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© 2004 ITW Trans Tech
An Illinois Tool Works Company
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| VersaDyne Application Case Study: Polypropylene Blender Housing Printing System  The system operates in the following sequence: 1 Operator loads housing onto fixture and presses foot pedal to start cycle.  2 Fixtured part automatically travels rapidly through the print and pretreat areas and stops just beyond the VersaDyne pretreatment heads. 3 The pretreat heads are turned on and the shuttle slowly brings the part back under the pretreat heads.  4 The part is rapidly indexed to the first print position where the logo is applied by the 60mm cup setup. 5 The part is then rapidly indexed to the second print station where the icons at the bottom and the dots around the dial are applied.  6 The part is finally indexed to the last print position where the numbers at the bottom and the numbers around the dial are printed.  7 The operator then unloads the part and repeats the operation. For more details on VersaDyne electrical surface treatment, click here! Any questions? Ask your Consumables representative at 630.752.4000 or e-mail us! |
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Polypropylene Printing Blends Cup Slide, Shuttle & VersaDyne
CHALLENGE: Design a system to pretreat and padprint a large two-color image on a polypropylene blender housing using closed ink cups, plus, deliver it in six weeks. The total image area to be printed is over five inches in diameter, printed over a curved surface with a total drop of one inch from one end of the image to the other. The printed image must withstand a variety of household cleaners as well as cooking oils.
Diagram of artwork placement
The alternative process is a heat-transfer decal. The heat transfers are very expensive which favorably influenced the decision to go to transfer pad printing–– if it could be done and within the six week delivery deadline.
The blender housing after printing showing relative positions of the images.
Flame Treating Option?
At first, we considered using a universal flame treating conveyor and two separate printers: a Combi 90 with a special, double 130mm cup slide for the two five-inch images, indexing with a two-position shuttle. We could then use a Sealcup 60 for applying the logo area. Because the proposed system, if installed, would require three operators and the equipment cost would be around $75,000, it was not eagerly accepted. Also we discovered that the housing had a gloss finish which meant that, if flame treating were used, it would leave a striping effect as it oxidized the surface and removed most of the gloss. This was unacceptable.
We learned from our customer that their parent company was successfully using a “spot treating” process to pretreat parts prior to printing. We were quickly running out of time and had to come up with something fast and that was basically “off the shelf”.
The part is loaded onto the fixture, then moved to the Combi 130 by the electronic shuttle under the VersaDyne double corona heads (A), then to the first pad (B), second pad (C), and finally to the third pad (D) before shuttling back to the unload position at the starting point.
Shuttling Through the System
We determined that if we turned the part sideways, we could divide the print into groups and print the five-inch images with two 130mm cups by locating the upper portion of the images outside the cup area. As long as the print operation was continuous where the ink constantly re-wetted itself, we would not have a problem with the ink drying out. The logo area would be printed using a 60mm ink cup in the same printer.
We would need to move the part to the three print positions for the system to be complete. We would also have to be careful that the adjacent pads would not come in contact with the fixtured part until it was their turn to print. Because we needed additional room to do this, we chose a Combi 130 printer. We also needed to find a way to pretreat the polypropylene part on the same system.
Detail view of the artwork after printing on the housing.
Pretreatment
Because the production rate was low enough, it enabled us to incorporate our programmable indexing shuttle to move the part through the three print positions. Since the total travel on the shuttle was over 23 inches and only 19 inches of that was being used for printing, it gave us the opportunity to use the remaining portion of the shuttle for pretreating. Flame-treating was not acceptable and corona discharge was cost prohibitive. Both would have produced better pretreating than EST (electrical surface treatment) or “spot treater”, but EST had already been proven acceptable on this product.
VersaDyne
For the spot treater, we selected a double-head VersaDyne. Each head is capable of providing a maximum treating area of two inches wide. However, the effectiveness starts to diminish toward the edges of the treatment pattern. To overcome this, we staggered the two heads so that the treating areas slightly overlapped each other. We then placed the power supply/generator inside the Combi 130 cabinet area.
VersaDyne electrical surface treatment unit
Although safely located away from the operator, we positioned the VersaDyne treating heads in a safety-interlocked, guarded chamber that will cut off all air and power if someone were to accidentally get caught between the fixture and the treating heads.
Production rate of the system including load and unload is about 300 parts per hour. (See the sequence description in the column at left.) Finally, the entire system was completed, delivered and the first parts were printed in less than six weeks.
If you have a new printing application or would like to improve on your current process, either contact your local Trans Tech sales rep or contact us directly at 630.752.4000. We will be happy to answer your questions and work with you to determine the best solution for your product decorating needs.
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