Sandwich coating (Silicone + Sylomer Green)

Sandwich coating (Silicone + Sylomer Green) – soft sandwich coating for timing belts

Sandwich coating (Silicone + Sylomer Green) combines a resilient Sylomer layer with a thinner protective top layer. The purpose is to maintain the soft and compressible contact of the foam, while protecting the foam from direct wear, puncture and crumbling. It provides a cleaner contact surface and can significantly extend the service interval in many applications compared to unprotected foam.

The structure is particularly suitable for bottles, labeling machines, feeding, positioning, fixing and other transport tasks where the workpiece must be supported softly and uniformly.

Key data

• Coating type: Sandwich coating – PU foam + protective top layer
• Substrate: Sylomer Green / fine-pored polyurethane foam / approx. 280 kg/m³
• Top layer: Silicone / approx. 35–40° Shore A
• Surface: Matt/smooth, elastic and with high friction
• Top layer thicknesses: 0.5mm / 1mm / 1.5mm / 2mm / 2.5mm / 3mm / 3.5mm / 4mm / 4.5mm / 5mm / 5.5mm / 6mm / 6.5mm / 7mm / 7.5mm / 8mm / 8.5mm / 9mm / 9.5mm / 10mm / 10.5mm / 11mm / 11.5mm / 12mm
• Sylomer thicknesses: 3mm / 4mm / 5mm / 6mm / 7mm / 8mm / 9mm / 10mm / 11mm / 12mm
• Indicative total temperature range: -15°C to +80°C
• Food approval: Not documented for the overall sandwich construction

Why sandwich instead of bare foam?

Bare foam is very resilient, but over time it can develop surface damage, become perforated or start to crumble. The sandwich construction provides a continuous wear surface over the foam. The product therefore meets the top layer, while the Sylomer layer can still be compressed and accommodate minor height differences.

Silicone top layer is especially chosen when high grip and a more elastic contact are desired. It is very suitable against smooth objects, but is usually more susceptible to cuts, tears and abrasive wear than a PU top layer.

Recommended minimum pulley diameter

A two-layer coating cannot be accurately described with a single thickness factor. The configurator therefore uses a practical calculation rule based on the diameter factors already used on FEC Consulting's single coatings:

Indicative coating Ø ≈ (10 × Sylomer thickness) + (25 × topcoat thickness).

The result is rounded up to the nearest practical pulley size. The model is deliberately suitable for slow and normally loaded transport tasks: the soft foam deforms around the pulley and can therefore often work on a smaller diameter than a solid coating with the same total thickness. At high speed, many bends per minute, large belt width or high load, a larger diameter should be chosen.

• 5 mm Sylomer Green + 1 mm Silicone: calculated approx. Ø 75 mm → practical starting pu approx. Ø 80 mm
• 5 mm Sylomer Green + 2 mm Silicone: calculated approx. Ø 100 mm → practical starting pu approx. Ø 100 mm
• 8 mm Sylomer Green + 2 mm Silicone: calculated approx. Ø 130 mm → practical starting pu approx. Ø 130 mm

Practical control: 5 mm blue or green Sylomer with 1.6 mm PU gives, depending on the model, approx. Ø 90 mm. A practical starting pu will therefore typically be around Ø 100 mm in a moderate transport application.

The minimum diameter applies to the coating. The selected tooth profile, belt type, reinforcement and width may require a larger pulley. Always use the largest requirement.

How to use the dropdown fields

Top layer and Sylomer are selected separately. Next to each thickness is a Island contribution. Add the two contributions together and round up to the nearest relevant pulley size. Sylomer also shows whether the thickness is standard or ground.

Tooth profile, width, length, PAZ and reinforcement

The tooth profile must match the existing timing belt pulleys. Width and length are entered in mm. PAZ nylon fabric and steel cord or aramid/Kevlar are selected separately, where the specific belt type can be manufactured as such. The final design is technically checked before production.

Typical applications

• Transport and stabilization of bottles, glasses and containers
• Labeling machines and controlled contact pressure
• Feeding and fixing of workpieces with minor height differences
• Gentle positioning and dosing
• Replacement for bare foam when less crumbling and longer service interval are desired

Frequently Asked Questions

Can the sandwich coating run on the same diameter as bare Sylomer?

Not necessarily. The top layer increases the bending resistance, and therefore its diameter contribution is added to the contribution of the Sylomer layer.

Why is the minimum diameter indicative?

Because speed, load, belt width, tooth profile, joint type, reinforcement and temperature affect the service life. The calculation is a configurator tool and not a manufacturer's warranty.

What information do I need to provide to get a quote?

Select tooth profile, top layer thickness, Sylomer thickness, nylon weave and reinforcement, and enter belt width and length. Please provide pulley diameter, speed, load and the item being transported.