Gas Assisted Moulding Animation and process
The main two applications of Gas Assisted Moulding are to either inject the gas into the component cavity (internal gas injection), or to use the gas on the outside surface, but still within the mould cavity, to consolidate the component (external gas injection).
Internal Gas Injection - Most widely used process
External Gas Injection - used for enhanced surface definition
A number of variants of gas use are incorporated into the Internal gas injection process:
Full Shot Internal Gas Assisted Moulding Short Shot Internal Gas Assisted Moulding Plastic Expulsion Process … PEP Moving Core Gas Assisted Moulding Gas Cool for Internal and External Gas MouldingEach variant has its uses and benefits. For more information, click here (Cinpres Web Page)
Why Gas Injection Moulding?
Techniques have been developed whereby inert gas nitrogen is injected into the still molten plastic in the mould cavity. Acting from within the component shape, the gas inflates the component and counteracts the effects of the material shrinkage. The effect is to keep an internal pressure on the material until it solidifies and skins at the mould cavity surface. This is independent of any gate freezing.
Internal Gas Injection - Most widely used process
External Gas Injection - used for enhanced surface definition
Wednesday, June 11, 2008
gas-assist injection molding
Nitrogen is Cheaper Than PlasticGas assist improves cosmetics — and cuts costsDesign News Staff -- Design News, September 4, 2006
With resin costs running through the roof, it's a good time to take another look at gas-assist injection molding.
You remember gas assist. It's a process that uses an inert gas, particularly nitrogen to create one or more hollow channels within an injection-molded plastic part. At the end of the filling stage, nitrogen is injected into the still-liquid core of the molding. The gas follows the path of the least resistance and replaces plastic, usually in thick sections, with gas-filled channels. Gas pressure subsequently packs the plastic against the mold cavity surface. The gas is vented to atmosphere or recycled.
It's not brand new. But acceptance was weak because of concerns over patents, rights and royalty fees. Many of those original patents have expired, and there is less acrimony in the gas-assist field. There are still many opportunities to convert current aluminum and steel applications in automotive as well as other industrial applications to gas assist. Many designers have used gas assist to achieve an excellent surface finish on a cosmetic part. You can also create larger, more complex parts with fewer injection gates than is possible with conventional injection molding.
The three examples here are winners from the recent design competition held by the Alliance of Plastics Processors.
With resin costs running through the roof, it's a good time to take another look at gas-assist injection molding.
You remember gas assist. It's a process that uses an inert gas, particularly nitrogen to create one or more hollow channels within an injection-molded plastic part. At the end of the filling stage, nitrogen is injected into the still-liquid core of the molding. The gas follows the path of the least resistance and replaces plastic, usually in thick sections, with gas-filled channels. Gas pressure subsequently packs the plastic against the mold cavity surface. The gas is vented to atmosphere or recycled.
It's not brand new. But acceptance was weak because of concerns over patents, rights and royalty fees. Many of those original patents have expired, and there is less acrimony in the gas-assist field. There are still many opportunities to convert current aluminum and steel applications in automotive as well as other industrial applications to gas assist. Many designers have used gas assist to achieve an excellent surface finish on a cosmetic part. You can also create larger, more complex parts with fewer injection gates than is possible with conventional injection molding.
The three examples here are winners from the recent design competition held by the Alliance of Plastics Processors.
Gas injection pin mechanism for plastic injection molding systems
Gas injection pin mechanism for plastic injection molding systems
A gas injection pin mechanism for introducing pressurized gas into a mold cavity or melt stream. A stationary pin member is positioned directly in a bore or opening in a mold member without a sleeve member. The pin member is an elongated body member with a first end facing a mold cavity and a first gas passageway through the pin member connected to a second passageway that is traverse to the first gas passageway. The second gas passageway has an opening on an exterior lateral surface of the pin member and gas through the second gas passageway is introduced into the cavity in annular space between the pin member and the mold opening.
