Plastics

What is an Extruding Machine and it’s Applications?

A continuous extrusion machine is a piece of equipment that serves chemical, polymerization or crystallization processes that are very demanding. Our engineers designed the UCP with innovative technologies that will consistently help your production process develop and excel. The twin screw system in the continuous extrusion machine insures that you end up with a homogenous mix that meets the quality standards you have set yourself to achieve.

An extrusion machine can be used to produce a wide variety of products from an equally large range of raw materials. It is also an attractive alternative to other manufacturing processes as it allows for a larger selection of profiles and is suitable for use with brittle materials. In industrial applications, plastics are extruded to produce food packaging film, cladding sheets, insulation, automotive parts, and tubing products such as electrical conduit and plumbing pipes. Steel and alloys are extruded to form rods, pipes, and wires as well as steel conduits and construction members for light engineering. The food and pharmaceutical industries also make extensive use of extrusions in the production of products such as pasta, cereals, cookies, and several drug carriers.


Plastic Recycling Machine for Waste Recycling

In the European Union alone, more than 47 million tons of waste plastic is produced each year. Of this, around 13% is recycled by the plastic waste recycling machine. A further 18% is burned to access its potential energy. The remainder contributes to the ever expanding problem of landfill. Additionally, there is carbon cost of transportation.

The plastic waste recycling machine provides complete and long lasting recycling solutions to turn waste into new, reusable resources with proven technologies. The equipment used for recycling the waste material is manufactured at our sophisticated infrastructure, using premium quality raw material. These are stringently tested on several parameters to ensure the delivery of a flawless range to customers. Furthermore, we also provide customized solutions to clients as per the specifications detailed by them to meet their varied requirements.


NIR Sensors Used with Identification Algorithms for Completing Tasks of Plastic Sorting Methods

Kunststoffmuell_Flaschen
Near-Infrared (NIR) sensor technology coupled with highly sensitive algorithms are likely the most efficient and consistent plastic sorting technologies due to their high sorting accuracy in separating desired plastics from mixed waste, as well as sorting plastics by color and resin types. Identification algorithms then rapidly categorize the different “signatures” of polymers from their infrared spectra.

While other sensor based sorting technologies, such as x-ray, laser, and light emitting device (LED), are capable of distinguishing between colors and densities, NIR with identification algorithms is likely to be the most consistent, accurate, and time-efficient of the various sensor based sorting options in terms of sorting plastics. Lasers and LED have the ability to detect color differences but cannot determine the different resin types of plastics. X-ray technology can decipher plastics from non-plastics but it cannot distinguish different colors and resin types, therefore lessening its overall efficiency in effective plastic sorting. NIR sensors used with identification algorithms are able to consistently complete all necessary tasks in the sorting of plastics. 


Introduction of Polycarbonate Sheet

02-polycarbonate-sheet
The polycarbonate sheet is a premium grade with proprietary UV protection, offering excellent weathering and resistance against yellowing and loss of light transmission of the polycarbonate sheet in external applications - this provides a significant advantage over cheaper polycarbonate sheets.

Polycarbonate sheet provides extremely high impact resistance making it particularly useful for use in areas where there is a risk of damage or vandalism. With good formability, polycarbonate sheet can also be used for skylights, covered walkways, roof lights, roof domes and barrel vaults.

Cut to size polycarbonate sheet is also ideal for windows, replacement greenhouse glass, bus shelters, polycarbonate machine guards, boat & car windows, and other glazing applications.


An Overview of Injection Molding

image from www.djmetalrep.com

Injection molding is a fast, automated, versatile process that can produce precise, complex three–dimensional parts from a fraction of a gram to more than a hundred kilograms, in virtually any plastic material. The process starts with feeding small plastic beads into a heated screw and barrel system that melts the plastic into a high–viscosity liquid. The screw then forces the molten plastic into a closed mold that provides the shape, cooling and solidification, and finally ejects the part.

