leading global printer and copier manufacturer is using what may be the world's
smallest timing belt in an application that requires a very small belt for
paper media transfer. The belt replaces a rubber o-ring with inherent drawbacks
including loss of shape and decay of tension over time due to stretch a circular
cross-section which did †not allow for
much surface contact and marking of the paper media.
this application, the customer was looking for a very small belt to drive two
shafts in the same direction for paper media transfer," says Hans Raj, technical
business development manager for Fenner Precision. "Space requirements,† maintaining coefficient of friction and
avoiding any loss of tension over time were main concerns. These requirements
prevented the manufacturer from using conventional solutions such as small
O-ring or gears."
the time they initially looked at the design, Fenner Precision
didn't have a belt
small enough (53 mm pitch length) in its product portfolio. So the core
development was the challenge of enhancing its product and manufacturing capabilities
to create these smaller-than-ever miniature belts.
design challenges for the new construction included miniature size, constant tension
and a reliable surface over the life of the belt. In addition, the ability to
not mar or bend the media during the transfer motion was a must. To achieve these
overall design objectives, Fenner modified the belt material to provide a
higher and more consistent coefficient of friction and used a specialized
molding/de-molding process to make the smaller belt.
end product is a 53 mm inside length belt constructed of a special polyurethane
compound reinforced with fiberglass. This reinforcement prevents stretching, so
that the belt does not lose its shape or decay over time, and the polyurethane
does not mark the paper. The belt's unique surface allows it to have more
contact area with the paper, as opposed to the minimal surface contact provided
by an o-ring. In addition the belt is washed and textured to increase its frictional
created a reinforced belt solution to respond to a particular customer need,"
says Raj. "This new belt solution can be utilized as either a drive belt or media
transfer belt as it maintains both tension and a high coefficient of friction
urethane reinforced with fiberglass is a technique that Fenner Precision has
used on other larger belts but, for this application, they applied the special
surface finish to provide a good texture and increase the reliability of
interfacing other secondary operations and using different production batches. The
Fenner engineering team also came up with manufacturing solutions and special
handling tools to reliably mold and de-mold the extremely small belts to meet
the customers demanding quality and high volume requirements.
terms of applications, this same profile can be a potential replacement for
gears and O-rings in a wider variety of designs," says Pete Haberbosch, Global VP
Sales and Marketing for Fenner Precision. "The compact size can provide new solutions
for designers of small medical devices, portable printers, scanners and other
says many customers are designing smaller devices. The trend is focused on
solutions †that can fit into smaller
packages to reduce space and costs requirements.
applications that require shaft-to-shaft motion and travel in the same
direction, the design advantage of mini pitch belts over using gears is that
the system requires only two shafts rather than three. Belts can also provide
space savings versus using gears, and belt systems also tend to create less
vibration and noise. In addition because the belt doesn't have any
metal-to-metal or plastic-to-plastic interfaces, lubrication can be avoided.