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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How to Get an Effective Press Release

There are actually some people that feels that press release doesn’t have as much weight compared before. Even when some people tend to misuse them, if this will be written properly, the releases will give out a big impact in order to aid you in generating good details regarding the products and brands. To help you out with this matter, below are some features which you need to make sure that the release have so it will give the best results possible.

It needs to be newsworthy also. If you try looking around, you are going to find a lot of people who provides unworthy news releases. For you to actually become successful, it is essential that you make certain that your release comes with something worth mentioning. A good example for this is an introduction to new products, abnormal profits or anything else. As the rule of thumb, it is essential that you avoiding writing a release which is not adding new information towards the people.

It’s also essential to make sure that it is informational. Before, people actually use press release to aid in popularizing brands. You will not be able to go anywhere if it’s not informational. The press release to which you must put down has to be informative. When you introduced a new product, you need to tell people more about the product and not about the firm. It is likewise important to talk on facts and statistics of the product for the journalist to pick it up and to distribute or publish this.

It’s also important that it is timely. A press release is not going to give an ideal impact if you release it at a wrong time. Experts in fact recommend to send the release during the productive hours of a day. You must however be cautious of the day when you send it out. It’s best to send it during Tuesdays or Wednesday. Avoid sending this during Mondays, Fridays or at weekends because there are only few people that reads it during this time.

It must be easy to read as well. There’s no one that is going to read your press release when this is going to be written at a language that’s hard to read. Even if it’s beautifully formatted, no one still will consider sharing or reading it. This would be why you should consider reading it in an easy language. This needs to be formatted easily so that people will have an easy time to navigate through.

Press releases are in fact still effective and are impactful if you are going to write and distribute it properly. When you lack the skills in doing it right, it is best if you hire a professional that will help you out.

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Should People Give Importance to Press Release Distribution?

There are a lot of benefits that you will be able to enjoy when it comes to press release distribution.

No matter what kind of business it may be they are still able to benefit from the press release distribution and this is what you need to know first. And when dealing with the press release distribution, even the size of the business does not matter. It also will not matter if your story is not that amazing. Coverage in podcasts, trade journals, blogs and magazines is what you will still be able to get from your stories. If you will not be telling your story then for sure you will not be able to get the kind of publicity that you want.

Another basic fact of press release distribution that you should know of is that this is actually affordable. There are actually a lot of companies that decide to hire their own press releases. Another benefit that you can get from the press release distribution services is that they can get the story in the hands of the media members. If you compare the press release distribution with paid advertising, the press release distribution is always more affordable.

The visibility of your company can actually boos with the help of the press release distribution. This will benefit the most the small businesses. There is still however a need to make sure that the large companies will fight for consumer mindshare. Being in the press release distribution will mean that you are letting your customers know why they need you, who you are and what you do when you stick to it for a long time. As a matter of fact you will also be able to attract the attention of the journalists. And as the journalists will trust you then they will be able to give you more even more media coverage.

The other benefit that you can get from the press release distribution is that it has the capability to establish you as an industry expert. It is important to be known as an expert? It is for sure that you will be able to gain the trust of your customers when you will be known as an expert. And if they trust you then they will buy more from your. It is also good for media relations when you are an expert. You can expect the media to be calling you first when there is a commend that they need in your industry.

A positive press release distribution means that it can spread wide and far. There is always a need for you to reach a wide target market at all times.

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Tips and Tricks in Writing Effective Press Releases

Are you one of those who know how to create press releases? Are these important to companies? What are the attributing factors of its demand and popularity? If you want to know more about press releases, its importance and tips on how to write one, then you are advised to continue reading this article.

Definition of a Press Release

Press release in one technical term that is used to describe a kind of written communication that features an event or a situation provided to new media for the prime purpose of promoting it in different channels. You can also come across press releases used in promoting companies, its different events, services or products. In the past, these press releases can only be found in conventional periodicals but today, there are lots of press releases submitted online.

Why Press Releases Are Important to Companies?

Creating press releases online are effectual in releasing information about companies like its successes, product launches and many more. There are growing number of businessmen who used press releases in attracting inbound links as well as link popularity among the diverse search engines. There are also those who used press releases as one marketing platform.