Plastic Moulding ExpertsDesign, tooling and moulding fast For all your plastic product needswww.rgegroup.comInjection Molding MachineFull line of vetical insert molding machines, shuttles or rotaryswww.gluco.comFlexPen®FlexPen® is superior to SoloStar® in dose accuracywww.NovoNordisk.comStorage of CoilsCoilstorage systems made of high quality plasticwww.lankhorst-mouldings.comExpert Vacuum ConsultingUltra/High Vacuum System Design, Hardware and Analysis. World Widewww.VACCLimited.comDrierite DesiccantsDesiccants and drying equipment -100 deg. F dewpointwww.drierite.comInjection Molding FilterOil Filtration on plastic injection molder. Fewer stops, longer life.www.cjc.dk/plastic_injection/filter
A gas injection pin mechanism for introducing pressurized gas into a mold cavity or melt stream. A stationary pin member is positioned directly in a bore or opening in a mold member without a sleeve member. The pin member is an elongated body member with a first end facing a mold cavity and a first gas passageway through the pin member connected to a second passageway that is traverse to the first gas passageway. The second gas passageway has an opening on an exterior lateral surface of the pin member and gas through the second gas passageway is introduced into the cavity in annular space between the pin member and the mold opening.
Plastic Moulding ExpertsDesign, tooling and moulding fast For all your plastic product needswww.rgegroup.comInjection Molding MachineFull line of vetical insert molding machines, shuttles or rotaryswww.gluco.comFlexPen®FlexPen® is superior to SoloStar® in dose accuracywww.NovoNordisk.comStorage of CoilsCoilstorage systems made of high quality plasticwww.lankhorst-mouldings.comExpert Vacuum ConsultingUltra/High Vacuum System Design, Hardware and Analysis. World Widewww.VACCLimited.comDrierite DesiccantsDesiccants and drying equipment -100 deg. F dewpointwww.drierite.comInjection Molding FilterOil Filtration on plastic injection molder. Fewer stops, longer life.www.cjc.dk/plastic_injection/filter
Wednesday, February 13, 2008
The Process of Compounding and Masterbatch
The Process of Compounding and Masterbatch Compounding is the process by which colour or additives are added to the basic thermoplastics material. This usually involves melting the thermoplastics material then mixing it with the required pigments and/or additive material in an extruder. The polymer melt is then extruded and chopped into pellets as it cools, which can then be used directly by the plastics processor. An associated process is masterbatch. This is where a high concentration of pigment and/or additives are dispersed in a carrier medium which can then be used directly by the processor in small quantities to pigment or modify the virgin polymer material.
The thermoplastics compounding industry forms a vital interface between resin production and the plastics converter. Most processors require the polymers they use to be coloured or modified in some way (e.g. with the addition of additives such as flame retardants or UV light stabilisers) and in the case of PVC, all resin has to be compounded before it can be processed. Whilst a few very large processors carry out their own compounding, particularly PVC processors, the majority buy-in ready compounded material either direct from the polymer supplier or through an independent compounder. It is this “free” market, i.e. compounds sourced externally by the processor, which will be covered in this chapter.
The thermoplastics compounding industry forms a vital interface between resin production and the plastics converter. Most processors require the polymers they use to be coloured or modified in some way (e.g. with the addition of additives such as flame retardants or UV light stabilisers) and in the case of PVC, all resin has to be compounded before it can be processed. Whilst a few very large processors carry out their own compounding, particularly PVC processors, the majority buy-in ready compounded material either direct from the polymer supplier or through an independent compounder. It is this “free” market, i.e. compounds sourced externally by the processor, which will be covered in this chapter.
