Post on 17-Sep-2015
description
ABS
krishnaswami.kaushikABS an Engineering Plastic
Description & TypesProperties & GradesApplication & UsesProcessingDescription & Types
ABS resins are thermoplastic resins composed of three different monomers I.e, ACRYLONITRILE, BUTADIENE AND STYRENEACRYLONITRILE stands- Tensile, Strength, Hardness, Heat resistance, Chemical Resistance etcBUTADIENE improves- Impact StrengthSTYRENE improves ProcessabilityABS has an combination of Mechanical, Thermal & Chemical Resistance. I.e (Tough; Hard & Rigid Material).
Acrylonitrile butadiene styrene
Acrylonitrile
Chemical ResistanceFatique ResistanceHardness & RigidityMelt StrengthH2C=CH
C=N
Butadiene
Low Temprature DuctilityImpact resistanceMelt StrengthH
C R
HC C
Styrene
Heat ResistanceProcessabilityColoringHardness & RigidityHC = CH2Properties
ABS is derived from acrylonitrile, butadiene, and styrene. Acrylonitrile is a synthetic monomer produced from propylene and ammonia;Butadiene is a petroleum hydrocarbon obtained from the C4 fraction of steam cracking;Styrene monomer is made by dehydrogenation of ethyl benzene - a hydrocarbon obtained in the reaction of ethylene and benzene. The advantage of ABS is that this material combines the strength and rigidity of the acrylonitrile and styrene polymers with the toughness of the polybutadiene rubber.The most important mechanical properties of ABS are impact resistance and toughness.A variety of modifications can be made to improve impact resistance, toughness, and heat resistance.Properties of ABS
Excellent freedom of DesignSuperior Dimensional Stability, Rigidity & ToughnessGood surface glossExcellent Chemical, Resistance & Non Corrosive Better Surface Hardness Better Insulating PropertyLight WeightGood Low Temperature Impact StrengthAvailability of built in good attractive coloursOdourless, TastelessPossible to imply in all Techniques e.g spraying; Screen Printing; Metallizing, Eletroplating without any surface treament.Grades of ABS
Graded by Injection Moulding; Extrusion & Thermoforming.Moulding can be graded asGeneral pupose;High Impact;High Gloss;High Flow;Heat Resistant;ElectroplatingExtrusion can be graded asLuggage;Refregerator lines;COP Sleeves.Alloys of ABS PC AlloyPVC AlloyPlastic extrusion molding
Plastic extrusion molding is a process of producing a continuous work piece by forcing molten plastic through a shaped die.As the hot material exits the die the material is carried along a conveyor, cooled, and cut to the desired length.In plastic extrusion molding thermoplastic materials are fed from a hopper into the heated barrel of an extruder.A rotating helical screw inside the barrel pushes the plastic through the barrel toward the die located at the end of the machine.A key advantage of plastic extrusion molding is it's low cost.Plastic Extrusion Molding Design Considerations
Walls must not be too thick to provide cooling.Use rounded corners.Use uniform wall thickness. Long items will have a slight curvature. Ends are rough cut.Machines of Plastics Extrusion Molding
Plastic extrusion molding of ABS
ABS Molding or Extrusion Compound
Product Description EXTRUSION IS A VERY IMPORTANT METHOD TO MAKE PLASTIC PRODUCTSLow Gloss ABS
Low Gloss Materials are used for Automobiles PartUltra Super Heat Resistant ABS
Very High Heat ResistantMedium Resistant Impact ABS
THIS IS THE GERERAL PURPOSE ABSHigh Impact ABS
This is Strong Plastic ABSHeat Resistant ABS
THE MATERIAL SHOULD WORK IN HIGH Temperature, FOR INSTANCE, AUTOMOBILE OR HAIR DRYER SHELLSPlating ABS
IT IS VERY IMPORTANT TO ABS USING, BUT NOT ALL ABS GRADE SUITABLE FOR PLATINGGlass Fiber Reinforce
WITH GLASS FIBER REINFORCE WORK, THE RIGIDITY OF ABS IS LARGELY IMPROVEDFlame Retardant ABS
Injection Molding
Injection Molding
Plastic Injection Moulding with ABS Plastics
Different grades of ABS plasic available today including high-impact, glass-filled, transparent and high luster formulations, available in a wide range of colors for applications that include office machines, electronics and consumer related products.Properties of ABS Plastic (Injection Moulding)
ABS is an amorphous thermoplastic copolymer blended from Acrylonitrile, Butadiene and Styrene.Being an amorphous thermoplastic, it is easily plastic injection molded, and it provides uniform shrinkage in both the flow and transverse-to-flow directions.This uniformity in shrinkage can be maintained over a wide processing range so precise dimensional control is easier to achieve when compared to a crystalline thermoplastic.Uniformity in shrinkage also results in minimal warpage after plastic injection molding.ABS Thermaplastics Injection Molding
