IT keeps things moving

Electronics manufacturer TDK-Lambda, always looking for ways to improve efficiency, has made IT a core part of its production system, as E&T reports.

A steep hill runs down into the suburb of Ilfracombe where TDK-Lambda has its plant. It's not the most obvious location for an electronics manufacturer. More than 40 years ago, Lambda was in a more conventional spot: a Reading industrial estate.

But the local council of the time decided that it was no longer keen on having any further industrial expansion around the city when the company outgrew its original location. So, Lambda cast around for a new location and several places offered development grants to encourage it to move.

Darlington was one location. However, people working there today reckon the MD in the 1960s was a keen sailor. Since the 1960s, although it has passed through several owners, Lambda has nestled at the bottom of a hill just outside a picturesque fishing town in north Devon.

Being in a relatively remote location means the manufacturing engineers need to take account of possible supply problems, maintaining larger banks of high-turnover components in case deliveries are delayed. "There is just-in-time," says Colin Turner, manufacturing engineer at TDK-Lambda. "Some of what we do is just-in-case."

Thinking about what could go wrong at the same time as planning the most efficient path for work-in-progress means the company can keep making products even when major equipment fails.

Thanks to installing a pair of vertical carousels for storing smaller components - an automated mini-warehouse meets dumb waiter - and other changes, Turner says the company was able to reclaim 20 to 30 per cent of its floorspace for manufacturing.

The risk with an automated carousel that disappears into the roof space is being unable to retrieve any components if it fails. So, the company maintains a secondary and smaller set of manually retrieved consignment stores that can be used instead.

Planning for potential problems is not a symptom of pessimism but of an approach to manufacturing that is geared towards improving efficiency wherever possible, and one that has made it possible to operate a plant able to turn out customised electronics without the high labour costs that it implies. It is an ongoing process.

Macro-level moving

"At a micro level we move equipment around quite a lot. At a macro level, it is every couple of years," says Turner. The latest major move, tagged the Blue Sky project, not only opened up additional space for an expanded custom-design section, it allowed new equipment to come in.

"We consolidated all the light processes. Rather than have one line doing one particular product we now have more flexibility and the ability to match to the product that we have," says Turner.

There were comparatively small but effective changes. For example, the move to a new generation of pick-and-place machinery that deposits components on a printed circuit board (PCB) made it possible to reduce the time it takes to restock the feeder reels. Typically, the reels - one for each variety of component - are replaced individually as they run out.

The company has, for some years, run several pick-and-place machines in series so that it is possible to have all of the components needed for each module placed without moving it to a different line. Although, compared with a plant that runs a large number of the same product through the lines, the machines are not fully loaded, the company makes up for that by a long way with massively reduced changeover times. The temptation with a traditional layout is to build in batches, which then increases module inventory and work-in-progress.

With the new pick-and-place machines, Lambda decided it would make more sense to replace complete sets in one go. "We wheel them in and out in one go on a trolley so we can do offline setups and replace at once rather than one at a time," says Turner.

Components tend to run out at different rates. "The machine will carry on running, placing all the other components and indicate that a reel is empty by means of a flashing lamp on its light-tower. The operator can then see which reel needs replacing from the machine's display and pick a replacement from the kanban."

As they come off the trolley, technicians scan the barcode and send the empty reels for recycling. "We don't pay until the reel's barcode is scanned," says Turner. The application checks the barcode of the replacement to ensure that the part numbers on the two reels match so that the correct parts are reloaded.

"This application also stores the 'use by' date of the reel. This information allows us to link batches of components received with the assemblies they were used on for traceability purposes and will also flag if any parts that have been previously loaded onto a machine have now reached the end of their shelf life and need replacing," Turner explains.

Barcode scanning

Barcodes play a vital role in steering both components and work-in-progress through the plant so that production can switch from one custom power supply to another instantly. On the production floor, as a job comes up, it is barcode-scanned or 'wanded' into the system - from that point on the fate of the power supply as it is built up is programmed in.

Wanding calls up the program that will pick the right parts for automated assembly and drive the screens that staff will look at to see which components they need to add for the parts that need manual assembly. The product needed for each module due to come down the line is picked off the carousel, with common parts arranged in circular bins at each workstation for ready access. And the barcode attached to the module will make sure it receives the kind of inspection from a variety of test instruments.

As power supplies still use a number of leaded components as well as surface-mount parts, the system identifies how leads need to be preformed. Rather than buy in a wide selection of components with leads preformed to different lengths, Lambda decided it was better to do the preforming on the line. "We can carry less stock that way," says Turner.

As well as a change in the architecture of the supplies themselves, the barcode system has made it easier for users to customise their products. Splitting the supplies into modules made it possible to have customers pick what they want from an online configurator that then automatically generates the bill of materials. The build queue is generated from those orders and the assembly labels printed on-demand.

"You can have one product followed by one completely different product so you don't have to build up a batch of 50 or 100. The line, essentially, doesn't care what is going down it," explains Martin Southam, director of marketing at TDK-Lambda EMEA.

Fast inspection

The problem for electronics manufacturers is that problems in automated processes can take a while to be spotted and rectified if things are done in batches. With placement, it's unlikely that a problem will show up on more than one board, unless something has gone badly wrong with the controlling program. Soldering is another matter. Temperature and other factors that alter over a period of time can damage a whole batch of boards. So, being able to spot a wave-solder machine going bad can make a big difference to cost.

Checking PCBs for solder problems such as dry joints or bridges, both of which will generally lead to failed circuits, is tough to do manually. So, manufacturers now routinely use automated optical inspection (AOI). This equipment shines light from a variety of angles to show up the profile of solder around a component pin as an imager on a robotic head whizzes over the board. With a lot of area to cover, it can take a while for older systems to make all the checks so Lambda recently bought a much faster machine that also allows tests programs to be compiled offline, reducing the amount of time that the inspector is out of action while new test routines are loaded.

"With the old AOI system, we often had a large buffer with perhaps 80 to 100 products waiting," says Turner. The new system deals with boards in real time, "so the work-in-progress that used to be here has now disappeared", he adds.

"The majority of errors thrown out by AOI are false calls," Turner says, so images of the problem boards are sent to operators who can perform a more accurate check. The computer at their workstation is sent an image of the area with a problem linked to an image of the full board showing where it is, so they do not have to hunt for it.

The statistics collected from those go/no-go decisions are collected by quality-monitoring applications. "That way, we can see the performance of the solder-wave process to see if things are going wrong. With the older system you could not get a good idea of when the product went through the solder oven."

Failover strategy

The wave-solder machine process has recently been streamlined. Instead of running two side-by-side, one is run continuously while the other is cleaned. "If one machine fails, we can switch to the other," says Turner.

To support products that need more specialised components, or where subassemblies come in from contractors with some parts already soldered in place, the company bought a point-to-point soldering system. A radio transponder attached to the power supply module's carrier tells the soldering robot which points to solder. But engineers at the company will keeping looking at how this machine, like all the others, fits into its overall system. There may be another way to do it.

Senior quality engineer Carl Besford says: "Within a manufacturing process, any movement from a 'do it the way it has always been done' ethic towards a thought-through systemic review and renewal of process can only serve to improve efficiency and productivity."

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