The Market for Packaging
The Market for Packaging No single process is used to make plastics packaging materials. Instead packaging forms the most important market for several plastics processes especially film extrusion, sheet extrusion and blow moulding. Indeed packaging is significantly the largest end use market for thermoplastics in Western Europe and one which has shown robust volume growth throughout the history of the industry; this despite the widespread progress of polymer and process technologies directed at the reduction of film thickness (“downgauging”) and package weights generally. Consumption of polymers for use in plastics packaging reached almost 16 million tonnes in 2000, equivalent to more than half of the total market for thermoplastics in Western Europe. Plastics packaging can be classified into several groups
Primary packaging for the final product, in the form of bags, pouches, bottles or other containers. Secondary packaging for the primary packaged product, in the form of shrink or stretch films, bottle crates and transit containers. Retail packaging in supermarkets and other outlets, in the form of bags on the reel, wicketed bags, check out bags and shoppers. Consumer packaging, in the form of freezer bags and cling films.
Primary packaging for the final product, in the form of bags, pouches, bottles or other containers. Secondary packaging for the primary packaged product, in the form of shrink or stretch films, bottle crates and transit containers. Retail packaging in supermarkets and other outlets, in the form of bags on the reel, wicketed bags, check out bags and shoppers. Consumer packaging, in the form of freezer bags and cling films.
The Building Market
The Building Market Building and construction consumed 5.3 million tonnes of thermoplastics in Western Europe during 2000. This represented 17% of total plastics consumption in the region, making the building industry the second largest market for plastics after packaging.
Unlike packaging, demand for building and construction products is notoriously cyclical, dependent on the overall strength of national economies and the availability of finance at municipal and household level. Central government policy is a driving factor in some countries, whilst pressure from the EU can impose standards of infrastructure development which in turn stimulate the demand for building products.
The plastics industry has gradually increased its share of the building products market through the substitution of traditional materials. Benefits such as freedom from corrosion and rotting, flexibility and ease of installation have enabled materials such as PVC and polyethylene to offer longevity, low maintenance and lower lifetime costs in comparison with materials such as wood, aluminium, ductile iron, copper, clay and concrete.
Standards play a role in materials selection and specifiers, architects and end users alike are conservative and slow to move away from tried and tested materials. The construction industry is competitive and low cost and reduced site times are the modern imperatives which then plastics industry is well placed to service. However, persuading specifiers to take a long term “lifetime cost” view ahead of initial outlay is an on-going challenge.
After some fifty years of market development, the position of plastics in applications involving a relatively straightforward substitution of traditional products - such as pipes and fittings, window systems and floorcoverings - is well established. Notwithstanding this, the industry continues to develop new products such as multi-layer pipes and to work in tandem with more traditional industries to offer innovations such as PVC/timber windows, PEX/Aluminium hot water pipes and plastics wood composites. The potential for the plastics industry to contribute towards innovative solutions for vertical surfaces, roofing systems and modular forms of construction remains.
Unlike packaging, demand for building and construction products is notoriously cyclical, dependent on the overall strength of national economies and the availability of finance at municipal and household level. Central government policy is a driving factor in some countries, whilst pressure from the EU can impose standards of infrastructure development which in turn stimulate the demand for building products.
The plastics industry has gradually increased its share of the building products market through the substitution of traditional materials. Benefits such as freedom from corrosion and rotting, flexibility and ease of installation have enabled materials such as PVC and polyethylene to offer longevity, low maintenance and lower lifetime costs in comparison with materials such as wood, aluminium, ductile iron, copper, clay and concrete.
Standards play a role in materials selection and specifiers, architects and end users alike are conservative and slow to move away from tried and tested materials. The construction industry is competitive and low cost and reduced site times are the modern imperatives which then plastics industry is well placed to service. However, persuading specifiers to take a long term “lifetime cost” view ahead of initial outlay is an on-going challenge.
After some fifty years of market development, the position of plastics in applications involving a relatively straightforward substitution of traditional products - such as pipes and fittings, window systems and floorcoverings - is well established. Notwithstanding this, the industry continues to develop new products such as multi-layer pipes and to work in tandem with more traditional industries to offer innovations such as PVC/timber windows, PEX/Aluminium hot water pipes and plastics wood composites. The potential for the plastics industry to contribute towards innovative solutions for vertical surfaces, roofing systems and modular forms of construction remains.
