Weed whacker
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Attached to the weed whacker head, is a reel that contains a long piece of wire. The wire is fed through two small holes exposing approximately 5 inches of wire. While the head is rotating, the wires are used to cut weeds. Due to the high speeds of the wire, there is no need for sharp edges, as the impact from the wire alone is enough to cut through plants. | Attached to the weed whacker head, is a reel that contains a long piece of wire. The wire is fed through two small holes exposing approximately 5 inches of wire. While the head is rotating, the wires are used to cut weeds. Due to the high speeds of the wire, there is no need for sharp edges, as the impact from the wire alone is enough to cut through plants. | ||
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== Failure Mode Effects Analysis (FMEA) == | == Failure Mode Effects Analysis (FMEA) == | ||
Revision as of 14:02, 17 September 2008
Contents |
Stakeholders
There are several stakeholders that will be affected by our changes to this product. They include:
The manufacturer
Fulltime/partime gardeners
Lawn owners
Raw material suppliers
Gardening/home improvement stores
Product Usage
Usage of a weed whacker is very straight forward. For situations and areas where a lawnmower would be difficult to use, the hand-held weed whacker becomes a tool of choice. The convenience of this gardening tool comes from its ability to quickly cut vegetation in hard to reach places without damaging structures that may surround it.
In order to power on the weed whacker, first make sure there is sufficient gas in the tank. Click the on/off switch to on. Intructions on how to start the motor are included on a sticker on the straight shaft, and are as follows:
For a cold engine:
1. Press bulb 10 times.
2. Move blue choke lever to "1".
3. Squeeze trigger and pull rope 5 times.
4. Move blue choke lever to "2".
5. Squeeze trigger and pull rope till engine starts. If it doesn't start, repeat steps 1-5.
6. Let engine run 15-30 seconds.
7. Move blue choke lever to "3".
For a warm engine:
1. Move blue choke lever to "2".
2. Squeeze trigger and pull rope till engine starts.
3. Move blue choke lever to "3".
Once the engine is running, it is a simple matter of pointing the spinning wire towards the vegetation you wish to cut. If you wish to lengthen the wire, tap the bottom of the weed whacker to the ground, and a pre-measured length of wire will be added on. To stop the motor, simply press and hold the off button.
System Functions
After starting the engine, the weed whacker is controlled by a single trigger. This trigger controls the fuel feed to the engine allowing the user to change the rotational speeds of the two-cycle engine.
The power of the engine is transferred to an axle contained in the upper shaft. The axle is held in the center of the shaft using spacers. The end of the upper axle is shaped to slip over the end of the lower axle. The two axles connect using a square cross section that allows the power from the upper axle to completely transfer to the lower axle. To compensate for the possibility of misalignment, the two axles are made to be flexible.
The lower shaft is held to the upper shaft using the shaft clamp. This shaft clamp is screwed directly into the upper shaft, and holds the lower shaft by the metal nub.
At the bottom of the lower shaft, there is a large metal housing. Within this housing, there are four bearings and a set of bevel gears. The lower axle attaches to the bevel gear in the same manner as the two axles. Two bearings are placed on each end to keep the bevel gears in contact. With the gears, the power transfers completely from the lower axle to the weed whacker head.
Attached to the weed whacker head, is a reel that contains a long piece of wire. The wire is fed through two small holes exposing approximately 5 inches of wire. While the head is rotating, the wires are used to cut weeds. Due to the high speeds of the wire, there is no need for sharp edges, as the impact from the wire alone is enough to cut through plants.
Components
Failure Mode Effects Analysis (FMEA)
| Item and Function | Failure Mode | Effects of Failure | S | Causes of Failure | O | Design Controls | D | RPN | Recommended Actions | Responsibility and Deadline | Actions Taken | S | O | D | RPN |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Wire safety | cell 1,1 | cell 1,2 | |||||||||||||
| Bevel Gears | Slip | Wire doesn't rotate | 5 | gears aren't properly aligned | 5 | Unalign gears and turn on | 5 | 125 | Check how much tolerance the shafts give the rod and gears | - | |||||
| Jam | Wire doesn't rotate | 5 | Not enough lubricant | 5 | Remove lubricant and turn on | 5 | 125 | Add more lubricant | - |
Design for Environment (DFE)
There are two main aspects of this product to scrutinize in order to reduce its impact on our environment - usage and production. Since the mechanics of how a weed whacker works are quite simple, there is little that can be done to reduce waste from the usage of this product. The The mechanics that go into a weed whacker are frankly quite simple.
