Tooling Cycle Time
In a higher volume or higher temperature environment, tooling often needs to be cycled quickly and frequently benefits from incorporating heating and/or cooling into the design. A good example is automotive high-pressure resin transfer molding (HP-RTM), which commonly features heated steel tooling in a dedicated press. Another example is wind blade tooling, which is too large to easily move to an oven, so air, electrical or water heating systems are integrated into the composite face sheet. Optimizing tool cycle time also can pay benefits by requiring less total tool count, which reduces facility needs and valuable floor space.
Getting Materials into the Tool
Tooling bushings (TBs) that allow laser trackers to “clock-in” allow for surface profile verification, ply projection and automated tape laying/automated tape placement indexing and are frequently required by aerospace customers. Marine and wind customers benefit from surface scribes to assist with both edge of laminate (EOL) and edge of part (EOP). Vacuum and/or resin feed ports also can be integrated, thus eliminating potential vacuum bag failures and reducing labor. Large tools require careful consideration when applying materials. Marine molds are commonly put on pivoting spindles. Another approach is illustrated with a NASA pressure bulkhead tool Janicki fabricated with a suspended walkway that rotates 360 degrees. The bulkhead part was fabricated from out-of-autoclave prepreg that could not be walked on prior to cure or critical air pathways would have prematurely collapsed.
Tooling Life Expectations
A critical issue in tooling design is balancing cost, quality and schedule within the expectations of tooling life. One needs a completely different approach for a single usage 350 F tool than for fabricating 200 parts at 350 F. I frequently see prototype tooling being stretched beyond its design life, which sometimes results in catastrophic failure!
Other factors that drive lay-up tool design are the release systems utilized by customers as well as indoor or outdoor storage. I have seen military tools stored in the desert that are sand etched and boat molds that are stored outside in Maine at -20 F. We recently shipped a tool to South Africa that sat on the deck of a transatlantic voyage. The steel substructure was not adequately painted and became badly corroded.
Tooling Cost
The phrase “there is a right tool for every job” certainly applies, and at Janicki we are stubbornly material agnostic with solutions ranging from $100 to more than $3,000 per square foot. Lower cost solutions exist across all markets, with performance and quality reductions.
Ancillary assembly tooling design is often overlooked, but can play a key role in such activities as trimming part edges, drilling accurate holes and cutting hatches. These do not need to be overengineered or expensive and often can be fabricated from fiberglass, steel or aluminum. Vacuum clamping of parts is effective, cheap and easy to incorporate.
Spend some time studying your tooling design needs upfront, and hopefully you will avoid putting parts together backwards!
