Compared with traditional manufacturing capacity designed to produce commodity items in large volumes, many of tomorrow's successful EMS businesses will be producing a wider mix of highly customised products. This high-mix climate will demand flexible manufacturing solutions to respond rapidly and profitably to low-volume contracts.
Among emerging equipment technologies, for example those serving screen printing applications, the emphasis will be to streamline changeovers to maximise productivity.
As far as screen printing is concerned, the some of the greatest gains in changeover efficiency will come from cutting the time to set up the tooling and install the stencil. A stencil changeover traditionally takes up to 20 minutes when a different size stencil is required, even when performed by an experienced operator. But until now the appeal of an adjustable stencil mounting has been limited; the dominant high-volume production model has focused attention more closely on technologies to reduce cycle times, since the time consumed by infrequent changeovers has had limited impact on overall throughput.
But manufacturer demand for such options is becoming more apparent, and a better solution is offered by the recent introduction of an adjustable stencil mount by DEK. The mounting has demonstrated that setting up a new stencil can be reliably achieved within 60 s, even if it is a different size from the preceding stencil. The stencil clamp is adjustable in x and y planes to accommodate a continuous variance of stencil sizes between 305 x 305 mm and 737 x 737 mm. The x and y rails are clamped pneumatically, and the clamping is released by simple press and hold buttons on each rail. The operator depresses the buttons to adjust the rail position in each plane as required, then simply releases them to reapply the pneumatic lock. The stencil is then placed in the clamp and secured by pneumatically actuated flaps in the same way as a non-adjustable stencil clamping mechanism. The entire process takes less than one minute.
Tooling set up, which also has an extensive influence on the complexity and execution time of a product changeover, typically requires pre-programming or manual placement. Both of these procedures are labour intensive and therefore time consuming and subject to operator error. This is particularly true when working with modern, high density assemblies where tooling pins must be accurately positioned because there is frequently very little unpopulated board real estate available.
Programming automatic tooling can take several hours or more, and the program must be maintained with the product file and retrieved when required, although retrieval is usually a matter of point and click. Manual tooling adds 10 or more minutes to the changeover time. Compliant tooling, such as DEK's FormFlex, is emerging to save time and enhance board support during printing. Its pin array complies automatically with the underside of each new board as it is run into the machine, and more significantly, requires no programming or manual placement of tooling pins. It reduces changeover time for a new board to a matter of seconds and eliminates programming altogether, allowing EMS companies to further remove time and cost from production and streamline new product introductions (NPI).
On the other hand, manufacturers need to be able to respond quickly to opportunities requiring a diverse range of capabilities; screen printing onto large format panels, for instance, has been regarded as a specialised niche requiring extensive manual processing and dedicated large format machinery. But these panels, primarily backplanes for telecom, networking and military applications, represent attractive business in the new manufacturing age. To bid successfully for these contracts - offering an attractive price to the customer but maintaining a worthwhile margin for the manufacturer - EMS businesses need to think carefully about investment in new equipment. For a company to maintain dedicated large format capacity that will be idle at other times is inefficient in terms of cost and manufacturing space. But EMS businesses need to be able to bring the necessary capability on line quickly, without needing to invest directly in equipment to win the business. There are many hidden costs involved in commissioning new machinery, including spares provisioning, operator training and machine installation.
Manufacturers looking to offer a competitive large format service need screen printing machines capable of supporting large panels on a regular line. As an example, DEK's Vista printing machine is aimed at the large format market, supporting board sizes up to 610 x 762mm. Importantly, Vista occupies no more floor space than the Horizon machine with which it shares its mechanical roots, user interfaces and many additional features. This means that it does not occupy valuable extra space on the production floor, enables highly automated manufacturing of large panels, and represents no additional training or familiarisation overhead; manufacturers can simply reassign the line to a large panel contract, and begin manufacturing immediately.
As the world's manufacturing industry grasps emerging opportunities, and comes to understand how it must change in order to service them profitably and quickly, demand will grow for solutions that streamline product changeovers and enhance flexibility. The first technologies designed to support this resurgent model are entering the market, and will be widely specified by forthcoming capital purchases.
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