Today is 13th Feb 2010 - the Chinese New Year Eve of the tiger year!
I representing our company best wishes to our customers of domestic and abroad, happly 2010 Chinese Tiger Year and a prosperous year for business and good health.
More of company and services you can visit our showroom: http://wuxiglory.en.made-in-china.com
Thanks & Regards,
Wuxi Glory Plastics Co.Ltd
Good new year to all of our customers!
Here we are providing this year’s best offer of our - 2″ Round Polypropylene Plastic EIFS Stucco Fasteners:
EIFS stands for Exterior Insulation and Finish Systems. The product is also called synthetic stucco, and refers to a multi-layered exterior finish that’s been used in European construction since shortly after World War II, when contractors found it to be a good repair choice for buildings damaged during the War. The majority of repairs to European buildings were to structures constructed of stone, concrete, brick, or other similar, durable materials.
Our plastic eifs stucco fastener/washer can nearly meet all your fixing needs in the EIFS wall system of stucco plaster, fiberglass mesh, trims …
For availability and price list, please contact us freely at plastic@plastics-china.com or call directly +86 13914259787
Our show room for this plastic fasteners on: http://wuxiglory.en.made-in-china.com
Thanks you!
Let us consider the methods of incorporating cavity and core. We have now seen that in general the core is incorporated in the moving half and the cavity in the fixed half. However, there are various methods by which the cavity and core can be incorporated in their respective halves of the mold. These represent two basic alternatives: (a) the integer methods where the cavity and core can be machined from the steel plates which become part of the structual build-up of the mold, or (b) the cavity and core can be machined from samll blocks of steel, termed inserts, and subsequently, bolstered. The choice between these alternatives constitutes an important decision on the part of the mold designer. The final result, nevertheless, will be the same whichever method of manufacturer is chosen. In either design the plate or assembly which contains the core is termed the core plate and the plate or assembly which contains the cavity is termed the cavity plate.
When the cavity or core is machined from a large plate or block of steel, or is cast in one piece, and used without bolstering as one of the mold plates, it is termed and integer cavity plate or integer core plate. This design is preferred for singke-impression molds because of the strength, samller size and lower cost characteristics. It is not used as much for multi-impression molds as there are other factors such as alignment which must be taken into consideration. Typical mold designs which incorporate an integer cavity and core.
Of many manufacturing process available for preparing molds only two are nomally used in this case. There are a direct machining operation on a rough steel forging blank using the conventional machine tools, or the ‘precision’ investment casting technique in which a master pattern is made of the cavity and core. The pattern us then used to prepare a casting of the cavity or core by special process. A 4-1% nickel-chrome-molybdenum steel ( BS 970-835 M30) is normally specified for integer mold plates which are to be made by the direct maching method. The precision investment casting method usually utilizes a high-chrome steel. For more plastic tools fabrication and parts molding plastic visit our website: http://www.plastics-china.com, thanks!
Basic Terminology
Impression: The injection mold is an assembly of parts containing within it an “impression” into which plastic material is injected and cooled. It is the impression which gives the molding its form. The impression may, therefore, be defined as that part of the mold which imparts shape to the molding.
The impression is formed by two mold members:
1, The cavity, which is the female portion of the mold, gives the molding its external form.
2, The core, which is the male portion of the mold, forms the internal shape of the molding.
Cavity and core plates: This is illustrated for a simple container. The basic mold in this case consists of two plates. Into one plate is sunk the cavity which shapes the outside form of the molding and is therefore known as the cavity plate. Similarly, the core which projects from the core plate forms the inside shape of the molding. When the mold is closed, the two plates come together forming a space between the cavity and core which is the impression.
Sprue bush: During the injection molding process plastic material is delivered to the nozzle of the machine as a melt; it is then transferred to the impression through a passage. In the simplest case this passage is tapered hole within a bush as shown. The material in the passage is termed the sprue, and the bush is called a sprue bush.
Runner and gate system: The material may be directly injected into the impression through the sprue bush or for molds containing serveral impressions it may pass from the sprue bush hole through a runner and gate system before entering the impression.
Register ring: If the material is to pass without hindrance into the mold the nozzle and sprue must be correctly aligned. To ensure that this is so the mold must be central to the machine and this can be achieved by including a register ring.
Guide pillars and bushes: To mould an even-walled article it is necessary to ensure that the cavity and core are kept in alignment. This is done by incorporating guide pillars on one mold plate which then enter corresponding guide bushes in the other mold plate as the mold closes.
