Vivak® plastics sheets offer superior thermoforming properties.

Vivak® unites design and function in complex transparent shapes.

The trademarks Vivak® and Vivak® UVstand for thermoplastic copolyestersheets with superior thermoformingbehaviour and very good mechanicalproperties. These benefits offer designers virtually unlimited scope forrealising complex transparent shapes.

The range of applications for this uni-versal material go from industry tovisual communications – displays, ven-ding machines, shopfitting – right upto medicine. The constant high qualityof these products is based on the useof carefully selected raw materials,

comprehensive quality managementand production processes certified toISO 9002.

Our solid sheet products: Vivak®

Vivak® Vivak® UV

Logo

The added • simple and cost-effective • simple and cost-effective

extra: processing processing

• good optical properties • good weathering resistance

• good chemical resistance

• good mechanical properties

• food compatible

Colors clear clear

bronze white translucent

fluo orange, red and green

black

2

Contents

1. Fabricating 1.1 General 4

1.2 Sawing 4

1.3 Cutting and punching 5

1.4 Drilling 5

1.5 Milling 6

1.6 Laser cutting 6

2. Forming 2.1 Cold forming 6

2.2 Thermoforming 7

3. Bonding & Fastening 3.1 Bonding with adhesives 10

3.2 Bonding with adhesive

tape 10

3.3 Welding 11

3.4 Mechanical fastening 11

4. Finishing 4.1 Polishing 12

4.2 Decorating 12

5. Cleaning 12

6. Material properties of Vivak® 13

Makroform Sales Offices 14

Suppliers 14

3

Rake angle γ

Clearance angle α

Rake angle γ

Section x

t

x

Section: x - x

10° - 15°

t

α

1. Fabricating

1.1 General

ToolsVivak® sheets can be machined usingthe standard tools commonly used formetal and woodworking. We recom-mend carbide-tipped tools. Above all,it is important to use sharp cuttingtools with the right geometry.

CoolingNo cooling is required during the nor-mal machining of Vivak® sheets. In theevent of local overheating duringmachining, we recommend coolingwith water or oil-free compressed air.

Oil emulsions and cutting oils shouldnot be used when machining Vivak® asthese may contain additives to whichVivak® is not resistant, resulting instress crack formation.

Dimensional accuracyThe coefficient of linear expansion ofVivak®, being 0.050 mm/mK, is signifi-cantly higher than for metal or glass.For this reason, dimensions shouldalways be checked at room temperat-ure. Remember that shrinkage ofapprox. 3 to 6 % depending on thickness occurs when the material isheated above the glass transition tem-perature (approx. 81 °C) for the first time.

Masking Vivak® sheets have a solvent-free PEmasking film on both sides to ensurethat the smooth surfaces are notdamaged during transport and machi-ning. This masking should be left inplace during machining. Sunlight andweathering can affect the properties of the film with the result that it mayunder some circumstances be very difficult to remove any remainingmasking.

MarkingMarking out drill holes, cut edges etc.should be done on the masking. If mar-king is required, use a soft pencil orfelt-tip pen. Marking tools should notbe used as the tracing mark has a not-ching effect, and a higher load at thispoint may cause the sheet to break.

1.2 Sawing

Hand sawsStandard hand saws may be used toseparate Vivak® sheets. A saw with finespacing between the teeth should beused.

Circular sawsUsing a circular saw is the easiest wayto cut Vivak® sheets. Experience hasshown that carbide-tipped circular saw

blades produce the cleanest cuts. Thepitch varies from fine for thin sheets tocoarse for thicker materials. Ensurethat no shavings are left on the cuttingsurface as these could damage themasking and scratch the Vivak® sheets.

When handling sheets thinner than 2 mm use a thick underlay board or apair of shears instead of a circular saw.

Band sawsBand saws are ideal for curved cuttingof formed parts or irregular shapes. Toachieve a clean cut edge it is importantto work on a solid cutting surface. Awide pitch is required when workingwith thick materials. For higher qualitycut edges, circular saws or routersachieve a better result than band saws.

