0
Research Papers

Refinement of the Thermal Press Curing Process for Advanced Composites

[+] Author and Article Information
Jaron Kuppers

Center for Automation
Technologies and Systems,
Rensselaer Polytechnic Institute,
110 8th Street,
Troy, NY 12180
e-mail: jaron@vistexcomposites.com

Daniel Walczyk

Center for Automation
Technologies and Systems,
Rensselaer Polytechnic Institute,
110 8th Street,
Troy, NY 12180
e-mail: walczd@rpi.edu

1Corresponding author.

Manuscript received July 2, 2013; final manuscript received November 10, 2013; published online February 5, 2014. Assoc. Editor: Donggang Yao.

J. Manuf. Sci. Eng 136(2), 021014 (Feb 05, 2014) (12 pages) Paper No: MANU-13-1266; doi: 10.1115/1.4026043 History: Received July 02, 2013; Revised November 10, 2013

Thermal press curing (TPC) is an alternative process to autoclaving for consolidating and curing thermoset and thermoplastic prepreg composite parts by pressing them between a heated “curing mold” and a customized rubber-faced “base mold” that are engineered to provide uniform temperature and pressure conditions. A study was performed with a kayak paddle part made from eight plies of woven carbon/epoxy prepreg material and formed by double diaphragm forming (DDF). The study expounds on the narrow body of TPC knowledge around three main objectives: (1) to experimentally compare TPC cured parts to a benchmark autoclave process using a realistic part shape with fine geometrical details, (2) to evaluate the necessity of vacuum bagging of TPC cured parts, and (3) to characterize the robustness/sensitivities of pressure application during the TPC process by varying both the total pressure applied to the base mold and the location the hydraulic press ram applied pressure to the base mold. Maximum temperature and pressure variations around the target levels over the entire clamped tool surface were measured as 5.0 °C and 5.5%, respectively, both of which were well within the manufacturer's recommendations. The TPC part had fewer defects, was generally thinner, and had a higher fiber volume fraction than a comparable autoclaved part. Little difference was observed between the TPC parts made with and without vacuum bagging. Parts with too little pressure (90%) resulted in more thickness variation and defects than too much pressure (110%). Finally, TPC parts exhibit some thickness variation, as expected, when ram force is applied off the center of pressure (COP).

Copyright © 2014 by ASME
Your Session has timed out. Please sign back in to continue.

References

Bullen, G. N., 2008, “Get Rid of Those Autoclaves!,” Manuf. Eng.: Aerosp. Defense Manuf., 140(3), p. 65.
Morey, B., 2008, “Automating Composites Fabrication,” Manuf. Eng.: Aerosp. Defense Manuf., 140(3), pp. 101–105.
Walczyk, D., Hoffman, C., Righi, M., De, S., and Kuppers, J., 2013, “Consolidating and Curing of Thermoset Composite Parts by Pressing Between a Heated Rigid Mold and Customized Rubber-Faced Mold,” U.S. Patent No. 8,511,362.
Walczyk, D., Kuppers, J., and Hoffman, C., 2011, “Curing and Consolidation of Advanced Thermoset Composite Laminate Parts by Pressing Between a Heated Mold and Customized Rubber-Faced Mold,” ASME J. Manuf. Sci. Eng., 133(1), p. 011002. [CrossRef]
Walczyk, D., and Kuppers, J., 2012, “Thermal Press Curing of Advanced Thermoset Composite Laminate Parts,” Compos. Part A, 43(4), pp. 635–646. [CrossRef]
Graham, N., 2000, “Method of Manufacturing Composites,” U.S. Patent No. 6149844.
Brosius, D., 2011, “Quickstep,” retrieved Jan. 7, 2011 from http://www.quickstep.com.au/files/document/238_Quickstep_Advantages_in_more_detail.pdf
Quickstep, 2012, “Quickstep: The Out-of-Autoclave Process for High Performance Autoclave Grade Materials,” retrieved Oct. 8, 2012 from http://www.quickstep.com.au/files/files/113_306_Quickstep_Process_Introduction.pdf
Bond, D., Nesbitt, A., Coenen, V., and Brosius, D., 2012, “The Evaluation and Development of the Quickstep Out-of-Autoclave Composites Processing Method,” retrieved May 6, 2012, from http://www.compositesuk.co.uk/LinkClick.aspx?fileticket=VoolDJanW94%3D&tabid=105&mid=505
Wengfang, S., and Rånby, B., 1994, “UV Curing of Composites Based on Modified Unsaturated Polyester,” J. Appl. Polym. Sci., 51(6), pp. 1129–1139. [CrossRef]
Saunders, C. B., Singh, A., Lopata, V. J., Seier, S., Boyer, G. D., Kremers, W., and Mason, V. A., 1991, “Electron-Beam Curing of Aramid-Fiber-Reinforced Composites,” Radiation Effects on Polymers, R. L.Clough and Shalaby, S. W., eds., Am. Chem. Soc., Washington, pp. 251–261.
Dispenza, C., Alessi, S., and Spadaro, G., 2008, “Carbon Fiber Composites Cured by γ-Radiation-Induced Polymerization of an Epoxy Resin Matrix,” Adv. Polym. Technol., 27(3), pp. 163–171. [CrossRef]
Boey, F. Y. C., and Lee, W. L., 1990, “Microwave Radiation Curing of a Thermosetting Composite,” J. Mater. Sci. Lett., 9(10), pp. 1172–1173. [CrossRef]
Blackmore, R. D., 1997, “Advanced Cured Resin Composite Parts and Method of Forming Such Parts,” U.S. Patent No. 5,648,137.
Blackmore, R. D., 1997, “Method of Forming Advanced Cured Resin Composite Parts,” U.S. Patent No. 5,656,231.
Blackmore, R. D., 1997, “Method of Forming Advanced Cured Resin Composite Parts,” U.S. Patent No. 5,591,291.
Park, J. F., 1997, “Method and System for Curing Fiber Reinforced Composite Structures,” U.S. Patent No. 5,643,522.
Kemp, D. N., 1989, “Fixed-Volume, Trapped Rubber Molding Method,” U.S. Patent No. 4,889,668.
LeGault, M., 2012, “Tooling Update: New Dimensions in Tooling,” retrieved Oct. 17, 2012, from http://www.compositesworld.com/articles/tooling-update-new-dimensions-in-tooling
Goodridge, H. M., and Skaggs, K. D., 1998, “Rigid Tooling With Compliant Forming Surface for Forming Parts From Composite Materials,” U.S. Patent No. 5,714,179.
Lownsdale, G. R., and Murch, R. W., 2011, “Method and System for Forming Composite Articles,” U.S. Patent application WO2012075252 A1.
Gardner Business Media, Inc., “Zone: Compression Molding,” retrieved Sept. 30, 2012 from http://www.compositesworld.com/zones/compression-pressure-molding
Kuppers, J., 2012, “An Innovation in Manufacturing Advanced Composites: Thermal Press Curing,” Ph.D. thesis, Department of Mechanical, Aerospace and Nuclear Engineering, Rensselaer Polytechinc Institute, Troy, NY.
Gurit Holding AG, 2012, “RC200T,” retrieved May 18, 2012 from http://www.gurit.com/files/documents/RC200T_1_.pdf
Gurit Holding AG, 2012, “SE 84LV Low Temperature Cure Epoxy Prepreg System,” retrieved May 18, 2012 from http://www.gurit.cn/Files/Documents/English%20Datasheets/SE%2084LV_v12.pdf
Wikipedia Contributors, “Center of Pressure (Fluid Mechanics),” retrieved July 10, 2012 from http://en.wikipedia.org/wiki/center_of_pressure_(fluid_mechanics)
Potter, K. D., 2009, “Understanding the Origins of Defects and Variability in Composites Manufacture,” International Conference on Composite Materials (ICCM)-17, Edinburgh,UK.

