Parasentation

Topic

:Elastomer:Reinforced Plastic

:Honeycomb Material

Members

• Imtiaz Ahmad(BSME01113115)• Khawer Saeed(BSME01113139)

Elastomer• Synthetic-rubber like material which, at room

temperature, can be easily bent, stretched, twisted, or deformed and, when released, quickly returns to its approximate original dimensions and shape.

Elastomeric Materials• Highly amorphous• Highly random orientation• High elongation

Stress

Stra

in

Elastomeric Materials

Metals

Conventional Plastics

Elastomers

Elastomeric Materials

No Stress

StressedIn tension

Elastomer

Unsaturated rubber that can be vulcanized (Thermosets) are

1=>Natural rubber(NR)2=>Polyisoprene(IR)3=>polybutadiene(PB)4=>choloprene rubber(CR)Saturated rubber1=>Epichlorohydrin rubber(ECO)2=> Silicone rubber(SI)3=Flourosilicone rubber(FVMQ) Thermoplastic

Aliphatic Thermoset Elastomers• These are the most common elastomers• These have a double bond after polymerization has

occurred• These are noncrystalline• These are highly flexible

Polyisoprene structure

Cis-poliisoprena

(Hevea rubber)

Trans-poliisoprena

(Gutta percha)

Natural Rubber

C C

C C

C

H H

H

H

HH

H

HHH

C

C C

C

C

H

HH

H

H

H

H

HH

H

Hevea Rubber(cis-polyisoprenene)

Gutta percha or Balatta(trans-polyisoprene)

Natural Rubber• Raw material extracted from trees

Natural Rubber• Material is processed

Thermoplastic Elastomer (TPE)• These materials are not crosslinked, have some distinct processing

advantages over traditional thermoset elastomers and physical properties of vulcanised elastomers

• TPEs are able to be molded like thermoplastic (injection molding, extrusion, etc)

• Thermoplastic elastomers are more temperature sensitive• Scrap and reject of these materials can be recycled-environmetal friendly

behavior• Normal crosslinked polymers cannot be recycled because they don't melt.

They don't melt because the crosslinks tie all the polymer chains together, making it impossible for the material to flow.

PROCESSING OF ELASTOMER

Common machine used for rubber compounding:-

1. Banbury mixer2. 2-roll mill

Manufacturing of Elastomer• Calendaring• Extrusion screw extrusion ram extrusion

• Compression molding Horizontal injection molding

• Transfer molding

calendaring• Calendar is consist of rollers(known as Bowls)

by using this we can control the thickness of elastomer sheat.the bowls can be horizontal of vertical the material from the mixer is fed between the nips of the bowls. the desiered sheet thickness can achieved by adjusting the nips.

typical calendar

Extrusion• Screw ExtrusionTheelastomer is first fed into the barrel via ahopper and then forced down the barrelby the screw whilst heat is added (createdby the shearing action and via the heatedbarrel and screw). At the end of the barrel,in the extruder head, is a die throughwhich the material is forced out.

ExtrusionRam ExtrusionFor a ram extruder theelastomer needs to be rolled and warmed,usually by placing it in a bath of hot wateror taking it directly from the mill/calender.This roll is then placed into the cylinderhousing the ram. The head of the extrudercontaining the die is then locked in placeat the front of the extruder and the ramtraversed forward, forcing the materialout of the die orifice.

Compression Molding

Compression moulding describes theforming process in which an elastomerprofile is placed directly in a heatedmould, then softened by the heat, andforced to conform to the shape of themould as the press closes the mould.

Injection Molding• Injection molding is a process whereheated elastomer is injected into a closedcavity via a runner system. Uncuredelastomer is fed into the injection cylinderwhere it is preheated and accuratelymetered into the mould. This is done bycontrolling the pressure, injection timeand temperature.

Transfer MoldingElastomer of setweight is placed in the transfer pot, and,as with compression moulding, the pot isclosed by the press forcing the elastomerdown the sprues and into the cavity.A small amount of excess materialflows out of the cavity through vents, withother excess material lying in the sprue grooves

and a mat of material left in the transfer pot.

Application of Elastomers

• AutomotiveTuned mass dampers, rubbers seals, tyre and tube manufacturing, pipes and hoses, boots, sleeves and covers.

• AerospaceAir management ducts, diaphragms, interior foils, hose and hoselines, air spring systems.

