Canadian Plastics

User-friendly Finishing

Just as designers attempt to turn two parts into one, processors are looking for new ways to integrate molding and finishing operations. The rationale for both trends is the same--by eliminating extra...

April 1, 2000   By Michael LeGault, editor



Just as designers attempt to turn two parts into one, processors are looking for new ways to integrate molding and finishing operations. The rationale for both trends is the same–by eliminating extra components and/or steps in a part or process, a company saves time, as well as reduces labor, material and capital costs.

“More of our customers are going toward press-side automation of graphics in-line with a conveyor system,” says Ken Thuro, vice president, Cassco Machines.

Running a decorating operation in-line with a conveyor or other automation equipment allows a manufacturer to run at the speed of the injection molding machine, notes Thuro. Label printing, for example, can then be accomplished across all three shifts as part of the regular operation, rather than on a single shift as a separate step. In-line decorating also eliminates the need for a more costly, high-speed printing machine.

Cassco’s Hot Stamp Decorating System combines advanced controls and automation to print crisp, permanent graphics in-line with the customer’s conveying system. The system is ideal for both round and square pails. The pails are automatically sensed, oriented, printed and released. A vision system can be added for programmed inspection of printing, supporting lights out molding capability.

Another advantage of Cassco’s Hot Stamp system is that it requires no pre-treatment of the substrate, wet inks, thinners or solvents, notes Thuro.

AUTOMATED DECORATING OPTIONS EXPAND

The OSMO Imprex screen printing machine from Graphics International Group is designed for high-speed, automatic container decoration. A variation on the company’s popular Novax M printer for bottle and container screen printing, the Imprex provides an output of 70 ppm (compared to 100 ppm for the Novax) and is retailed at a lower price. The modular machine can handle a wide range of container shapes and can accommodate printing in two, four or six colors. It is an ideal machine to run behind a shuttle blow molding machine where top printing speeds may not be required.

United Silicone’s automated Uni-Printer pad transfer printing machines can be designed and manufactured for custom, fully integrated decorating operations in a wide-range of applications. One system recently bought was designed to apply two single color graphics on two locations on medical sleeves. The system features two model UP 303 Uni-Printer machines integrated with a six-position rotary index table. The first machine applies decoration to the top side, while the second decorates the bottom side. The system’s rate is approximately 15 parts per minute.

The RP-3 and SC-6X system from Dependable Machine provides semi-automatic silk screening with the advantages of off-line UV curing. The RP-3 features a gear and rack drive, automatic registration, reciprocating squeegee and flood bar. The system can print round, oval and flat containers. All three shapes can be dried by the SC-6X UV curing tunnel.

The new Virtek Industrial Laser System (VILS) can be used to permanently mark any plastic material, even on wet, oily or dirty surfaces. The new systems combine leading edge precision laser technology and proprietary software to offer speed, cost and quality advantages over conventional marking processes. According to the company, anything that can be viewed on a computer screen can be marked with repeatable accuracy, including text, numbers, machine-readable codes, graphics and codes. Alphanumeric characters as tiny as 0.025 in. (0.6 mm) can be legibly marked.

Teca-Print’s TPU 130/131 Series pad printing machines have PLC control and an operator-friendly interface which accommodates quick, easy changing of operating modes, dwell time adjustments and vertical pad stroke settings. Up to 50 different print job settings can be stored and recalled from the PLC’s memory.

The TPU 131 features the patented Teca-Print sealed ink cup technology. The cup rotates with each doctoring motion to reduce wear on plate and cup. The cup’s proprietary internal design affords reliable operation with minimal amount of ink.

MAKING THINGS STICK TOGETHER — PRECISELY

Advances in technology, along with higher customer expectations, have gradually raised the bar for quality in plastic bonding and welding operations. Reject rates that were once acceptable are no longer so, says Mike Finer, general manager, Branson Canada, a division of Branson Ultrasonics Corporation.

Branson has recently introduced its 2000f ultrasonic assembly system equipped with servo, closed-loop control for enhanced welding reliability and consistency. The 2000f system features Branson’s patented amplitude stepping, as well as the improved Advanced+ power supply. The system also has improved data capabilities for configuration and information management. It is designed for use in manual, semi-automated or fully automated environments with most materials handling devices and is capable of being interfaced with digital control devices such as PLCs and PCs.

“Servo control gives you total control of the force on the part as you weld,” says Finer. “This in turn enhances process control and production and part quality.”

Finer also notes that the ability of newer ultrasonic equipment to control a host of other parameters such as weld energy, amplitude and force has significantly expanded the applications of the process to a wider range of resins.

Sonics & Materials’ enhanced ultrasonic 20 kHz hand held welder, model H-520, is designed for staking, inserting and spot welding applications. The 1.5 lb. hand gun is supplied with an integral 0.5 in. diameter titanium front driver with a replaceable flat face tip. The autotune feature of the welder enables the use of different style tips without the need to retune the system for each application. The welder also contains a microprocessor-based programmable timer for weld times from 0.1 to 9.9 seconds.

Developed for low-quantity assembly projects, the Model 101 Universal Assembly Press from ToolTex, Inc. can be fitted with an ultrasonic handgun, a heat staker or a hot air/cold staker. The press can also be converted from a hand press to a pneumatic one. The press is small and inexpensive and easy to use for those who aren’t regular operators of assembly tools.

Plastic Assembly Systems (PAS) has launched a line of ultrasonic welders integrated with closed-loop energy, time, force and distance control options it claims is significantly cheaper than systems with comparable features currently on the market.

“The price range of our integrated ultrasonic welders is in the range of $9,000 to $13,000 (U.S.),” says Michael Brunetti, president of PAS. “This is approximately half the price of any brand with similar features currently selling in Canada or the U.S.”

ASSEMBLY STAKES OUT NEW GROUND

PAS is currently building a heat staking machine that will place 64 brass inserts of various sizes into different levels and positions of a structural foam molded housing. According to Brunetti, it will be the largest heat staking machine ever built.

Brunetti feels the capabilities of heat staking and insertion have been underrated by processors. “Heat staking has been done an injustice as a finishing process. Advanced controls now available on heat staking equipment prevent materials from sticking and stringing and give a surface that looks like an extension of the molded product itself.”

Brunetti notes that heat staking and insertion offers the advantage of performing multiple operations on several planes simultaneously.

KVT Technologies Inc. has recently built a system for boring, welding and assembling six layer co-extruded fuel tanks for a European customer. The system consists of three processing stations where a number of boring and welding operations are performed. Tanks are automatically transferred from one station to the next. Welded components such as valves, clips and filters are manually or automatically loaded to the various hot plate welding units. All boring tools utilize chipless boring technology and include automatic slug retention and disposal s
ystem with an optical slug sensor. The hot plate welding systems are designed with self-aligning heat platens and component holding fixtures.

Transmission welding using laser beams is suited for joining plastic materials with different optical absorption. The laser light penetrates the transparent component where it is converted into heat.

Laser welding systems from Leister Process Technologies utilize Modulus S (simultaneous welding) and Modulus C (contour welding) to join parts or components made of different thermoplastics or elastomers. The equipment can also be used to form metal/plastic joints. Advantages of laser welding include a small heat zone, the ability to construct three-dimensional joints and the capacity to place welds in close proximity to sensitive components or structures.

New or traditional, all types of finishing equipment continue to evolve to keep pace with processors’ objectives to provide added value at lower costs to their customers.CPL


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