Manufacturing Businesses Need To Supply Training To Move Forward

Every business attempt to move forward, to complete more, and to attract more earnings. For manufacturing businesses, this implies creating more products and also having the capacity to accept much more potential clients. To be able to do that, they have to make sure their own workers are top-of-the-line and competent to perform the job properly, rapidly, as well as with as little waste materials as is possible. This means companies are going to wish to ensure they benefit from scientific molding training for their particular staff members.

Although it may cost money as well as time to educate workers, the organization is able to see the advancements almost instantly and will regain what they lost from the higher income after the education is done. Employees who take part in scientific molding seminars recognize more about just how to do their particular jobs as well as, therefore, are able to do their own jobs much better and also more quickly. This may lead to the company having far better results for all their projects and also being able to take on a lot more clients than they would have before the education was carried out.

Employees who experience the scientific molding classes understand exactly how to interact much better in order to produce the final project. They’ll find out just what the other workers do so they’re able to work closely together with them on the project. They’ll in addition understand precisely how to avoid common mistakes, precisely what to do if perhaps something just isn’t working right, as well as learn a lot more regarding the systems they will be working with. All around, this may bring about greater productiveness, higher earnings, and less waste materials when they may be focusing on a project.

Business people are likely to wish to make certain they’ll spend some time in order to look into the training that’s obtainable to be able to make sure their staff members have the instruction they have to have in order to achieve far more and to do much better. It will help the enterprise keep growing and also to move ahead, and it’s probably going to be worth the cash ultimately. If you want to obtain the extra training your staff members could need, make sure you look into injection molding training now.

Benefits Offered by Ducted Air Conditioning Systems

When it comes to home comfort, there is no system more relied on than a home’s air conditioning system. However, from time to time, some issues may arise. Eventually, it may be time to consider replacing the entire unit. If this time has arrived, there are a few options to consider. If a person is on the fence, they should consider the many benefits offered by installing a ducted Air Conditioning system.

Consistent Cooling Through the Home

If a homeowner decides to install a split system, they are only going to be able to cool the zone or room where the system has been installed. This means that the entire area would have to be closed off in order to maximize the effectiveness of the unit. This can cause issues if the home is configured to an open living design. A larger and more powerful unit will have to be purchased to cool the bigger areas effectively.

However, with a ducted system, this isn’t the case. A homeowner will have the ability to cool their entire home with just the touch of a button. The central unit is unseen and the air is pumped through ducts and out of vents throughout the home. This is an efficient process that provides consistent, even cooling throughout the entire house.

Ducted Systems are More Affordable

While ducted AC systems may cost more initially, in the long term they may actually help homeowner’s save money. Several split systems would have to be installed to do what one ducted system does. Also, there are service costs associated with maintaining and servicing each of the units. This can add up quickly. With a ducted system, there is just one unit and the costs are focused on just that. Over time, this can lead to significant cost savings.

If a homeowner isn’t sure what type of system they should install in their home, they should consider the benefits offered by a ducted unit. In the long run, it may actually help them save money. Keeping this in mind is the best way to ensure a home is cooled efficiently and thoroughly even during the hottest days of the year.

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 Brief study about PSLE

The Primary School Leaving Examination (PSLE) is a national examination organized every year for the Students who are studying the sixth year of Primary School in Singapore. Every student must clear this to move on to the Secondary school. And it administered by the Ministry of Education Singapore. As many students consider Maths as one of the difficult subjects to study. Students choose to attend PSLE Math tuition center to clear this exam. The purpose of the Mathematics examination is to assess the students’ understanding of mathematics at the end of primary education with respect to the objectives of the Mathematics (Primary) syllabus.