Jared Bruton and Dr. Randy Lewis, Chemical Engineering
Washing clothes is time consuming and physically difficult for women on the islands of Lake Titicaca. Women fill buckets with water and soap, allow the clothes to soak, rub them together to get the dirt out, and then wring them out. Doing this is physically demanding, especially during the harsh cold of winter. This project develops a human-powered, affordable, and easy to build clothes-washing device that allows women to save time and energy washing clothes. It builds on a similar washing machine project from one year ago, but seeks to reduce the cost of the hand-powered machine from 300 Peruvian Soles (about 120 USD) to between 100 and 200 Soles (40-75 USD) while maintaining the machine’s functionality1. Collaboration with the islanders was a crucial part of the design process. Their frugality and improvisation helped us design a high quality, durable machine that was also cost-effective.
By conducting preliminary research (from last year’s project team as well as the islanders), specific areas were identified on which to focus our efforts We decided to focus on maintaining functionality while reducing cost, which was the most significant barrier to last year’s team effectively distributing their machine. We decided that the best way to reduce expenses while preserving the most important aspects of the device’s functionality was to eliminate a spin-wringing feature from last year’s machine. This was done with a goal to reduce costs by at least half and make the machine more affordable for an average Uros Islands family. Our machine still washed the clothing, but wringing out and drying features were not pursued.
We gathered information about existing human-powered washing machines from many sources. We found designs that were manufactured, and other designs that were homemade. Some were powered by foot pedals, and different rotation patterns were seen that influenced our design. After reviewing and synthesizing the different existing methods, we chose to base our design on a horizontally rotating barrel made from scrap materials.
We made contact with two professional laundry companies. One of them, ALSCO, gave valuable insight about their clothes washing program, and directed us to what we should focus on and how to test it. According to an ALSCO representative, there are four main parts involved in washing clothes:
1. Temperature of water
2. Time spent washing
3. Chemical cleaners
4. Mechanical action (agitation)
Because we cannot control temperature, time spent washing, or what chemicals are used, we focused our design on refining the basic mechanical action of washing clothes. We learned from two independent laundry professionals that the most important mechanical action that cleans clothes is the movement of water and soap back and forth through an article of clothing, rather than clothes rubbing on each other or the machine.
After design creation, prototyping, and revisions, we settled on a single-barrel rocking design. To reduce costs, a single barrel was used that rocked back and forth on the ground rather than a frame-mounted barrel rotating around a fixed axis. Mechanical action was enhanced by wrapping a sheet of corrugated plastic around the inside of the barrel (See Figure 2). As the water moves back and forth past the corrugated plastic, waves are created, which increases the amount of water moving through the clothing. To converge on this concept, we gathered data comparing amount of agitation, ease of use, and cost for several different variations and designs. Availability of materials locally in Peru was also considered. See Figure 1 for final design and instructions.
To confirm that our design effectively cleaned clothing, tests were done with food coloring and other dyes and results were compared to hand-washed clothing. See Figure 3 and Figure 4 for results of dye test.
Meeting our project goals, we went to Peru and sold a completed washing machine for approximately 120 Soles, or about 50 USD, which was about 2/5 the previous cost. We were able to construct our machine with hand tools in under 4 hours, and proved to the Uros islanders that it cleaned their clothing as effectively as hand washing, and was much easier to use. The project was a success.