Driven by high consumer expectations, auto manufacturers around the
world are constantly looking for ways to improve the appearance and
quality of the finishes applied in their paint shops. The most common
method is electrostatic painting, a process that runs a mild electrical current
through a body panel, creating an electromagnetic charge. Misted paint
molecules are attracted to the charged metal, creating uniform coating
coverage, while reducing wasteful overspray. Other paint processes are
utilized for lightweight plastics, fiberglass and carbon fiber materials.
It typically takes eight hours for an auto body to move through an entire
paint line, including initial submersion in coating tanks, primers, base
color coats, clearcoats and baking ovens. Applied by a series of highly
specialized robotic arms, auto body painting can account for more than
60 percent of an auto assembly plant’s total energy use.
Modern automotive paint is composed of a complex blend of resins,
binders, fillers, additives and carrying agents (solvents or water). All of these
components need to be properly mixed to ensure a high quality application.
CONTROLLING CRITICAL STIRRING SPEEDS
The main purpose of paint agitators (mixers) is to keep wafer thin
metallic particles evenly distributed in suspension within the paint. The
speed of stirring is critical: too slow and the particles will settle and form
thick clusters at the bottom of the container; too fast and the particles
collapse, becoming globular instead of flat, resulting in an undesirable
granular paint finish.
UNIQUE HUCO DYNATORK PISTON AIR MOTORS
MEET THE CHALLENGE
Paint stirring speed at auto plants can be controlled
directly through Huco Dynatork air motors because they
have built-in variable-speed capability.
With piston air motors, power is related to the supply
pressure and volume air flow, so an inlet valve can be
adjusted to control both speed and torque. The motors
can also be fitted with torque sensors for closed loop
feedback. With this simple arrangement, a Huco Dynatork
motor will hold its set speed steady; almost indefinitely.
To achieve this speed consistency with an electric
motor you would need an expensive variable-speed
drive that requires on-site installation, programming and
A number of automotive manufacturers have adopted Huco Dynatork Air Motors to drive the agitators in their paint shops.
SIGNIFICANTLY REDUCED COMPRESSED AIR USAGE
The free-floating piston design of Huco Dynatork air motors
is intrinsically efficient and consumes far less compressed
air than a conventional vane-type motor, usually needing
less than a quarter of the air supply for the same power
output. Furthermore, the dynamic characteristics of the
motor, including instant start/stop under load, mean that
it can be used in indexing applications, just like a stepper
In operation, air at up to 100 psi is supplied to each of
three pistons, in turn, via an integral rotary valve. The
free-floating pistons transmit maximum torque on start-up,
which can be adjusted via a pressure regulator. The
resulting performance features include: high torque, even
at low speed; variable speed control; and very low noise
Because the motors are supplied only with compressed air
and no electrical cables are required, there is no possibility
of sparking, making the motors intrinsically safe for use in
ATEX Zone 1 applications. Due to the flammable nature
of paint vapors, this feature is a significant advantage to
modern high-throughput paint shops.
In one paint shop application, the daily cost of running a
paint spraying system with a vane motor was $5.50 - $6.75
(based on 85% compressor efficiency). By incorporating a
Huco self-lubricating piston air motor, the operating cost
was reduced to just $.85/day.
EASY INSTALLATION AND MAINTENANCE
The simplicity of both the air motors and their air supply
system, when compared to an electric drive equivalent,
makes installation and maintenance very easy. The
lightweight, compact air motors are easy to lift and
position during routine maintenance. Connection to, and
disconnection from, the air supply is straightforward.
Furthermore, there is normally no need for a step-down
gearbox between the motor and stirrer; an electric motor
would require a gearbox, as would a vane-type air motor.
Even without a step-down gearbox, the Huco Dynatork
motor can run comfortably at output speeds below
100 RPM, the typical range for stirring applications.
Huco Dynatork motors are available with aluminium,
stainless steel or acetal bodies. Stainless steel and acetal
versions are ideal for use in industries such as food
processing, pharmaceuticals and medical equipment
manufacturing. Three standard sizes are offered, with
maximum torques of up to 16 Nm in direct drive, or up to
550 Nm through a gearbox.
PREFERRED BY MAJOR PAINT SPRAYING SYSTEM OEMs
Several leading manufacturers of robotic and automated
paint finishing equipment have begun to incorporate Huco
Dynatork piston air motors into their systems, replacing
industry standard vane motors. The Huco Dynatork air
motors have substantially reduced compressed air usage
and provide consistent agitator blade RPM. The result is a
better surface finish and lower operating costs.