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| | = Executive Summary = | | = Executive Summary = |
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| - | Toasters are commonly used kitchen appliances, and are typically not too expensive to purchase. They can be found at most department stores from anywhere between 6$ to 50$. They are small and compact, and are used to toast or heat slices of bread, and other bread-like foods. There are 3 kinds of toasters; pop-up, toaster oven, and toaster conveyer. For this design project, we will focus on the pop-up toaster.
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| - |
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| - | The following study involves analysis of a $10.00 Chefmate toaster which was purchased from Target. In the course of this semester, we may analyze a more expensive toaster to compare what extra features are included for the price. Our hope is to find an innovative way to change current toaster designs, to address some common problems which users complain about most frequently.
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| - |
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| - | Our analysis involves studying how the toaster is usually operated and how it works, combined with evaluating the toaster through Design for Manufacture and Assembly (DFMA), Failure Mode Evaluation and Analysis (FMEA), Design for the Environment (DFE), and a quantitative mechanical analysis.
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| - |
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| - | Our first steps were to disassemble the toaster, to figure out what parts and components were involved in its operation. We were also able to understand the basics about how each of the parts of the toaster functioned. We categorized all the parts and assemblies, which can be seen in the assembly parts list.
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| - |
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| - | After disassembly, we concluded that there were far too many parts in a toaster. We believe that this makes assembly extremely tedious, and increases the complexity of the product.
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| - |
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| - | = Product =
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| - |
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| - | 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.
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| - |
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| - | == Function ==
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| - |
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| - | 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.
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| - |
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| - | To pictorially explain how a toaster is used, pictures from our <u>[[usability study]]</u> 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:
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| - |
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| - | *800 Watts of power
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| - | *food into the slot
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| - | *a toast setting
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| - | *a force to activate the latching and heating mechanisms.
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| - |
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| - | With these inputs provided, the activating handle is depressed, which completes two separate circuits:
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| - | *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.
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| - | *The second circuit that is completed is the heating circuit. A current is run through high resistance Nichrome wire, creating heat.
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| - |
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| - | [[Image:ToasterElectroboard.jpg|700px]]
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| - |
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| - | The timing system works as such:
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| - | *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.
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| - | *A spring then pulls the bread holder and toastee back up to where it can be safely removed from the toaster.
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| - | *As the spring pulls up the bread tray, the mechanism breaks the heating circuit.
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| - | [[Image:ToasterControlBoard.jpg|700px]]
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| - |
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| - | Thus, the outputs of the toaster are heat and warmed food.
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| - |
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| - | == Stakeholders ==
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| - |
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| - | There are at least four major stakeholders in the production and distribution of a toaster:
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| - | * Customer
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| - | * Company
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| - | * Distributors
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| - | * Engineers
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| - |
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| - | 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 <u>[[usability study]]</u> was conducted, which helped us further identify the customer's specific needs and opinions of the product.
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| - |
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| - | 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.
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| - |
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| - | 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.
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| - |
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| - | 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.
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| - |
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| - | == Assembly ==
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| - |
| |
| - | {| class="wikitable" border="1"
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| - | |-
| |
| - | ! Part Number !! Name !! Qty. !! Weight !! Function !! Material !! Maunfacturing Process !! Image !!
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| - | |-
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| - |
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| - | | style="text-align: center;" | 001
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| - | | Plastic Casing
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| - | | style="text-align: center;" | 1
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| - | | style="text-align: center;" | 224g
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| - | | Seperates the internal heating mechanisms from the user.
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| - | | Polypropylene (PP)
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| - | | Injection Molded
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| - | | [[Image:toaster-001.jpg|200px]]
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| - | |-
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| - | | style="text-align: center;" | 002
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| - | | Crumb Tray
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| - | | style="text-align: center;" | 1
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| - | | style="text-align: center;" | 36g
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| - | | Collects bread crumbs.
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| - | | Aluminum
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| - | | Stamp
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| - | | [[Image:toaster-002.jpg|200px]]
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| - | |-
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| - | | style="text-align: center;" | 003
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| - | | Crumb Tray Handle
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| - | | style="text-align: center;" | 1
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| - | | style="text-align: center;" | 10 g
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| - | | Handle to pull out crumb tray.
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| - | | Plastic
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| - | | Injection Molded
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| - | | [[Image:toaster-003.jpg|200px]]
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| - | |-
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| - | | style="text-align: center;" | 004
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| - | | Toaster Loader Top
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| - | | style="text-align: center;" | 1
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| - | | style="text-align: center;" | 62g
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| - | | Bread is loaded through slots.
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| - | | Stainless Steel
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| - | | Stamping, Deep Drawing
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| - | | [[Image:toaster-004.jpg|200px]]
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| - | |-
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| - | | style="text-align: center;" | 005
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| - | | Toaster Base
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| - | | style="text-align: center;" | 1
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| - | | style="text-align: center;" | 108g
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| - | | Base of toaster.