Though, press releases are very important to big and small companies, we cannot formulate and write one whenever we want to because there are certain guidelines and elements that must be taken into account for it to become informative and effective. Should you want to be adept in writing press releases, then the first thing that you can do is to consider the pointers and steps found underneath.

Tips in Creating and Developing Press Releases

1. Prior to writing a press release, it is important for you to know and to analyze the type of audience that is geared at. Be sure to investigate deeper to know the target audience and the things that attracts their attention.

2. Be sure to determine first on the websites where you plan to submit and to post your press releases. Make sure that you know what are the websites that are visited by your target market.

3. Make sure that you formulate catchy and attractive titles for your press releases. These are crucial as it will motivate your target audience to read the press releases deeper as well as visit your sites.

4. You are advised to write your own original press releases and not those copied from somewhere to prevent being sued for copyright infringement.

5. Be precise on what information you want to relay in your press releases.

6. Avoid writing lengthy press releases but write one which is concise, informative and short.

7. Make sure that you choose your terms and terminologies wisely and opt for those which are simple and those that are familiar to your target audience.

Follow the guidelines found in here should you want to formulate effective and informative press releases.

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Essential Concepts About Press Release Services

Having a favorable image for your company or your organization is highly necessary that is why it is not surprising for business owners and other organizations to acquire press release services. Each organization or company has their own public relations team or manager and it is their duty to acquire the aforementioned services. Most of the time public relations offices will be the one that will order the release of the official statement by a particular organization.

Through this services, establishment owners are able to establish a positive relationship among clients and promote awareness on the services and products they can offer. As of today there are already several companies that offer press release services so you see there is not much to worry when it comes to finding one. Some of the services they offer includes distribution and drafting of the whole content release in the public. When it comes to the content that you want rest assured all everything will be included.

When it comes to the content of the news, you have the assurance that every details will be in accordance with your likes and it will written professionally. It would also be best if the service provider that you are going to transact with is knowledgeable in the elements of PR so that media outlets will not reject it. This way all the details is not overlooked. As much as possible the content should be brief, complete and most importantly catchy for the readers.

As part of the press release services, there should be some important ideas included about the company. Relevant information of the company includes the name of their websites, important officials, contact information as well as their address. The one in charge with the draft should never put an intent to market the product and services of the company. Instead it should be impartial and signify fundamental information pertaining to a particular circumstances.

You also need to make sure that the service provider that you are going to deal with should not overstate things or circulate information that are not factual. It would be best if the press release can be easily grasp by people reading it. If the news release is already good and permitted by the organization then more likely it can be release by several media outlets. Several publications will depend on the type information that is to be circulated. Some information are made for the public to read however some are more focus on a particular audience hence place in specialized writing collections. That is why it is important that you are going to choose the most proficient and competent public relation service providers so that the content will be appropriate and in accordance with your preference. As much as possible you need to seek for quality output.

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The Beginners Guide To Attorneys (Chapter 1)

How To Protect Your Rights With The Help Of A Car Accident Lawyer Losing a compensation is what usually happens the moment that a person involved in a car accident do not know the rights that he has. That is why when you are in this kinds if situations, it is very important that you will get yourself a car accident lawyer. It is during these cases that complicated steps are involved that is why it is very important that you will get the help of a car accident lawyer in the early stages of the process. It is being involved in a car accident that you will be able to sustain permanent injuries or even death. The protection of the right of the person involved will be protected with the help of a car accident lawyer as there are different laws in every state. They are the ones that has a full understanding of the law concerning these kinds if accidents. There is physical and mental pain in every car accident that is why it is not all about the money. As a result of the accident, you will be facing a number of different expenses like medical and many more. A minimum payout is what you will get when you have an insurance coverage as they will do their best that this is what you will get. There will trauma in your part and the worst is that you will also be facing huge debts as a result of the accident.
5 Key Takeaways on the Road to Dominating Services
A car accident lawyer shines during these kinds of situations. Shedding light over the complicated process is what the lawyer does. The moment that the insurance company will provide a minimum amount of compensation, then it is the car accident lawyer that will step on and protect the interest of his client. They will make sure that you will get the right amount and even ore and if not, they are also willing to go to court with you.
How I Became An Expert on Lawyers
There may also be times that you will not be experiencing any kind of serious injuries during car accidents. You will not be paying any large amount of medical bills but the car that you have will still be ending repairs. The proper assessment of the damage your car will be done by the car accident lawyer so that it will not pose any danger to you in the future. An immediate action is what is warranted from you the moment that you will be involved in a car accident. The reason for this is for you to be bale to the maximum benefit. By the time that you will receive the compensation is also the time that you will be paying your lawyer.

