Microphone
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== Team Members and Roles== | == Team Members and Roles== |
Revision as of 00:56, 21 September 2009
Contents |
Executive Summary
-Dan
this page needs a fricking backlink!
Engineering_Design_II_-_Conceptualization_and_Realization_Course
Stakeholders
The major shareholders of microphones and microphone stands are the consumers, retailers, manufacturers, transporters and society.
Consumer
- Ease of use - Microphone must be easy to use, stand must be easy to orient.
- Ease of assembly - Microphone should be plug and play, stand should be easy to put together.
- Effectiveness - Microphone should pick up sound without user having to be too loud, stand should hold microphone in desired place.
- Ease of storage - Microphone should not need any special storage, stand should be collapsible/occupy less space.
- Reliability - Products should perform consistently without maintenance.
- Safety - Product should not harm the user in any way.
- Cost - Microphone is priced depending on its sensitivity but should be affordable, stand should be priced reasonably depending on quality.
- Customization - Products should have replaceable or interchangeable parts for use in multitude of settings.
- Portability - Products should be lightweight but sturdy enough to be transported.
Retailers
- Appeal - Products should attract customers.
- Profit margin - Products should produce a profit so there is reason to carry product in store.
- Storage - Products should be easy to stack and store.
Manufacturer
- Material cost - The materials should be cheap and easy to obtain to maximize production and keep price down.
- Manufacturing cost - The methods of manufacture should be cheap and efficient.
- Standardization - Parts should be standardized to reduce complexity of design.
- Assembly - Products should be easy to piece together in the factory.
- Time for manufacture - Time should be minimal to produce in large quantities.
Shipping/Packaging
- Weight - Products should be light to reduce transportation costs.
- Durability - Products should be able to survive transit.
Society
- Social Media - Musical concerts, gatherings, sports games, etc., that are dependent on capturing sounds to reach masses require reliable microphones.
- Long distance communication - Reliant on microphone processing sounds so it can be transmitted to another location.
Product Function
Boom Stand:
The purpose of the boom stand is simple: to be able to hold the microphone still in various orientations according to the user’s need. The boom stand which we dissected was designed to have 5 degrees of freedom, allowing the user to position the microphone in diverse settings. The stand and extension allows the user to adjust the total height of the two to a desired height between 33-61 inches. The joint connecting the boom shaft and stand has 3 degrees of freedom, allowing the shaft to pivot, rotate, and translate along its axis. The last degree of freedom is at the microphone holder, allowing the user to orientate the microphone at various angles. The microphone can be positioned at a low height downward angle for miking a drum set or high at various angles depending on the user’s height for stand up.
There are two rubber pads inside the joint connecting the stand and shaft. The friction between the surfaces of the two pads and the boom holder is strong enough to keep the entire boom stand above it still. At the same time the user can easily adjust (pivot) it. If there is too much force, whether it be too heavy of a load or a person pushing on it too hard, the force will simply overcome the frictional force and move the shaft so it won’t be directed to the pipes. One would almost have to be intentional to bend the steel pipes of the microphone stand.
The last benefit of the stand is that it is foldable and can be taken apart.
User Study
Setting up the microphone stand was relatively easy. Everything was intuitive and its 5 degrees of freedom allowed for all the desired orientations. The addition of the boom arm allowed the microphone to be raised over 7 feet, accommodating most users. Attaching the microphone clip to the boom arm wasn't as straightforward. Microphone clips are not standardized, different manufacturers make different sizes, causing us to go out and buy another microphone with an appropriate size.
During the testing of the microphone system, we found that:
- Microphone was not very sensitive, we had to talk fairly loud for it to register.
- Microphone will not pick up speech-level sound from more than a foot away.
- The joint in the microphone clip is very loose, its hard to keep the microphone in position.
- Solder inside microphone was loose, microphone stopped working after a few on-off switches.
- Microphone picks up a lot of static, background noise.
- It makes me sound so bad.
Assembly
-Justin
- Note: Refer numbers from the Part List Section
Mechanical Analysis
-Nakul
Parts List
-Dan & Justin
Design for Manufacturing and Assembly (DFMA)
Design for Manufacturing
Materials: Plastic and Metal
Engineered products can be made out of a variety of materials. Depending on the application the choice of materials can allow a product to perform well or cause it to fail. Even among appropriate material choices, some materials have advantages over others for a number of different reasons. The parts that construct the boom stand and microphone are mainly constructed of either plastic or steel. In general, plastics can be good for inexpensive, complex shapes, while metals are good for it's durability and long lasting applications.
