JAY ELSTOMER PVT. LTD.

Transcription

1 JAY ELSTOMER PVT. LTD. How important is Role of a Roll In Colour Coating Industry A Presentation by JAY ELASTOMERRS PVT. LTD,INDIA

2 JAY ELASTOMERS PVT. LTD. We divide this presentation in to 5 categories 1. Roll making consisting of -: Roll specifications Roll drawings Roll fabrication Roll machining, finishing Roll balancing Roll inspection

3 JAY ELASTOMERS PVT. LTD. 2. Roll to be used for type of colour coating. Polyester Paints Varnishes Silicone Modified Polyester(SMP) Plastisols Epoxies Polyurethane PVDF Solvent free UV Curable

4 JAY ELASTOMERS PVT. LTD. 3. Roll may be covered with-: Rubber-Natural Rubber-Synthetic EPDM HYPOLON/CSM Polyurethane Chrome Plasma Coatings

5 JAY ELASTOMERS PVT. LTD. 4. Roll may be used to coat on-: Steel coil Sheet Metal Aluminium coil, foil Paper

6 5. Rolls are used for Applications such as,-: Corrosion Protection Release Paper FDA Approved varnishing Can Coating, P P Cap making sheets Roofing Sheets Appliance Grade Coatings Car Body Coatings U V Curable Spreads

7 Section I The Roll performs best, if taken care while making such as, -: 1. Roll drawing is with all revisions and up to date. 2. Roll fabricated in accordance with all specifications. 3. Roll is dynamically balanced at specified speed. 4. Roll is with appropriate sized drilled centres.

8 5. Roll is having proper air escape passage. 6. Roll is with properly ground at bearing seat. 7. Roll is required to be fabricated with double flange design or with shrink fit method. 8. Roll is designed to take what Torque! 9. Roll can be used at what minimum shell thickness!

9 Fitment of the shaft either shrink fit or double flange Welded joints create imbalances. Flanges if not machined from both sides. Shrink fit shaft does not accommodate air escape Roll shaft centre and bearing seat finish not in alignment.

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11 Section Ii-: Various kinds of coatings are in use for Plastic films, Paper, Metal Foils and so on.. Adhesives Barrier Coats Anti Fungus/Anti Curl Coatings Sealable coatings Release Coatings Varnishes and Lacquers

12 Various Kind of Coating Methods are available-: 1. Gravure Coating 2. Comma Coating 3. Reverse Roll Coating 4. Hot Melt Coating 5. Metering Rod/Myer Bar Coating 6. Knife Over Roll Coating 7. Slot Orifice Coating 8. Immersion/Dip Coating 9. Curtain Coating

13 Paint Compositions -: JAY ELASTOMER PVT. LTD. Type Of Paint/Binder Solvents Areas Of Use Inside Outside CEMENT PAINT WATER OK OK EPOXIDE PAINT OR VARNISH XYLENE,BUTANOL,GLYCO LS,MIBK,MEK OK OK POLYURETHANE ETHYL ACETATE,BUTYL ACETATE,MEK,MIBK,DMF DMSO,CYCLOHEXANONE OK OK ALKYED OIL/VARNISH XYLENE,TOLUENE OK OK

14 Coating Method : Capability & Limitation -: Coating Method Viscosity in cps Max. Speed Mtrs/minute Coating wt. Gm/sq. meter Gravure Comma Reverse Roll Nip Reverse Roll Pan Hot Melt Myer Bar Knife Over Roll Slot Orifice Immersion/Dip Coating Curtain Coating Heavy

15 JAY ELASTOMERS PVT. LTD. TYPICAL TWO-COAT PAINT SYSTEM

16 Section Iii-: Roll covering material selection Hardness more than 60 Shore A Bridle Roller Polyurethane, Plasma Coated Pinch Roller polyurethane Snubber Roller Polyurethane,CSM Squeeze Roller CSM,Rubber,Polyurethane Contact Roller Polyurethane, Rubber Conveyor Roller Metal, Polyurethane Cradle Roller polyurethane, Rubber Deflector Roller CSM, Polyurethane

17 Coating roller covering material selection Hardness less than 60 Shore A -: Applicator Roller Rubber, Polyurethane Squeeze Roller - Rubber, CSM,Polyurethane Pickling line Roller Rubber, Neoprene, Metering Roller - Polyurethane Pick up Roller - Rubber, Polyurethane

18 ccl s faq s 1. Problems of roller covering getting sliced off 2. Roller covering swollen or with undulation over the surface. 3. Roller covering unsatisfactory to transfer uniform paint 4.Roller life is erratic with change of color coating system. 5. How to maintain a roller removed for grinding.

