JEC COMPOSITES MAGAZINE - Issue #76 - October/November 2012 - 57

Fig. 4: Automated 1-piece flow RTM work cell

Fig. 3: Platen presses used to heat the molds for injection were also designed by Nammo

one-piece flow approach was the best solution. The one-piece flow approach results in the fastest production of launchers as the supply of moulded parts meets the demand of the next process step. For example, since the bonding, painting, part marking and inspection processes are all single piece process based, the supply of composite launchers always meets the quantity demand of the next step in the manufacturing process. Were a multi-cavity tool approach used, the resulting batch of products would overload the incoming bin in the next process step. A batch style approach would be costly in that piles of work in progress would be stored at the subsequent process stations.

Nammo also found the use of a single-cavity tool to be the safest and lowest risk solution. The design team evaluated workforce safety as a design consideration. The resulting size and weight of a single-cavity tool are significantly lower than that of a large multi-cavity tool; thus the tool, press and oven supporting infrastructure is a more robust and safer work environment than the alternative batch process designs. While performing a process risk mitigation analysis, the team found the one-piece flow work cell design also came out on top. With this approach, if something were to go wrong in the cure or resin injection process, the potential resulting scrap is limited to one part, rather than a batch.

The work cell
Multiple heated presses control the closure of the tools and tool tempe-

Located in Salt Lake City, Utah, Nammo Composite Solutions (Nammo CS) is an engineering and composite manufacturing company with more than 20 years of operation. The composite manufacturing operations are based in a state-of-the-art 6,200 m² facility. The company’s staff includes engineers, designers, managers, composite technicians and skilled machinists. The facility operates under a robust QA system compliant to AS9100 Rev C requirements. Nammo CS has been in the business of designing and building advanced composite structures since 1991. The expertise comes from many years of extensive composite manufacturing and engineering using filament winding, resin transfer moulding (RTM), autoclave processing and bladder moulding for a broad range of products.

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rature ramping, while recording both tool temperature and vacuum during the resin injection sequence. These presses are linked to a conveyor oven for post-curing and cooling of the matched metal tools. Ethernet cables permit data acquisition for each part, which results in an electronic file containing the temperature history for each component. 227 kg of resin are housed in a central storage station and fed to each press via automated precision dispensing, resulting in rapid yet efficient movement of just 1 kg of resin to each press station. Bar coding is employed to reduce the amount of shop floor paper and act as electronic data loggers for each serial number. This work cell design permits the production of up to 100 parts per day by shuttling tooling from room temperature preform-liner-harness assembly to elevated temperature cure and post-cure then back to room temperature conditions for part demoulding and tool cleaning. This automation of temperature ramping, dwell and cooling within the process takt time allows Nammo to meet the aggressive demands for product from their customer. n
More information: www.nammo-cs.com

No76 October - November 2012

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JEC COMPOSITES MAGAZINE - Issue #76 - October/November 2012

Table of Contents for the Digital Edition of JEC COMPOSITES MAGAZINE - Issue #76 - October/November 2012