The category of plastics as a whole also has advantages and disadvantages. It is generally relatively easy to create highly complex plastic parts, with both small and large features, and with high aspect ratios. This is because plastics are easily molded in a variety of ways. Plastics also tend to be less dense than metals. From an aesthetic perspective, some plastics can be used to create unique shapes for beautiful products. However, many people tend to associate plastics with cheaper products, which can be both an advantage, or a disadvantage. For example, plastic is a good material choice for single-use forks and knives, but these utensils will never look as good as metal utensils. A major disadvantage of plastics is that they are usually made out of petroleum, which is an unsustainable resource. However, progress is being made in creating plastics from organic materials.
Another major materials category is metals. Metals tend to be very strong in both tension and compression, and tend to have a very long life span. They are less likely to deform than plastics, which makes them good for high-precision applications. From an aesthetic perspective, metals have a unique place in the human psyche. Metals also have a unique luster that people often find very appealing. The major disadvantages of metals are the potential to rust (depending on the type of metal), and the fact that they need to be mined, which can often be an inefficient process that causes a lot of environmental damage.
Microphone:
During the disassembly, one issue we encountered was removing part M6 from the body. M6, a rubber disc used to hold the pins in place, seems to have been attached to the base via ultrasonic staking. Ultrasonic staking is a process by which
figure out what manufacturing process this is-------
Although this manufacturing method makes disassembly difficult, it is ideal for this product. The pins need to line up perfectly with the holes in the cable, possibly thousands of times during the product's life span. This means that the rubber disc must not be allowed to shift within the body. Even thought the disc is already press-fit inside the body, it is important that it is securely joined as well.
One possible area of improvement is in the soldering of electrical components and wires. Inconsistency in the soldering could be a sign that this was performed by hand. Automating this process would not be very difficult; both the chip and the switch electronics are rectangular. Considering the high volume of microphones being produced, it would be feasible to create a soldering rig that would quickly attach wires to the components.
Boom Stand:
The few parts that plastic (handle and end of thumbscrews) along with the rubber ends on the bottom are most likely made through injection molding. Injection molding provides a high volume mass production of identical parts with very low tolerance. The initial tooling costs are very high but the unit costs are low (meaning a high initial fixed cost but in exchange the marginal cost per unit is sufficiently low), thus when a large quantity of identical parts are produced injection molding will save money in comparison to other processes.
The counter weight on the end of the boom shaft and the tripod core are both solid pieces of metal made through the casting process. The counter weight is then either press fitted or glued onto the end of the boom shaft. The casting process (my guess is die casting) has a similar manufacturing feature as injection molding cost-wise. They are generally a high volume production with high initial tooling costs but low unit costs.
All the steel tube components have identical thicknesses and diameter, meaning that they can all be produced by the same machinery while each part is cut into the desired length. The raw steel is cast then made into a pipe by stretching the steel out into a tube. The steel tubes are seamless, which are suitable for the job as the shafts for being strong, durable, and light weight. The exterior of all steel components are sprayed on a metta-black finish for a good look to appeal to the consumers.
Design for Assembly:
The assembly of the parts can be either by man or machine. In our opinion, it would make more sense to use man power instead of having the assembly process be automated. To our surprise, the after the stand was dissected and analyzed it took less than 5 minutes for a single person to reassemble everything part together. Pliers were the only tool needed for the process, used for tightening bolts.