19 6. When to grind the roller removed after coating activity 7. What rubber thickness is perfect to good color pick up 8. Standard acceptance norms for color coating line roller. 9. Specifications set for roller manufacturing 10.Unintentionally happened operational oversights

20 Some typical problem leads misunderstanding Coil thickness is in variation or Change in line speed or Change in angle of sheet passing over,individually or together can create additional torque, leading to compression of roller covering Roller covering gets compressed leads to undulation of surface Compressed surface gets crushed and smaller cracks develop with in surface All remains unnoticed leads to fracture of surface and a small lump gets dislodged from surface

21 Closer view JAY ELASTOMER PVT. LTD.

22 PARTICULAR PLACE TO RFLECT UNEVEN PRESSURE RESULTED DURING OPERATION.

23 ROLLER DAMAGE SEQUENCE A small section of roll covering gets extra load due to unequal tightening of pressure screws to adjust gap between Metal roll & coater roll, Result, polymer gets crushed

24 Yellow patch showing undulation of surface

25 Some More Observations-: Roller covering soaks some amount of thinner or dilutant in the paint system employed and surface due to adsorption phenomenon goes soft. Next if polymer has foreign particles, air pockets, flow marks, which may lead to tearing of soft polymer. During coil change interface sheet is not fitted properly or Metal roller adjustment with coater roller not handled properly and extra pressure gets exerted then at times only one side of coater roller shows damage..

26 Strips fitted imperfectly at interface

27 Jay Elastomers Pvt. Ltd. Section I V-: Substrate for colour coating is in accordance with application or end use. Prepainted Steel Coil is widely used for, 1. Roofing sheets 2. Domestic or Industrial Appliances 3. Car body The level of asthetics,abrasion resistance, and flexibility is the essence of the requirement.

28 JAY ELASTOMERS PVT. LTD. Prepainted Aluminium coil/foil is widely used for 1. Packaging. 2.Roffing Applications. 3.Smaller Appliances. 4.Composite Panels. Aluminium being lighter and more ductile material requires special surface treatments before coating.

29 JAY ELASTOMERS PVT. LTD. Varnishing is a typical application and usage 1. Sheets for can coating activity 2. Coating on Electrical grade steel 3. FDA approved coatings. This process requires a typical oven curing system also coating are thinnest possible ranging from 15 micron to 80 micron. solvent based as well as water based coating are available.

30 JAY ELASTOMERS PVT.LTD. Section V-: Recommendations for surface finishes, Rubber Roll Surface Finish to be define with Ra value and may be Application oriented. To maintain required finish, Thinners and solvents used for cleaning must be certified. Polar solvents may be avoided. Surface finish also monitored for required kind of coating thickness Type of coating with Solvents, solvent free or water based can also influence surface finish.

31 JAY ELASTOMERS PVT LTD. Recommendations for easy operations. 50+ hour formula 1.Every applicator roll is recommended to be used for 50+ hours to avoid swelling and softening of polymer surface. 2.once used roll may be allowed to evaporate soaked Thinner/Solvents FOR 50+ hours, before taken for grinding. 3.We roller grinding is hazardous from fir and safety regulations.

32 JAY ELASTOMERS PVT.LTD. Summery-: Metal Roll making has become more subjective and precise. Paint systems have grown from Polyester paints to PVDF and soon to enter aqueous coatings. Substrates changing from Steel coil to Aluminium foil, Release paper to can coating and currency note coatings Oven curing to air drying, hot air blowing to UV Curing every stage change is observed.

33 But, natural and synthetic rubbers are struggling to achieve good-better-best. With changes in systems and conditions only conclusion can be drawn with present polymer coverings shall perform best if studied properly with respect to solvents, thinners, acidic solutions and line speeds. Here we conclude for best of coating technique to be explored further to make this presentation perfect.

34 THANK YOU!