Band saw Circular saw

Clearance 20 -40° 10 -30°angle α

Rake angle γ 0 -5° 5 -15°

Cutting speedv (m/min) 600 -1000 1000 -3000

Tooth pitch t(mm) 1,5 -3,5 2 -10

(see Figures 1 and 2)

4

Fig. 1: Ribbon saw Fig. 2: Circular sawblade

Vivak®

0.01 - 0.03 mm

Vivak®

1 mm

60°60°

30°

30° Shearing tool

0.5 mm 0.75 mm 0.01 - 0.03 mm

1 mm2 mm

Trouble-shootingFused cut edge:

Check tool sharpnessCheck cutting speed and reduce ifnecessaryCheck feed rate and reduce orincrease as necessaryCool if necessary

Notched cut edge:Check tool sharpnessCheck tool geometryCheck cutting speed and increase ifnecessary Improve cutting surface (use anunderlay if necessary)

1.3 Cutting and punching

Vivak® sheets up to 3 mm thick areeasy to cut and punch, producing agood result. The thicker the sheet, thepoorer the quality of the cut and thegreater the risk of cracking. Goodresults can be obtained using a sharpshearing tool with a wedge angle ofmax. 30°, with clearance between thetool and the cutting surface of 0.01 to0.03 mm (see Fig. 3).

If you require smooth cut edges it isbetter to saw or mill Vivak® sheets witha thickness of 1.5 mm and upwards.When punching close-tolerance holes,

allowance must be made for shrinkageif machining is to be followed by heattreatment of over 80 °C. This meansthat the hole should be measuredapprox. 5 % larger than actually requi-red. The bigger the hole and the thicker the sheet, the lower the ten-dency for the sheet to shrink. Goodresults are obtained using symmetri-cally bevelled shearing tools.

For punching/shearing Vivak® sheetsthat are more than 1.5 mm thick, werecommend asymmetrically bevelledblades. To achieve right angles, bladeson one side bevelled with a wedgeangle of 30° should be used. Makesure that the back-up pad (polyamideor high density polyethylene) remainsin place and is properly centered withthe punching tool to ensure clean cutedges.

1.4 Drilling

Standard drills used for metalworkingare perfectly suitable for machiningVivak®.

Make sure that the cutters on the drillare sharp. Cooling during drilling isgenerally not necessary. When workingwith relatively large drilling depths werecommend using water or compres-

sed air and/or regularly with- drawingthe drill from the hole to reduce heatand remove shavings.

Oil/water emulsions or cutting oilsshould not be used when drillingthrough Vivak® sheets. Standard circle-cutting equipment (e.g. circle cuttersor compass saws) is suitable for large-scale drilling.

The drill holes should be smooth andas free as possible of notches or roughareas to ensure secure fastening.

Recommended angles for drilling:

Point angle ϕ. 110° - 130°Helix angle β‚ 19° - 40°Cutting speed 30 -60 m/min.Feed 0,1 -0,3 mm/Rev.

(see Fig.5)

The distance between the drill hole andthe edge of the sheet should be at least1.5 times the diameter of the hole.

5

Fig. 4: Depending on sheet thickness, various differtent types of cutters are recommended for punching.

Fig. 3: Clean cut edges

6

Fig. 5: Drills for Vivak® sheets. Fig. 6: Hot line blending

2.Forming

1.5 Milling

Vivak® sheets are easy to processusing milling machines. The choice ofmilling machine depends on the typeof machining required.

Ensure that your tool has good chipclearance and sharp cutters.

1.6 Laser cutting

Various designs of laser can be usedfor the thermal separation of Vivak®

sheets – with or without masking.Lasers are particularly suitable for cut-ting complex contours. It is recommen-ded that the sheets be annealed afterthe cutting process.

2.1 Cold forming

Cold bendingAll Vivak® sheets can be subjected tocold bending with a minimum radius of150 times sheet thickness.

Minimum radius = 150 x sheet thickness

Thermoforming is recommended forsmaller radii.

Cold brakeVivak® sheets can be cold formed. Thebest results are achieved with a rota-ting bending machine. Cavity folding ispossible up to a thickness of 2 mm.

The relaxation immediately followingthe cold folding process means thatthe sheet has to be overstretched byapproximately 25°. The internal andexternal stress levels take a few daysto become balanced with the partsonly then taking on their final shape.

The sheet should be folded parallel tothe extrusion direction marked on themasking.

