From DDL Wiki

First Report

We received your report on the paper shredder, and we were impressed with your work; however, your conclusions and recommendations were difficult to locate quickly. We found some of your opportunities quite interesting. Detailed comments follow:

• In our company (and in most companies that we know of) reports will contain an executive summary that typically outlines your conclusions, not just a summary of what topics will be discussed in the report. This would be helpful for us in the next report, since our executives typically do not have time to read the full report.
  • Executive summary has been added in beginning of wiki article
• Many of the aspects of the report appear to be only headings with bulleted lists. We are happy to see your bulleted lists, but we would normally expect to see a paragraph explaining each list and outlining conclusions of each section. For example, there is no introduction under the “product study and dissection” heading to let us know what aspects you are focused on, and does the heading “inputs/outputs” refer to a list of material, energy and information inputs and outputs of the product during normal use? Some explanation would be helpful.
  • Concise introductions or conclusions have been added to each heading to assist the client
• We noticed that the user doesn’t appear on the stakeholder list – is this because it is assumed?
  • We assumed that it was known, but "user" has been added for clarification
• We enjoyed your outline of the operation procedure. What conclusions did you draw from this analysis?
  • We concluded that many of the steps that the user has to do in order to operate the shredder are necessary for safety reasons. Therefore, we should not scrifice safety for ease of use.
• Your description of the functional operation was very clear, although it was difficult for us to tell how the damper switch is activated by presence of the paper. If you could label the part numbers in your assembly picture, it would be a big help. Based only on the report, it’s hard to see how certain components function. Also, how does shredder know to shut itself off if it has been running too long?
  • We added labeled diagrams in the components section of our wiki in order to give the client a greater understanding of the interactions of the various components. The damper switch returns to its starting position after a period of time and the motor is turned off. We also discovered that the paper shredder does not automatically turn off when it runs for a long period of time. (By experiment)
• The videos were very interesting, but what do you conclude from them?
  • Our main conclusion was how difficult it is to feed paper into the shredder. The company added feeder lips to ensure the safety of its users but we feel that there is a way to make it easier to use while maintaining its safety.
• The FMEA looks like an interesting table, but what are your conclusions? Do you recommend taking any or all of the suggested actions? We are particularly concerned about any failures that could present safety issues.
  • From this analysis it can be concluded that even the most catastrophic failure is not detrimental to the user with respect to physical safety and wellbeing. It also shows that there is room for improvement, but it must be determined at what cost. (This was added to the section)
• You have some great ideas for DFE – do you recommend we look into any of these in particular? How would adding a heat sink and bigger fan or noise dampening materials reduce environmental impact?
  • Conserving materials in production is probably the best way to reduce environmental problems. Using alternative energy sources for power would be good but using alternative energy sources for paper shredders will not have a major impact on global environmental problems. Noise panels would reduce noise pollution.
• Great DFX analysis – you really identified a lot of important features and some interesting opportunities for improvement.
  • Thank you
• Good idea with the feeder, does such a product already exist? You have identified some interesting other opportunities like easier emptying of the basket, mounting, and noise reduction - What is the primary source of noise? Motor? Gears?
  • We do not think that this exists in inexpensive desktop shredders. However, this probably exists on larger models.
• Also, please include a free body diagram with numerical analysis of input and output torque and speed in the geartrain. Is the current gear reduction the right ratio?
  • This has been added. We conclude that the ratio is good because if the blades moved much slower, it would take too long to shred and if they moved faster there would not be enough torque to shred multiple pages.

Additional Comments

While you have shown a great deal of detail in your investigation of our product in it's various stages, you are lacking a unifying front page tying together your findings. It should summarize the various aspects of your research simply, presenting the data in an easy to ready format. Your individual sections should also feature short summations. For example, your section on components should have a short preface explaining what materials predominated your product, and how they were made. You might also consider making an appendix in which to place your large charts, leaving only the preface on the main page.

Executive summary and introductions/conclusions for each section have been added.

You mentioned adding a heat sink and fan as a means of solving an environmental problem. However, you also expressed the possibility of cutting down on noise levels. Wouldn't a fan be counterproductive to this goal? And what environmental problem would a heat sink and fan solve? They would dissipate waste heat faster, not reduce it. And if these were added to mitigate possible fire hazards when the shredder has been running for long periods of time, wouldn't this be better placed in the FMEA, or listed as a safety improvement?

We were suggesting different solutions to making a better design. Making a good design involves balancing various factors and we were merely suggesting two different solutions. Heat sink and fan have been removed.

Your Parts listing is very complete, however it is difficult to see how these various parts all fit together. If you were to provide an image in an exploded view, or with the various parts fitted together and labeled, it would make understanding how the product functions internally much easier.

Labeled sub-assemblies have been added for clarification.

Revision

We received your response to our comments on the first report, and we are generally satisfied, but we have some questions. In your analysis, you conclude that “We conclude that the ratio is good because if the blades moved much slower, it would take too long to shred and if they moved faster there would not be enough torque to shred multiple pages,” but we did not see where you calculated torque or how you determined how much torque would be enough. Also, if you do decide to pursue the feeder concept, it is important to first determine with certainty what competing products may be out there.