About Polymers
Polymers; Polymers are large molecules, consisting of repeated chemical units, which are joined together – usually in a line. Polymers are traditionally used to make solid plastics and there are many ways in which these materials can be classified. One major classification is to split them into three major types of materials; thermoplastics, elastomers and thermosetting plastics.
Thermoplastics are materials which soften on heating and harden on cooling. This process can be repeated many times. Approximately 80% of the plastics used in the world are thermoplastics and this group can be further divided into; commodity thermoplastics, engineering thermoplastics, thermoplastic elastomers or rubbers and blends/alloys Thermosetting plastics are materials which, once shaped by heat and pressure, cannot be re-processed by further application of heat and pressure. Elastomers or rubbers are materials which can be stretched extensively, and which will return to their original shape once the stretching force is released. Once this property was always associated with vulcanised rubber but now thermoplastic elastomers can be designed to have the same properties. Many plastics have long complex chemical names and for ease of use these are often shortened to use letters referring to part of the chemical name. For example Polyvinyl Chloride is usually referred to as PVC. For a list of common polymers and abbreviations in English, Italian, Spanish, German and French
Thermoplastics are materials which soften on heating and harden on cooling. This process can be repeated many times. Approximately 80% of the plastics used in the world are thermoplastics and this group can be further divided into; commodity thermoplastics, engineering thermoplastics, thermoplastic elastomers or rubbers and blends/alloys Thermosetting plastics are materials which, once shaped by heat and pressure, cannot be re-processed by further application of heat and pressure. Elastomers or rubbers are materials which can be stretched extensively, and which will return to their original shape once the stretching force is released. Once this property was always associated with vulcanised rubber but now thermoplastic elastomers can be designed to have the same properties. Many plastics have long complex chemical names and for ease of use these are often shortened to use letters referring to part of the chemical name. For example Polyvinyl Chloride is usually referred to as PVC. For a list of common polymers and abbreviations in English, Italian, Spanish, German and French
AMI - Polymer abbreviations
English
German
French
Italian
Abbreviation
Abkürzungen
Abbréviations
Abbreviation
Abbreviation
English
Deutsch
Français
Italiano
Espnañol
PS
Polystyrene
PS
Polystyrol
PS
Polystyrène
PS
Polistirene
PS
Poliestireno
SAN
Styrene Acrylonitrile
SAN
Styrol Acrylnitril Copolymerisat
SAN
Copolymère styrene-acrylonitrile
SAN
Stirene acronitrile
SAN
Estireno Acrilonitrilo
ABS
Acrylonitrile Butadiene Styrene
ABS
Acrylnitril Butadien Styrol Polymerisat
ABS
Copolymère d’acrylonitrile butadiène styrène
ABS
Acronitrile butadiene stirene
ABS
Acrilonitrilo Butadieno Estireno
LLDPE
Linear Low Density Polyethylene
LLDPE
Lineares Polyethylen niedriger Dichte
PELBD
Polyéthylène Linéaire Basse Densité
LLDPE
Polietilene lineare a bassa densità
LLDPE
Polietileno de Baja Densidad Lineal
LDPE
Low Density Polyethylene
LDPE
Polyethylen niedriger Dichte
PEBD
Polyéthylène Basse Densité
LDPE
Polietilene a bassa densità
LDPE
Polietileno de Baja Densidad
HDPE
High Density Polyethylene
HDPE
Polyethylen hoher Dichte