Bear in mind that cold brake formingplaces high stresses on the edge areasof the material. Avoid the use of

Helix angle β

Point angle

ϕ

Moveable shielcooled if neces

Fig. 7: Adjustment of heating zone

aggressive chemicals, particularly withcold brake formed and cold bent parts.

The use of cold folding should berestricted to thin Vivak sheets.

2.2 Thermoforming

Vivak® sheets can be thermoformed evenat low temperatures (100 to 160 °C).

Pre-dryingVivak sheets do not need to be predried.

Hot line bendingHot folding is a relatively easy formingprocess for the production of uniaxial-ly formed parts. The Vivak® sheet sim-ply requires local heating to approx.100 °C. The masking does not need tobe removed.

The Vivak® sheet is heated using IRheaters or heating elements in a linearmanner (see Fig. 6). As soon as theideal temperature is reached, the sheetis removed from the heating element,folded, placed in the mold and clampedinto position. The desired shape shouldbe fixed until the material rigidifies.

If using one-sided heating, the Vivak®

sheet must be turned over severaltimes to guarantee even heating on

both sides. With sheet thicknesses of 2 mm or more and when producinglarge numbers of units, we recommendsimultaneous heating of both sidesusing a sandwich heating appliance. Byadjusting the heating width using theshields (see Fig. 7), various differentbending radii can be achieved, althougha minimum bending radius of 3 times thesheet thickness should not be undershot.

Local heating creates stresses in thefinished part. Care should be takenwhen using chemicals with bent for-med parts.

Heating during thermoformingTo achieve compliant formed parts, theVivak® sheets should be heated evenlyas part of a controlled process to atemperature of 100 to 160 °C. The bestforming precision of the parts is achie-ved at the upper end of the formingtemperature range.

Vivak® sheets cool quickly, so that werecommend that the sheets be heateddirectly on the forming machine andnot – as is frequently done with otherthermoplastics – in separate air circu-lating ovens.

For heating the Vivak® sheets we re-commend IR heating systems, if possi-

ble two-sided, which can be heated uprelatively quickly. The advantage oftwo-sided heating lies in the moreeven and quicker heating of the mate-rial. This enables shorter cycle timesand is more economical.

Cooling the finished partIt is very important that Vivak® materi-al is cooled quickly. It should be cooledusing compressed air or – where possi-ble – water fog mist until the parts arecompletely cooled.

Vivak® shrinks by 0.4 % upon cooling.

Male formingYou can stretch simple, uniaxially curved mouldings with large bendingradii. The Vivak® sheets are heated to the correct temperature in an air-circulation oven and rapidly con-veyed to a mould heated to approx. 55 °C.

The inherent weight of the sheet or theexertion of slight pressure using glo-ves or fabric is sufficient to shape thesheet over the male mould.

Afterwards, the sheets must be sub-jected to air cooling. Caution:draughts may cause warping andinternal stress.

7

IR heating element + reflector

elds, ssary

Vivak®

Heating zone X (mm)

D X

X = 0.026 x D x α

α

Vivak®

8

Fig.: 8:

Female tool:Details on the outer surface

Male tool:Details on the inner surface

We advise you to remove the maskingfilm before heating the sheet in an oven.

ThermoformingDepending on the size of the produc-tion series and desired surface quality,tools made from different materialscan be used.

Please note that the material selectedwill influence cooling time and surfaceproperties. The mold should be suffi-ciently rounded.

Vivak® sheets effectively reproducedetail.

We recommend not polishing the sur-face of the mold but slightly matting itto avoid impressions on the formedpart. When constructing formingmolds, allowance should be made forshrinkage of 0.4 %. Special materialsare available for producing porous for-ming tools without vents.

Male and female toolsThe decision on whether to use a maleor female tool depends on the applica-tion. To achieve a better surface quali-ty on the outer side of the finishedpart, use of a female tool is recommen-ded to attain greater detail.

Free blowing or free drawingThis technique is used to form domes.Blowing without a countermold invol-ves working with air pressure, whilstthe thermoforming process without acountermold is carried out in a vacu-um.

To produce perfect moldings, thesheets should be evenly heated. At asheet temperature of approx. 80 °C,the part retains its desired shape andcan be removed.

