Glass container manufacturing is a mature market in the developed world, where machinery has replaced manual labor at every level of hollow glass production-except lubrication.
The hollow glass market has to catch up on new technologies to achieve higher efficiency and reach customer expectations, said Francois Breye, sales and technical manager for VDV Lubricants outside Dendermonde, Belgium. A lot of innovations have already taken place, but there is still a lot to do.
Recently, a cadre of glass industry companies in Europe teamed up to push this technology forward. Belgian company Socabelec, known for turnkey automated production lines, developed an automatic lubricant spray system for Heye International, a glass production machine manufacturer. The Ardagh Glass factory in Moerdijk, Netherlands, agreed to field-test the system.
The missing piece was the lubricant itself. Highly viscous, traditional glass mold swabbing lubricants cannot be sprayed, so a new, tailor-made product had to be developed.
This is where VDV Lubricants stepped in. Already established in the glass industry with its manual swabbing products, the company was tasked with formulating a lubricant thin enough to be sprayed by the robot without compromising performance.
The final system has produced impressive results. In its field testing, Ardagh found that the robot and lubricant together eliminated bottle rejects and the need for section stops, improved operator safety, and reduced lubricant consumption by more than 75 percent.
Glass from the Past
Container glass includes products such as food, beverage, cosmetic and perfume bottles, as well as tableware such as wine glasses, cups, ashtrays and more. The production process must be flexible to accommodate the various sizes and shapes that a factory might produce.
During production, Breye explained, molten glass is cut into gobs which are then formed into bottles. The forming operation is handled by individual section (IS) machines using blank metal molds. An average high-speed production line for small beer bottles spits out nearly 300 bottles per minute. For a modern plant equipped with four lines of 20 double-gob sections each, that adds up to 3 million bottles per day.
A typical glass furnace holds hundreds of tons of molten glass, making shutdown for any reason highly impractical and costly. This means glass factories run every hour of every day throughout the entire year. There is little opportunity to speed up or slow down production rates more than a few percent.
Until recently, more than 90 percent of glass container plants swabbed lubricant onto their hot-end process equipment manually. Swabbing is the biggest variable in the bottle forming process because the product is applied by hand, says French lube manufacturer Total, which makes Kleenmold swabbing compounds, in an operator training video. While proper swabbing will eliminate defects, on the other hand, improper swabbing can sometimes cause them.
Worker safety is another major concern. During the forming process, molten glass shoots through the IS machine like glowing orange rockets, transforming 1200-degree gobs into 500-degree bottles. If operators respect safety rules, they will push a button to stop each section before swabbing the molds. Most of the time, Breye says, operators do swab on the fly without stopping the production, to save time.
At such high temperatures, swabbing creates an oil mist that could also be a health hazard for operators.
Robots Save the Day
Breye believes that the automatic swabbing system solves all of these operator problems, and more.
The Socabelec robot is installed on the front of the IS machine and travels along a rail installed at the top or bottom of the production line. VDVs specially designed Glassline SwabMatic oil is pumped from a tank through a flexible pipe along a mechanical arm, then sprayed through a nozzle into the blank molds. The entire system is operated by software that is linked to the setup of the IS machine, and can be tailored for different mold shapes and designs.
When swabbed by hand, molds are lubricated every 15 to 30 minutes, depending on the process and the operators habits. Operators never swab the same way from shift to shift, Breye explains. Also, their mentality is, If I use more lubricant, it will run better. By contrast, the automated system runs every six minutes, applying a thin, uniform layer of product. This approach-frequent lubrication with a limited quantity-produces the best results, Breye emphasizes. The thin layer of lubricant burns off within a few minutes, leaving very little carbon deposit on the glass or the mold.
Thinning Out the Formula
According to Total, an effective swabbing oil must provide lubrication so the glass can move around inside the mold without distortion, prevent the glass from sticking to the equipment, and regulate heat transfer by providing a thermal barrier between the glass and the metal.
Traditional swabbing compounds are made from graphite, mineral oils, sulfur, binders, surfactants and suspending agents, Total says. The graphite is responsible for lubrication, as it shows better temperature and pressure resistance than oil; the oil is strictly a carrier and burns off quickly.
The Socabelec/VDV system is not the first attempt at developing automated swabbing, which proved to be no simple task. Manual swabbing compounds are highly viscous, both to keep the graphite in suspension and to withstand high operating temperatures for longer periods of time. However, these high viscosity formulations cannot be sprayed at room temperature and require a high-tech nozzle. Nozzle blockages were a problem, and controlling spray quantity was difficult.
Corrosion prevention is also a key property for swabbing compounds, Breye reminded. Glass molds are typically made of cast iron, but nickel and bronze are also used. The latter two metals are particularly sensitive to sulfur corrosion, but sulfur is important for good gob-to-mold contact.
A Brave New Lube
According to the product information sheet, Glassline SwabMatic 180 is a black fluid composed of about 68 percent oil, 5 percent sulfur and 1 to 3 percent solids, among other proprietary ingredients which Breye declined to disclose. The products viscosity at 25 degrees Celsius is 100 to 300 centiPoise-quite a contrast to the companys hand-applied product, which is a sticky 6500 to 7500 cPs.
VDV says it has optimized the sulfur content in SwabMatic oil to protect production equipment from pitting and corrosion. The company also sells a sulfur-free version for molds made from sensitive metals.
Although many glass containers are used for food and beverages, swabbing oils are used on the outside of the bottles and therefore not subject to food regulations. However, Breye points out that there is no guarantee that some oil or mist wont end up inside the bottle, and a post-production rinse will not necessarily clean it away.
In response, VDV has developed a swabbing compound based on food grade base oil that produces limited mist. The product was recently approved by SGD Pharma, a global pharmaceutical glass manufacturer. While the SwabPharma compound is meant for hand swabbing, it has been successfully modified for use in the Socabelec robot. Breye is hopeful it will launch as a SwabMatic oil soon, adding that the company aims to have all SwabMatic products certified as Kosher and Halal.
Breye boasts that SwabPharma is the first glass mold lubricant on the market formulated with synthetic oil rather than mineral oil. This is an added boon for workers, who will not be exposed to mineral oil mist, VDV claims.
Into the Future
The swabbing robot system is currently running on all four production lines at Ardaghs plant in Moerdijk, as well as the companys plant in Milfort, Massachusetts. Five more installations will start up in Europe, Asia and Australia before years end, more than 100 robots are scheduled for installation over the next three years. VDV estimates there are more than 12,000 IS production machines worldwide, providing plenty of opportunities for expanding the systems reach.
While SwabMatic is currently formulated for narrow-neck press blow, VDV intends to produce versions that can be used for all glass forming processes, including blow-blow and press-blow. And while the current system can lubricate the blank and neck ring molds, the company expects to add other functions to help glass manufacturers run a more efficient forming process.
See a video of the swabbing robot in action in our digital edition.