Fixed half and moving half: that the various mold parts fll naturally into two sections or halves. Hence, that half attached to the stationary platen of the machine is termed the fixed half. The other half of the mold attached to the moving platen of the machine is known simply as the moving half. Now it has to be decided in which of the two halves the cavity or core is to be situated. Generally the core is situated in the moving half and the overriding reason why this is so, is as follows:
The molding, as it cools will shrink on to the core and remain with it as the mold opens. This will occur irrespective of whether the core is in the fixed half or the moving half. However, this shrinkage on to the core means that some form of ejector system is almost certainly necessary. Motivation for this ejector system is easily provided if the core is in the moving half. Moreover, in the case of our single-impression basic mold, where a direct sprue feed to the underside of the molding is desired the cavity must be in the fixed half and the core in the moving half.
Plastic foam sheets have many applications. They can be used for thermal insulation or packaging purposes, or can be thermoforming into meat trays, eggs cartons, fast-food plates, and containers.
Generally the production of polymer foams by extrusion consists of the following steps. First, a polymer resin is melted in the extruder barrel by the shear heat generated from the screw motion. A blowing agent, which is a substance that can provide the gas (es) needed to foam the polymer, is premixed with the polymer resin or injected into the polymer when the polymer is melted. There are two types of blowing agents, namely chemical blowing agents and physical blowing agents. Chemical blowing agents are compounds or mistures that release a gas or gases as a result of chemical reactions. Possible reactions include the thermodecomposition, chemical reactions of the blowling agents, or interactions of the blowing agents with other components in the formulation. Physical blowing agents are substances that release a gas or gases as a result of physical processes, such as evaporation, or desorption at elevated temperature or reduced pressure. No matter what kind of blowing agent is used, the generated gas is dissolved in the polymer melt to foam a polymer/gas mixture. The mixture is extruded through the die where foaming and shaping take place. The pressure drop at the die exit causes the solubility of the gas in the polymer melt to drop. Consequently, the dissolved gas is separated from the polymer in the foam of bubbles; this process takes place as long as gas is available in the polymer melt and little resistance is encountered.
Two different foaming processes are used in industry, namely free-rise foaming extrusion and controlled foaming extrusion. In the free-rise foaming process, the extrudate is allowed to expand freely without any restrictions after it leaves the die. The die is designed to deliver the extrudate with a shape and size that approximates the desired profile. This pricess is good for production of a sheet or product with a simple cross section and a wall thickness in the range of 2mm ~ 6mm.
In the controlled foaming process, the extrudate is mechanically restricted by a cooled shaping section located right after the die. Because of the cooling, a solid skin layer of polymer is formed on the extrudated, which means foaming takes place only in the core of the extrudate. This process can be used to produce a sheet, tubing or any desired cross sectional shape with a wall thickness of over 6mm. As for solid plastic parts, most of them made by the process of injection molding.
Plastic foams can be defined as plastic materials that container at least two phases: a solid polymer matrix and a gaseous phase. It is possible to have extra solid phases in plastic foams, such as blend of polymers or fillers. Because of the void present in the material, foamed plastics have less material in a given volume than neat plastics. Therefore, the production cost of foamed plastic products can be significantly reduced since the material cost can constitute up to 70% of the total cost of a plastic product.
Plastic foams can be produced with densities ranging from 1.6kg/m3 to over 960kg/m3. In general, the mechanical properties of the foams sre directly proportional to their densities. As a result, high-density foams are usually used for load bearing applications, whereas low-density foams are used for thermal insulation or packaging purposes. With different production and post-processing techniques, plastic foams can be manufactured in a variety of shapes as required by their individual application.
For more informations or techniques about plastic injection molding process and production please visit our home page of Wuxi Glory Plastics of China, thanks for visiting my webblog.
In the extrusion process, polymers is propelled continuously along a screw through region of high temperature and pressure where it is melted and compacted, and finally forced through a die shaped to give the final object.
Extrusion is used to make three main types of products:
1. Standard frofile shapes such as rod, pipe, sheet, and irregular cross scections.
2. Extrusion around wire and cable as a protective coating.
3. Flim to be used alone and as coating for paper, cloth, amd other surfaces.
Each of these types can be made in varying sizes depending upon the size of the machine. Extruders are designated as to size by the diameters of the rotating screw. They range from large industrial extruders with screw diameters up to 6 in. or 8 in., down to the labotatory model with a 3/4 in. diameter screw. Extrusion is used only for the processing of the thermoplastic resins.
The scerw of an extruder is divided into serval sections, each with a specific purpose. The feed section picks up yje finely divided polymer from a hopper and propels in into the main part of the extruder. In the cpmpression section, the loosely packed feed is compacted, melted, and formed into a continuous stream of molten plastic. Some external heat must be applied, but much is generated by friction. The metering section contributes to uniform flow rate, required to produce uniform diamensions in the finished product, and builds up sufficient pressure in the polymer melt to force the plastic through the rest of the extruder and out of the die. Since viscous polymer melts can be mixed only by the application of shearing force, and additional working section may be needed before the die.
