Page 26 - IT_June_2020_Classical

MACHINE BUILDING

MINIATURE MOTORS

ELECTRIC MOTORS

he 21st Century has seen something of a COMPACT, LIGHTWEIGHT, PORTABLE AND OFTEN BATTERY OPERATED,
renaissance for the tattoo industry that has swept
across the world. Fine artists and increasingly TATTOO MACHINES PLACE STRINGENT REQUIREMENTS ON THE
Tsophisticated technology have redefined what is ELECTRIC MOTOR, AS VISHAL SAPALE OF PORTESCAP EXPLAINS
possible in body art, and what was once regarded as
symbolism for countercultures is now very much
mainstream for self-expression. Seeing them on our
favourite pro athletes, musicians and celebrities only adds
to the popularity of this art form. Tattoos have even
crossed over into the fashion and beauty industry. With
the millennial generation in particular driving the take-up
of tattoos, the industry worldwide is now worth many
billions of dollars, and is estimated to be growing at over
7% per year, according to research by IBISWorld.
Tattoos are created with machines that use
reciprocating needles to repeatedly penetrate a person’s
skin at high speed, depositing insoluble ink with each
penetration into the dermal layer of skin. Three principle
inking strokes – lining, shading and colouring – are used
to build up the final image.
For lining, a single needle is used to penetrate the skin.
The stroke length, or ‘throw’, need not be great to achieve
proper skin depth penetration of the needle. For shading,
which generally follows lining, a set of multiple needles is
used simultaneously to penetrate the skin. Here, the throw
given by the machine needs to be greater than the throw
used for one needle lining strokes. The last type of stroke
is colouring, wherein multiple needles, in a greater
number again, are used. For colouring, the throw needs to
be greater than the throw used for shading strokes.
The differences in force speed and depth for lining, Conventional rotary tattoo machines are trigger- means increased fatigue for the artist – an important
shading and colouring means that artists have traditionally activated, in that the cam-slider and motor assembly are consideration where each session can last several hours.
used three separate machines; eliminating the need for perpendicular to the needle-armature assembly. But the Motor regulation is the parameter of the motor which
adjustments of throw, and speeding up the overall latest development in rotary tattooing machines is a pen defines the speed torque characteristics. The lower the
process. However, this arrangement is costly in that three type design, with the mechanism and needle arrangement motor regulation, the more powerful the motor. As the
machines need to be purchased, maintained and cleaned in line in a cylindrical casing, offering an ergonomic design torque (load) increases, the speed decreases. If the motor
after each job. New generation machines have a for the tattoo artist which is easy to manoeuvre. regulation is better, then there is less speed drop with the
mechanism with added features that can adjust stroke, The most critical aspect of these new machines is the increase in load. This gives better stability for tattooing, as
speed and forces. This enables a single machine to cover motor. Not only must it be compact, lightweight and there is less speed variation with respect to load, resulting
all three stroke types, in addition to being effective on all portable, but it must also deliver the required speed and in less vibration and noise of the tattoo machine.
types of skin textures. energy density to meet the performance requirements of For next generation, battery powered machines,
the three lining, shading and colouring strokes; sustaining efficiency of the motor is also a critical parameter. Higher
Tattoo machine types all the different reciprocating loads created by the efficiency will minimise power losses and reduce current
The history of tattooing dates back many thousands of mechanism. Increasingly, the motor choice also must consumption, which will increase the battery life.
years, but the first prototype of an electric tattoo machine enable the tattoo machine to be battery powered. Further, the motor should be compact in size for proper
as we’d recognise it today was patented by US tattoo artist ergonomics and handling of the tattoo machine. It should
Samuel O’Reilly in 1891, based on the design by Thomas Motor selection also be lightweight to reduce the overall weight of tattoo
Edison for an electric pen. There has been a tremendous Tattoo machines require motors with variable speed and machine, which will again contribute to reducing artist
evolution over the years, and today there are two torque, so these design parameters are critical fatigue during longer tattooing operations.
fundamental operating principles, named for their characteristics to consider. Insufficient speed and torque Because the latest generations of rotary tattoo
construction and the way the mechanism operates. causes vibrations, which does not allow the colouring machines are being developed with additional features,
Coil tattoo machines utilise an electromagnetic circuit liquid to spread within the skin uniformly. This is because such as the ability to perform lining shading and colouring
to provide linear motion to the needle. Generally, a coil the pigment does not have the time to be absorbed by the in a single machine, there are further implications for the
tattoo machine has one or more DC coils and spring points epidermis when the tip of the needle reaches the end motor. Adjusting the stroke length (through a cam change)
coupled with armature bar to move needle groupings. The position. If the motor has insufficient power, then the artist as well as the speed and the force all impact on the
alternative rotary tattoo machine, in contrast, uses an will have to apply more pressure to the tattoo machine variable load amplitude and variable frequencies on the
electric motor with a rotating shaft having an offset cam and to incline it. This increases the penetration of the motor.
mechanism at its end to convert the rotary motion of the needle and accordingly the pain for the person receiving In looking at a suitable motor, the designer must also
motor into linear motion for the needle. the tattoo, as well as causing trauma to the skin. It also take into consideration the various axial and radial forces

26 INDUSTRIAL TECHNOLOGY • May/June 2020