Oral hygiene awareness is growing around the world, with almost 97% of populations in developed countries using at least one variety of toothpaste. By 2015, the global market for toothpaste is expected to reach close to $13 billion, according to Global Industry Analysts (GIA).
With Colgate-Palmolive increasing its share of the global toothpaste and toothbrush market to almost 45% recently, its no wonder that it needs to fill toothpaste tubes faster and more efficiently than ever.
Oystar IWK Verpackungstechnik in Stutensee, Germany, rose to the challenge, revving up the output of its tube-filling machine by almost 50% and adding measures to reduce overfilling as well.
New Technology Answers the Call
With a pulse frequency of 94 cycles/min, Oystar's eight-part TFS 80-8 machine fills and closes 750 28 mm diameter tubes a minute, or 45,000 tubes an hour (Figure 1). That's up from 510 tubes a minute for the company's previous machine, the TFS 80-6. And it's accomplished in a similar footprint to the TFS 80-6.
The new machine uses two synchronized robots. State-of-the-art control electronics work together with a safety soft-start/quick exhaust valve (Figure 2). Connected upstream to a traditional 5/3-way directional control valve, it meets new Machinery Directive standards, and guarantees correct exhausting in emergency or non-emergency situations.
The dual-circuit pneumatic design of the TFS 80-8 sees to it that tubes are fed in accurately, and is used primarily for safety reasons, notes Andreas Siegele, head designer at Oystar IWK. The robot hand and the box feed operate independently of each other. A valve terminal controls all the pneumatic drives of the machine, while the input modules of the terminal process all the sensor signals (Figure 3). Both the CPX/MPA valve terminals as well as MS-6 series exhaust valves, all made by Festo, have long been defined as the standard by the Oystar Group.
Correctly Positioned and Filled
Advances to Oystar's tube filler come not only in the form of speed, but accuracy as well. Besides increasing output by nearly 50%, the new machine reduces overfilling of the tubes by precisely checking its weight.
In the first step of the process that leads to a perfect tube of toothpaste, a robot feeds the empty tubes, which are open at the bottom, to the tube holder. The next step transports the tubes safely through the machine. A high-resolution camera checks the edge of the tube for possible defects, and another camera watches as the tube is opened with compressed air.
Using a printed mark, the TFS 80-8 precisely aligns the tubes. It ensures that the tube remains in the correct position during the work process and keeps a stable shape when it is filled. If the alignment is not right, the printed design could be askew or shifted when the tube is closed later. So that each tube is allocated to the correct product batch, the machine reads the code again at the same station. This enables customers to clearly see where a tube delivery came from or on which day it was filled.
If a production error occurs — or rather, if a predefined number of errors are reached in a specific operating period — the machine stops and the operators look into the source of the error. Reject tubes are clearly identified and do not impair the overall quality of the batch.