Thermoforming Tips

Problems Possible causes Solution Hot bending Thermo-forming Free blowing/

free drawing

Badly formed

parts Sheets too hot Reduce heating • • •

Production cycle too long Shorten cooling period • •

Vacuum speed too fast Limit vacuum •

Sharp edges Round off edges •

Thin edges Sheets too small Use larger sheets •

Wave formation Uneven heating Check heating surface • •

Too small a distance between molds Increase min. distance between parts • •

Vacuum too fast Limit vacuum • •

Sheet surface too large Distance between clamp and tool

< 50 mm •

Reduced details Insufficient vacuum or Increase vacuum or compressed air or

compressed air check for lack of tightness • •

Sheet temperature too low Increase heating •

Molding sticks

to mold Mold too hot Reduce mold temperature •

Release angle too small Release angle > 4° •

Impressions

Mold surface too smooth Slightly matt tool •

Sheet temperature too high Reduce heating/heating time •

Surface defects Dust on sheet or mold Clean with ionized compressed air • •

Uneven finished

parts Heating/cooling Check for draughts; check heating • •

Release too fast Sufficient cooling of part •

Tears or cracks Excessive stress Slow heating, heat large surface area • • •

9

3. Bonding & Fastening

When bonding Vivak® sheets, makesure to distribute the load evenly overthe entire adhesive layer. Please ensu-re that the bond is not exposed to pee-ling stress, but only to shear or tensilestress (see figure: Recommendedbonds).

Solvent-type adhesives are the sim-plest and most economical means ofbonding parts made of Vivak®.

The addition of 8 % Vivak® chips provi-des a solution adhesive with reducedevaporation speed and increasedviscosity, which makes it much easierfor you to apply and handle. A furtheradvantage of this solution adhesive isthat it is gap-filling, meaning that thesurfaces to be bonded do not need tobe so flush as when using a pure sol-vent-type adhesive.

Please bear in mind the followingduring bonding:

Thoroughly clean the surfaces ofgrease, dirt and other impuritiesusing a soft cloth soaked in isopropyl alcohol;Apply the solvent-type adhesive ina thin layer to only one adherendsurface (excess adhesive producesweak bonds);

Place the surfaces on top of eachother immediately and press themtogether briefly to ensure closecontact over the entire surface; The bonded parts can be movedafter only a few minutes, althoughthe bond only reaches maximumstrength after a few days, at normalroom temperature (as the solventgradually escapes from the bondedpart.

Vivak® can also be bonded with otherthermoplastics whose surface can bepartially dissolved, using solvent-typeadhesives. These bonds are generallyrather weak, depending on the combi-ned materials. In this case, preferenceshould be given to adhesive bonding.

3.1 Bonding with adhesives

Please observe the general protectivemeasures recommended by the respec-tive adhesives manufacturer. Vivak®

parts can be bonded with each other orwith other materials using commercial-ly available adhesives suitable forpolyester.

When selecting the adhesive for a par-ticular application, please bear in mindthe following parameters: heat resi-stance, elasticity, appearance of the

adhesive layer, ease of processing, etc.

Please remember during bonding:the adherend surfaces must beroughened and thoroughly cleanedto improve adhesionthe instructions for use stated bythe adhesives manufacturer mustbe observed.

3.2 Bonding with adhesive tape

Transparent, double-sided adhesivetape (acrylic based) may be used forrapid bonding. These tapes are elasticand adhere well to Vivak. They are par-ticularly suitable for bonding thinVivak sheets to other plastics, glass ormetal.

Tips for good bonding:Fold the sheet so that it is slightlywider than the adhesive tape.Clean this area with isopropyl alco-hol.Carefully apply the adhesive tape.Use a roller to apply even pressureto remove any air bubbles andimprove adhesion.

Abb. 9: Bonding using adhesive tape.

Be careful when working with solvents, since they may be toxic or contain carcinogenic substances. Good ventilation isessential. Please observe the indications in the safety data sheets of the respective solvent manufacturer.

10

Vivak®

Double sidedadhesive tape

11

Fig. 10: Avoid screws with beveled heads.

3.3 Welding

Welding is mainly performed on opa-que sheets. It does not produce opti-mum optical quality, and should there-fore be carefully considered.

Should you nevertheless decide toweld the material, please bear in mindthe following points:

The Vivak® workpieces and weldingrod, if required, must be cleanedbefore welding is performed to prevent dirt becoming trapped inthe weld;To release the internal stress thatoccurs during welding due to localthermal expansion, the workpieceshould be annealed after welding.

