P18485: Biochar Concrete Roofing Tile Manufacturing and Complete Roof System
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Subsystem Build & Test

Table of Contents

Team Vision for Subsystem Level Build & Test Phase

Phase Objectives:

In this phase the team would like to accomplish these tasks:

Individual tasks:

In this phase, the team has divided these goals into these themes and assignments:

Updates - Where are we?

Pulse of the Project

With only one and half weeks until Dan leaves for his trip to Nicaragua, the Engineering team has been working on making sure that there are a few molds created. As of right now, some updates include:

Nicapomez Updates

From the sound of Ricardo’s E-mails, it seems that the Pumice Roofing Company that Ricardo had mentioned is actually still in production, but based only on orders. There has been no signs of marketing since 2013, however he speculates they still work on tiles whenever there is a request.

Subsystem Decomposition

Below is the Subsystem Decomposition showing what features the team has been working on this phase:

Subsystem Architecture

Subsystem Architecture

Saunders Update

Below is an update coming from the Saunders team. Karina will be explaining the following screenshots of an extensive spreadsheet outlining the business’s feasibility:

Materials and Costs

Yearly Costs

Yearly Costs

Forecasting Profit
Revenue Projections

Revenue Projections

Some notes on the matter include:

Test Results Summary (DOE)

Below are the results comparing the different cure methods used. All of the samples in this graph didn't have any reinforcement in order to directly examine the effect of the cure. Based these results, it was determined that water curing is the best method.
Comparison of Curing Methods Used

Comparison of Curing Methods Used

Based on mixing observations and test results, we have decided to go with the Higher (40% Pumice, 30% Sand, 30% Cement) Ratio. While mixing the lower and higher ratio, it was observed that both mixtures contained too much water. Concrete has been shown to have an inverse relationship between water and strength. The reason for the equal ratio's performance was due to less water being used.

Below are the results comparing the different reinforcements used in the samples. All of these samples were water cured since it was determined to be the best cure method. These results show that the plastic string had an adverse affect on strength while the onion bag reinforcement maintained most of the strength of the concrete.

Comparison of Reinforcements Used (Water Cured Samples Only)

Comparison of Reinforcements Used (Water Cured Samples Only)

On most occasions, the onion bag and plastic string was able to sustain a load after initial failure. The plastic string was able to maintain a larger load after initial failure the onion bag. Based on this behavior, we determined that the best reinforcement method is plastic string placed randomly in one layer near the bottom of the tile.

Effects of Plastic String (Water Cured Samples Only)

Effects of Plastic String (Water Cured Samples Only)

All of the testing data can be found here.

Test Roof

Cost has been mitigated from the test roof design
Updated Test Roof Budget

Updated Test Roof Budget

Materials Testing

Mold Form Testing

In order to make the mold, we planned to thermoform plastic over a carved piece of foam with a protective coating on it. In order to determine the best combination of foam and coating, we thermoformed plastic over several test samples.
Thermoforming Test

Thermoforming Test

Test Samples

Test Samples

Test Results

Test Results

Based on the results of this test, the foam insulation board with epoxy was the most viable option. However, we would need to spend too much money on epoxy in order to coat the whole surface. We have instead decided to carve a negative out of the foam and use it to make a positive out of our leftover plaster, which we will then vacuum form over.

Tile Build

We built a tile using the last team's equipment, but with our pumice concrete mix. We did this in order to get used to the process of making a tile, and to take note of any problems that may occur when we eventually build our tiles. We learned the following lessons:
  1. Mix buffer of 1.35 produces the right amount of concrete
  2. Water mixing needs to be done very carefully in order to achieve the right viscosity
  3. Too much water hinders the concrete's ability to keep shape of the nubs
  4. Our tile is indeed significantly lighter than the previous team's tile
  5. Crushing our pumice to size is too inefficient; ordered more pumice at the right size
Pumice Tile

Pumice Tile

Mold Design

Mold shape remains unchanged. CAD simulations and mold material tests give us confidence that a 1/16" piece of plastic will be strong enough for the mold. However, since we already have 1/8" plastic, we will be using this for our first three molds and then possibly making thinner molds after spring break.

Manufacturing

Outline Below is an overall flowchart of our process. Please note the changes made to include the plastic string processing and layering into the tiles.
Updated Flowchart

Updated Flowchart

Manufacturing BOM

Manufacturing BOM

Manufacturing BOM

Recently sent this document to Saunders team so they could develop cost estimation for the cost of these materials.

Manufacturing Time Estimations

Manufacturing Time Estimations

Manufacturing Time Estimations

Times were gathered from the Eco Sur South videos of tile production & other sources for estimation.