• DefenseCoating for radar and other defense equipments

Application Of Elastomer• Biomechanics and the medical/dental professionsSurgery devices, prostheses, orthopedics, orthodontics, dental implants, artificial limbs, artificial organs,

wheelchairs and beds, monitoring equipment

• Highway safety and flight safetySeat belt design, impact absorbers, seat and padding design, passenger protection

• Sports and consumerHelmet design, shoe design, athletic protection gear, sports equipment safety

• Others• Dental Products, paints and coatings, cement and concrete adhesives, special wood protection

coatings, biocompatible materials, medical and dental adhesives

Comparison B/W thermoplastic and Thermo sets

Thermoplastic

• These soften and melt on heating.• These can be remolded recast and reshaped• These are less brittle and soluble in some

organic solvents.• These are formed by addition polymerization.• These have usually linear structures.Ex.

Polyethylene, PVC, Teflon.

Thermosets

• These do not soften on heating but rather become hard in case prolonged heating is done these start burning.

• These can not be remolded or reshaped.• These are more brittle and insoluble in organic

solvents.• These are formed by condensation

polymerization.• These have three dimensional cross linked

structures. Ex. Bakelite, urea, formaldehyde, resin.

Industries In Pakistan Ideal IndustryMailing Address: Plot # 109, Kerbath Soling, 1 km Off Main Bedian Road, Lahore Pakistan.Pabx: 92 42 35600211/12Cell: 92 344 6001111Fax: 92 42 35600209Email: [email protected]

Rainbow Rubber IndustryFactory Address:Near Rabbani Masjid, Mirza Adam Khan Road, Karachi-Sindh, PakistanTelephone: 0092.21.32521070 & 0092.21.32542033Fax: 0092.21.32542033Director Marketing's : 0092.300.9279057 Director Product's : 0092.300.2172782Email: [email protected] [email protected]

Reinforced Plastics

Composites• Composites can cut weight by not being isometric and still

maintain the strength in the desired directions• Composites are, by definition, solid materials composed

of more than one substance in more than one phase

Composites

Processes

• Thermoplastic processes –Very short fibers• Matched die/compression molding• RTM• Spray-up• Hand lay-up for wet and prepreg materials• Filament winding and fiber placement• Pultrusion

Matrix Materials• Resins

– Both thermosets and thermoplastics can be used– Short fibers are generally used in thermoplastics– Long fibers are generally used with thermosets

Matrix Materials• Short fiber composites

– Less than 0.2 inches (whiskers)– Processed through standard thermoplastic processes

• Must pass through gates, runners, and gap between processing screw and barrel walls

– Thermoplastics generally benefit greatly from even the short reinforcement materials

Matrix Materials – FRP• Intermediate length fiber reinforcement

– The longer the fibers, the more difficult it is to coat the fibers enough to reap strength benefits

– Low viscosity thermosets “wet-out” the materials better than high viscosity thermoplastics

– Generally use unsaturated polyester and vinylester resins for FRP

Reinforcements• Three main types of fibers

– Fiberglass– Carbon fiber or Graphite– Organic fibers, aramids (kevlar)

Fiberglass• Spin molten glass• Different types of glass can be made

– E-glass (improved electrical resistance)– S-glass (high strength)– C-glass (high chemical resistance)

Carbon or Graphite Fiber• Originally some distinction was made—now the two refer

to the same material• Made from PAN fibers, pitch or rayon fibers• Through heating, raw material looses most non-carbon

atoms in the chain• Processing also aligns carbon chains• Carbon fibers have very high modulus (stiffness)

Organic Reinforcement Fibers• Aramid fibers have greatest strength and modulus

properties of organic fibers• Kevlar is the most commonly used aramid fiber• Aramids are strong and stiff but their greatest value is in

impact applications– Front of airplane wings– Armor applications

Reinforcement Forms• Fiber manufacturers package the fibers on spools called

tows• Fibers are generally converted to other forms after

manufacturing– Chopped fibers (including whiskers)– Mat (random)– Woven fibers– Tapes– Prepregs

Manufacturing Methods• Thermoplastic processes using short fibers

– Injection molding– Extrusion– Minor changes are made to accommodate the fiber

reinforcements• All gaps in flow path should be increased• A resin viscosity decrease may be necessary

Manufacturing Methods• Matched die or Compression molding

– Reduced flow path over injection or extrusion– SMC compression molding allows for continuous fibers, mats or

weaves– These processes offer parts that are finished on both sides

where most other composite processes do not

Manufacturing Methods• Resin transfer molding

– Fiber preform is placed in the mold cavity– Preform doesn’t move—resin is pulled/pushed in