Injection molding is fast and can be economical. But because every part needs its own costly injection molding tool, the process is economically viable only for mass production, usually more than 10,000 parts. Injection molding tools take weeks or months to build. Often, design mistakes become apparent, requiring time–consuming mold corrections. Multiple iterations may go from the producer to the tool builder until the final part design and quality are achieved, increasing costs and product time to market.


The Process of Plastic Injection Molding

image from www.superiorplastics.biz

The Process and Equipment

Because most engineering thermoplastic parts are fabricated by injection molding, it is important for the designer to understand the molding process, its capabilities and its limitations. The basic process is very simple. Thermoplastic supplied in pellet form are dried when necessary, melted, injected into a mold under pressure and allowed to cool. The mold is then opened, the parts removed, the mold closed and the cycle is repeated.

 

The Molding Machine

Melting the plastic and injecting it into the mold are the functions of the plastifying and injection system. The rate of injection and the pressure achieved in the mold are controlled by the machine hydraulic system. 

 

The Mold

Mold design is critical to the quality and economics of the injection molded part. Part appearance, strength, toughness, size, shape, and cost are all dependent on the quality of the mold. Key considerations for Engineering Thermoplastics are:

-Proper design for strength to withstand the high pressure involved.

-Correct materials of construction, especially when reinforced resins are used.

-Properly designed flow paths to convey the resin to the correct location in the part.

-Proper venting of air ahead of the resin entering the mold.

-Carefully designed heat transfer to control the cooling and solidification of the moldings.

-Easy and uniform ejection of the molded parts.

When designing the part, consideration should be given to the effect of gate location and thickness variations upon flow, shrinkage, warpage, cooling, venting, etc. Your DuPont representative will be glad to assist with processing information or mold design suggestions. The overall molding cycle can be as short as two seconds or as long as several minutes, with one part to several dozen ejected each time the mold opens. The cycle time can be limited by the heat transfer capabilities of the mold, except when machine dry cycle or plastifying capabilities are limiting.

 


Polymer Insulators Pros and Cons

image from www.compaqinternational.com

Ceramic and glass insulators have long been the materials of choice for high-voltage insulators and lightning arresters, offering good resistance to electrical stress and outdoor exposure without significant deterioration. However, they do have disadvantages such as poor hydrophobicity and low performance under contaminated environmental conditions, low seismic performance, are prone to punctures, suffer from cement growth, pin erosion, susceptible to vandalism, relative higher installations costs.

Polymer insulators were first developed by GE in 1959 and since then many manufacturers have been trying to improve their characteristics and performances.

NCIs or composite insulators designs offer lighter weight, less breakage,improved seismic performance, high hydrophobicity and withstanding contaminated condition and more flexibility in design than ceramic insulators. These features often translate into lower installation cost, greater durability and more aesthetically pleasing line design. Yet, along these benefits problems were detected such as: bonding failures leading to flashover, hardware separation of the fiberglass core leading to line drops, chalking, crazing and shed's splitting allowing humid penetration causing electrical failure.

Polymer insulators cons are their fast aging` susceptibility to UV radiation (sun & corona); handling and storage concerns and lower withstanding to mechanical loads. Often it is being stated that the lack in experience in the HV market (less than 3 decades of use) makes trending analysis of polymer insulators hard to get.

NCI's general structure:Where the end-fittings are made of metal, the core rod is made of FRP - Fiberglass Reinforced Plastic, with an outer housing made from either silicone rubber, EPDM or EPR

One of the major and most important characteristics of Silicon is hydrophobicity i.e. the capability to form beads of water allowing a resistance to wetting. When contamination build-up is exposed to moisture, an electrolytic film can develop, leading to excessive leakage current, dry band arcing and eventually to flashover. such as wetting corona activity resulting from non-uniform wetting and high electrical field mainly on the energized and ground end-fittings.

Grading rings are being introduced lately to insulators of lower voltages. The role of corona rings is to lower the e-field stress and shift it away from the end fitting. Grading rings can prevent corona and it's derives: radio interferences, audio noise, and formation of nitric acid and ozone. (read more...).