Grinding pumice does not have a time because the team is discussing the possibility of having enough pumice for next weeks production grinded to size at the end of each week to be ready for production the following Monday.

Based on the estimation of 10 minute lead time of one tile, we can assume that if one person ran the system alone they could produce at least 6 tiles an hour= 42 tiles in a 8 hour workday (8hrs.-1 hr. for breaks & lunch).

Note: This number is valid for if the person did not have to transport the tiles, grind any pumice, had 100% yield, no downtime of machines, or any other subprocesses that would keep the facilities production at a constant. Due to these additional factors, production would not be met with only 1 worker creating tiles.

Facility Design/Layout

Facility Design/Layout

Facility Design/Layout

Space Analysis

Calculated the amount of space needed for each curing area.

Assumptions:

-Business will have a total of 40 molds in manufacturing system (Maximum throughput of 40 tiles per day)

-Tiles in 7 day water cure and 21 day air dry cure are leaned on one another at an angle of 10 degrees.

-First in First Out (FIFO) process will be used for 21 day air dry cure method (oldest tiles will be sold & used first)

1 Day Cure Inside Mold:

Cure Inside mold requires a minimum of 15 ft.^2.

Recommend the space is a 5'x4' area (20 ft^2) where the molds will be stacked into two separate piles (maximum height of 3.125 ft.).

7 Day Water Cure: Requires a minimum of 61.25 ft.^2.

Recommended pool space of (3'x23') (69 ft.^2) or two (3'x12') (72 ft.^2) pools. 1 row of tiles has a width of 1.5 ft. (buffer of 2 in. for each row, two rows in pool). Pools being a maximum of 3 ft. in width allows for easy picking up of watered down tiles from either side of pool.

Height of water in pool must be at least 2 feet to completely cover tiles (2in. of extra water)

Note: In next phase we will preform a test to determine whether or not the tiles can touch each other during this curing method without forming to one another.

21 Day Air Cure: Requires a minimum of 227.5 ft.^2.

Recommended space of two (6'x20') sections (240 ft.^2). (Space for 21 days of production of 40 tiles a day + 200 finished curing tiles (5 days of max production))

-The 6 ft. wide sections will have a 3 ft. open space as aisles on both sides of itself ~ 1 middle aisle and two side aisles = three (3'x20') (180 ft.^2) totaling to be 420 ft.^2 of space needed.

-This makes it easier for storage and picking of tiles because workers will only have to pick or place tiles at a max of 3 ft. away from their body (2.25 ft. if holding center of tile).

-Tiles will fill two rows at a time to one side of the aisle (two 1.5 ft. rows) picking and placing tiles so that they always have space to move their center of gravity closer towards where the tiles must be placed or picked.

Standard Work: The team is planning on focusing in on the specific details for work procedures more in next phase. For example, the idea to wrap colored rope/string around the sections of tiles produced each day. These colors will correlate on a whiteboard inside the facility that keeps track of the time groups of tiles have been both water curing and air curing. -Number of workers & roles of workers

Costing and Material Requirements Planning

A Spreadsheet to outline Demand and Materials Demands was created to help the business students understand different values and quantities that are important to the project. The first part of figuring out the materials requirements was to understand the quantities of demand. Below outlines the Worst Case Scenario, or WCS of the Demand. We can see a yearly Demand of 4872.
Demand

Demand

To figure realistic scenarios for a business and manufacturing model, we worked with a few assumptions, outlined below. An important note is that the manufacturing process will have defects, and we want to plan to be at worst a 3 Sigma process, or having less than 66,807 defects per million opportunities, or less than 6.7 percent of our tiles being damaged or broken at any part of our process.

Assumptions

Assumptions

The following table focuses on the dry material weights and volumes per tile, per roof and per year. This can be used by the business students for pricing, as well as the Engineering team for manufacturing and space requirements.

Dry Material Amounts

Dry Material Amounts

The following table also incorporates other materials required in the roof, including the water and the wire used to wrap around the c-beam supports.

Other Materials

Other Materials

Risk and Problem Tracking

Risk Assessment
Risk Assessment

Risk Assessment

Problem Tracking Below is our problem tracking table. This tool is useful in conquering some of the obstacles in an organized manner. Note that not all problems have been solved yet.

Problem Tracking

Problem Tracking

Dan's Trip

What's been done

What still needs to be done

Backup Plans

If molds are not made by the time I go on my trip, I will focus on experimenting with making molds using materials in El Sauce

Plans for next phase

The team will focus on these deliverables before Dan’s Trip:

The team will focus on these deliverables in the next Phase:

Below is a Gantt chart for our plan.

Phase Planning

Phase Planning

Individual Plans

Connor's Three Week plan

Derick's 3 week plan

Dan's 3 week plan

Matt's MSD II Plan


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