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First Report

We received your report on the automatic can opener, and we found the analysis interesting, but had some trouble understanding some aspects of the functionality, and we have some questions about your conclusions and recommendations. Detailed comments follow:

• You stated that there is not much opportunity for misuse – have you watched any novice users attempt to use the product without instruction? Do they have any trouble placing the opener on the can properly? What happens if a user attempts to open a can that has been badly dented?
  This is addressed mainly in the executive summary
• You have identified some interesting opportunities, including the limitation of the cycle distance leading to failures of making a continuous cut, and sealing for waterproofing (is this feasible?)
  Touched on in executive summary and possible opportunities
• We appreciate your description of the product’s function, but we found it difficult to follow completely without labels on your picture of the assembly. Also, the description appeared to be incomplete: How is the cutting wheel moved out of the casing? How is circuit maintained after button is released? How does opener know when to stop? A set of free body diagrams would help here.
  

This is addressed in the functional operation portion

• Some component pictures appear to be missing and not labeled in the assembly picture, and it was difficult for us to match some pictures against assembly drawing. For example, we can’t identify what “Movement wheel” is. Parts 008 and 009 seem to show the same picture, and one of the items looks like a plastic part, which would not likely be stamped. If the cutting wheel is only stamped, how is it made sharp enough and strong enough to cut through cans?
  

This is discussed in the components section

• You mention the opportunity of removing some components to reduce assembly time: Which components can be removed?
  

This is now in DFMA

• Your DFMA analysis talked mostly about how parts are made, rather than guidelines for design. What are your conclusions? Is the product already as well designed as possible? We appreciate the idea to reduce the number of fasteners – is this the only opportunity?
  

This was addressed in DFMA

• We found your DFE analysis to be quite vague, and it’s not clear what the recommendations are. What “better components” would you suggest?
  

This was fixed in our DFE section

• You suggested changing the geartrain to reduce the number of components – will this be possible with packaging constraints? What do you suggest?
  

This is in opportunities for improvement

• You suggested improving motor torque? How would you suggest we do this, and what would be gained?
  This is in opportunities for improvement
• You have written an interesting FMEA table, but what are your conclusions and recommendations? One of our primary concerns is what happens if the opener gets stuck? How can the user stop operation mid-cycle – will this create problems?
  

This is addressed in the FMEA section

• 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? How is the force amplified to press the blade through the can, and what piercing force results?

Additional Comments

You have a very full FMEA, with a failure and effect for almost every part. However, is it not possible that a single part can fail in more than one way? For example, couldn't the switches falsely trigger instead of merely not triggering at all? Could this be represented in your FMEA? Additionally, some comments on you FMEA findings would be most welcome.

Your component listing is a little sparse, picture wise, however, you have provided a very nice open shot of the complete gear train. It might be useful if you could label the gears and refer to them in your Listing. It might also be useful for you to calculate the speed reduction, and torque increase that the gears provide, at least up until the intermittent gearing begins, as you mentioned in your improvements.

You mentioned that the opener could be used on larger cans than can be cut in one cycle, and that you may wish to improve on this. Is the magnet capable of lifting up the lids of these larger cans? In the course of cutting, will the lids break leaving jagged edges as a result of improper support due to a weak magnet? Additionally, you have the magnet listed as being cast. However, is this actually how magnets are made?

You have the blade listed as being stamped. Would stamping provide the stiffness, and edge needed to cut metal reliably for any length of time?

Revision

We received your response to our comments on your first report, and we are satisfied with some of the responses, but we were unable to find the requested free body diagram and numerical analysis.