ABS, also known as acrylonitrile-butadiene-styrene, is a common engineering thermoplastic that has good impact strength and toughness along with mechanical and electrical properties that make it idea for a variety of uses:Medical devicesElectrical and electronicsHardwareEnclosuresBusiness machine and computer housingsIndustrial partsAppliances; Automotive & MoreFactors Affecting the Injection Molding of ABS
A constant problem in injection molding processes is that of flash. Flash results in wasted material, time, money and poor product quality. The variables affecting the IM of ABS are:Injection pressure (35% or 45% of Maximum Pressure 62 Bars)Holding Pressure (35% or 45% of Maximum Pressure 62 Bars)Holding Pressure time (1 second or 4 seconds) affect the flash of ABS tensile specimens,The combination of variables that produced the least amount of flash are injection pressure (35%), low holding pressure (35%), and either low or high holding pressure time (1 or 4 seconds).ABS molded products include:
Standard injection moldingThin- and thick-walled partsStructural foam moldingABS properties:
Tough, versatile, cost-effective engineering thermoplasticGood impact strength Good rigidityGood surface appearanceFDA and U.L. grades availableUltraviolet light sensitive; requires stabilizers for weatherabilitySecondary Operations for ABS Plastics Parts
Other ABS plastic injection molded components are parts that require post molding operations such as:secondary machining operations;installation of metal inserts,ultrasonic insertion anddecorated moldings using hot stamping, pad printing, and laser marking processes.A unique characteristic of ABS is the ability to chrome plate the material, thus lending itself to applications such as decorative trim, automotive parts, medical devices and toys.SPECIFIC GRAVITY
The ratio of the weight of the molded piece as compared to the weight of an equal volume of water ASTM D792 ABS 1.04-1.07Specific gravity of major polymers
ABS (High Impact)1.01 - 1.04ABS(Medium Impact)1.04 - 1.07ABS High(Heat Resistant)1.05-1 .08ABS Self Extinguishing 1.15 - 1.21Thermal, Electrical and Optical Properties
Thermal Properties:-ABS has good high temperature performance and the softening point is generally higher than standard PS.The heat deflection temperature can be increased by several methods to between 120 to 130oC. ABS can be used down to about -40oC.Fire Behaviour
Most ABS variants are flammable and will burn freely (giving off typical styrene odours).The flame and fire properties of ABS can be improved by blending bromine compounds at 15 - 20 pts phr - an expensive solution that seriously compromises the toughness of the material.Another method is to create an ABS/PVC blend and to let the chlorine on the PVC act as a fire retardent.Electrical Properties
ABS has relatively good electrical insulating properties and products are suitable for secondary insulating applications. Optical properties Natural ABS is milky-opaque but can be easily coloured in a wide variety of colours.Special glass clear versions are available.Chemical Resistance Property
ABS is resistant to most acids and alkalis, hydrocarbons, oils and fats.It is not resistant to acetone, ether, ethyl benzene, ethyl chloride and ethylene chloride.Applications of ABS
Domestics Food Mixers & Grinders;Washing Machine; Hair Dryers; Vaccum Cleaners;Doors & body lines, handles of Refrigerators;Luggage'sBusiness Xerox Machine; Typewriters, Computers; Telephones;Textile;Electroplated parts;Automobiles etcApplication- Material ABS
Material ABS - acrylonitrile butadiene styrene ABS is an amorphous thermoplastic blend.The recipe is 15-35% acrylnitrile, 5-30% butadiene and 40-60% styrene.Depending on the blend different properties can be achieved.Acrylnitrile contributes with thermal and chemical resistence,The rubberlike Butadiene gives ductility and impact strength.Styrene gives the glossy surface and makes the material easily machinable and less expensive.Application Lego Building Bricks
The LEGO building bricks illustrate the attractive properties of ABS plastic: impact strength and glossy surface.The dimensional stability of ABS contributes to the narrow tolerances required when joining the building bricks.The bricks are mass produced by injection mouldingApplication Product Computer Mouse
Products Computer mouse Three-dimensional decoration of these mice is achieved by water transfer technology. As it can be seen, decoration with very complex patterns and with a variety of colours can be achieved.One of the commercial names for water transfer technology is cubic printingApplication of Vacuum Jug