PEHD
Polyéthylène Haute Densité
HDPE
Polietilene ad alta densità
HDPE
Polietileno de Alta Densidad
PP
Polypropylene
PP
Polypropylen
PP
Polypropylène
PP
Polipropilene
PP
Polipropileno
EVA
Ethylene Vinyl Acetate
EVA
Ethylen-Vinylacetat
EVA
Copolymère d’éthylène-acétate de vinyle
EVA
Copolimero etilene acetato di vinile
EVA
Etileno Vinilacetatos
Rigid PVC
Rigid Polyvinyl Chloride
Hart PVC
Hart-Polyvinylchlorid
PVC Rigide
Chlorure de Polyvinyle rigide
PVC rigido
Cloruro di polivinile rigido
PVC rigido
Cloruro de Polivinilo Rígido
Flexible PVC
Flexible Polyvinyl Chloride
Weich PVC
Weich-Polyvinylchlorid
PVC Souple
Chlorure de Polyvinyle souple
PVC flessibile
Cloruro di polivinile flessibile
PVC flexible
Cloruro de Polivinilo Flexible
Acetals
Acetals
Acetale
(POM) Polyoxymethylen
POM
Polyacétal
POM
Polimeri acetalici
POM
Poliacetales
Nylon
Nylon
PA
Polyamid
PA
Polyamide
PA
Poliammide
PA
Poliamidas
Acrylics
Acrylics
Acryle
(PMMA) Polymethylmethacrylat
PMMA
Acrylique
PMMA
Polimetilmetacrilato
PMMA
Metacrilato de Polimetilo
Phenolics
Phenolics
Phenolharze
Phenolharz Formmassen
Phénoplastes
Phénoplastes
Resine fenoliche
Resine fenoliche
Fenólicos
Fenólicos
PC
Polycarbonate
PC
Polycarbonat
PC
Polycarbonate
PC
Policarbonato
PC
Policarbonato
PPO
Polyphenylene Oxide
PPO
Polyphenylether
PPO
Oxide de Polyphénylène
PPO
Polipropilene ossidato
PPO
Óxido de Polifenileno
PEEK
Polyether Ether Ketone
PEEK
Polyetheretherketon
PEEK
Polyétheréthercétone
PEEK
Polieterchetone
PEEK
Polieteretercetona
PET
Polyethylene Terephthalate
PET
Polyethyleneterephthalat
PET
Polyéthylène téréphtalate
PET
Polietilentereftalato
PET
Tereftalato de Polietileno
PBT
Polybutylene Teraphthalate
PBT
Polybutylenterephthalat
PBT
Polybutilène téréphtalate
PBT
Polibutilentereftalato
PBT
Tereftalato de Polibutileno
DMC
Dough Moulding Compound
DMC
Plattenextrusionscompound
DMC
Dough Moulding Compound
DMC
Masse da stampa in resina poliestere insatura
DMC
Moldeo de Compuestos de Resina de Poliester Insaturada
PSU
Polyether Sulphone
PSU
Polyethersulfon
PSU
Polysulfone
PSU
Polietersulfone
PSU
Polietersulfona
TPEs
Thermoplastic Elastomers
TPEs
Thermoplastische Elastomere
TPEs
Elastomères Thermoplastiques
TPEs
Elastomeri termoplastici
TPEs
Elastómeros Termoplásticos
Polymers are normally processed by melt processes such as moulding and extrusion and can be modified significantly by the use of plastics additives.
The Market for Thermoplastics
The West European thermoplastics industry in 2003 represents a 31 million tonne plus business worth in excess of EUR 55 billion. The industry is subject to constant change as plastics seek to replace traditional materials and as plastics materials and techniques compete against each other in the marketplace for applications. Companies are constantly seeking to gain a competitive advantage both through the introduction of new materials or material grades or by the acquisition of other competitors’ business. Making sense of all this is a full time job but AMI are specialists in plastics and we relish the challenge.
At the Heart
Since our formation in 1986 we have established a series of polymer databases for Europe and Asia which chart the supply and demand for all commodity and engineering thermoplastics. These databases also contain end use applications for each material on both a historical and future forecast basis. The databases are constantly refined and updated in the light of AMI’s whole research effort and together with our processor databases underpin much of our consulting and publishing work programmes.
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