Message in a Bottle

A cool beer or soda on a hot day. Surely there's nothing better? And when that beverage comes in a bottle, the feeling of gripping that cold glass is almost as good as the first taste of icy liquid running down your parched throat.

It is probably correct to say that not many people stop to think about the container as opposed to the Coke. But that seemingly humble glass bottle plays a bigger part in a satisfying drinking experience than most of us realize.

First of all, unlike cans or cartons, the bottle is transparent such that you can actually see what's inside before you purchasing and partaking of the contents. Secondly, glass is an inert material and so does not react chemically with the liquid and change its flavor. This, in combination with glass' natural ability to keep harmful materials at bay, translates to a long shelf life for the product.

For beverage suppliers, the ability of glass to be molded into various shapes and sizes and to come in different colors enables them to create a differentiated presence and more unique brand identity.

And finally, in these days of ever increasing concerns for the environment and the earnest jockeying for green credentials, both manufacturers and consumers can ease their consciences – because glass passes the sustainability test with flying colors. In fact, it is 100 percent recyclable, and broken-down used bottles form part of the material mix in the creation of brand new bottles.

Lots of bottles
“We produce more than 100 million bottles every year in this plant,” says Andrey Serato, staff engineer, Engineering Services, San Miguel Yamamura Packaging Corporation (SMYPC) Mandaue Glass Plant. “And we run 24 hours a day, seven days a week.”

The SMYPC Mandaue Glass Plant is located in Mandaue City, Cebu, in the Philippines. The fully integrated facility employs more than 250 people, who have an average 21 years of service. And while its name may immediately conjure up a picture of the famous San Miguel beer bottle, the plant also produces bottles for other companies such as Coca-Cola, Cosmos bottling Corp, Pepsi Cola, Ginebra San Miguel and many more. And a significant 20 percent of total glass bottle production is destined for export markets such as Australia, Saudi Arabia, Hong Kong, Indonesia and South Africa.

“This is a growing business,” says Alan Olmilla, manager, Engineering Services and Power Plant. “People have attempted to use plastic bottles for beer but there is just too much of an impact on shelf life. And of course, when it comes to something like wine, it is just more elegant in a bottle.” (Wine bottles are also produced by SMYPC in Mandaue.)

The Engineering Services department that Olmilla heads up is a support group to Mandaue Glass Plant operations. And it includes an Instrumentation & Control section, which was recently responsible for replacing a two-decade-old single loop control system with a modern process automation system, specifically, PCS 7 from Siemens.

Fire & sand
It certainly is a fascinating and instructive experience seeing glass bottle manufacturing in action at the Mandaue plant. It's hot, noisy, and also quite dramatic as the flashes of orange molten metal are seemingly magically transformed into glass.

The glass manufacturing process is essentially all about the application of very high temperature heat to sand. Additional materials in the raw mix include soda ash (helps melt the sand evenly and at a lower temperature), limestone (aids the later forming process), and cullet (recycled crushed glass, which improves durability).

The batch house is where these materials are weighed and carefully mixed together. The “fire” takes place in the furnace, where temperatures in excess of 1500 deg C serve to melt the materials to produce molten glass.

Following a refining process to remove trapped bubbles, the glass enters the forehearth, where its temperature is reduced so that it becomes thicker and less liquid such that it can undergo forming to produce the desired bottle shape.

The SMYPC Mandaue Glass Plant has three bottle forming lines. It is in these machines where the molten glass finally assumes the shape of a bottle after it pushed through an orifice, cut by shears, and then blank and (via the injection of compressed air) blow molded.

The newly formed bottles then enter the lehr, where an annealing process of heating plus gradual cooling takes place in order to equalize the bottle's interior and exterior surfaces. The rest of the process comprises mainly of QA inspection and packaging.

Up for an upgrade
“We really did not have much of a choice to upgrade the control system,” explains Alan Olmilla. “The previous supplier (from the US) had already informed us that it could not provide spare parts as they had exited this business. But anyway, the system was 14 years old and already outdated in terms of controls capability compared to what was now available from other suppliers.”

Other specific issues around the old control system included the main host PC no longer working with the working end, forehearths and lehr controls, and the input modules of digital controllers and recorders on thermocouple inputs frequently having to be replaced because of passive component drift.

On the wish list for the new system: real-time monitoring and archiving of control parameters and alarms; the turbo mixer to be integrated in the batch weighing system; and loopback trending to be available as a basic feature.

“We evaluated the vendors on their ability to provide the right technology along with a high level of customer support – with this 24/7 operation we really need the supplier to react immediately if we have a problem,” says Olmilla. “After doing the evaluation we came to the conclusion that Siemens could deliver on our requirements. I should also add that the proposal was at a competitive price and within our budget.”

The PCS 7 implementation commenced in 2009 and encompassed replacing the controls for the furnace melter, working end, forehearths, and lehr. S7-400 controllers in a redundant configuration were installed in the furnace control room and in the glassforming control room, with one set for the melter, one set for the working end and forehearths combined, and one set for the lehr.

Profibus DP cable connects out from the controllers to ET 200 remote I/O units, which in turn out connect out to the field devices for the various equipment. This first implementation stage was followed in 2010 with migration of the batch house controls. As well as availing itself of the latest process automation technology in PCS 7, SMYPC was able to take advantage of the specialized expertise and experience of Arvin de Jesus, now assistant vice president for Industry Automation, Siemens Philippines, who previously worked in the glass bottling industry himself.

His process knowledge was especially useful during the furnace control implementation, which was required to be done online i.e. while the furnace was still operating. “We did this by segregating the process and transferring the control loops one at a time onto the new system. It was important that there was no disruption to the operation,” explains de Jesus.

Making an impact
So what has been the impact of the PCS 7 investment? “I really see its affect mainly on process accuracy,” says Alan Olmilla. “We now have more accurate weighing and more accurate temperatures, and this translates into a more efficient process.”

For instance, the volume of oil to the furnace burner can be accurately controlled, which makes for far more efficient combustion. And in the batch house, with less operator intervention now needed, the batching rate has been able to be increased from the previous 10 batches per hour to 14 batches per hour, and with minimal material deviation.

The implementation of PCS 7 has also meant a step change in the visibility of the production process. The operator workstations provide real-time indication of key parameters, and there are extensive data trending and historical reporting capabilities. “We can now compare the volumes of raw materials that are input at the start of the process to the number of bottles coming out of the process, which is very useful information to identify inefficiencies,” notes Olmilla.

“Frankly speaking, I am very satisfied with the performance of the PCS 7 system, and we have already identified a number of areas in the plant that we can extend it to,” he adds.

“It's also pleasing to see that whenever we have had concerns, the local Siemens Philippines staff has been quick to respond. I mean, you can supply us with equipment but what's the use if you are not there when we need you? No, what we want is a partner, not just a supplier. And I think we found that with Siemens.”