Production Oriented Prototyping (POP) is a novel approach involving both the individual component and full assembly designers from the start of the application development phase

Prototyping goes POP! Alan Francis of Productiv examines

the pitfalls of traditional prototype manufacture, and discusses why a new method, based

on prioritising final production, can reduce both time to market and costs

have arrived do engineers start worrying about how, and indeed whether, they will fit together. The number of tolerance and assembly issues identified at


or almost every engineering sector, the accurate manufacturing of prototype parts

and assemblies is vital. Often, the prototype will be the only component subjected to every testing and performance validation procedure, ultimately influencing key decisions on design modifications, published performance attributes, warranties and service intervals. At this stage, consistency and accurate

process documentation are key. In the testing stage, for example, prototypes must remain faithful to the original design as any deviations – in shape, thickness or material – can render test results unreliable or invalid. If results are inaccurate, individual parts, or

even the whole assembly, must be examined, remanufactured and reconfigured, resulting in delays and additional costs. Worse still, if inaccurate data is carried forward into the next production stage, the ramifications can be severe: from a shortened service life or failure to meet warranted standards, to a catastrophic in-service failure. A prototype must, therefore, be the best, most accurate, part a company ever produces.

THE PROBLEM WITH PROTOTYPING Unfortunately, this field has not always received the attention it deserves. Production prototypes are often expensive, particularly when compared to the cost-per-unit of the final component. There has also, arguably, been an inconsistent approach to prototype development – it has not kept pace with its design, engineering and manufacturing counterparts. Unlike the mass-production of finished parts -

involving detailed operations sheets, photos, precise written instructions, and guidance on correct handling and fixing – prototype assembly often works based on a CAD representation at best. Quality and repeatability can therefore suffer. With most projects working to strict deadlines, re-engineering a component at a later stage incurs project delays and budget overruns. Why, then, has prototype manufacture been

so neglected? Traditionally, prototypes have been prioritised and progressed according to timeframe. Product development and project managers tend to focus on ensuring all required components are available by a certain date. In the worst cases, only once the components

this stage is higher than many would care to admit. Fixturing can also cause problems; investment in adequate work-holding equipment when adding remaining components is often shelved in the drive to reduce project costs. However, awkward working processes caused by incorrect fixturing can result in both damage and sub-standard assembly.

A NOVEL SOLUTION Each step in the prototype manufacture and assembly process must be driven by final production objectives. Overall risk, cost and time can be reduced, while increasing the chances of accurate production, reducing final assembly time and lowering re-work costs. Production Oriented Prototyping (POP) is a

novel approach involving both the individual component and full assembly designers from the start of the application development phase. The aim is to build production standards into the prototype, while minimising cost and delivery time, and optimising safety. Using virtual builds, simulation and validation

via CAD, manufacturers can ensure all components fit together for each design release and can be accessed and manipulated during the build. Any issues with compatibility, design or accessibility can be tackled much earlier and, crucially, before time and money have been

invested in one-off component manufacture. Using this methodology, the team can

develop operation sheets as they go, making final assembly easier and more intuitive. Fixturing and work-holding are also considered earlier, meaning manufacturers have more time to specify and produce a bespoke system, if required. This is especially true when dealing with larger or more complex assemblies, which do not lend themselves to easy movement or manipulation. In effect, assembly process design –

including process, flow, tooling and fixturing – is completed before the physical components are ready to be assembled. With this approach it’s easier to identify and

fix issues faster than would be the case during final assembly, with programme time savings exceeding 25% often achievable. Meanwhile, the extra efficiency afforded by POP allows assembly technicians to identify cost reduction opportunities for components and processes through ‘practice runs’ for future assembly. In one instance, the assembly time for the

first prototype build of a complex automotive transmission was reduced from eight weeks, to just eight days. The approach can be applied in any sector

where precision and replicability are vital to enable accurate testing and validation. We hope this will finally give prototypes the attention they deserve.



In order to develop new filaments for wear-resistant parts in high-temperature applications, igus has built its own high- temperature 3D printer. For the mechanical system, heat-resistant stainless steel components of the maintenance-free drylin W linear guide and smooth-running dryspin high-helix leadscrews in the X-, Y- and Z-axes were used. Lubrication-free liners and leadscrew nuts made from the wear-resistant high-performance iglidur X and iglidur C500 plastics ensure precise adjustment of the building board, even at temperatures of up to 200˚C. The nozzle used can melt the filament at a temperature of up to

400˚C, enabling the company to develop and extensively test a new filament for high-temperature environments with iglidur J350. Using the HT-3D printer, the filament can be processed well on a printing plate equipped with

a PET film. Typical application areas of the new iglidur J350 filament include vending machine technology, automotive, glass processing and general mechanical engineering.





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