Typical failures of polymeric insulators are brittle fractures (read more...), mechanical and electrical rod failures as flashunder, end-fitting detachments, flashover and others, all of which can be detected by a UV camera such as DayCor®

Ofil's DayCor® cameras extend the advantages of NCI insulators and diminish their disadvantages because they can alert at the early stages of partial discharges before theses turn into full discharge, arcing flashover and deterioration of the insulation material. 


Polycarbonate Sheets

image from image.made-in-china.com
Polycarbonate sheet is a high quality plastic, often referred to by its brand names (Lexan, Makrolon, and Palsun). In its clear solid form, polycarbonate sheet delivers the transparency of glass at less than half the weight, combined with unmatched strength, often used as safety glazing or security panels.

Polycarbonate sheet can be cold bent, fabricated and/or formed, making it ideal for applications such as skylights, barrel vault roofing, architectural roofing and general glazing. They are available in clear, translucent or opaque, and prove useful as machine guards.

Polycarbonate sheet has similar properties to perspex sheet and is often described as having an acrylic appearance, but with much greater strength and a class 1 fire rating. Polycarbonate can be described as bulletproof and used in a variety of applications such as aircraft windscreens to DVD's and CD's.


Molding Process

image from 99-ideas.co

Injection molding utilizes a ram or screw-type plunger to force molten plastic material into a mold cavity; this solidifies into a shape that has conformed to the contour of the mold. It is most commonly used to process both thermoplastic and thermosetting polymers, with the former being considerably more prolific in terms of annual material volumes processed. Thermoplastics are prevalent due to characteristics which make them highly suitable for injection molding, such as the ease with which they may be recycled, their versatility allowing them to be used in a wide variety of applications, and their ability to soften and flow upon heating. Thermoplastics also have an element of safety over thermosets; if a thermosetting polymer is not ejected from the injection barrel in a timely manner, chemical crosslinking may occur causing the screw and check valves to seize and potentially damaging the injection molding machine.

Injection molding consists of high pressure injection of the raw material into a mold which shapes the polymer into the desired shape. Molds can be of a single cavity or multiple cavities. In multiple cavity molds, each cavity can be identical and form the same parts or can be unique and form multiple different geometries during a single cycle. Molds are generally made from tool steels, but stainless steels and aluminum molds are suitable for certain applications. Aluminum molds typically are ill-suited for high volume production or parts with narrow dimensional tolerances, as they have inferior mechanical properties and are more prone to wear, damage, and deformation during the injection and clamping cycles; but are cost effective in low volume applications as mold fabrication costs and time are considerably reduced. Many steel molds are designed to process well over a million parts during their lifetime and can cost hundreds of thousands of dollars to fabricate.


Injection Mold

image from www.mespecialties.com

Material is introduced into the injection molding machine via a Hopper.  The injection moulding machine consists of a heated barrel equipped with a reciprocating screw (driven by a hydraulic or electric motor), which feeds the molten polymer into a temperature controlled split mould via a channel system of gates and runners. 

The screw melts (plasticises) the polymer, and also acts as a ram during the injection phase. The screw action also provides additional heating by virtue of the shearing action on the polymer.

The polymer is injected into a mould tool that defines the shape of the moulded part. 

The pressure of injection is high, dependant on the material being processed; it can be up to one thousand atmospheres.  Tools tend to be manufactured from steels, (which can be hardened and plated), and Aluminium alloys for increased cutting and hand polishing speeds.  The costs associated with tool manufacture means that injection moulding tends to lend itself to high volume manufacture.  Details of process costing can be found at:

The tool can be used to manufacture one consistent part in a repeating process or incorporate multi cavities (a multi impression tool), that is many components can be manufactured on the same tool repeatedly with a single injection. 

It should be noted that, whilst in the animation the flute pitch of the screw is shown as constant along its length, in practice it varies considerably dependent upon the polymer being processed. In particular the root diameter increases from hopper to nozzle to provide compression to the melt.
Source: http://www.bpf.co.uk/plastipedia/processes/injection_moulding.aspx