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Executive Summary

Product

Our product to dissect and analyze was a toaster. For this part of the project, we purchased a $9.99 Chefmate toaster to dissect. We also purchased a $29.99 Hamilton Beach toaster that we hope to compare with our first toaster at a later date.

Function

The purpose of a toaster is to assist in the making of food. Specifically, if the user wants toasted bread or bagels, warmed up waffles, etc. The toaster provides these functions.

To pictorially explain how a toaster is used, pictures from our usability study were taken to show customer product interaction. Following from that, we will delve into how a toaster actually works. From the outside, one might not think a toaster is a complex piece of equipment, but its internals are actually quite intricate. The inputs to the toaster are:

800 Watts of power
food into the slot
a toast setting
a force to activate the latching and heating mechanisms.

With these inputs provided, the activating handle is depressed, which completes two separate circuits:

First, a circuit is completed which provides power to an electromagnet and the timing circuit, holding the toastee inside the toaster where it can be heated.
The second circuit that is completed is the heating circuit. A current is run through high resistance Nichrome wire, creating heat.

The timing system works as such:

The variable resistor (regulator knob) controls current to a capacitor, regulating its charge rate. As soon as the capacitor reaches its maximum voltage, it discharges and breaks the power to the electromagnet.
A spring then pulls the bread holder and toastee back up to where it can be safely removed from the toaster.
As the spring pulls up the bread tray, the mechanism breaks the heating circuit.

Thus, the outputs of the toaster are heat and warmed food.

Stakeholders

There are at least four major stakeholders in the production and distribution of a toaster:

Customer
Company
Distributors
Engineers

The customer is only interested in a product if it fulfills their specific needs. In this case, the users need to be able to toast their bread easily and quickly. This is why they are going to purchase a toaster. Although the toaster does fulfill their basic needs, the customers also have minor needs that go along with using the toaster. If these types of needs can be met (ie. containment of crumbs, easy to use, easy retrieval of bread, cool-touch exterior), the toaster would be in much higher demand. In order to fully understand the customer's interactions with the product a usability study was conducted, which helped us further identify the customer's specific needs and opinions of the product.

The company needs are mostly limited to marketing and finance. They main interest and need is to make a profit. This requires finding customers, low manufacturing costs, and low material costs. This requires the company to decipher customer needs and apply them to their product. It also requires the company to work with the engineers and suppliers to ensure a low-cost product that can easily be sold to stores, or distributors, and thus bought by customers.

The distributors have similar needs to the company, they are looking to make a profit. Thus their need is to purchase products from various companies that fulfill needs of their customers. So they depend on the company to have come up with the lowest cost product possible.

The engineers are critical stakeholders, since every other stakeholder's needs has to be met by the engineer's design. The engineers needs are to decrease the amount and cost of material used in the toaster design. It is also the engineers job to design the product using cost and time efficient methods of manufacturing and assembly. Another need of the engineer is to balance cost and design of the product with the environmental impacts caused by the products production/use.

