Rubber Roller Manufacturer, Exporter and Supplier

A rubber roller is a steel or aluminium core covered with a bonded layer of rubber that is ground to size, and it is used wherever a machine must grip, press, drive, coat or spread a web without damaging it. Krishna Engineering Works manufactures every common type of rubber roller in Ahmedabad, India, for packaging, converting, plastic, textile, foil, paper, lamination, metal and leather machinery.

The company also re-covers worn rollers. This page sets out the range, explains how to choose the rubber and the hardness, and lists the data needed to make or re-cover a roller.

What is a rubber roller used for?

A rubber roller is used to do a job that a bare metal roll cannot: to give grip, to form a soft nip against a hard roll, or to carry liquid in a controlled film. The rubber layer deforms slightly under load, so pressure spreads over a band instead of a line, and small variations in web thickness are absorbed.

The main duties in the industries KEW serves are these.

• Nipping and pulling. A rubber nip roll presses the web against a driven steel roll to pull it at a set speed.
• Impression. In printing, a rubber impression roller presses the web onto the engraved cylinder or the plate.
• Squeezing. In textile padding and washing, rubber and ebonite rolls squeeze liquor out of the fabric.
• Laminating and coating. A rubber roll presses two webs together, or meters and applies adhesive.
• Spreading. Bow rolls, grooved rolls and slat expanders stretch the web sideways to remove wrinkles.
• Carrying. Web carrying rollers support and guide the web between processes.

Rubber roller types made by Krishna Engineering Works

Krishna Engineering Works makes rubber rollers by function, and the names below are the ones the company uses in its range. The table says what each does and where it normally works.

Anilox rollers for flexo printing are also listed in the range. Metal surfaced rollers such as hard chrome plated, cooling and knurling rollers are a separate family on the industrial roller page.

Spreading rollers: bow rolls and slat expanders

Spreading rollers remove wrinkles, open the web to its full width, take up a baggy centre, control slack edges and separate slit webs on a winder. KEW makes three kinds.

A rubber expander, or bow roll, is a curved roll with a rubber sleeve. Its performance depends on the lead in and lead out distances, the wrap angle and the position of the bow, which is adjustable. Krishna Engineering Works states that a lead in to lead out ratio of 3 to 1 is considered best. The product itself is on the bow roll page, and the working principle is explained on the group’s banana roll engineering site.

Slat expander rollers are straight rolls with slats that move outward from the centre through a cam mechanism as the roll turns. KEW supplies them with wooden slats covered in felt or with aluminium slats, in 6 inch, 8 inch and 12 inch diameter, in any working width, and with foot mounting pedestals. For longer widths three slats are fitted and the middle slats are fixed. They are particularly suited to slow speed machines such as cloth coating machines, flat bed printing machines and artificial leather cloth lines before the batching machine.

Grooved rollers are straight rolls with spiral grooves cut from the centre toward each end, which give a light spreading action with no adjustment.

How do you choose the rubber compound?

Choose the compound by what touches the roller: the inks, solvents, adhesives, water, steam and heat at that position. No single rubber resists everything, and the wrong one swells, softens or cracks within weeks.

The table gives general industry guidance. It is not a list of grades offered by Krishna Engineering Works, so confirm the compound for your chemicals when you enquire.

Nitrile rubber and EPDM rubber have nearly opposite resistance, which is why a roller that lasts for years with one ink system can fail quickly when the plant changes solvent. Always state the solvent, not only the process.

How hard should a rubber roller be?

The hardness should be the softest that still gives the required pressure and life. Roller hardness is measured on the Shore durometer A scale for normal rubbers, and a few points of difference change how the nip behaves.

A softer cover gives a wider nip, more grip and more tolerance of uneven web thickness, but it heats up more and wears faster. A harder cover gives a narrow nip and high pressure, holds its shape, and lasts longer, but it forgives less. As general practice, pressure and squeeze rolls sit toward the hard end, printing and laminating nips in the middle, and delicate film nips and spreader sleeves toward the soft end.

Surface finish matters as much as hardness. A ground matt finish grips, a fine polished finish releases and transfers evenly, and grooves let air out from under a fast web.

How a rubber roller is made

A rubber roller is made in a fixed sequence, and its life depends mostly on the first two steps, which nobody can see in the finished product.

1. The metal core is machined, and for a re-cover the old rubber is stripped off.
2. The core surface is blasted and coated with bonding agent.
3. The rubber compound is built up on the core to more than the finished diameter.
4. The roller is vulcanised under heat and pressure, which cures the rubber and bonds it to the core.
5. The cover is ground to the finished diameter and profile, including any crown.
6. Grooves are cut, and the surface is finished to the required texture.
7. The roller is checked for diameter, run out and hardness, and balanced where the speed requires it.

