able to produce a part of acceptable quality support weight of the part maintain structural integrity and dimensional stability following multiple heating and cooling cycles sustain handling loads ID: 1042067
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1. TOOLING
2. WHAT IS REQUIRED OF THE TOOL?able to produce a part of acceptable qualitysupport weight of the partmaintain structural integrity and dimensional stability following multiple heating and cooling cyclessustain handling loadsable to achieve a specified temperature at a specified rateaccommodate fabrication process
3. DECISIONS REGARDING THE TOOLINGmale (convex) or female (concave)- which face of part should be tool surfacetooling materialswoodplasterfoampolyurethane, silicone, latexsalt/sand (single use)metalcompositeissues driving the selection of tooling materiallife (number of cycles)costnonrecurring - machinability (aluminum easier to machine than steel)recurring - ease of repairheat transfer capabilityheat up and cool down timesability to control tool temperaturethermal characteristics of tooling materials
4. “HARD” TOOLING VS “SOFT” TOOLINGhard toolingmany cycleshigh costsoft toolingfew cyclesdifficult to maintain tight toleranceslow cost
5. THERMAL EXPANSION MUST BE ACCOUNTED FOR IN THE DESIGN OF TOOLINGprior to gel, “wet” part and tool expand togetherat certain time/temperature part gelstool and part expand at own rate depending on respective CTEscool down at respective CTEsthermal stresses can be introduceddifficulty extracting tooldimensioning tool to account for the different CTEs and change in temperaturetolerances on tooling typically ¼ tolerances on part
6. TOOLING DESIGN EXAMPLEDesign the tooling (material and dimensions) to produce each of the two C-channel designs defined below. The program requires production of 5,000 C-channels of each design. A smaller C-channel is bonded to the inside flanges of the C-channels shown below to form a box beam configuration. The C-channels are fabricated with a carbon/epoxy system. The C-channels are cured in an autoclave at 350°F, 100 psi.design #1: [±50°]s, CTE (90° direction) = -0.2893 x 10-6 in/in/°Fdesign #2: [±25°]s, CTE (90° direction) = 9.4869 x 10-6 in/in/°FC-channel sketch
7. METAL TOOLINGmachinedelectroforming (typically nickel, 0.125 in thick)fiberglass plating mandrel placed in nickel solutionthickness build up 0.0005 in - 0.001 in/hr
8. COMPOSITE TOOLINGgood match between tooling CTE and part CTElightweight - reduces handling costslower costlimited life in comparison with metal tools
9. FABRICATION OF COMPOSITE TOOLINGfemale tool (model (plug) - splash - master - tool)model - wood, plaster, ...splash - room temp cure (low cost E-glass)master (transfer tool) - room temp cure/high service temp resintool - high temp cure/service temp resin (temp capability > part cure temp)male tool (model - master - tool)lay-upisotropic (0°/±45°/90°)slightweight fabrics against gel coat (will not print through), medium fabrics next, heavy weight fabrics to build up thicknessface sheet - reinforcing ribs - base (egg crate)substructure should be of similar materials to minimize thermal stresses due to CTE mismatchminimize effect of substructure to create thermal gradients through face sheet
10. METAL-COATED COMPOSITE TOOLINGcombine advantages of metal and compositemetallong lifeexcellent mold surface finishfaster heat up timesease of repaircompositelightweightlower costease in producing large moldsmethods of fabricatingplate composite tool with metal by electrolytic or chemical platingplate or thermal spray metal on master, then fabricate composite tool over metal surface
11. OTHER TYPES OF TOOLINGsegmented tools (mandrels) to prevent “trapped” toolingelastomeric (silicone rubber) toolingtrapped rubber moldingused in areas with special pressure needs (pressure intensifiers)internal bladder/female moldintegral toolingcaul platesdistribute applied pressure evenly over partmaintain heat transfer similar to tool sideply locating templates
12. EXTRACTING THE TOOLINGtool should be designed to facilitate extractiontapertake advantage of CTE mismatchjacking pointsgrapple pointsblow holes
13. PROTOTYPE TOOLINGcomposite tooltwo-part mold (mold #1, mold #2, part)aircraft cowling (using foam plug)polyurethane, silicone tool (Freeman Mfg videos)latex tool