This vacuum jug illustrates how chemical resistancy and strength can be achieved at boiling temperatures.The black top of the jug is made from POM plastic which hardly absorbs the taste or smell from tea or coffee.The colored plastic jug furthermore shows how shiny scratch resistant surfaces are obtained using ABS plasticApplication-Product Kim Box Suitcase
This suitcase illustrates how a glossy surface is obtained using ABS plastic shaped with vacuum forming.The interior is made from PUR foam cut into shape using waterjet cutting.The suitcase is only produced in a very limited number for the Danish Museum of Craft and Design (Kunstindustrimuseum).It is used for transporting a collection of designed products that introduce children and teenagers to good industial design.Application Ceramic ABS
Products Ceramic advanced wet shave razor The ceramic blade in this razor stays sharp up to 40 times longer than conventional razor metal blades.The razor is made from ABS plastic shaped with the insert moulding technique.The sharp blade is made of yttria stabilised zirconia ceramic.The present version of the razor is a prototypeApplication- Product Hedge Cutter
Products Hedge cutter This hedge cutter shows how many different plastic materials are used in a product to obtain different properties.The handle and the shielding plate are made from ABS plastic which ensures good impact strength.The motor housing, in PA plastic, has good heat resistance.The sheath shows that a very long narrow hollow geometry can be produced in HDPE plastic by conventional injection moulding.Application-Handle for High Pressure Cleaner
This hollow handle is produced with air assisted injection moulding.Better quality and reduced cost are achived compared with the traditional solution: a handle assembled from two half shells using snap locks.This handle is part of a high pressure cleaner. The cleaner can rotate around the joint at the bottom of the handle.The material is a blend that combines the qualities of ABS and PAApplication-Product Shaver Rechargeable
This shaver shows how soft rubber-like plastic is integrated with hard plastic.It also illustrates that it is realistic to produce strong, thin, sharp cutting blades with a complex geometry.The green rubber-like parts are produced by multicolor injection molding using PP for a stiff basis and SEBS plastics for the rubber-like surface.The hard blue part of the cover is injection molded in ABS plastic.The blades are made by electroformingApplication-Product Ensemble Chair
This stable chair is made from Stapron N which is a blend of ABS and PA plastics.The blend gives good acoustic properties (a sound unlike plastic!), a soft consistency, chemical resistance (coffee, food, alcohol), and good moulding properties.Using air injection moulding, air cavities are integrated into the seat and the back of the chair to give the right elasticity.In this way a good sitting comfort is achievedMoulding Condition of ABS
Moulding Temperature C 180-240Injection Pressure a KGS/Cm 800-1400Mould Temprerature C 55-60Pre Drying of ABS Type of Oven : Air Circulating TypeThickness of Granules in Tray : 2 18mm Pre-drying Time : 2-3 HrsPre-drying Temperature : 80-90Processing
ABS is an amorphous material and softens over a range of temperatures rather than melting quickly as do the crystalline materials.The materials have a broad processing window and can be processed on most standard machinery.ABS is available in standard and easy-flow grades and the easy flow grades are very good for complex mouldings.Pre-drying is not always needed for injection moulding with a vented cylinder but if drying is needed then 4 hours at 80oC is generally sufficient.Signs of moisture are stripes, streaks or bubbles in the moulding and if any of these are seen then the material should be pre-dried.Injection Moulding
Mould temperature is usually between 30 and 80oC and the higher the mould temperature the better the surface quality.Weld lines may also become less prominent with increasing mould temperature. Moulding is carried out with an injection pressure of 1000 to 1500 bar and using a follow-up pressure of relatively short length but in the region of 30 - 60% of the injection pressure.Extrusion
Screws should be chrome plated, single lead, full flighted constant pitch screws.Compression ratio should increase from around 2:1 to 2.5:1.In the absence of special ABS screws, low-compression PVC or shallow flighted PS screws can be used at low production rates. Reprocessing of up to 30% can be used provided the regrind has not been subjected to previous thermal degradation.ABS
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