JEC COMPOSITES MAGAZINE - Issue #67 - August/September 2011 - 28

productivity

Consumables or reusable – a case for a more economic and ecological approach
The use of film infusion techniques for composite manufacture is well established and widely employed in the industry for a vast range of products including large marine and wind power applications.
are accepted as unavoidable waste cost due to the nature of this well-established composite moulding technique. However, by way of example, this means that a 10-m composite part moulded 20 times will result in a total material waste cost of 1,200 euros! Add to these costs the labour time for bagging up, sealing and resin and vacuum connection preparation followed by removal and waste management per production cycle, it soon becomes significant concern to seek less costly and wasteful alternatives. Reusable films are a natural alternative as they offer identical technical performance and, although more expensive at the outset, do offer an economicallyviable alternative. The chart below (Fig. 1) illustrates the material cost break-even point for the mould material cost consumption for the two systems based on a generic 2m mould. The chart clearly shows that, although the reusable silicon bag material cost is fixed at the outset at 200 euro throughout its life, the consumable material cost equals this after only a series production run of 20 parts. It follows therefore that after 30 parts, the moulder has saved 100 euro on this small part and continues to save a further 100 euro for every 10 additional parts produced. This argument is true for ester-based resins as a silicone membrane bag has a life expectancy of over 500 production cycles. This life expectancy, however, is greatly reduced when using epoxies, where a silicon membrane bag has a useful life of only 30 cycles (60 at best). Even so, on tooling material cost alone, there is still a significant saving of over 30%

ALAN

ALAN HARPER FOUNDER HARPER COMPOSITES

jec composites magazine / No67 August - September 2011

here is a large infrastructure of supply for consumable films, sealants, peel ply, breather cloth, etc. to meet this manufacturing need and yet the industry appears to make little effort to develop a less consumable approach for these materials which are consumed and wasted after each production cycle. With the development of silicon reusable films, their method of production, ancillaries and advances in infusion techniques, it is now possible to significantly reduce waste while offering a more acceptable ecological impact with the added bonus of greater economic benefits to the moulder. In worldwide manufacturing, there are few industries that produce parts employing

systems that involve the use of consumable tooling for each and every production cycle. Exceptions like metal foundry production using sand casting techniques are among the minority in which the mould is destroyed after each cast but industrial waste, for obvious reasons of cost and environmental impact, is kept to a minimum by recycling. In the field of composite film infusion, however, we observe an industrial production process whereby B-side film infusion mould materials are destroyed and discarded after each production cycle as recycling is not possible.

Economics

Conservative cost estimates between 5 -6 euro per square metre for composite film infusion material consumables

Fig. 1: Cost/production for a 2-m² infusion mould

JEC COMPOSITES MAGAZINE - Issue #67 - August/September 2011

Table of Contents for the Digital Edition of JEC COMPOSITES MAGAZINE - Issue #67 - August/September 2011