A Quick Rundown of Attorneys

How To Find The Most Suitable Personal Injury Lawyer. It is vital to seek the services of a competent individual that will not waste your money and time. Ensure that you rely on word of mouth so that you can receive genuine information. It is easier to talk to friends and relatives that you are aware that have dealt with personal injury lawyers in the past. Ensure that you contact the professionals that are recommended to you and determine if they are the right choice for you. Also, you should ask about both the negative as well as the positive experiences so that you can get the whole picture. The professional that you pick ought to have worked as a lawyer for many years. It would be frustrating to hire an individual that is not sure about what to do. Ensure that you ask to view the lawyers’ portfolio so that you can look at the number of cases that they have won in the past.
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It is advisable to look for a professional that is good at his work. Remember that there are some lawyers that handle very many customers and hence they such lawyers are not able to offer you the required attention. You should not rely on the word of mouth of your potential lawyers and instead, you ought to carry out your own research.
What Has Changed Recently With Professionals?
When searching for a lawyer on the internet, you should ensure that you read the online comments so that you can understand the reputation of your potential lawyer. Thus, ensure that you do not hire a lawyer that has only negative comments from his former customers because that means that you will also be disappointed in the results that you will obtain. Also, you can ask for a references list from all your potential lawyers. Make an effort to contact them and ask whether they were satisfied with the services that were rendered to them. The cost of the personal injury services is also significant. Ensure that you compare the prices that are listed on the different sites or you ask your potential lawyers to send a price estimate. Hiring a professional personal injury lawyer is very crucial rather than arguing the case by yourself. Therefore, the best step is to seek the assistance of an individual that is competent and will assure you of a win. Also, this is kind of work that a personal injury lawyer does every day, and therefore he has adequate knowledge. Also, a personal injury lawyer is able to negotiate a good settlement for you. The work of the support staff is to carry out research, perform interviews and many other important processes.

If You Think You Understand Companies, Then This Might Change Your Mind

The Reasons For Using Document Management Solutions Effective document management is one of the most common means of promoting efficiency, effectiveness and success of any business organization. The document management companies offer a broad range of services that enhance the performance of routine roles to meet the needs of the administration as well as clients. Subject to the unique needs of your organization, you can engage different service firms for each service or just one company for numerous services. The leading doc management firms aim at increasing safety and security of sensitive information on different documents. With the development in technology, the document management solutions help store your documents in different methods including the digital storage systems. These services prevent or minimize loss of vital records and common human errors arising from manual handling and storage of various records. Unlike paper records, the computerized document management systems prevent unauthorized access to sensitive records. Another a key advantage of document management services is enabling the effective exchange of documents among various departments, employees and the management. For example, the digital documents can be available through the internet for the interested parties and this facilitates teamwork and coordinated performance of business activities. Staffs working in offices situated in diverse locations can play important roles towards the achievement of a common goal due to easy access to significant information. Furthermore, various departments can utilize document management solutions for continuous sharing of ideas, records, instructions and recommendations. If your corporation has massive piles of paper documents, you can create some space and eliminate clutter by hiring the service of document management company.
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Industries that need many records, for instance, healthcare, legal services, engineering and secretarial can increase productivity through proper document management. However, since every business needs records for future use, document management solutions are available to all companies so they can safeguard sensitive information and reduce clutter in the offices.
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Creating and producing paper documents leads to additional expenses associated with purchasing ink, papers, and energy while excellent document management solutions offer an environmentally-friendly substitute. With the help of advanced document management solutions, you will produce paper documents that are absolutely necessary therefore reducing expenses, environmental effects and damages that usually paper-based records. The modern day document management systems help your business to create a the appropriate impression and attract the potential customers, associates and stakeholders. In addition, you can partner with people from various parts of a nation or across the sphere to achieve a collective objectives. The services helps your commercial entity to increase the number of customers, improve clients’ experience, reduce expenses and gain from the contribution of different partners. Finally, proper document management also increase efficacy and output of the workers of a firm since they can access records promptly, work on them comparatively fast, share info and meet their goals.

