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Carbon C.A.S.T (Composite Adaptive Surface Tooling) is a reconfigurable surface mold for making carbon fiber parts able to recreate a variety of complex curved surface geometries, significantly reducing the costs to produce molds for prototyping or low-volume carbon fiber parts.
My Role
Designed and fabricated the various systems of Carbon C.A.S.T - silicone mold membrane, collet-based pin mechanism, XYZ gantry - with an extreme focus towards DFMA as the machine totals 2000 parts, providing a 25x25cm working area for male/female molds in VARTM-based CFRP production.
Problem Statement
After years of working with single-use molds for CFRPs (carbon fiber reinforced plastics), two things were very clear. Traditional molds require high material costs and extensive labour demands.
My group and I sought to conceptualize & develop a cost-effective & reconfigurable solution tailored for low-volume production of CFRPs using industry standard equipment/techniques.
Architecture
I developed the architecture for the machine:
Reconfigurable pin array to interpolate part geometry
Silicone membrane to form the mold surface
Integrate all the equipment for vacuum infusion
Gantry-mounted actuation controlled with an Arduino
Pin Actuation Mechanism
What: Mechanism for variable length pin array with the following criteria
Independent control of each pin with actuation travel of 15cm
Achieve an axial holding force of 100N and 80N transversely
(act against fiber compaction)Reliable & simple toggle between the rigid or movable states
High packing factor with ≤ 2cm between pin centres
(smooth interpolation & detailed curve control)
Various concepts were considered, such as individual lead-screws or off-the-shelf linear actuators for each pin.
A custom collet mechanism, inspired by mechanical pencils, provided the most cost-effective option that enables optimal packing factor of 17mm between pin centres and was optimized for DFMA with 3x 3D printed parts & 3x stock components repeated for a 15x15 pin array.
Lead Screw Concept
Collet Mechanism Diagram for Adjustable Pin Length
Collet Actuation State Diagram
Silicone Mold Membrane
What: An elastic & dimensionally-stable interface to drape across the working area, conform to the inputted surface geometry, and conduct a vacuum infusion over top of.
I conducted the material selection for a 2-part silicone mixture:
Exhibited mechanical properties to elastically deform to any surface geometry with a draft angle up to 60 degrees.
Tested the chemical properties to ensure the silicone is compatible with the VARTM process through coupon testing.
Silicone+Resin Chemical Compatibility Test
Coupon Silicone Air-Permeability Apparatus
Manufacturing Carbon C.A.S.T
Across each of the sub-systems, I managed and coordinated the manufacturing of ~2000 parts using FDM and SLA 3D printers as well as CNC milling. Through consistent application of DFMA principles, the entire fabrictaion and assembly of Carbon C.A.S.T took place over a 3 month timespan.
SLA 3D Printed Custom Collets
CNC Milled Collet Seat & Guide Plates
Axial Load Capacity Testing
As a group, we were rewarded the Best Automotive Award of $500 by Toyota Motor Manufacturing Canada for the versatility Carbon C.A.S.T has towards the automotive industry.
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