you can get the one which is free from dyes and fragrances. It is now possible for you to use cleaning product that can relieve you a number of skin allergies and also very amiable to the friendly.

All in all, there are countless reason why you should consider using these natural cleaning products, ranging all the way from taking care of your health as well as your environment. You must be aware of the many diseases whxich are caused by the use of these cleaning products that contain chemicals. To be free from these illnesses which are caused by harmful chemicals that you can avoid, it is always good to consider using natural cleaning products and you will be guaranteed of clean, healthy and safe place. This also shows that you mind about your health.

Getting To The Point – Businesses

A 10-Point Plan for Businesses (Without Being Overwhelmed)

Why Options Aren’t As Bad As You Think

The Ultimate Guide to Buying the Suitable Office Telephone System

In any country, there are certain fields key drivers to its economic growth. The industrial activities are essential as they will in one way or the other lead to the production of items or products. It is suitable to understand that it is your duty as a manager of a company in ensuring that it makes positive steps towards the overall goals. As you think of many other aspects in making your institution effective, do not leave behind the nature of your offices. Always make sure that you will have effective communication systems at your place as this will bring about efficiency in your operations. It is crucial to understand that you have various choices regarding developing tips to be effective in your internal and external communication.

Buying the office telephone systems is very essential as you will end up transferring information well. It is prudent never to rush when looking forward to purchasing an office telephone system as scanning the environment will do you good. Screening the market comprehensively will reward you in that you will see all the dealerships of the office telephone systems which are available. Through this article, I will give you the elaboration on the factors which carry much weight when you are choosing the best office telephone system.

At first, select the office telephone system which will match the current technological trends. It is suitable to make sure that you find time and check the characteristics which it have as you will know about the suitability of buying for it. It becomes very prudent of you to buy an office telephone system from a dealer who has a good reputation since you will not regret at the end of the day. It will be essential to read the testimonials which other people give regarding their experience in buying a specific office telephone system from a certain dealer.

Aim at making a purchase from a seller who will avail different options of the office telephone systems to base your selection on. Having several options of the office telephone systems will increase the chances of you narrow down to the one which will exhibit perfection. The buyers will mostly have different choices of the designs of the systems, and hence it is for a perfect dealer to understand this and avail all the possible options of the telephone systems for offices which are available.

Lastly, the best office telephone system is the one which will be affordable for you. You should make sure that you go for the dealer in the office telephone system who will not charge you favourable prices at the expense of the quality of the communication equipment.

Questions About Phones You Must Know the Answers To

Learning The “Secrets” of Resources

Study: My Understanding of Training

How to Choose the Best Cannabis Job Training Centers

The Cannabis plant has become very popular in the recent past and has thus become very celebrated as one of the best herbs there are in the world The healing properties contained therein are many and the list of the ailments it can cure is endless. It has been used in a wide range of ways, from CDB oil, hemp oil, and so on and so forth. This being so, it has opened up a lot of avenues for business and jobs. There now are very many jobs that one can find in this field. All Cannabis dispensaries want to have trained personnel working for them and this is why one needs to undertake training for any of these jobs. Settling on one Cannabis job training center can seem like quite a challenge based on the very reason that there is quite a large number of such centers opening up now. This is why it is crucial for one to think about a few key factors first. See below some key factors to consider when looking for the best Cannabis job training centers.

Research is of great importance and therefore needs to be the first step you undertake. Find out which of the options top the list of such centers and shortlist a few for more evaluation. View their websites to discover more in regards to their courses and such. Read more here for more info. Find out if online courses are also available as they make life so much easier. Budtender training online can be done and you can learn more about by clicking here. Find out if the training center is in a position to guide one to dispensary jobs upon course completion.

It is important to check the fees that you are expected to pay for the training. So contact the Cannabis job training center to ask for the fee structure. Weigh your options to be able to see what options fit into your budget. It is best if the center accepts such payments in flexible amounts as this make it easy for everyone.

Consider the reputation of the center. Look at the reviews and feedback from those that have used this center before. These reviews will help you decide very quickly whether taking up this course at the center is the right thing or not.

Find out more about licensing and accreditation of the center. There have been a lot of fights and battles won in legalizing Cannabis but this is not the case for all the states. Legalizing Cannabis job training centers has also been problematic. As it happens, not all the centers have the right paperwork. It is however wise to ensure you have chosen one that has the right licensing and authorization as this is the only way to ensure that the certifications you get are valid and usable. It also means that the staff there has the right qualifications to train you.

The 5 Laws of Marijuana And How Learn More

The Best Advice on Cannabis I’ve found

How I Became An Expert on Sales

High Quality Kitchen Cabinets

A house is made up of a number of rooms that are all essential for the comfort of the people living inside the house for instance a bathroom where people will freshen up and a kitchen. A kitchen is a standout amongst the most fundamental rooms in any home since this is where sustenance is prepared and safely stored also. There are certain things that should not lack in any kitchen, for example, kitchen cabinets where cutlery is stored in an orderly manner.

Kitchen cabinets additionally make a kitchen look increasingly delightful and there are a lot of kitchen cabinets with various designs that you can purchase. When you are building a house, it is vital to make room in the kitchen for kitchen cabinets and it is vital to take note of the measurements of the space you reserve. The measurements will be used to pick a kitchen cabinet that will fit in the reserved space without leaving any spaces which would then make your kitchen look unattractive. It tends to be genuinely difficult to pick the sort of kitchen cabinet you need on the grounds that there are a lot of different designs hence you should consider various vital elements while picking one.

The fundamental factor that you ought to think about when you are picking a kitchen cabinet is the cost they are being sold at. The price of the kitchen cabinets will depend on a number of factors as well such as the material used and the finishing design of the cabinet. A few cabinets are more costly than others since they are made utilizing superb material that is precious while others are averagely priced.
With the many designs of kitchen cabinets accessible, you should pick one whose cost is sensible and within your set spending plan.

Another important factor that you ought to take into account when you are choosing a kitchen cabinet is the design which ought to ideally match that of your kitchen. It is only fitting that the kitchen cabinet you pick ought to also have a similar design with your kitchen so your kitchen looks fantastic and you can seek the input of a home designer to be absolutely sure about your choice. Extra accessories to the kitchen cabinet should likewise be considered when picking one since they will likewise affect the outward presentation of your kitchen. Examples of kitchen cabinet accessories are door handles which should be fit properly so you can easily open the cabinet with no struggle. You should similarly pick a kitchen cabinet with an alluring style.

Short Course on Kitchens – What You Should Know

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