Assembly

Part Number	Name	Qty.	Weight	Function	Material	Maunfacturing Process
001	Plastic Casing	1	224g	Seperates the internal heating mechanisms from the user.	Polypropylene (PP)	Injection Molded
002	Crumb Tray	1	36g	Collects bread crumbs.	Aluminum	Stamp
003	Crumb Tray Handle	1	10 g	Handle to pull out crumb tray.	Plastic	Injection Molded
004	Toaster Loader Top	1	62g	Bread is loaded through slots.	Stainless Steel	Stamping, Deep Drawing
005	Toaster Base	1	108g	Base of toaster.	Polypropylene (PP)	Injection Molding
006	Regulator Knob	1	2g	Adjusts Toast time.	Polypropylene (PP)	Injection Molding
007	Press handle	1	8g	Easy surface to press, to lower bread into toaster.	Polypropylene (PP)	Injection Molded
008	Cancel button	1	2g	Cancels toast process	Polypropylene (PP)	Injection Molded
009	Power Cord	1	12g	Used to power toaster	Rubber and Copper	Extrusion
010	Ejection Assembly: Shaft	1	12g	Guide rail for ejection assembly	Steel	Extrusion
011	Handle and Locking Part 1	1	18g	Assists in triggering toasting.	Steel	Stamped and Bent
012	Handle and Locking Part 2	1	20g	Assists in triggering toasting.	Steel	Stamped and Bent
013	Toast Shelf	2	10g	Holds toast in place	Aluminum	Bent
014	Mystery Spring	1	1g	Used as a spacer, preventing ejection assembly from moving beyond a certain distance.	Steel	Extrusion
015	Restoring Spring	1	4g	Restoring Spring	Steel	Extrusion
016	Magnetic Lock Piece	1	8g	Attracts to magnet to lock the toasting shelf.	Steel	Stamped and Bent
017	Insulating caps for locking mechanism.	2	2g	N/A	ABS	Injection Molding
018	Shaft Spacer	1	2g	Spacer	ABS	Extrusion
019	Trigger Switch	1	2	Triggers switch that activates the heating coils.	ABS	Injection Molding
020	Circuit Board	1	12g	Controls heating mechanism and switch release.	Silicon and Electrical Components	N/A
021	Electromagnet, Switch Release, Circuit Board #2	1	46g	Electromagnet releases shelf, releasing the switch. Also powers the heating elements.	Silicon and Electrical components	N/A
022	Heating Coil	3	1g	Heats up when current passes through it.	Nichrome	Extrusion
023	Mica Insulating Sheet	3	14g	Insulating sheet, also carries the heating coil.	Mica	Pressed and chemically treated
024	Mica Aligning Strips	6	1g	Used to keep heating coils in place.	Mica	Pressed and chemically treated
025	Circut Board Insulator	1	1g	Prevents the two circuit boards from shorting.	Mica	Pressed and chemically treated
026	Heater leads	3	2g	Used to carry current to heater coils	Steel	Extruded and Bent
027	Smaller Mica Insulator	2	1g	Insulating purposes	Mica	Pressed chemically treated
028	Toaster wall #1	1	32g	Structural support, guides toast shelf	Steel	Stamped and Bent
029	Base Plate	1	60g	Holds everything in place, structural support	Steel	Stamped and Bent
030	Toaster wall #2	1	24g	Guides far end of toast shelf	Steel	Stamped and Bent
031	Radiation Shield	2	32g	Prevents heat from radiating to the walls of the toaster.	Steel	Stamped and Bent
032	Small mica tabs	7	1g	Holds various wires in place	Mica	Pressed and chemically treated
033	Bread Holder support wires	8	2g	Supports the toastee to be upright.	Aluminum	Extrusion and Bent
034	Mica sheet support beams	3	4g	Helps keep mica sheets in place.	Steel	Stamped and Bent
035	Rubberized No slip pads	2	0.5g	Helps keep toaster from sliding	Urethane	Extruded, Cut
036	Control knob ring	1	6g	Support for knob	Polypropylene (PP)	Injection Molded
037	Clamp for power cord	1	1g	Prevents power cord from being pulled out	Polypropylene (PP)	Injection Molded
038	1/2 Philips screw	6	1g	Screw	Steel	Machined
039	1/4 Philips screw	4	1g	Screw	Steel	Machined

Product Analysis

For our product evaluation, we looked at four different types of analysis. Design for Manufacture and Assembly (DFMA), Failure Mode Evaluation and Analysis (FMEA), Design for Environment (DFE), and a quantitative mechanical analysis.