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| - | | Polypropylene (PP)
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| - | | Injection Molding
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| - | | [[Image:toaster-005.jpg|200px]]
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| - | |-
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| - | | style="text-align: center;" | 006
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| - | | Regulator Knob
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| - | | style="text-align: center;" | 1
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| - | | style="text-align: center;" | 2g
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| - | | Adjusts Toast time.
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| - | | Polypropylene (PP)
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| - | | Injection Molding
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| - | | [[Image:toaster-006.jpg|200px]]
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| - | |-
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| - | | style="text-align: center;" | 007
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| - | | Press handle
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| - | | style="text-align: center;" | 1
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| - | | style="text-align: center;" | 8g
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| - | | Easy surface to press, to lower bread into toaster.
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| - | | Polypropylene (PP)
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| - | | Injection Molded
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| - | | [[Image:toaster-007.jpg|200px]]
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| - | |-
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| - | | style="text-align: center;" | 008
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| - | | Cancel button
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| - | | style="text-align: center;" | 1
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| - | | style="text-align: center;" | 2g
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| - | | Cancels toast process
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| - | | Polypropylene (PP)
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| - | | Injection Molded
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| - | | [[Image:toaster-008.jpg|200px]]
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| - | |-
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| - | | style="text-align: center;" | 009
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| - | | Power Cord
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| - | | style="text-align: center;" | 1
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| - | | style="text-align: center;" | 12g
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| - | | Used to power toaster
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| - | | Rubber and Copper
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| - | | Extrusion
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| - | | [[Image:toaster-009.jpg|200px]]
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| - | |-
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| - | | style="text-align: center;" | 010
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| - | | Ejection Assembly: Shaft
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| - | | style="text-align: center;" | 1
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| - | | style="text-align: center;" | 12g
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| - | | Guide rail for ejection assembly
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| - | | Steel
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| - | | Extrusion
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| - | | [[Image:toaster-010.jpg|200px]]
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| - | |-
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| - | | style="text-align: center;" | 011
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| - | | Handle and Locking Part 1
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| - | | style="text-align: center;" | 1
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| - | | style="text-align: center;" | 18g
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| - | | Assists in triggering toasting.
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| - | | Steel
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| - | | Stamped and Bent
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| - | | [[Image:toaster-011.jpg|200px]]
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| - | |-
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| - | | style="text-align: center;" | 012
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| - | | Handle and Locking Part 2
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| - | | style="text-align: center;" | 1
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| - | | style="text-align: center;" | 20g
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| - | | Assists in triggering toasting.
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| - | | Steel
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| - | | Stamped and Bent
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| - | | [[Image:toaster-012.jpg|200px]]
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| - | |-
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| - | | style="text-align: center;" | 013
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| - | | Toast Shelf
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| - | | style="text-align: center;" | 2
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| - | | style="text-align: center;" | 10g
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| - | | Holds toast in place
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| - | | Aluminum
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| - | | Bent
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| - | | [[Image:toaster-013.jpg|200px]]
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| - | |-
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| - | | style="text-align: center;" | 014
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| - | | Mystery Spring
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| - | | style="text-align: center;" | 1
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| - | | style="text-align: center;" | 1g
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| - | | Used as a spacer, preventing ejection assembly from moving beyond a certain distance.
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| - | | Steel
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| - | | Extrusion
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| - | | [[Image:toaster-014.jpg|200px]]
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| - | |-
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| - | | style="text-align: center;" | 015
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| - | | Restoring Spring
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| - | | style="text-align: center;" | 1
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| - | | style="text-align: center;" | 4g
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| - | | Restoring Spring
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| - | | Steel
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| - | | Extrusion
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| - | | [[Image:toaster-015.jpg|200px]]
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| - | |-
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| - | | style="text-align: center;" | 016
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| - | | Magnetic Lock Piece
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| - | | style="text-align: center;" | 1
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| - | | style="text-align: center;" | 8g
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| - | | Attracts to magnet to lock the toasting shelf.
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| - | | Steel
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| - | | Stamped and Bent
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| - | | [[Image:toaster-016.jpg|200px]]
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| - | |-
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| - | | style="text-align: center;" | 017
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| - | | Insulating caps for locking mechanism.
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| - | | style="text-align: center;" | 2
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| - | | style="text-align: center;" | 2g
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| - | | N/A
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| - | | ABS
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| - | | Injection Molding
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| - | | [[Image:toaster-017.jpg|200px]]
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| - | |-
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| - | | style="text-align: center;" | 018
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| - | | Shaft Spacer
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| - | | style="text-align: center;" | 1
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| - | | style="text-align: center;" | 2g
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| - | | Spacer
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| - | | ABS
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| - | | Extrusion
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| - | | [[Image:toaster-018.jpg|200px]]
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| - | |-
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| - | | style="text-align: center;" | 019
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| - | | Trigger Switch
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| - | | style="text-align: center;" | 1
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| - | | style="text-align: center;" | 2
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| - | | Triggers switch that activates the heating coils.
