November 3, 2008

Plastic Forming – Vacuum Forming Guide

Filed under: Technometer — admin @ 6:08 pm

What is vacuum forming? What does it do? What are the methods used in forming vacuums? Vacuum forming is basically the procedure used in shaping any kind of plastic. The shaping of unusual shapes like dishes, boxes and others is called Vacuum forming process. The simplest explanation to its method is by placing the mould into an oven, heated for it to take shape and cooled within a significant amount of time. The advantages of using vacuum forming as a method is limitless and effective. Majority of the vacuum forming products are affordable, since not many produce vacuum forming products. The moulds could be made of low-costing materials and the process of the vacuum forming could be possibly faster than any forming process.

- The most common product made using vacuum forming is a simple plastic toy

- All of the process used includes three important stages. Heating, shaping and cooling.

- There are factors that would be vital in the process selection of the vacuum forming.

- Quantities of the product

- Material of the product

- Shape and details of the product

- Final product’s shape and size

1. Clamping process

The clamp or the fastener gives security to the materials being processed. By using this vacuum forming method, you could process even the thickest materials. It is important that the frame of the clamps is strong for the materials not to move during the whole vacuum forming process.

2. Heating process

This vacuum forming method makes use of infra-red heaters and aluminum plates. Although this kind of process is usually handles by larger machines, it could former thicker plastics rapidly. The heaters are located both above the aluminum plates and below it, to produce quality outcomes.

3. Bubble

When the plastic material is inside the machine and it has reached the temperature needed for it to form, this method pre-stretches the plastic to give a smoother outcome product. The bubble method is important because it could assure that unusual shaping materials with extraordinary angles could be reached by the heat.

4. Sheet level

This method involves an electric beam inside the machine that inspects the plastic material and the bottom heater. This method is used when the plastic starts to sag. When the plastic sags, the beam would automatically break down and a quantity of air would enter the machine causing the sagginess to stop.

6. Vacuum

This vacuum forming method pre-stretches the plastic material. The vacuum serves as assistance in the forming of quality sheets. There are two vital parts in a vacuum – the vacuum tank and the vacuum pump. These two parts enable the machine to rapidly mold the hot sheets.

Once the materials have been shaped and formed, a cooling procedure is done before releasing the plastic.

- Cooling is important because when the materials are released, the molds would become deformed and would cause a rejected outcome

- High speed fans are made use to fasten the cooling process. There is also an option in using s spray mist which is directed into the product sheet

- When cooled, it is inserted again into the machine to perform a reverse pressure method that strips excess product from the mould

7. Finishing Up

There are several trimming methods that could be used in vacuum forming. These methods would depend on the size of the part, production number needed, the kind of trimming, and the material’s thickness. The finishing of the product or the post-forming processes depends upon the materials processed in the vacuum forming method. Some finishing includes designing, printing of decorations, strengthening of the product and construction. Although there are many kinds of method used in forming plastics, you could always make use of the easiest method – vacuum forming. Anybody could do it. With just the right tools and these friendly procedures, you could make your own toy in a jiffy.

For more great vacuum forming related articles and resources check out http://www.plasticsadvisor.com

DTV and HDTV – Why You Need To Understand the Difference

Filed under: Technometer — admin @ 5:16 am

There are so many acronyms used in defining television technology that is difficult to keep it all straight, and even worse, sometimes the acronyms are almost the same. That’s the case with DTV and HDTV. At first glance they would seem to be very similar, and yes they are definitely related, but there are also significant differences as well.

DTV stands for Digital TV, and HDTV stands for High Definition TV. To understand DTV, you have to go back before cable and satellite TV to the time when all broadcasts were picked up by antenna. Those television signals were broadcast in analog format, which is severely limited in how much audio and video information it can transmit. Back then all TV sets received analog signals and the main choice you had to make was how large the TV screen was going to be.

When first cable and then satellite came on the scene, they changed things dramatically. Instead of just sending analog signals they were able to broadcast in digital instead. That immediately improved both the picture and sound for televisions that were ready to receive digital signals. The improved video was far sharper and smoother than anything before, and the sound quality took a similar leap forward too. So DTV is simply a higher standard for TV broadcasting than was available in previous analog TV systems.

HDTV however, is the next evolutionary step in digital broadcasting. It takes DTV to a new level and makes both the television sound and video so much better. For instance, many DTV programs are sent in 525i format, which means that 525 lines of information are displayed on the screen and interlaced, or shown in alternate order. In other words, all the odd lines are shown in 1/10 of a second and then all the even lines are shown in the next 1/20 of a second. Because it all happens so fast you never clearly see the alternating pattern, but it is there.

Broadcasts made in HDTV however can reach up to 1080p, which is a standard where 1080 lines of information are shown on the screen and they are all shown together in a progressive scan instead of interlaced. What that means for you is a picture with much higher clarity and definition and action sequences that are much smoother to watch.

There are also other features of the HDTV format, including widescreen and Dolby 5.1 surround sound that take television viewing to a whole new level too, so DTV was the start of all of this improved entertainment, but HDTV is where we will really see the benefits unfold for all of us.