DFMA Analysis

FMEA Analysis

Part #	Name	Function	Failure Mode	Effects of Failure	S	Causes of Failure	O	Design Controls	D	RPN	Recommended Actions	Responsibility
001	Plastic Casing	Enclose and protect internal components	Warped	Improper fit, Unintended contact with heating element	10	Repeated heating and cooling, Improper Manufacturing	1	Material Selection, Mold Design	1	10	HALT for Temperature Variations	Reliability
001	Plastic Casing	Enclose and protect internal components	Fractured	Exposure of internal components	8	Improper handling	3	Material Selection, Poor Packaging	2	48	Drop Test with and without packaging	Reliability
#	Name	Function	Failure	Effects	S	Causes	O	Controls	D	RPN	Recommended	Responsibility
#	Name	Function	Failure	Effects	S	Causes	O	Controls	D	RPN	Recommended	Responsibility
#	Name	Function	Failure	Effects	S	Causes	O	Controls	D	RPN	Recommended	Responsibility
#	Name	Function	Failure	Effects	S	Causes	O	Controls	D	RPN	Recommended	Responsibility
#	Name	Function	Failure	Effects	S	Causes	O	Controls	D	RPN	Recommended	Responsibility
#	Name	Function	Failure	Effects	S	Causes	O	Controls	D	RPN	Recommended	Responsibility
#	Name	Function	Failure	Effects	S	Causes	O	Controls	D	RPN	Recommended	Responsibility
#	Name	Function	Failure	Effects	S	Causes	O	Controls	D	RPN	Recommended	Responsibility
#	Name	Function	Failure	Effects	S	Causes	O	Controls	D	RPN	Recommended	Responsibility
#	Name	Function	Failure	Effects	S	Causes	O	Controls	D	RPN	Recommended	Responsibility
#	Name	Function	Failure	Effects	S	Causes	O	Controls	D	RPN	Recommended	Responsibility
#	Name	Function	Failure	Effects	S	Causes	O	Controls	D	RPN	Recommended	Responsibility
#	Name	Function	Failure	Effects	S	Causes	O	Controls	D	RPN	Recommended	Responsibility
#	Name	Function	Failure	Effects	S	Causes	O	Controls	D	RPN	Recommended	Responsibility
#	Name	Function	Failure	Effects	S	Causes	O	Controls	D	RPN	Recommended	Responsibility
#	Name	Function	Failure	Effects	S	Causes	O	Controls	D	RPN	Recommended	Responsibility
#	Name	Function	Failure	Effects	S	Causes	O	Controls	D	RPN	Recommended	Responsibility
#	Name	Function	Failure	Effects	S	Causes	O	Controls	D	RPN	Recommended	Responsibility
#	Name	Function	Failure	Effects	S	Causes	O	Controls	D	RPN	Recommended	Responsibility

DFE Analysis

Putting a slice of bread in the toaster, one does not often think about the environmental implications this act may have: “What steps were taken to enable this toaster to arrive on my countertop, how much power is it using while toasting, and what will happen to it after it I throw it away?” Delving into the life cycle of a toaster, we see that there is much room for improvement.

The key element in the life cycle of this appliance is energy. Being made of nearly completely recyclable materials, we are not focusing on the post-use phase. In both the production and use phases of a toaster, power generation and supply is the overwhelming contributor of greenhouse gas emissions. This seems fairly straightforward for the use end – in use, toasters produce little more than heat, from electrical power, and (hopefully) golden brown toast – but this may come as a surprise for the manufacturing end. Indeed, power generation and supply produces nearly four times as much CO2-equivalent than the nearest sectors, truck transportation and steel mills, during the manufacturing of such appliances.

Using the EIO-LCA software from Carnegie Mellon University’s Green Design Institute (results pictured below), we see that every $1,000,000 of production in the ‘Electric housewares and household fans’ sector produces 693 MTCO2E. Given our $10 toaster, this shows us that approximately 0.007 MTCO2E caused by the manufacturing of one toaster. To compare that to the use end, a simple calculation is done:

From the EIO-LCA, we see that for every $1,000,000 of production in the ‘Power generation and supply’ sector, 9910 MTCO2E are emitted.

Assuming: $0.10/kWh electricity cost, power consumption is 800W, usage is 6 min (0.1hr) per day, used 300 days out of the year, over the course of a 4 year use-life.

We see that it would cost approximately $9.60 to run this toaster over the course of its life. Given this information, it is seen that the use phase of a toaster’s life emits approximately 0.095 MTCO2E. This is an entire order of magnitude higher than the emissions production phase. Clearly, one of our assumptions, above, needs to be modified. The only option which may not impact the functionality and longevity of the toaster is the power consumption. Furthermore, looking at other toasters, we see that this 800W usage is on the low end of the spectrum. All residential toasters use the same heating method – running current through a filament, which generates heat.

The results for conventional air pollutants, such as SO2, NOx, and CO, show the same result: power generation, both for the creation and use of a toaster, is the largest contributor to harmful emissions.

The numerical results of GHG emissions, above, come with a good level of confidence. Though there are many sub-sectors of the ‘Electric housewares and household fans’ segment, the ‘Small electric household cooking appliances’ sub-sector represents nearly 1/3 of the overall sector.

From our analysis, it appears the best way to approach the DFE is to reduce the power consumption of a toaster. Perhaps an alternative heating method should be considered. A more realistic and attainable possibility is to better insulate the toasting area, as to reduce the amount of heat lost during the toasting process.

EIO-LCA GHG Results for Electric Housewares and Household Fans