Hot-gas weldingWe recommend an air volume of 50 –100 l/min and an air temperature of250 – 300 °C, measured 5 mm in frontof the nozzle. Round or profiled extru-ded rods, or even narrow strips cutfrom a Vivak® sheet, can be employedas welding rods.

Ultrasonic weldingVivak® sheets can be joined by meansof ultrasonic welding. Please contactthe relevant manufacturers for detai-

led information on ultrasonic weldingdevices and welding conditions.

3.4 Mechanical fastening

Due to its good impact resistance,Vivak® can be fastened mechanicallyusing any method.

When using screws, opt for screws witha cylindrical head to bond variousparts further and avoid any with beve-led heads, as these can cause cracking(see Fig. 10). Drill holes should bemeasured to allow for expansion andshrinkage.

All plastic screws are suitable. Whenusing metal screws a suitable plasticunderlay is required. Avoid over-tighte-ning screws. Use a through bolt ratherthan cutting a thread in the sheet.

The table below shows the expansionof a sheet measuring 1 m in lengthunder a temperature increase of 20 °C.

Linear thermal Expansionexpansion at ∆ 20 °Ccoefficient (mm)(mm/mK)

Vivak® 0.050 1.00Aluminium 0.024 0.48Steel 0.012 0.24Glass 0.008 0.16

Fig. 11: Mechanical fastening

Distance a:2 x ø hole, but at least 10 mm

Vivak®a

a

4.1 Polishing

Flame PolishingPropane, butane or other types of gasburner may be used for flame polis-hing.This technique can produce excel-lent results but requires experienceand ongoing practice. Cracks mayappear in the polished area in the longterm.

BuffingMedium-density reiter polishingwheels with a peripheral velocity of 20to 30 m/s can be used to polish Vivak®

sheets with alkali-free polishingpastes. A clean polishing wheelwithout polishing paste is then used tocomplete the polishing process.

Large-surface polishing should be avo-ided.

4.2 Decorating

Before treating Vivak® sheets – e.g. bycoating, screen printing or thermofor-ming – we recommend removing anyloose particles of dirt or dust adheringto the surface using ionized air (seeSection 5 on Cleaning).

Transfer printingVivak® sheets and finished parts canbe printed using transfer printing.

Screen printingVivak® may be printed with standardscreen printing equipment and inkssuitable for thermoplastic polyesters(PETG). The ink manufacturer ’s recom-mendations should be followed.

Vivak® sheets can be printed with UV-cured inks. The short-term UV radia-tion has no impact on the physical pro-perties.The maximum application temperatureof 65 °C should not be exceededduring the drying process.

CoatingAfter prior cleaning, Vivak® may becoated without being pre-treated. Thecoatings must be suitable for use withVivak®.

5. Cleaning

12

4. Finishing

Vivak® has a pore-free surface to whichit is difficult for dirt to adhere. Dustyparts can be cleaned with water,a soft cloth or a sponge but shouldnever be rubbed when dry!

For thorough cleaning, we recommenda non-abrasive detergent. Razor bla-des or other sharp tools, abrasive orstrongly alkaline detergents, solvents,leaded benzine and carbon tetrachlori-de should not be used.

The only way to achieve effective clea-ning without streaks is to use a micro-fiber cloth that is simply dampenedwith water. In the case of a greaterbuild-up of dirt or greasy stains in par-ticular, benzene-free pure petroleumspirit (cleaner ’s naphtha or light gaso-line)may be applied.

Splashes of dye, grease etc. may beremoved using a soft cloth soaked inethyl alcohol, isopropyl alcohol orpetroleum ether (boiling point 65 °C)and gentle rubbing prior to curing.

Vivak® has good electrical insulationproperties resulting in electrostaticcharging and the attraction of dustparticles.

Before treating Vivak® sheets werecommend removing any loose parti-cles of dirt or dust on the surface byblowing with ionized air. The particlescannot be removed using a normalcompressed air gun or a cloth but willgenerally just be moved around.