Failure Modes and Effects Analysis
Considering ways in which a product could potentially fail is an important part of the design process. All products should be designed so that they are safe and reliable for use. Potential dangers must be eliminated before production. FMEA reports identify potential failure modes and assign corrective measures. Risk priority numbers (RPN) are calculated (S*O*D) and then assigned to each failure mode to assure proper prioritizing. Higher RPNs are addressed first. The scale used for measuring S,O,D can be found in the Engineering Design textbook by Dieter and Schmidt. <ref>Dieter, E and Schmidt, L (2008). Engineering Design. Fourth Ed. McGraw-Hill.</ref>
S= Severity of Failure
O= Probability of Occurrence
D= Detectability of Failure
Assembly/Parts | Failure Mode | Consequence of Failure | S | Causes of Failure | O | Prevention | D | RPN | Recommendations | Responsibility |
---|---|---|---|---|---|---|---|---|---|---|
On/Off Switch | Soldering Becomes Loose | Microphone will not turn on | 5 | Bad soldering | 2 | N/A | 2 | 20 | Check soldering before assembly | Controls engineer |
Diaphragm | Torn Diaphragm | Inoperable | 5 | Misuse or Outside particles gets inside microphone | 1 | Foam Cover | 2 | 10 | N/A | N/A |
Wire Coil | Torn | Microphone inoperable | 5 | Improper use/production | 1 | Testing during production | 6 | 30 | N/A | Controls Engineer |
Wire Coil | Inadequate coating to separate each wire | Decreased electromagnetic effect | 4 | Improper use/production | 1 | N/A | 8 | 32 | N/A | Controls Engineer |
Magnet | Looses magnetism | Decreased sensitivity of microphone, inoperable | 4 | Over time or microphone is subjected to strong magnetic field | 1 | N/A | 7 | 28 | Don't go near extreme magnetic fields | N/A |
Microphone Housing | Broken | Microphone in pieces, wires exposed | 5 | Impact | 1 | N/A | 1 | 5 | Do not drop on floor after serving someone | N/A |
Microphone Clip | Loose Joint | Unable to orient to desired location | 3 | Loose Screws, wear from use | 6 | N/A | 1 | 18 | Tighten Screws constantly, add friction to joint | Controls Engineer |
Microphone Clip | Broken clip | Unable to attach to microphone | 4 | Improper use, impact | 4 | N/A | 1 | 16 | N/A | N/A |
Boom Stand Screw | Loose fastener | Unable to stay in position, falls down | 7 | Improper use, wear | 3 | Rubber pads inside boom housing | 2 | 42 | Replace rubber pads to ensure boom stays gripped in position | N/A |
Extending Stand | Grip fails | Stand does not stay extended | 7 | Wear from lots of use | 2 | Exploded end | 1 | 14 | Add rubber stoppers or grips | Design Engineer |
Rubber Pads | Worn down thickness | Boom shaft is unstable, gravity overcomes friction force | 3 | Worn pads | 1 | N/A | 1 | 3 | Do not pivot shaft aggressively or unnecessarily | N/A |
Rubber Ends | Torn or lost | Stand may slide | 2 | Worn down ends | 1 | N/A | 1 | 2 | N/A | N/A |
Cord Clip | Broken or lost | Loose Cord | 1 | Misuse | 1 | N/A | 1 | 1 | N/A | N/A |
All steel/metal parts of stand (Stand, tripod legs, boom arm , etc) | Oxidation | Aesthetic value, uncomfortable to touch | 3 | Neglect, exposure to water | 2 | N/A | 1 | 6 | Anti-rust finishing | Controls Engineer |
From the generally low RPNs, we can see that this product is extremely safe and only has one part (falling boom stand) that could potential harm the user. Most problems can be avoided with a product test before packaging.
Design for Environment
In designing a product, it is important to consider the environmental effects along with the consumer. Conducting a Life Cycle Assessment (LCA) can improve the product's environmental-friendliness and reduce costs in the long run.
Toxic Release
This table and graph show the amount of toxic release into the environment. Note that the amount released by specifically the manufacture of audio-video equipment is minuscule compared to the other sectors involved.
Greenhouse Gas Emissions
Greenhouse gases, such as carbon dioxide and chlorofluorocarbons, contribute to the prevalent problem of global warming. With a $1 million injection into the Audio-Video Manufacturing sector, the overall global warming potential (GWP) increase by 574 metric tons of CO2 equivalent.
As we can see from the graph above, the actual audio-video manufacturing process only contributes 19.7 MTCO2E, less than 4% of the total. Most of the emissions come from power supply. If a CO2 tax was passed, the manufacture of audio-video might take a hit, but not as hard as most of the other sectors.
Air Pollutants
Conventional air pollutants such as carbon monoxide largely affect weather patterns like causing smog which in turn can cause respiratory and other health problem in affected areas. Most of the problem comes from power generation and the manufacture of petroleum. Audio-video manufacturing was not even in the top 10 pollutant sources.
Conclusion and Recommendations
Team Members and Roles
Luo Xing Ni- DFE, Stakeholders, FMEA, User Study
Daniel Liptz- Parts List, Executive Summary, Conclusion, DFMA
Justin Yi- Parts List, Executive Summary, DFMA, Product Function
Nakul Gupta- Mechanical Analysis, Product Function
References
<references/>