Figures

Grahic Jump Location
Fig. 1

Schematic of the TPC process for composite consolidation/curing; variable thickness elastomer mask creates hydrostatic surface pressure on composite when the mold set is compressed with a specific vertical force. (While this figure shows a 2D part shape for clarity, the actual process is intended for complex 3D shapes.)

Grahic Jump Location
Fig. 2

CAD model of the kayak paddle (a) as a rendering and (b) original scanned surface (based on 3D scan of existing plastic paddle) with dimensions

Grahic Jump Location
Fig. 3

Manufacturer-specified autoclaving temperature, pressure, and vacuum schedule for curing the composite prepreg material

Grahic Jump Location
Fig. 4

(a) top of the finished Kayak curing mold (with holes for registration pins as marked by black arrows) and (b) bottom of the mold (showing the pocket for heaters)

Grahic Jump Location
Fig. 5

Surface pressure contour plots for the initial rubber mask shape, after progressive iterations of the surface shape algorithm, and after the application of the boundary constraint

Grahic Jump Location
Fig. 6

CAD models of (a) the initial base mold, (b) the final base mold geometry (with sidewall features), (c) the curing mold side of the rubber mask, and (d) the base mold side of the rubber mask

Grahic Jump Location
Fig. 7

(a) The finished base mold and (b) the rubber mask

Grahic Jump Location
Fig. 8

Cutting and consolidation of the composite prepreg blank shape, (a) prepreg on the cutter bed, (b) preconsolidation of laminates on registration plate, (c) DDF apparatus with curing tool shown before forming, and (d) DDF apparatus during forming

Grahic Jump Location
Fig. 9

Kayak paddle TPC setup in a 10-ton hydraulic press

Grahic Jump Location
Fig. 10

(a) COP with the x- and y-offsets and (b) vacuum-bagged part before TPC experiment

Grahic Jump Location
Fig. 11

Eleven test points for thickness measurements, and approximate location where three-point beam bending specimen was removed from part; 0 deg prepreg ply orientation shown

Grahic Jump Location
Fig. 12

TPC cured parts and defects, (a) example part under standard curing conditions and (b) worst case of the recurring void defect as a single large void

Grahic Jump Location
Fig. 13

Autoclave cured parts and defects, (a) example part, (b) voids due to laminate wrinkling, (c) recurring void defect at point 11, and (d) void defect along the ridge of the kayak paddle blade

Grahic Jump Location
Fig. 14

Deviations from average thickness of standard part (1.57 mm) for parts with varying applied pressure at 11 points shown in Fig. 11

Grahic Jump Location
Fig. 15

Deviations from average thickness of standard part (1.57 mm) for parts with varying location of force application at 11 points shown in Fig. 11

Grahic Jump Location
Fig. 16

Deviations from average thickness of standard part (1.57 mm) for autoclaved and vacuum-bagged parts at 11 points shown in Fig. 11

Tables

Errata

Discussions

Some tools below are only available to our subscribers or users with an online account.

Related Content

Customize your page view by dragging and repositioning the boxes below.

Related Journal Articles
Related eBook Content
Topic Collections

Sorry! You do not have access to this content. For assistance or to subscribe, please contact us:

  • TELEPHONE: 1-800-843-2763 (Toll-free in the USA)
  • EMAIL: asmedigitalcollection@asme.org
Sign In