JEC COMPOSITES MAGAZINE - Issue #56 - April 2010 - 59

PAVILION USA
Automation
reduction of scrap and quality consistency are most important, the industry requires a bold new paradigm. In a “part centric” design approach, a robust examination of the part design and the planned automation drives the overall design effort. It also leads to a series of steps which lead the part designer to developing a machine specification that is idealized for the manufacture of a specific part or a series of similar parts, hence a “part purpose” machine. Aerospace parts can have complex geometries that complicate their automated manufacture. By taking a part centric approach during initial part design, engineers can consider design changes to minimize automation challenges. By working “hand in hand” with a custom automation supplier, this process methodology allows harmonization of part and machine design to yield a completely connected process. Although flat parts may seem simple at first examination, the inclusion of internal padups and unusual ply boundaries pose challenges to even the nimblest “machine centric” machine. If optimizing fabric placement would improve automated production and yield, it may be important to consider processes other than automated fibre placement (AFP) or automated tape laying (ATL). In some cases, a complete work cell may be the most appropriate approach as it combines multiple aspects of the manufacturing process. This use of work cells is common in many other manufacturing industries. Clearly, the future of automating the manufacture of composite based is going to take a new approach. The following is one option to address the new challenges: 1. Evaluating part requirements including: part geometry, ply orientation, desired manufacturing rate, material (UD or fabric) and process evaluation and validation; 2. Establishing a machine timing diagram; 3. Developing machine concepts; 4. Applying Accudyne’s AT-POS analysis software to predict ply behaviour on contoured shaped parts (for tow/tape placement); 5. Developing a trade study to validate the process and potential machine operation.

Fig. 4: Image processing used to calculate tow strains along a curved trajectory

Fig. 5: Flat charge laminator – Capable of laying unitape and fabric at rates of 25 kg/hr demonstrated

was conceived and built. Shown in Figure 5, this machine manufactures the part using a combination of fabric and unidirectional prepreg material at a rate of 25 kg/hr or a stringer every 15 minutes. This rate will allow the manufacturer to supply the customer with parts to accommodate the rate of 10 planes per month (published target manufacture rate).

Aircraft radome
Figure 6 shows another common aircraft part, a composite radome. Radomes typically utilize materials that are transparent to radar signals and are best manufactured using fabrics due to the shape and required performance characteristics. Manufacturing these parts entails the use of precut pieces of prepreg fabric which are then hand laid on a mandrel. Making each unit by hand is expensive and time

Part evaluation
Following are examples of various parts and the machines that were produced to manufacture them.

Hat-shaped stringer
Traditional ATL/AFP machines were deemed to be too expensive and too slow to produce the “hat”-shaped stringers used to reinforce the fuselage shown above (Figure 4). After careful analysis of the part the flat charge laminator

Fig. 6: Composite radome

No56 April 2010 / jec composites magazine

JEC COMPOSITES MAGAZINE - Issue #56 - April 2010

Table of Contents for the Digital Edition of JEC COMPOSITES MAGAZINE - Issue #56 - April 2010