aluminum tooling via composite manufacturing - sites.udel.edu

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Aluminum Tooling Via Composite Manufacturing

Zach Melrose, Tom Mulrooney, Kyle Steelman, Brian Traylor

Department of Mechanical Engineering &

Center for Composite Materials

Trabant MPR B 12/13/2010

Senior Design


Project Description

Alcore is one of the world’s leaders in providing lightweight structural honeycomb materials for use in many industries.

Alcore utilizes aluminum tool to cut the honeycomb structures to their precise geometry.

Our project is to create an efficient process to convert one of Alcore’s current aluminum tools into a composite tool.

Our project revolves around researching and developing this process for Alcore.

5 axis mill

cutting head

Aluminum Tool


Project Introduction

Problems

Alcore’s aluminum tools are provided by an outside company, and have

a turnaround time of 2-6 months

Aluminum tools are heavy and require forklifts or hand carts to move

Tooling can cost up to $1,000,000 for large parts

Our aluminum tool costs ~$15,000



Solution

Replace aluminum tools with equally functioning composite tools

Goals

Allow Alcore to make new tools in house

Reduce cost of tooling

Reduce turnaround time of tools


Steps

1. Using an existing aluminum tool as a mold, copy the surface

using carbon fiber composites and the VARTM process

• Verify materials

• Observe dimensional stability

2. Thermally cycle tool to test part stability

3. Perfect dimensional stability and infusion of parts

4. Find an inexpensive, machinable material (e.g. foam) to create

new tool molds

5. Use these molds to form carbon fiber tools



Needs and Wants

Needs

Reusable- ~ 1000 uses

Versatile- Adaptable to different part geometries

Thermal Stability- Withstand temperatures up to 350oF

Wants

Cost- Affordability of the system

Light Weight- Ease of use for one operator

Simplicity- Mold making process

Compatibility- With supporting structure

Dimensional stability- 1/100 inch

Durability- Resistant to damage


Constraints

Frame

Compatibility with current CNC operation

Tooling Surface

Impermeable to cleaning fluids and release agents.

Tooling Surface

Frame


Project Overview

Composite Tool Materials

VARTM process

LIMS Analysis

Composite Tool Assembly

Concept Validation

Results

Future Development


Materials

Resin System

Toolfusion 3A/3B: Airtech Advanced Materials

Substance that is infused into the fiber to create the composite

tool.

Fiber

3K count 4-Harness satin weave carbon fiber

produced by Hexcel


Materials

Gel Coat

Infusion Coat 1A/1B by Airtech

Increases Hardness

Increases Thermal Conductivity

Creates a smooth and glossy finish to the composite tool.

Release Agent

Frekote produced by Henkel

Reduces fracturing and deformation when the composite tool

is separated from the aluminum tool.


Vacuum Assisted Resin Transfer Molding

Carbon Fiber Preform


Vacuum Assisted Resin Transfer Molding

Resin Front

Resin Inlet

Vacuum

Outlet

Tacky

Tape Seal


VARTM of Negative Tooling Surface


Resin Flow Simulations-LIMS

LIMS: Simulation for Liquid Composite

Molding

Displays the resin flow as a function of

time for a given part

Prevents dry spots and errors in

composite manufacturing.

Optimizes vacuum and injection line

placement on the part.


LIMS: Required Properties

Permeability, k

Measureable through an experimental procedure

Unique to each type of fabric.

Injection Pressure, Pa

Vacuum pressure that pulls the resin across the part

Known value from laboratory vacuum pump

Resin Viscosity, cps

Measure of the resistance of the resin when flowing

Measured value based on ambient air temperature

Fiber volume fraction, Vf

Measure of the amount of fiber present in cured composite

Assumed value is 50%

Thickness, cm

Overall thickness of the fabric layers


LIMS Simulation

Figure below shows the LIMS simulation result with the worst case

scenario parameters. To ensure adequate resin flow in less than ideal

conditions.

• The varying colors denote the time elapsed before the resin

reaches that respective area.

• Red denotes an area that is infused immediately while purple

represents the last area to be infused.


Composite Tool Assembly

Our initial composite tool design was constructed via a single solid piece of

composite. Bagging issues due to the tool complex geometry required a

design change.

Our team decided to manufacture and assemble 3 separate pieces to

eliminate these bagging issues while still maintaining the tool’s dimensional

stability.

Manufacturing 3 separate pieces reduces the amount of materials used during

VARTM reducing Alcore’s expenditures.

Initial Concept Final Concept

VARTM Side Panels

VARTM Positive Tooling

Surface within Negative

Original Aluminum Tool

Tool Assembly

VARTM Negative of Surface

Assemble with Adhesives

Final Construction


Results

Verified composite manufacturing

process.

Produced a composite negative

to form the final composite tool.

Produced composite tool replica

based on the original aluminum

tool.

Successfully used materials with

high service temperatures to

produce the composite tool.

Composite tool surface is

impermeable to cleaning fluids.


Metrics & Target Values

Reduce weight so tool requires one operator to maneuver.

• Weight of Aluminum Tool : 310 lbs.

• Weight of Our Composite Assembly : 6.5 pounds

Rapid Manufacturing of new Tools.

• Aluminum tool Lead time: 2 months

• Our Composite Assembly: 6 days

Low viscosity resins to apply VARTM to large parts.

• Sponsor wanted viscosity < 250 cps.

• Measured Toolfusion 3 viscosity: 110 cps.


Concept Validation

Ensure the dimensions of the composite tool match the

dimensions of the original aluminum tool. Use a high precision optical scanner to measure dimensional

stability

To test the deflection of the tool under load, the tool will be

subjected to elastic deformations up to the tolerance limit to

determine the maximum load.

Validate our process by thermal cycling our composite tool to

measure thermal fatigue.


Future Development

Alcore will thermal cycle the composite tool our team produced

to ensure its durability and endurance.

Dimensional stability of the composite tool will be validated

through optical scanning and force tests.

If the tool is passes the thermal testing, Alcore will proceed to

develop processes and procedures to employ composite tooling.

Alcore will determine the most efficient and beneficial methods

of utilizing composite manufacturing to replace their aluminum

tool stock.


Acknowledgements

Special Thanks:

Alcore Mr. Eric Franzoi

Center for Composite Materials Phil Roach, Hope Deffor, Ray McCauley

Department of Mechanical Engineering Dr. James Glancey, Steve Beard, Dr. Erik Thostenson

University of Delaware


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