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| - | | ABS
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| - | | Injection Molding
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| - | | [[Image:toaster-019.jpg|200px]]
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| - | |-
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| - | | style="text-align: center;" | 020
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| - | | Circuit Board
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| - | | style="text-align: center;" | 1
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| - | | style="text-align: center;" | 12g
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| - | | Controls heating mechanism and switch release.
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| - | | Silicon and Electrical Components
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| - | | N/A
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| - | | [[Image:toaster-020.jpg|200px]]
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| - | |-
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| - | | style="text-align: center;" | 021
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| - | | Electromagnet, Switch Release, Circuit Board #2
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| - | | style="text-align: center;" | 1
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| - | | style="text-align: center;" | 46g
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| - | | Electromagnet releases shelf, releasing the switch. Also powers the heating elements.
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| - | | Silicon and Electrical components
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| - | | N/A
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| - | | [[Image:toaster-021.jpg|200px]]
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| - | |-
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| - | | style="text-align: center;" | 022
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| - | | Heating Coil
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| - | | style="text-align: center;" | 3
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| - | | style="text-align: center;" | 1g
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| - | | Heats up when current passes through it.
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| - | | Nichrome
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| - | | Extrusion
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| - | | [[Image:toaster-022.jpg|200px]]
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| - | |-
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| - | | style="text-align: center;" | 023
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| - | | Mica Insulating Sheet
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| - | | style="text-align: center;" | 3
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| - | | style="text-align: center;" | 14g
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| - | | Insulating sheet, also carries the heating coil.
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| - | | Mica
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| - | | Pressed and chemically treated
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| - | | [[Image:toaster-023.jpg|200px]]
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| - | |-
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| - | | style="text-align: center;" | 024
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| - | | Mica Aligning Strips
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| - | | style="text-align: center;" | 6
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| - | | style="text-align: center;" | 1g
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| - | | Used to keep heating coils in place.
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| - | | Mica
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| - | | Pressed and chemically treated
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| - | | [[Image:toaster-024.jpg|200px]]
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| - | |-
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| - | | style="text-align: center;" | 025
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| - | | Circut Board Insulator
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| - | | style="text-align: center;" | 1
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| - | | style="text-align: center;" | 1g
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| - | | Prevents the two circuit boards from shorting.
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| - | | Mica
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| - | | Pressed and chemically treated
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| - | | [[Image:toaster-025.jpg|200px]]
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| - | |-
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| - | | style="text-align: center;" | 026
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| - | | Heater leads
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| - | | style="text-align: center;" | 3
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| - | | style="text-align: center;" | 2g
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| - | | Used to carry current to heater coils
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| - | | Steel
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| - | | Extruded and Bent
| |
| - | | [[Image:toaster-026.jpg|200px]]
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| - | |-
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| - | | style="text-align: center;" | 027
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| - | | Smaller Mica Insulator
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| - | | style="text-align: center;" | 2
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| - | | style="text-align: center;" | 1g
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| - | | Insulating purposes
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| - | | Mica
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| - | | Pressed chemically treated
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| - | | [[Image:toaster-027.jpg|200px]]
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| - | |-
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| - | | style="text-align: center;" | 028
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| - | | Toaster wall #1
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| - | | style="text-align: center;" | 1
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| - | | style="text-align: center;" | 32g
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| - | | Structural support, guides toast shelf
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| - | | Steel
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| - | | Stamped and Bent
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| - | | [[Image:toaster-028.jpg|200px]]
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| - | |-
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| - | | style="text-align: center;" | 029
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| - | | Base Plate
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| - | | style="text-align: center;" | 1
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| - | | style="text-align: center;" | 60g
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| - | | Holds everything in place, structural support
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| - | | Steel
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| - | | Stamped and Bent
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| - | | [[Image:toaster-029.jpg|200px]]
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| - | |-
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| - | | style="text-align: center;" | 030
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| - | | Toaster wall #2
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| - | | style="text-align: center;" | 1
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| - | | style="text-align: center;" | 24g
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| - | | Guides far end of toast shelf
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| - | | Steel
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| - | | Stamped and Bent
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| - | | [[Image:toaster-030.jpg|200px]]
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| - | |-
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| - | | style="text-align: center;" | 031
| |
| - | | Radiation Shield
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| - | | style="text-align: center;" | 2
| |
| - | | style="text-align: center;" | 32g
| |
| - | | Prevents heat from radiating to the walls of the toaster.
