One thing is certain in the North American
plastics industry: automation is the future. Automation is now an essential
part of being competitive in a developed economy. Since low-end commodity
work often can be moved off shore, many molders are finding advantages to
automation where the majority of the work is at the high end of the
high-tech spectrum. At the high-tech level, the goal is to reduce labor
content and automate the process whenever possible.
Benefits to Automation
Advances in control systems have helped to
reduce the human content in a manufacturing process. High-tech usually means
high quality, as well as modern day advances in sensors, vision systems,
test systems, robotics, and the ability of manufacturing processes to raise
the bar on quality standards.
Systems integrators and OEMs must be
committed to working in partnership with clients to develop cost effective
industrial machinery and control systems that improve productivity,
competitiveness, and profitability. Monitoring each automatic tool at each
stage of the manufacturing process is vital to controlling the variables.
Before a product is allowed to go to the next operation, the process
variables need to be satisfied. Error proofing operations at each station
can be sequenced so that an operator is required to perform a required
operation in a prescribed order.
Key outcomes of a successful automation
project include improved productivity, reduced operating cost, and creation
of innovative products. However, automation success stories are often
overshadowed by failures of the design and automation team to engage early
enough in the product life cycle. For ultimate success, it is imperative
that the “design-for-manufacturability” philosophy be part of any new
product development activity. Best in class companies ensure design teams
have representation from all professional segments including automation,
process and industrial engineers, and product developers.
In this day and age, cost savings can be
realized by a better use of energy. Advances in stepper and servomotors have
contributed to higher production rates, improved quality, and, in many
cases, a reduction in energy. Some of the major automotive assembly plants
are now restricting the use of air cylinders and pneumatic devices in favor
of electric powered units to improve energy efficiency. Keep in mind that
compressed air is a utility, often the only one produced on site, and is
tremendously inefficient and costly.
In some geographic regions, utility rates
have forced molders to review the cost benefit of retrofitting existing
machinery and processes with electric powered motion devices. In addition to
the energy savings, this investment also improves the speed and accuracy of
the various motions, contributing to improvement in quality of the end
product.
The constant demand for lower cost and
optimization places increasing pressure on manufacturers and their
automation systems. Automation is rising to the challenge with more advanced
diagnostics, controls, and tremendous growth in software sophistication.
Many machines are equipped with probing devices and sensors to verify the
positions of various components and establish a work-coordinate system.
Encoders, linear and rotary, are used as feedback devices to a prime mover,
usually an electric powered motor, to determine precisely the position of
the moving component. By using probes combined with software, manufacturers
can monitor, correct, and document in-process operations.
Vision systems are more accurate, with
improved controls, robust integration capabilities, and easier to learn
operating features. High-speed cameras can detect flaws or missing parts on
an assembly, thus improving quality.
Automating with Robots
The versatility of robots lends itself to
the plastics industry, from high-speed de-molding through to assembly and
inspection. While labor rates continue to rise and the availability of
certain skills provides ongoing difficulties, the cost of robots has been
decreasing. There has never been a better time for manufacturing to invest
in robotics and automation. Payback times have been reduced through
increased productivity, reduced wastage of materials, and the benefits of
operator safety.
Manufacturers and system integrators are
discovering that multi-axis robots provide a consistent and practical
solution to all of the automation applications in the plastics sector. Six
axis robots are ideal for accurate and meticulous tasks, and are
particularly suited to such tasks as de-molding, sprue removal, gluing,
powder coating, painting, assembly, inspection, and packaging. With featured
high-speed for rapid acceleration and deceleration, today’s robots are
capable of following complex trajectories and have extremely large work
envelopes.
Most processors are knowledgeable about
molding equipment; however, the significant opportunities to improve one’s
competitive position occur downstream from the press, where value can be
added through assembly, gluing, welding, marking, testing, and packaging.
Given the high cost of labor, automation offers a clear path towards
improved productivity in these areas. A sensible approach for identifying
opportunities and their correlated return on investment is to establish a
partnership with an automation vendor who can supply both hardware and
extensive application engineering know-how.
Although some manufacturing companies do
have the expertise to design and implement automation solutions, many
companies are utilizing technology partnerships to efficiently adopt
automation solutions. In cases where molders decide to proceed on a “do it
yourself” basis, the probability for successful implementation decreases.
Since the purchaser most likely knows little about the mechanics of
automation, the purchasing decision is often based upon price. The
production department is then told to install the equipment, learn how to
use it, program it, and maintain it. There is little regard for the hours
spent in-house getting the system to work successfully. In the end, the
molder doesn’t receive the payback he expected and is convinced that robots
and automation “just don’t work”.
The fact is that robots and automation do
work very well when applied correctly. Automation is rarely “plug and play”,
and molders need to pay less attention to the hardware and more attention to
finding a vendor who can deliver a complete integrated system that meets and
exceeds their production requirements.
The goals of automation in plastics
molding operations are to boost productivity and generate cost savings.
Robots accomplish these goals by speeding up production, reducing the labor
content (which is a major part of value-added operations), reducing scrap,
and improving quality. Additional cost and productivity benefits, including
reductions in work-in-process and floor space, can be achieved when
secondary operations are automated and integrated beside the molding
machine.
Improvements in controls, software, and
user interfaces are making robots easier and faster to program, set-up, and
operate. Highly-graphic touch screens are used as input devices, which
significantly reduces any intellectual barriers to effective use.
Controllers are now adopting a “Windows” approach, with plain English
instructions that are far more accessible to the average operator.
“High-speed” and “precision” are the two
buzzwords associated with robotics, and more industries now can take
advantage of the latest robot technology. The injection molding industry
can benefit with vertical molding machines that are designed to lend
themselves to automation. These machines are targeted towards customers who
do not intend to use operators. The machine can be sent directly to an
automation source for integration of the robotics and other automation
devices. The customer then has a turnkey system, which can include insert
presentation, molding, and part removal. Using a robot as the main handling
component provides flexibility. Changes to the part design will not require
an entirely new piece of equipment – only minor software changes and robot
end of arm tooling changes - which will enable a new product to be
introduced in a shorter time.
The automation process can be both costly and cumbersome to implement,
but the cost savings and paybacks simply cannot be ignored. It is not
uncommon for a fully integrated system to have a payback of less than one
year, based on reduced labor costs and enhanced quality. The quality cost
reduction is easily measured since highly repeatable and consistent
automation provides excellent control of the process. Processors today
simply cannot ignore the benefits that automation technology can bring to
their operation.
John Tite is project manager, automated systems for Global Tool &
Automation Corp. (GTA). He holds both undergraduate and graduate degrees in
mechanical engineering. Tite has been involved in automation of all kinds
for more than thirty-four years. GTA, located in Fort Wayne, Ind., is a
designer and fabricator of special machines for plastic processors. Don
Dimberio, the president of GTA, has over thirty-five years of experience in
the plastics industry. |