Manufacturing Methods• Spray-up

– Fibers are chopped, coated with resin and sprayed onto the mold

Manufacturing Methods• Hand Lay-up (wet and prepreg)

PrepregWet

Fiber Orientations• Isometric materials have equal strength in all directions• Composites can be lighter weight by not having strength

in the directions that it is not needed• Lay-up still has to have some balance and symmetry

Vacuum Bagging• Provides for increased part consolidation• Reduces matched die mold costs

Manufacturing Methods• Filament winding and fiber placement

– Fiber placement has greater accuracy– Fiber placement can wind on less symmetrical and even

partially concave mandrels • Tubes, tanks, wind turbine blades and rockets

Manufacturing Methods• Roll wrapping

– Faster than filament winding– Limited to symmetrical mandrels

Manufacturing Methods• Pultrusion

– High volume production– Comparable to extrusion but the main processing force is

tension– Profile is pulled from the machine

Plant Concepts• Many of the processes require considerable space• Curing equipment for large parts can be very large (and

expensive)• Controlling volatiles (solvents and resins) must be taken

care of• Molds can be both expensive and fragile

Honeycomb material

Honeycomb structures are natural or man-made structures that have the geometry of a honeycomb to allow the minimization of the amount of used material to reach minimal weight and minimal material cost. The geometry of honeycomb structures can vary widely but the common feature of all such structures is an array of hollow cells formed between thin vertical walls.

Today honeycomb cores are manufactured via the expansion process and the corrugation process from composite materials such as glass-reinforced plastic (also known as fiberglass), carbon fiber reinforced plastic, Nomex aramide paper reinforced plastic, or from a metal (usually aluminum)

Recently a new process to produce thermoplastic honeycombs has been implemented, allowing a continuous in-line production with direct lamination of skin to cost efficient sandwich panel production. Continuous in-line production of metal honeycomb can be done from metal rolls by cutting and bending.Today, a wide variety of materials can be formed into a honeycomb composite. For example paperboard honeycomb is used in paper pallets and package cushioning, blocking and bracing

Manufacturing method

Expansion methodcorrugation processslotted metal strips

Expansion method• In this process thin metal sheet is first cut into panels and strip bonded• This process is referred to as the “honeycomb before expansion” or HOBE method. This

can be cut and stretched perpendicular to the strip bonds to create a hexagonal structure. The expansion process requires moderately high inter-sheet bond strengths (sufficient to enable sheet stretching). For low density honeycombs with very thin webs

Corrugated method• In this approach, a metal sheet is corrugated, and then

stacked into a block. The sheets are bonded by welding (or any suitable method) together and the core sliced to the desired thickness and the corrugated layers either adhesively bonded or welded to face sheets.

Corrugated method• the process for forming a hexagonal honeycomb core;

however this process may be used for numerous additional topologies including square and triangular shaped cells

Slotted metal strips• slotted metal strips can be assembled in the form of square and triangular honeycombs• Since no metal bending is required, this slotted sheet process is also well suited for

making honeycombs from low ductility materials. The honeycomb cores are bonded by welding/brazing (or any suitable method) together and bonded to face sheets to form a sandwich structure. Even brittle composite or ceramic honeycombs can in principle be made by this approach.

Application of honeycomb

Composite honeycomb structures have been used in numerous engineering and scientific applications.

Application of honeycomb

Lightweight honeycomb solutions are used in a wide range of industries, including the aerospace, marine, military, construction and automotive markets. Aluminum honeycomb, for example, is used as flooring material in various aircrafts, as it provides exceptional strength and low weight. It is also suitable for use at high temperatures and can withstand a variety of environmental factors

Application of honeycomb• Aramid fiber honeycomb is also used in aerospace applications, but

often in more advanced capacities, such as missile and hull components. This type of honeycomb also finds use in various marine and military structures. Polypropylene honeycomb, on the other hand, is used in various noise and vibration reduction applications, such as acoustical panels. It also offers relatively high strength for its weight and is easily formed by various thermoforming techniques.

Application of honeycomb• Honeycombs utilize far less material than a solid panel but still

provide exceptional strength, making it a highly economical option for many applications. In addition, the strength of the honeycomb increases with its thickness, meaning it is well suited to structures needing considerable core materials. Honeycombs are available in a wide range of standard and custom shapes and sizes.