Krishna Engineering Works makes its machine components in its own factory and inspects them from raw material to final assembly. Rubber rolls are among the items the company produces in house.

Rubber roller re-covering

A worn rubber roller does not need a new core. Re-covering strips the old rubber, re-bonds a new cover and grinds it to the original size, and Krishna Engineering Works offers re-covering of rubber rollers alongside new rollers and precision rollers.

Send a roller for re-covering when you see any of these signs.

The specialist site on rubber rollers by compound and hardness covers selection in more depth. For the service scope at KEW, see repairing and servicing.

Where KEW rubber rollers are used

KEW rubber rollers work in the company’s own machines and in machines from other builders. On a flexo printing machine they form the impression and metering nips. On a lamination machine the rubber nip roll presses the webs against a heated or chilled roll. On a stenter machine rubber and ebonite rolls squeeze the fabric in the padding mangle, and curved rubber sleeve expanders straighten it. On a slitter rewinder machine rubber nip and lay on rolls control the web into the reel.

Related parts in the catalogue include the rubber fillet that covers textile machine rollers, and the air shaft, which uses a rubber tube to grip the core. The whole range is on the products page.

Storage and care

Rubber rollers last longest when they are kept clean, unloaded and out of sunlight. A few habits prevent most early failures.

• Open the nip whenever the machine stops, so the cover does not take a flat.
• Clean with the mildest cleaner that works, and never soak the cover in solvent.
• Store rollers on their journals, not resting on the rubber face.
• Keep spares wrapped, away from sunlight, electric motors and heat.
• Check hardness from time to time, since a rising reading warns that the cover is ageing.

What to send for a rubber roller quotation

A rubber roller is made to your drawing or to your old roller. Send:

• Roller type and its position on the machine
• Core drawing, or journal and face dimensions: face length, finished diameter, overall length
• Whether you supply the core or need a new one
• Rubber compound and hardness, or the inks, solvents, adhesives and temperature at the roller
• Surface finish: plain, ground, polished or grooved, with groove details
• Crown, if any, and the running speed if balancing is needed
• Quantity, and whether it is a new roller or a re-cover

Send these through the contact page.

Frequently Asked Questions

What types of rubber rollers does Krishna Engineering Works manufacture?

Krishna Engineering Works manufactures nip rolls, pinch rollers, impression rollers, printing rollers, silicone rollers, EPDM rubber rollers, super hard rubber rollers, ebonite rolls, grooved rollers, brush rollers, web carrying rollers and wrinkle removing rollers. The range also includes inflatable rubber tubes for air shafts, bow rolls and slat expander rollers.

Which industries use rubber rollers?

Rubber rollers are used in packaging, converting, plastic, textile, foil, paper, lamination, metal and leather industries. Any machine that handles a continuous web or sheet needs them: printing and laminating machines for nips, textile machines for squeezing and guiding, and winders and slitters for pulling, spreading and laying the web into the reel.

Can a worn rubber roller be re-covered?

Yes, a worn rubber roller can be re-covered as long as the metal core and journals are sound. The old rubber is stripped, the core is cleaned and bonded, and a new cover is vulcanised and ground to size. Krishna Engineering Works offers re-covering of rubber rollers as well as new rollers.

How do I know which rubber compound my roller needs?

The compound depends on the chemicals and temperature at the roller. Nitrile generally suits oil based and many solvent based inks, EPDM suits water, steam and ketone or ester solvents, and silicone suits high temperature and release duties. Tell the roller maker the exact inks, solvents, adhesives and temperature, and the compound is selected from that.

What is the difference between a rubber roller and an ebonite roll?

An ebonite roll is covered in hard rubber that has been vulcanised to a rigid, almost plastic state, while a normal rubber roller stays elastic. Ebonite gives a hard, chemically resistant surface that holds its shape, so it is used for textile mangle and guide rolls. Elastic rubber is used where grip or a soft nip is needed.

Why does a rubber roller need a crown?

A rubber roller needs a crown when it bends under nip load. A long roller pressed at its journals deflects in the middle, so the nip is tight at the ends and open at the centre. Grinding the roller slightly larger in the middle compensates for the bend and gives even pressure across the web.

How does a slat expander roller carry the web outward?

A slat expander roller is a straight roll whose surface is made of slats that slide outward from the centre as the roll turns, carrying the web with them. Krishna Engineering Works supplies it with felt covered wooden slats or aluminium slats, in 6 inch, 8 inch and 12 inch diameter, for slow speed machines such as cloth coating lines.