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Cover Your Pet with an Insurance Policy

Insurance cover should make sure that your pet gets the best medical care. You will save a lot of money in case your pet gets admitted with the best insurance cover. The cost incurred when treating a pet would be covered by the insurance policy. To avoid problems that might come due to the sickness of your pet you should make sure that your pet is healthy when traveling.

When you insure your pet, any contingency could be covered by the insurance company. The insurance cover would take care of the medical bill of your dog. Even when you pay for the treatment of your pet from your pocket you could always get a reimbursement from the insurance company. Insure your pet to make sure that the medical expenses that might occur due to the injury or sickness of your dog or cat do not come from your pockets but the insurance company.

When planning to get an insurance cover for your dog investigate various insurance companies that cover the pets. Before you get the insurance cover for your pet try and enquire the level of coverage the policy could provide. You should also dig deep into the insurance policy to know the time limit for every condition of your dog or cat that could be covered.

The amount of money that the insurance cover contributes towards your dog or cat for every condition should be well known to you. It is also good to know if the policy could provide flexible coverage options that fit your budget and needs.

Considering the reputation of the insurance company that you plan to cover your dog through is paramount. The best policy is the one that covers your pet for all the entire travel destinations. You should get a recommendation from the insurance company from your veterinary, breeders or other pet owners. A top-rated insurance company that provides a cover for pets should be the one you seek. A good insurance company for the pets should give discounts to its customers.

A good insurance company for the pets would help you get a cover for your dog or cat. The best insurance company for the pets is the one that covers your dog in your entire travel destinations. Save yourself from the hiccups of unexpected travel expenses that come as a result of the illness or injuries of your dog by getting the best insurance cover. A reputable insurance company should help you rest with ease especially when footing the bill for the treatment and medical acre of your pet. Make sure when you are traveling with your pet the insurance cover for the pet is renewed.

Practice Pro Helps Dentists Stand Out Online and Attract New Patients

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VANCOUVER, British Columbia — Dentists in Vancouver and elsewhere in North America now have an important new option, as Practice Pro opens up its services to all. With a focus on dental website design and marketing, Practice Pro offers everything from affordable starter website packages or fully custom designs to new patient marketing programs.

Coupling over a decade of successful experience in website design and marketing with a deep familiarity with the dental industry, Practice Pro delivers the kinds of solutions that dental practices benefit from the most. A simple, six-step process produces results custom-tailored to each client’s needs, helping any practice move forward. With the company now accepting new clients, those interested can submit questions and request a free quote at

“Running a dental practice in today’s competitive environment can be challenging, but this isn’t to say it’s necessary to go it alone,” said Practice Pro representative Tom Nimchuk, “We understand the challenges that dentists face and have developed effective ways of addressing them. As visitors to our website at will see, Practice Pro can equip any dental practice with an online presence that helps it find new patients and secure the loyalty of existing ones. Getting started couldn’t be easier, and we’re ready and eager to help.”

Particularly compared to other forms of health care, dentistry has traditionally been one where small, independent practices have dominated. Although that is starting to change, with the American Dental Association and others projecting steady market-share growth for larger corporate clinics, dentist-owned and -managed practices remain, in many respects, the backbone of the industry throughout North America.

Practice Pro was founded to help such practices thrive online. With over a decade of experience at web design and marketing, including many successful projects for healthcare-industry clients, the firm’s founders also have deep familial ties to the dental industry. Using state-of-the-art design approaches and cutting-edge technologies, the company produces and markets websites that help dental practices achieve their goals.

Since launching earlier this year, Practice Pro has already delivered impressive results for many clients, including website projects for major dental conferences. With about 40 percent of the average dental practice’s production coming from new patients, according to a report issued by the Levin Group, Practice Pro’s local marketing and ad retargeting services build on its engaging, conversion-oriented websites to produce real returns. Practice Pro is now accepting new clients, and visitors to the company’s site at can learn more and request a free quote.

About Practice Pro:
At Practice Pro, we’re focused on helping your dental practice succeed. With top-quality web design and highly effective digital marketing services, we provide clients in Vancouver and throughout North America with online presences that stand out and produce results.

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