With a dual objective of quiet, dependable operation and manufacturing cost
reduction, Italian lawn and garden equipment maker Harry S.P.A. is using a
self-propelled lawnmower transmission gear set made of Stanyl® TW200F6, a 30%
glass-fibre reinforced polyamide 4,6 (PA46) from DSM Engineering Plastics.
Stanyl provides the superior wear and friction characteristics, mechanical and
heat endurance required to handle the engagement forces and the transfer of
energy from the engine to the mower’s driven wheel. At the same time, Stanyl
helps reduce noise, especially important for environmentally friendly and
extra-quiet designs from Harry. Because gear surfaces and other complex
geometry are cost effectively produced by injection moulding, the Stanyl gear
set does not require the machining, polishing, or fitting required by metal
counterparts.
The design incorporates three Stanyl parts: a driven gear, a mechanical
clutch, and a shifting fork that actuates the clutch. The transmission itself
is a positive drive to one rear wheel and is engaged by the user while the
engine is running. The forces generated during rapid engagement are high, and
Stanyl’s strength and relatively low coefficient of friction provide long life
for the assembly. “We were able to realise a design that’s both long-lasting
and economical with DSM's materials,” said Mr. Figini, Technical Manager at
Harry. “Metal gearing proved to be too noisy and involve too many
manufacturing steps.”
“Stanyl’s strengths were a good fit for the Harry application,” said Marco
Vincre, Account Manager, Stanyl, DSM Italy. “The strength of Stanyl especially
made it a good fit for this mechanically demanding use.”
Stanyl grade TW200F6 is one of the Stanyl family of heat-resistant polyamide
moulding compounds, produced and marketed exclusively by DSM and available
worldwide. Stanyl is used in demanding applications in the automotive and
electrical and electronics industries, as well as many other applications.
Stanyl is offered in a wide variety of grades including high- flow,
abrasion-resistant, and unfilled (non-reinforced), as well as grades
containing glass and other fibers, minerals, lubricants, impact modifiers
and/or flame retardants.
The higher crystallinity and a faster rate of crystallization give Stanyl a
technical edge over such engineering plastics as PA6, PA66, polyesters, and
other high heat-resistant resins such as semi-aromatic polyamides (PPAs), PPS
and LCPs. Compared to these, Stanyl grades show better heat resistance,
mechanical properties at elevated temperatures, wear and friction behaviour
and, with faster cycle time and increased flowability, improved processing
economics. A dedicated staff of DSM specialists provides technical support in
design, moulding, and material selection of Stanyl.
