The term lagging describes the variety of elastomers used to coat the contact surface of a conveyor pulley. Its primary purpose is to enhance traction by increasing the coefficient of friction between the surfaces. The enhanced friction may also improve belt life by allowing lower belt tensions and reducing abrasive conditions between the pulley and belt. PCI offers two types of lagging products; those that are hot vulcanized and those that are cold bonded using adhesives or mechanical agents. Most hot vulcanized lagging products can be formulated using Food Grade Materials and modified to include several groove patterns (Chevron, Herringbone, Diamond, etc).
SPIRAL WRAP ROUGH TOP
Spiral Wrap Rough Top (SWRT) is 2-ply 60A Durometer SBR belting that is wrapped around the pulley and secured with adhesive & rivets. SWRT has a nubby, rough profile for added traction. Resilient lagging is also available upon request.
An elastomer in its raw state is extruded and wrapped around the circumference of the conveyor pulley. The pulley is then processed in an autoclave to cure the rubber, ground to size and grooved (if specified). Vulcanized lagging is specified by selecting a rubber compound and durometer (hardness).
60A Durometer rubber is vulcanized to steel plates that are formed to the shape of the pulley rim. These rubberized plates are held in place by retainers which are welded or bolted to the rim. This style of lagging has either diamond grooves or a smooth surface and is field replaceable without removing the pulley from the conveyor.
Individual dimpled ceramic drive tiles are molded into a base of premium grade rubber. The combination of the ceramic tiles and the rubber compound provides improved traction and abrasion resistance especially in wet or heavily soiled environments.
WING: SLIDE-ON SMOOTH
Wing tips are the primary wear component of a wing style pulley. To increase the service life of a wing pulley, PCI offers two wing tip lagging options. 90A Durometer Slide-On Smooth Urethane is shown.
WING: WELD-ON DIAMOND
Wing tips are the primary wear component of a wing style pulley. To increase the service life of a wing pulley, PCI offers two wing tip lagging options. 70A Durometer Weld-On Steel Back Diamond Urethane is shown.
PCI’s patented Eradi-Lag™ is an innovative approach to wing pulley lagging for the Eradicator® or on any round bar angled wing pulley product. Eradi-Lag™ is constructed using a proprietary blend of 60A SBR for maximum wear life and a weldable steel backing plate for ease of installation.
Proper selection of a lagging material should address the following variables:
CHEMICAL & ENVIRONMENTAL CAPABILITY
Resistance to temperature, light, oils, fats, acids, alcohols and water, as well as compatibility with food products, are all factors that need to be considered when selecting a lagging material. Select a lagging material that is compatible with the conveyed material and has resistance to the conditions of the intended environment.
The durometer, strength, and abrasion resistance of the lagging material will impact its ability to provide traction, wear properly, and hold up to tearing, peeling, or eroding.
The type and style of lagging selected will impact the serviceability of the conveyor pulley when it requires recoating. Some styles allow for field installation of replacement lagging while others require that re-lagging services be conducted at a re-lagging facility.
The type and style of lagging selected will not only impact the coefficient of friction that is achieved between the conveyor pulley and conveyor belt, but also may impact the likelihood of reversion (see troubleshooting guide for complete explanation). Consult belt manufacturer specifications when selecting a lagging material.
The type and style of lagging selected will impact its ability to prevent sticking or adherence of foreign particulate to the surface. If ease is desired in eliminating foreign material from exposed lagged surfaces, then a lagging compound with good release properties should be considered.