| |
| - | | Steel
| |
| - | | Stamped and Bent
| |
| - | | [[Image:toaster-031.jpg|200px]]
| |
| - | |-
| |
| - | | style="text-align: center;" | 032
| |
| - | | Small mica tabs
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| - | | style="text-align: center;" | 7
| |
| - | | style="text-align: center;" | 1g
| |
| - | | Holds various wires in place
| |
| - | | Mica
| |
| - | | Pressed and chemically treated
| |
| - | | [[Image:toaster-032.jpg|200px]]
| |
| - | |-
| |
| - | | style="text-align: center;" | 033
| |
| - | | Bread Holder support wires
| |
| - | | style="text-align: center;" | 8
| |
| - | | style="text-align: center;" | 2g
| |
| - | | Supports the toastee to be upright.
| |
| - | | Aluminum
| |
| - | | Extrusion and Bent
| |
| - | | [[Image:toaster-033.jpg|200px]]
| |
| - | |-
| |
| - | | style="text-align: center;" | 034
| |
| - | | Mica sheet support beams
| |
| - | | style="text-align: center;" | 3
| |
| - | | style="text-align: center;" | 4g
| |
| - | | Helps keep mica sheets in place.
| |
| - | | Steel
| |
| - | | Stamped and Bent
| |
| - | | [[Image:toaster-034.jpg|200px]]
| |
| - | |-
| |
| - | | style="text-align: center;" | 035
| |
| - | | Rubberized No slip pads
| |
| - | | style="text-align: center;" | 2
| |
| - | | style="text-align: center;" | 0.5g
| |
| - | | Helps keep toaster from sliding
| |
| - | | Urethane
| |
| - | | Extruded, Cut
| |
| - | | [[Image:toaster-035.jpg|200px]]
| |
| - | |-
| |
| - | | style="text-align: center;" | 036
| |
| - | | Control knob ring
| |
| - | | style="text-align: center;" | 1
| |
| - | | style="text-align: center;" | 6g
| |
| - | | Support for knob
| |
| - | | Polypropylene (PP)
| |
| - | | Injection Molded
| |
| - | | [[Image:toaster-036.jpg|200px]]
| |
| - | |-
| |
| - | | style="text-align: center;" | 037
| |
| - | | Clamp for power cord
| |
| - | | style="text-align: center;" | 1
| |
| - | | style="text-align: center;" | 1g
| |
| - | | Prevents power cord from being pulled out
| |
| - | | Polypropylene (PP)
| |
| - | | Injection Molded
| |
| - | | [[Image:toaster-037.jpg|200px]]
| |
| - | |-
| |
| - | | style="text-align: center;" | 038
| |
| - | | 1/2'' Philips screw
| |
| - | | style="text-align: center;" | 6
| |
| - | | style="text-align: center;" | 1g
| |
| - | | Screw
| |
| - | | Steel
| |
| - | | Machined
| |
| - | | [[Image:toaster-038.jpg|200px]]
| |
| - | |-
| |
| - | | style="text-align: center;" | 039
| |
| - | | 1/4'' Philips screw
| |
| - | | style="text-align: center;" | 4
| |
| - | | style="text-align: center;" | 1g
| |
| - | | Screw
| |
| - | | Steel
| |
| - | | Machined
| |
| - | | [[Image:toaster-039.jpg|200px]]
| |
| - | |-
| |
| - | |}
| |
| - |
| |
| - | =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==
| |
| - | The toaster is a fairly inexpensive kitchen appliance which is always in demand. Almost everyone owns a toaster or has access to it, meaning that it needs to be designed to allow mass production.
| |
| - |
| |
| - | === Design for Manufacture ===
| |
| - |
| |
| - | The toaster is manufactured using several different processes. The main two process used are injection molding and stamping. Extrusion, deep draw methods, and an hydraulic press were also used.
| |
| - |
| |
| - | Exterior of Toaster - <br/>
| |
| - | The case, bottom, and user interface of the toaster were all injection molded. Although injection molding is an expensive process due to its high price equipment and molds, with the toaster it is probably a good option. With the number of toasters being made and the consistency of the toaster design, the mold for a toaster is more than paid for. There are probably three different injection molds for this product: one mold for the case, one for the bottom, and one for the various buttons and knobs on the user interface. This combination of multiple parts in one mold is allowable due to the small size of the various parts and the lack of detail needed for each part. The shape of each of these parts were designed to be most efficient for injection molding. The bottom, which consists of many slots or vents, is the most complex of the shapes and is made up for this by having four locations that the plastic is injected.
| |
| - |
| |
| - | Exterior Metal Slots- <br/>
| |
| - | The slots of the toaster was made through a deep draw process. This is a special type of stamping that gives radial stress to the flanges of the metal, and allows it to be stretched radially as well linearly. This gives the metal a rounder finish, making it look more complete and attractive. This process was used only for the exterior metal on the slots for the toaster. Its purpose was to make the toaster attractive. Although this process is more expensive than just stamping and bending metal, in mass quantities the cost is not unreasonable. This process in the toaster manufacturing could definitely be taken out, but it would also hinder the quality and attractiveness of the product.