Modern trends in exturder usage include the twin-screw or multiple-screw extruder, in which two screws move side by side to opposite direction, providing more working of the melt, and the vented extruder, having an opening or vent at some point along the screw that can be opened or led to vacuum to extract volatiles from the polymer melt. Glory plastics company in China not only provides plastic injection molding solutions but also have plastics extrision molding services upon request.
Fingering, gas bubbles, hesitation lines, burning of resin, witness lines, cold slug, and gas blow-out are typical defects normally encounterted in GAIM.
Fingering, or gas permeation, is a common problem encountered in GAIM. In fingering, gas escapes from the gas channel and migrates into undesired areas of the part. Severe gas fingering can results in significant reduction in part stiffness, impact strenghth and reliability of the final molded parts. During the has holding phase, the transitional region between the gas channel and the flat area is possible for fingers to form within the flat area. In this case, the main cause if the fingering effact is the thickness of the flat area of the part. The thicker flat area, the higher its shrinkage potential, and hence the greater danger of the fingering effect. In order to largely exclude the fingering effect through design, it is necessary to implement the following criteria: a basic wall thickness of 4mm or greater should be avoided for flat areas, a material with favorable solidification behavior sould be selected, and the lowest possible gas pressure should be applied.
Gas bubbles are caused by fingering. When fingering occurs, gas sometimes gets trapped in the thin-wall sections of the part where the gas is unable to fully vent. These trapped gas can cuase bubbles that will still be in the gas core after the mold is opened.
Hesitation lines appear on the surfac of a part produced by GAIM when the short shot of resin stops in the cavity, when starts moving again as the gas completes the fill.
Burning of the resin can appear on either the outer surface of the part or within the gas channel itself. Burning if the part surface can be caused by gas pressure that is too high or by insuffucient venting of mold. Burning the resin within the hollow sections of the part is also possible. Burning within the gas channel can cause gas injection pins to become plugged.
On thin-walled parts, molded in certain resins, a witness line, or gloss-level change, can occur over the gas channel. Excessive gas pressure can also cause witness lines over gas channels.
When gas is injection through the molding machine nozzle, cold slugs resin many occur on the part surface. A cold slug is caused when a samll amount unmeleted resin is injection into the part.
Gas blowout occurs when there is not enough resin in the cavity to hold the gas inside the part. If the part is short, gas will migrate to the non-filled area of the cavity and blow through. When blowout occurs, the part will sometimes look like a short shot.
Most case of defects are produced by the interface of the gas and the melt. There problems can be overcome by internal water cooling between the interface of the gas and the melt.
All the above the described details are come from the production experience of plastic injection molding process of Wuxi Glory Plastics Co. Ltd, All rights reserved.
Mosco city mayor Yury Luzhkov recently open fires on plastic shopping bags, hoping the supermakrts no longer provide nondegradable plastic bags to shoppers and will also charge them on environmental-friendly bags - this money will be used for charity purpose.
Also the Mosco officials declared a plan, that is till the year 2012 we will fully using degradable plastic shopping bags instead of nondegradable bags.
By keeking with Luzhkov’s order, this plan has been drafted by the company named NKO-Services, and will make discussion in the City hall next month, NKO-Services spokesperson said. ” a polluted nondegradable plastic bag which need at least 200 year for its biodegradation, and new biodegradable bags will finish the biodegradable process within 12 months.” said also by NKO-Services’ spokesperson.
That’s really a good news for protecting the environment by starting from plastic bags or other plastic scrap recycling.
All processes have their disadvantages, but those of GAIM and GAMIC ( Gas-assisted injection molding with internal-water cooling) appear relatively minor compared with their significant advantages.
1. Large hollow sections
GAIM is not well suited for thin-walled hollow parts such as bottles or tanks. However, the thin-wall part has also tried out for some specific applications.
2. Vent hole
The gas must be vented prior to opening the mold, leaving a hole somewhere on the part. Normally this can be placed in a non-visible location, but if appearance or function ia affected or secondary operations are required, it may be necessary to seal the hole.
3. Mold temperature control
Since wall thickness along the gas flow channel is a function of cooling rate, consistent wall thickness requires precise mold temperature control.
4 Surface blush
The gas channel may leave surface blush, with arises from differences in surface gloss levels. The tendency for blush is a function of processing conditions and types of plastics.
5. Unique design
The unique part design and mold design required is most cases to fully utilize that GAIM might to be considered by some to be a disadvantages. The gas part design takes a relatively longer time than with the conventional injection molding process.
6. Extra cost of controller
In order to control the gas injection, the process requires extra equipment. Gas-assisited injection molding with internal cooling requires a system for controlling the gas and the water, and expense not required with traditional injection molding process.
