Boost manufacturing with wireless communications

21st February 2013

Customers change their demands faster and more unpredictably than ever before. Patric Hogstrom looks at how wireless communications can help.

Today's customers expect made-to-measure products. They want to place orders around the clock via the internet and other channels. They think nothing of altering -- or indeed cancelling -- orders at the last minute. Yet they insist on high quality, fast delivery and a low price.
Production systems must therefore master uncertainty and change to a degree previously unheard of. They have to produce goods in numerous variations for different countries, regions and market segments. At the same time, they must maintain low inventory levels and high effectiveness. The ability to master the unexpected while still turning a profit is critical in remaining competitive in today's manufacturing and process industries marketplace. And it is fast becoming so in many other sectors.
Agility is the ability of a production system to quickly respond to unplanned changes in customers' preferences, and to other surprises. Most production systems have considerable latent agility. This is the structurally inherent potential for agility in existing equipment, manpower and space.
But to turn its latent agility into real agility, an organisation must be able to quickly respond to changes that the production system has not foreseen or cannot control.

The path to real agility

Capacity planning is typically done in a timeframe of about one year. Scheduling allocates capacity and resources to different tasks, activities or customers in a timeframe of months, days and hours.
Dispatching rules then specify which job should be selected for processing next from a queue of jobs. In reality, it is difficult to follow the schedule because of disturbances originating outside the organisation (rush orders, delayed materials) or within it (a machine breaks down; a key operator calls in sick).
To be really agile, the organisation must be able to adjust scheduling in real time. For example, by splitting jobs at bottlenecks and exploiting unforeseen free capacity. An hour added at the bottleneck will add an hour of capacity to the entire factory.

More capacity, higher delivery precision

Wireless communications speeds up response and liberates the latent agility in an organisation. Key staff in order processing, materials supply, production, quality control and maintenance can communicate instantly -- between management layers, across departments, regardless of location.
They can communicate with one another, with processes and with support systems -- within systems, across systems, and while on the move. An organisation can then squeeze more capacity out of its existing structure, or sometimes gain enough to postpone investing in new capacity. It can also cut lead times for critical orders without negatively affecting lead times for other orders, and improve average delivery precision.
SBE's (Svenska BrikettEnergi) plant in Malmbäck, Southern Sweden has an annual production capacity of 48000tonnes of wood briquettes, 30000tonnes of powder and 12000tonnes of pellets. An Ascom solution helps ensure optimal raw material stock levels -- and a trouble-free production process.
Producing refined bio fuel is a complex, multistep process. The first step involves receiving and storing the raw material (sawdust and wood shavings) in silos. Next comes separation, where metal, stones, gravel and other foreign bodies are removed. The cleaned material is then broken down in a mill and sorted according to size; larger fragments being used for briquettes, smaller ones for pellets and powder.
But a lot remains to be done says Ingemar Klaesson, production manager at the Malmbäck plant. The next step in the phasedryingis critical. We have to get the raw material as dry as possible. This we do with a drum dryer that increases the dryness ofsaysawdustfrom 47percent to 92percent. This boosts the energy content from 2.12kWh/kg to 4.8kWh/kg."
The dried material is then conveyed to presses where briquettes and pellets are formedor to a mill where the wood is reduced to powder. Briquettes and pellets are formed by heat. As the wood is pressed together (in the case of briquettesat a pressure of 1000kp/cm2) the temperature increases and the lignin in the wood is released. As the temperature dropsthe lignin stiffens and binds the wood together as pellets or briquettes.
Comments Klaesson: "Obviouslyall these processes demand a smooth material flow. Just as importantthey demand an accurate flow. For examplea conveyor belt overloaded with raw material will automatically shut down. And that's bad newsespecially since we produce around the clockseven days a week."
The Ascom solution in use at Malmbäck helps ensure a smoothaccurate material flow in several ways. "That's right says Klaesson, our operators canfor instancebe automatically alerted to problems in our raw material storage silos. Should the stock level in the silo approach our pre-set critical pointa clear text message can go out to the people on duty -- wherever they are in the facility."
Apart from monitoring raw material levelsthe Ascom solution also gives early warning of possible production problems. "We have hundreds of process alarmsand any potential problems -- deviant pressure or temperature readingsfor example -- go directly as text message alerts to the responsible operators.
And the benefits of the system? "Wellwe know how much material is in stockand we can respond faster to any problems says Klaesson. But less stress on our workers is another major benefit. Previously we had a system where alarms went out in code. Once alertedan operator would have to drop whatever he was doing and dash to a terminal to decipher the code. And all too often it was a very minor alert that didn't warrant disturbing the worker in the first place. Valuable time was wasted. Nowwith the Ascom solution's clear text alertsthe operator knows the severity of each alarmand can react accordingly."

Patric Hogstrom is Business Unit Manager for IndustryAscom Wireless SolutionsGothenburgSweden.



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