| |
| - |
| |
| - | [[Image:Toaster-deepdraw2.jpg]]
| |
| - |
| |
| - | Interior Metal Plates and strips- <br/>
| |
| - | The metal in the interior of the toaster was all stamped and bent. This is an easy process which uses sheet metal and then stamps out the shape of the metal needed. All unused sections of sheet metal can then be re-melted and used again. This is a very cost-effective method of manufacturing. You start of with the sheet metal, cut it in to shape by stamping it and then bend it to give it more strength and durability. This process is easy, low time, and easy to automate.
| |
| - |
| |
| - | [[Image:Toaster-Stamping.jpg]]
| |
| - |
| |
| - | Metal Rods and Wires-<br/>
| |
| - | All of the metal rods and wires in the toaster were made through metal extrusion. Where metal is heated and then pushed through a die to its desired shape. This process is easy to do, and it is cost-efficient as while extruding the pieces can be easily cut to their desired length. This creates very little waste in material and makes the whole process extremely quick.
| |
| - |
| |
| - | Mica Sheets- <br/>
| |
| - | Mica is a great insulator and hard to burn. Thus is a great choice to contact the heating wires and insulate the various circuits and wires. In order to produce mica sheets, mica is ground fine and mixed with a colloid agent and water. A single sheet of uniform thickness is formed by pouring the mixture onto a mesh screen. Vacuum means and a hydraulic press are used to complete the formation of a sheet. Mica is not inexpensive, but its special properties make it a extremely valuable material, its used in a wide variance of products from dry wall to cosmetics for this reason. In this product's case, due to the restraints of needing an insulation, structure, and resistance to heat, mica was a perfect choice.
| |
| - |
| |
| - | === Design for Assembly ===
| |
| - |
| |
| - | The toaster is designed to be assembled by hand. It is made in China, where labor is cheap, and its parts were designed to allow easy and quick assembly.
| |
| - |
| |
| - | Each of the metal plates in the entire were connected together with a series of tabs. The plates connected together when the tabs fit into small slots and were then folded over by hand. This allowed the plates to be easily and quickly adhered together. The one problem is that is it requires a lot of tedious work for the laborer. It was easy to see that different people worked on the tabs on our toaster, as different tabs were folded dramatically different for each plate.
| |
| - |
| |
| - | There were also holes punched into the metal plates to allow for easy assembly of having either rods, wires, or metal pieces fit easily through a space into their correct location. This once again was optimized for hands-on assembly. As you can see from the picture below, this design was even incorporated for somewhat complex shapes and assembly to quicken the process and keep it accurate.
| |
| - |
| |
| - | [[Image:Toaster-_hole_punched.JPG]]
| |
| - |
| |
| - | The injection molded bottom had some built in slots that the circuit boards easily slipped into, making the circuit board addition a last minute process. All that needed to be done was to slide them in, connect the two boards together, and solder the wires to the leads.
| |
| - |
| |
| - | Looking at the whole assembly process, the toaster has a lot of parts to put together. Automating more of this process would be beneficial for time and getting rid of labor. This would also increase costs due to machinery and maintenance. Although the toaster is made entirely by hand, the parts were designed to limit the laborer to easy tasks, improving time and reliability of the assembly.
| |
| - |
| |
| - | ==FMEA Analysis==
| |
| - |
| |
| - | Off the shelf, this product should function just fine. Most failures should be found before the product leaves the factory. The major failure modes mostly involve fatiguing of parts and mechanisms. Therefore, this product should be put through Hyper Accelerated Life Testing (HALT) to determine an average lifespan and address major failures. This testing should include average and heavy use under normal and extreme conditions.
| |
| - |
| |
| - | The risk may also be lowered if the properties of the metals used are already known. If the components will be able to function properly after 4 years of use, then the product will have reached an acceptable lifespan. This will cut down on reliability testing costs and keep the overall product costs low.
| |
| - |
| |
| - | The following table outlines the basic Failure Modes and Effects Analysis (FMEA) for the toaster. The first nine parts on the list were analyzed at the component level while the rest were at assembly level. Since most failures for the assembly level parts had similar failures and effects, they were analyzed together.