6. Material properties

13

Properties

Physical

Density

Moisture absorption: 23 °C, 24 h immersion (3 mm)

Refractive index at 20 °C

Mechanical

Tensile stress at yield

Elongation at yield

Tensile strength

Elongation at break

Tensile modules of elasticity

Limiting flexural stress

Impact strength: - Charpy unnotched

- Charpy notched

- Izod notched (4 mm)

- Instrumented impact (4 mm) at Fmax

Rockwell hardness

Thermal

Glass transition temperature

Thermal conductivity

Coeff. of linear thermal expansion

Heat deflection temperature under load acc. to ISO/R75

- Method A: 1.81 N/mm2

- Method B: 0.45 N/mm2

Max. service temperature in air(3)

Min. service temperature

Electrial

Dielectric strength(4)

Volume resistivity

Surface resistivity

Dielectric constant bei 103 HZ

bei 106 HZ

Dielectric factor bei 103 HZ

bei 106 HZ

Values

1.27

0.2

1.57

50

5

26

›100

2050

77 - 83

no break

16

90

28

R104-R117

81

0.32

0.050

63

70

65

-40

20

1015

1016

2.6

2.4

0.005

0.020

Unit

g/cm3

%

%

N/mm2

%

N/mm2

%

N/mm2

N/mm2

kJ/m2

kJ/m2

J/m

J

class

°C

W/m °C

mm/m °C

°C

°C

°C

°C

kV/mm

Ohm.cm

Ohm

-

-

-

-

Test method

DIN 53479

DIN 53491

DIN 53455 (1)

DIN 53455 (1)

DIN 53455 (1)

DIN 53455 (1)

DIN 53457 (2)

DIN 53452

DIN 53453

DIN 53452

ASTM D256

ASTM D3763

ASTM D785

DIN 52612

DIN 53461

ASTM D149

DIN 53482

DIN 53482

DIN 53483

DIN 53483

DIN 53483

DIN 53483

The above -mentioned values are typi-cal values at 23 °C, unless otherwisestated. They are intended as a guideli-ne for material determination. Theycannot be used for drawing up materi-al specifications. They do not dischar-ge the user of effecting his own testsin order to determine whether a mate-rial is suitable for the application.

(1) Test speed: 50 mm/min.

(2) Test speed: 5 mm/min.

(3) Temperature resistance over a period of several

month to several years. The given temperature limits

are determined by the thermal-oxidative degradation

which takes place and causes a fall-off in properties

(embrittlement). Besides, as for all thermoplastics, the

maximum service temperature depends essentially on

the duration and the magnitude of the mechanical

stress to which the material is subjected.

(4) Measured on a 2 mm thick test specimen. As with

other materials, the dielectric strength dimishes with

increasing sheet thickness, e.g. for 3 mm sheet the die-

lectric strength is 16 kV/mm, for 6 mm sheet 11 kV/mm.

THE LONG-TERM-PARTNER

Makroform Sales Offices.

Product liability clause:This information and our technical advice – whether verbal, in writing or by way of trials – aregiven in good faith but without warranty, and this also applies where proprietary rights ofthird parties are involved. Our advice does not release you from the obligation to verify theinformation currently provided – especially that contained in our safety data and technicalinformation sheets – and to test products as to their suitability for the intended processesand uses. The application, use and processing of our products and the products manufac-tured by you on the basis of our technical advice are beyond our control and, therefore,entirely your own responsibility. Our products are sold in accordance with the current versionof our General Conditions of Sale and Delivery.MF 0085 e 01/08

Germany:

Makroform GmbHDolivostrasseD-64293 DarmstadtPhone +49 (0) 6151/183 90 00Fax +49 (0) 6151/183 90 07

Belgium:

Makroform N.V.Wakkensesteenweg 47Industriepark ZuidB-8700 TieltPhone +32 (0) 51/42 62 00Fax +32 (0) 51/42 62 02

Italy:

Makroform S.p.A.Via Ludovico di Breme 13I-20156 MilanoPhone +39 02/39 23 15 1Fax +39 02/39 23 15 643

Makroform is a Joint Venture between Bayer AG and Röhm GmbH & Co. KG.

Makrolon®, Vivak®, Axpet® and Bayloy® are registered trademarks of Bayer AG.

E-mail: sales@makroform.comMakroform on the Internet:www.makroform.com

Suppliers:

We will be pleased to provide details of compa-nies that can provide specialist tools and acces-sories. Please contact the Makroform TechnicalService Department.