Learning Infusion 2.0

The decision was made at the start of S2021 to transition the composite manufaturing process from prepreg to infusion for both Aero and Interiors parts. Some time will be spent onsite after the stay at home order lifts on June 2 to conduct test infusions. The purpose of this is to “fail hard, fail fast” in order to determine a proper process/workflow for when true manufacturing begins.

This page contains all the info on the infusion process including:

Background Information
Testing plans for the infusion learning period
Lessons learned from testing
Advice and feedback from external sources (team advisors, other teams, etc.)
Final process outline

An effort will also be made to fully document onsite testing with pictures and video to supplement the written documents

Background Information

What is Infusion?

Infusion is a type of composite manufacturing process in which the material stack is sealed and a vacuum is used to pull the resin through the part. This produces a quality part with a good strength-to-weight ratio (due to the smaller resin fraction), making it an ideal choice for MSXIV’s Aerobody and Interiors panels.

Compared to hand layups and prepreg, infusion is in the middle in terms of overall ease of manufacturing. See comparison table below

Process Characteristics	Hand Layup	Infusion	Prepreg

Process Characteristics	Hand Layup	Infusion	Prepreg
Complexity	Easy to do, similar to paper mache.	A lot more materials involved but once everything is set up, pulling resin is easy. Most difficult part is the setup	Easy to do, cloth is already pre-impregnated with the correct amount of resin so no other steps needed. Most difficult part is curing in the autoclave
Material & Equipment Cost	Low cost since you’re doing everything by hand	A lot of materials and equipment involved so cost is a bit higher, although some things such as vacuum bag are cheap	Need an autoclave to cure parts (expensive)
Manufacturing Time (excluding cure)	More time since you’re doing everything by hand	Can be slow due to the extra setup, but once you lock down your process then it can become more efficient	Less time since all you need to do is lay your cloth and pull vacuum
Cleanliness	Messy since you’re dealing with loose fibers and resin in an open space	If done properly, can be pretty clean since everything is contained in the vacumm bag	Cleanest since you’re not dealing with liquid resin

The basic steps to infusion are:

Prepping mold/layup surface
Laying process materials (composite cloth, peel ply, flow mesh)
Sealing the process materials to the mold/layup surface with a vacuum bag and tacky tape
Pulling vacuum and performing a vacuum drop test
Pulling resin through the component (fun part)
Curing overnight
Removing finished part from mold/layup surface

talk about

basic principle
what it’s used for, when/where/why it’s used
process materials
pros,cons

Resin Flow and Darcy’s Law

Resource: https://www.vacmobiles.com/Darcys_Law.html

talk about:

how to use law to increase process efficiency and produce the best quality part

Onsite Infusion Learning (2 weeks)

Purpose: Get experience with infusing a part from start to finish so we can lock down our process

To hit 2 birds with 1 stone, the parts that will be produced during the learning period will be used as specimens for the material testing project.

The document below will be actively updated with new info as learning progresses and will be re-formatted into a final manufacturing plan by the end.

https://docs.google.com/document/d/1hdaBqM8IUVkfiXmHkiPnHU1eRb3LK0Gh8Lg8GkjLn40/edit#

https://docs.google.com/spreadsheets/d/134g90ytgT7qQcQjT9B1WtSwHvMti0be5a07Op0NeREs/edit#gid=0

Progress Tracker

Date	Individual	Goals for Today	Progress/Updates	Notes and Concerns

Date	Individual	Goals for Today	Progress/Updates	Notes and Concerns
2021-06-19	@Michael Hanley	Infusion test prep	cut 2x1 ft and 1x1 ft material	catch pot is trash, no regular cf fabric
2021-06-24	Mackenzie Lui	Cut vac bags/spiral tubing	Cut vac bags/spiral tubing	Found another catch pot. Old catch pot has gauge that is intact but the pot leaks. New catch pot might not be leaking but has a busted gauge. Swap the gauges?
2021-06-25	@Renzo Villanoy	Test 3D printed connector Cut carbon fibre for testing	Prep all done	The new mold release wax has same expiry date as old one (Sep 2021) Connector tight around tube, Increase diameter by 1.5mm spiral tube 11mm diam, connector 16mm
2021-06-29	Kyle Lacson + Mackenzie Lui	Test Catchpot for Leaks	created vacuum bag and sealed a cf sample clamped catchpot and left it for 15 min, was able to hold pressure added soap to the catchpot (inlet and outlet) and found no bubbles pressure was constant throughout the 15 min we left it on, at around -28inHg	although gage pressure was constant, when we unclamped the catchpot we heard a hissing sound at around -15inHg the tube clamps and tubes were not compatible so we had to use tacky tape to close of any gaps used the catchpot valve to clamp for 15min. Did not have a clamp strong enough or big enough to clamp the tube we used
2021-06-29	Kyle Lacson + Mackenzie Lui	Drill 1/2 inch by 1/2 inch holes into the foam	successfully drilled the holes into the foam left it near the rest of the materials for resin infusion	took an excessive amount of time, thought of CNC a mold or 3d print a plastic stamp to make it easier next time
2021-06-29	Kyle Lacson + Mackenzie Lui	Find buckets + stir rod for resin infusion prep	found some buckets and paint stirrer and left it near the rest of the materials	none
2021-07-05	Kyle Lacson + Mackenzie Lui	Fix catchpot pressure gauge	removed an inlet off the catchpot. Used to be 3 now it has 2 inlets. (The valve that was attached to the pressure gauge was transferred to an inlet) held a vacuum for 15min, applied soap to areas where a leak may occur. No bubbles were formed and no leaks were heard Updated catchpot: before vacuum: vacuum applied and clamped: after 15 min:	pressure gauge reading is off. Reading around -10 inHg when it should start off at 0 inHg before the vacuum was applied after 15 min, pressure seemed to lower by 1inHg. tried to adjust some screws within the pressure gauge but was not able to move the needle.
2021-07-16	Mackenzie Lui Kyle Lacson	Apply mold release wax to a 1ft x 1ft area on the large glass pane	Taped out a 13”x13” area with masking tape on the large glass. Follow instructions on wax can. Applied 6 coats of wax using disposable cloth. Buffed glass 1 minute after application of each wax layer (when the wax solidifies) using disposable cloth. Buff until smooth. Application/buffing technique demonstrated in Rock West video.	Used existing boundary outlined with masking tape for 2 sides, Wait time before buffing differs from Rock West video since they are using a different wax. Large glass pane already has Locktite residue, will tacky tape stick to the border???

Advice/Feedback From Outside Sources

Also see the child pages for detailed notes on the meetings with the MSXII Alum and UW Rocketry Team.

https://docs.google.com/document/d/1f6c3DN-VuKRZ0nG_MEYSBflOx-FNKaQQeF-k_1dtEHs/edit