| |
| - |
| |
| - | {| class="wikitable" border="1"
| |
| - | |-
| |
| - | ! Part # !! Name & Function !! Failure Mode !! Effects of Failure !! S !! Causes of Failure !! O !! Design Controls !! D !! RPN !! Recommended Actions !! Responsibility
| |
| - | |- valgin="center"
| |
| - | | rowspan=4 style="text-align: center;" | 001
| |
| - | | rowspan=4 | Plastic Casing
| |
| - | * Enclose and protect internal components
| |
| - | * Shield user from internal components and heat
| |
| - | | rowspan=2 | Warped
| |
| - | | rowspan=2 | Improper fit, Unintended contact with heating element
| |
| - | | rowspan=2 style="text-align: center;" | '''6'''
| |
| - | | Repeated heating and cooling || '''4''' || Material Selection || '''8''' || style="text-align: center;" | '''192''' || HALT for Temperature Variations || Reliability
| |
| - | |-
| |
| - | | Improper Manufacturing || '''1''' || Material Selection, Mold Design || '''1''' || style="text-align: center;" | '''6''' || None || Manufacturing
| |
| - | |-
| |
| - | | Fractured
| |
| - | | Exposure of internal components
| |
| - | | style="text-align: center;" | '''8'''
| |
| - | | Improper handling || '''5''' || Material Selection, Packaging || '''4''' || style="text-align: center;" | '''160''' || Drop Test with and without packaging || Reliability
| |
| - | |-
| |
| - | | Wrong color / surface finish
| |
| - | | User dissatisfaction
| |
| - | | style="text-align: center;" | '''1'''
| |
| - | | Incorrect material / process || '''1''' || Material Selection, Mold Specs || '''1''' || style="text-align: center;" | '''1''' || None || Manufacturing
| |
| - | |-
| |
| - | | rowspan=2 style="text-align: center;" | 002
| |
| - | | rowspan=2 | Crumb Tray
| |
| - | * Ease the process of removing crumbs
| |
| - | * Keep toaster clean
| |
| - | | rowspan=2 | Warped, Bent
| |
| - | | rowspan=2 | Will no longer fit in bottom of toaster, may get stuck in toaster
| |
| - | | rowspan=2 | '''3'''
| |
| - | | Improper manufacturing || '''4''' || Assign process and tolerance || '''1''' || style="text-align: center;" | '''12''' || none || Manufacturing
| |
| - | |-
| |
| - | | Cleaning, bent while in use || '''7''' || Material selection || '''4''' || style="text-align: center;" | '''84''' || HALT for typical washing cycles || Reliability
| |
| - | |-
| |
| - | | rowspan=3 style="text-align: center;" | 003
| |
| - | | rowspan=3 | Crumb Tray Handle
| |
| - | * Enable removal of crumb tray
| |
| - | | rowspan=2 | Warped
| |
| - | | Improper fit onto crumb tray
| |
| - | | '''4'''
| |
| - | | Incorrect manufacturing || '''1''' || Assign process and tolerance || '''1''' || style="text-align: center;" | '''4''' || None || Assembly
| |
| - | |-
| |
| - | | Improper fit when slid into assembly, may stick out too far
| |
| - | | '''3'''
| |
| - | | Incorrect manufacturing || '''1''' || Assign process and tolerance || '''1''' || style="text-align: center;" | '''3''' || None || Assembly
| |
| - | |-
| |
| - | | Broken attachment clip
| |
| - | | Handle may disconnect from tray
| |
| - | | '''4'''
| |
| - | | Incorrect manufacturing or assembly || '''2''' || Assign process || '''1''' || style="text-align: center;" | '''8''' || None || Assembly
| |
| - | |-
| |
| - | | rowspan=2 style="text-align: center;" | 004
| |
| - | | rowspan=2 | Toaster Top
| |
| - | * Protects user from internal components
| |
| - | * Aligns components and material to be toasted
| |
| - | | Warped, Bent
| |
| - | | Misaligned components
| |
| - | | '''8'''
| |
| - | | Improper Manufacturing || '''2''' || Assign process, Material selection || '''1''' || style="text-align: center;" | '''16''' || None || Manufacturing
| |
| - | |-
| |
| - | | Corroded
| |
| - | | Deterioration of part
| |
| - | | '''2'''
| |
| - | | Heavy use, poor upkeep || '''2''' || Material selection || '''1''' || style="text-align: center;" | '''4''' || None || Design
| |
| - | |-
| |
| - | | rowspan=2 style="text-align: center;" | 005
| |
| - | | rowspan=2 | Toaster Base
| |
| - | * Protects user from internal components
| |
| - | * Aligns components
| |
| - | | Warped
| |
| - | | Misalignment of components
| |
| - | | '''8'''
| |
| - | | Improper manufacturing || '''1''' || Specify process, Material selection || '''1''' || style="text-align: center;" | '''8''' || None || Manufacturing
| |
| - | |-
| |
| - | | Fractured
| |
| - | | Exposure / Misalignment of components
| |
| - | | '''8'''
| |
| - | | Improper handling || '''3''' || Material Selection, Packaging || '''2''' || style="text-align: center;" | '''48''' || Drop test with and without packaging || Reliability
| |
| - | |-
| |
| - | | rowspan=2 style="text-align: center;" | 006
| |
| - | | rowspan=2 | Regulator Knob
| |
| - | * Enables user to adjust toasting time
| |
| - | | Warped
| |
| - | | Improper fit onto variable resistor or into casing
| |
| - | | '''6'''
| |
| - | | Improper manufacturing || '''2''' || Material selection || '''1''' || style="text-align: center;" | '''12''' || None || Manufacturing
| |
| - | |-
| |
| - | | Fractured
| |
| - | | May detach from variable resistor
| |
| - | | '''5'''
| |
| - | | Poor handling, Impact || '''4''' || Material Selection, Packaging || '''1''' || style="text-align: center;" | '''24''' || None || Manufacturing, Assembly
