[rp-ml] A note for designers in plastcs plus .. a great solution

From: sands uk <tony.sands_at_virgin.net>
Date: Thu Apr 16 2009 - 11:20:28 EEST

Ref: TS 002


Hi again rp-ml members


After more than twenty years of Rim-Casting I left the industry a while back to concentrate on writing technical stuff plus a novel or two. also I spent a period as a Columnist for Time Compression Technology, expressing some off-the-wall and sometimes controversial comment on the RP/RM industry.


Recently I had a discussion with some past colleagues and was not surprised to learn that things are very much 'as-ever-was' in the industry. As a writer I made a few notes of the points raised and thought they may be of interest to some members.


Designers and the Holistic approach


A high proportion of RP clients are Designers, some still coming to the technology for the very first time. Often their products are destined for high-volume low-cost markets and the combination of ALP (Additive Layering Process) model, which gives them fit, function and 'touchy/feely' for shape, followed by product launch with PU castings or similar, precedes hard tooling in metal for volume. Low volume items sometimes stayed with Rim-Cast type processes long-term, taking on niche market variants or Mk2/ Mk3 versions in parallel at low investment.


One major and absolutely crucial disadvantage however comes up repeatedly.


For type approval, safety tests, and final specification, the plastic items need to be made available quite early in the program in the actual production-intent materials and even more crucial they needed to be dimensionally identical to the production items. ALP models and Rim-Cast replicas cannot satisfy this.

If the item is relatively simple and not too large, companies have emerged that will make a Rapid metal tool for less cost than a full production tool and some Designers go down that route as a further intermediate step after Prototyping.


The process I wish I had invented


Relatively recently I came across Space Puzzle Molding and in discussion I was surprised to find that a surprising number of my colleagues were still unaware of the process. The concept is brilliantly simple and the results quite spectacular. Only the tool surfaces in immediate vicinity of a product are high-speed machined in metal and interfaced with each-other like parts of a 3D 'Space Puzzle'. The strength to with stand injection molding pressures is supplied by a patented bolster system and in all other respects to tooling is perfect, producing up to 3000 series identical parts in almost any material serving both prototype and early production needs around half the cost of a production tool.

Size also is not a major issue with shot sizes from 3gm to 2.5 kg and a longest dimension of 800 mm. Unlike the 'tool-in-a-day' offers that are around for simple tooling, Space Puzzle Molding (SPM) takes a little longer but absolutely thrives on complexity.


This process would not put Rim-Casters out of business but as a tool in the holistic needs of Designers it represents probably the fastest and most economical route from CAD to final item. It has been around for over 25 years but seems to have been one of Germany's best kept secrets.

Try putting Space Puzzle Molding into Yahoo Search. or read my article submitted in 2006 to Engineering Talk.

Use the link: http://www.engineeringtalk.com/news/pya/pya107.html to learn more about this process.


SPM ticks all the boxes for Rapid, Prototyping, Manufacturing, and Early-to-Market Production, 'bridging' direct from CAD to the finished product. I visited the factory at Fuerth near Nuremberg airport to see for myself and was suitably amazed by the results I was shown.


As a new member of this list I have been reading some of the rp-ml archive material and thought my comments might be useful to somebody out there needing from 1 plastic molding to 3000 series identical items in the correct material.


Still a bit nostalgic for the old 'hands-on' prototyping days.


Tony Sands

Ex Rim-Casting Guru and now Freelance Writer

Received on Thu Apr 16 11:20:24 2009

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