| |
| - | |-
| |
| - | | rowspan=2 style="text-align: center;" | 007
| |
| - | | rowspan=2 | Press Handle
| |
| - | * Allows user to easily start toaster
| |
| - | | rowspan=2 | Warped
| |
| - | | Detaches from ejection system too easily
| |
| - | | '''4'''
| |
| - | | Improper Manufacturing || '''2''' || Material selection, mold design || '''5''' || style="text-align: center;" | '''40''' || None || Assembly
| |
| - | |-
| |
| - | | Incorrect fit into casing channel, toaster may stick
| |
| - | | '''8'''
| |
| - | | Improper Manufacturing || '''1''' || Material selection, mold design || '''2''' || style="text-align: center;" | '''16''' || None || Assembly
| |
| - | |-
| |
| - | | rowspan=2 style="text-align: center;" | 008
| |
| - | | rowspan=2 | Cancel Button
| |
| - | * Allows user to cancel toaster operation
| |
| - | | rowspan=2 | Warped
| |
| - | | Detaches from toaster
| |
| - | | '''4'''
| |
| - | | Improper Manufacturing || '''1''' || Material selection, injection mold design || '''5''' || style="text-align: center;" | '''20''' || None || Manufacturing, Assembly
| |
| - | |-
| |
| - | | Does not fit into casing or gets stuck
| |
| - | | '''8'''
| |
| - | | Improper Manufacturing || '''1''' || Material selection || '''1''' || style="text-align: center;" | '''8''' || None || Assembly
| |
| - | |-
| |
| - | | rowspan=2 style="text-align: center;" | 009
| |
| - | | rowspan=2 | AC Power Cord
| |
| - | *Provides electricity for toaster unit
| |
| - | | rowspan=2 | Short circuit
| |
| - | | rowspan=2 | Unit cannot function
| |
| - | | rowspan=2 | '''10'''
| |
| - | | Cord pinching || '''2''' || Set assembly process || '''5''' || style="text-align: center;" | '''100''' || Test completed units before distribution || Assembly
| |
| - | |-
| |
| - | | Internal cord problem || '''1''' || Choose reliable supplier || '''5''' || style="text-align: center;" | '''50''' || Test completed units before distribution || Assembly
| |
| - | |-
| |
| - | | rowspan=7 style="text-align: center;" | 010 - 019
| |
| - | | rowspan=7 | Ejection Assembly
| |
| - | * Ease the process of inserting and removing toasted materials
| |
| - | * Activate heating wires and timing circuit
| |
| - | | rowspan=2 | Mechanism fails to activate circuit
| |
| - | | rowspan=2 | Unit is inoperable
| |
| - | | rowspan=2 | '''8'''
| |
| - | | Warped switch || '''1''' || Material selection || '''1''' || style="text-align: center;" | '''8''' || None || Assembly
| |
| - | |-
| |
| - | | Switch fatigue || '''4''' || Material selection || '''5''' || style="text-align: center;" | '''160''' || HALT for normal use || Reliability
| |
| - | |-
| |
| - | | rowspan=5 | Mechanism fails to release
| |
| - | | rowspan=3 | Heating elements stay on
| |
| - | | rowspan=3 | '''9'''
| |
| - | | Internal circuit failure || '''1''' || Circuit test || '''1''' || style="text-align: center;" | '''9''' || None || Assembly
| |
| - | |-
| |
| - | | Warped internal components || '''2''' || Material selection, Set manufacturing process specifications || '''1''' || style="text-align: center;" | '''18''' || None || Assembly
| |
| - | |-
| |
| - | | Fatigue || '''5''' || Material selection || '''5''' || style="text-align: center;" | '''225''' || HALT for normal use || Reliability
| |
| - | |-
| |
| - | | rowspan=2 | Finished product does not eject
| |
| - | | rowspan=2 | '''6'''
| |
| - | | Warped internal components || '''2''' || Material selection, Set manufacturing process specifications || '''1''' || style="text-align: center;" | '''12''' || None || Assembly
| |
| - | |-
| |
| - | | Fatigue || '''5''' || Material selection || '''5''' || style="text-align: center;" | '''150''' || HALT for normal use || Reliability
| |
| - | |-
| |
| - | | rowspan=5 style="text-align: center;" | 020 - 034
| |
| - | | rowspan=5 | Heating and alignment assembly
| |
| - | * Heat product for time provided by user
| |
| - | * Properly align product for even heating
| |
| - | | rowspan=2 | Heating elements turn on partially
| |
| - | | rowspan=2 | Uneven heating
| |
| - | | rowspan=2 | '''7'''
| |
| - | | Short circuit || '''1''' || Ensure electrical elements have sufficient clearance || '''1''' || style="text-align: center;" | '''7''' || None || Manufacturing and Assembly
| |
| - | |-
| |
| - | | Fatigue || '''5''' || Material selection || '''5''' || style="text-align: center;" | '''175''' || HALT for normal use || Reliability
| |
| - | |-
| |
| - | | rowspan=2 | Heating elements do not turn on
| |
| - | | rowspan=2 | No heating of product
| |
| - | | rowspan=2 | '''8'''
| |
| - | | Short circuit || '''1''' || Ensure electrical components have sufficient clearance || '''1''' || style="text-align: center;" | '''8''' || None || Manufacturing and Assembly
| |
| - | |-
| |
| - | | Fatigue || '''5''' || Material selection || '''5''' || style="text-align: center;" | '''200''' || HALT for normal use || Reliability
| |
| - | |-
| |
| - | | Improperly aligned product
| |
| - | | Uneven heating
| |
| - | | '''7'''
| |
| - | | Wrong dimensions || '''1''' || Material selection, set tolerances || '''1''' || style="text-align: center;" | '''7''' || None || Assembly
| |
| - | |-
| |
| - | |-
| |
| - | |}
| |
| - |
| |
| - | ==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.
| |
| - |
| |
| - | While nearly all the materials in the toaster are recyclable, due to the complex nature of a toaster, it is costly to fully recycle one. Thus, toasters generally end up in landfills at the end of their lives.
| |
| - |
| |
| - | However, the key element in the life cycle of this appliance is energy. 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. Also, reducing the complexity of a toaster would increase its potential to be recycled, further reducing its environmental footprint.
| |
| - |
| |
| - | {|-
| |
| - | | '''EIO-LCA GHG Results for Electric Housewares and Household Fans'''
| |
| - | |-
| |
| - | | [[Image:ToasterghgTable.jpg]]
| |
| - | |-
| |
| - | | [[Image:ToasterghgChart.jpg]]
| |
| - | |-
| |
| - | | '''EIO-LCA GHG Results for Power Generation and Supply'''
| |
| - | |-
| |
| - | | [[Image:ToasterghgPowertable.jpg]]
| |
| - | |-
| |
| - | | [[Image:ToasterghgPowerchart.jpg]]
| |
| - | |-
| |
| - | |}
| |
| - |
| |
| - | ==Mechanical Analysis==
| |
| - | The toaster bread shelf is a very important part of the toaster. Not only does it pop the toast back up after it has completed the heating cycle, but it keeps the bread at the appropriate position between the heating coils. If the shelf happens to fail, the toaster becomes a potentially dangerous appliance. This analysis is intended to find the probability of failure for the shelf.
| |
| - |
| |
| - | [[Image:Toaster-Model.jpg|500px]]
| |
| - |
| |
| - | This part is made from steel sheets, stamped and bent into the above shape. The bent tabs are intended to support the bread while fitting in between the side guide wires of the toaster. A long indent along the side of the shelf helps improve lateral stiffness.
| |
| - |
| |
| - | [[Image:Toaster-Stress.jpg|500px]]
| |
| - |
| |
| - | The above picture shows a basic stress distribution when the shelf is supporting one pound of weight.
| |
| - |
| |
| - | [[Image:Toaster-disp.jpg|500px]]
| |
| - |
| |
| - | As seen above, even with the heaviest anticipated load of one pound, the shelf only deflects 0.0004" at the furthest point. The probability of shelf deformation is very low. Accordingly, this failure mode, while potentially serious, is extremely unlikely. The shelf was obviously designed to withstand much more than it should ever encounter.
| |
| - |
| |
| - | =References=
| |
| - |
| |
| - | Degentesh, Drew. "Metal Processing." 24-443: Design for Manufacture. Carnegie Mellon University. 11 Sept. 2008.
| |
| - |
| |
| - | Degentesh, Drew. "Injection Molding." 24-443: Design for Manufacture. Carnegie Mellon University. 4 Sept. 2008.
| |
| - |
| |
| - | Degentesh, Drew. "Plastics Processing." 24-443: Design for Manufacture. Carnegie Mellon University. 2 Sept. 2008.
| |
| - |
| |
| - | Thompson, Rob. Manufacturing Processes for Design Professionals. London: Thames & Hudson, 2007.
| |
| - |
| |
| - | [http://ddl.me.cmu.edu/ddwiki/index.php/ED2 Engineering Design II Course]
| |
| - |
| |
| - | Carnegie Mellon University Green Design Institute. [http://www.eiolca.net/ (2008) Economic Input-Output Life Cycle Assessment (EIO-LCA) model]
| |
| | | | |
| | =Team Members= | | =Team Members= |
| Line 738: |
Line 25: |
| | * Dissect second toaster to continue analysis | | * Dissect second toaster to continue analysis |
| | * Brainstorm Innovations and Improvements | | * Brainstorm Innovations and Improvements |
| | + | |
| | + | = Appendix = |
| | + | |
| | + | List of 100 ways to innovate a toaster: |
