Paper shredder
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Contents
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Executive Summary
The purpose of this information page is to analyze in entirety all manufacturing and working aspects of a paper shredder, specifically the Ativa™ DQ81M Diamond-Cut Shredder, and to subsequently prototype a design modification. This shredder can shred up to eight pages in a single pass. Moreover, it shreds them into .3" x 1.9" diamond shapes. The maximum shred speed is 7.22 feet per minute, and the shredder will accept letter-size and legal-size pages as well as credit cards and staples. The product includes a 4 gallon wastebasket, as well as a manual reverse and auto start/stop switch.
Initially a product study will be done to gain a complete understanding of the product. The study will take into account the components, functionality, and operation procedures of the system as well as more social and economic concepts such as stakeholders, requirements, and purposes. Information regarding the product will not be gained simply through dissection and conception, research will also be done involving other users through focus groups (where users are asked to comment on the experiences had with the product) and observations. Furthermore, the analysis will address the following: Failure Mode and Effects, Designs for Manufacturing, Assembly, Environment, Reliability, Safety, Usability, and Ergonomics. After all the data has been compounded and many modifications have been proposed, the focus will be narrowed and a specific modification will be designed, built, and implemented.
From the analysis, the following conclusions have been drawn:
- There is room for improvements in the system that stem from various problems
- Difficult to feed paper
- Difficult to empty basket
- Motor turns off after excessive use
- Switch control requires dexterity
- Product is well designed concerning manufacturing and assembly
- Cost effective materials and manufacturing processes
- Few excess parts, base used as locater
- Product is simple to operate safely and properly
- With the exception of feeding the paper, system is easy to set up
- If used properly, user should not be able to access blades or motor
- There are areas of possible failure however none pose a likely safety risk
- If used as intended, product is reliable
- Hard, coated blades
- If used as intended, product is easy to maintain
- Easy to lubricate with liquid or oil paper
- Easy to disassemble to change parts
- Product has integrated safeties
- Must be on basket to operate (difficult to get hands into blades through bottom entrance)
- Feeding slot is too small for extremities to fit
- Expected malfunctions are easy to remedy (reverse switch)
Based on the aforementioned conclusions, possible modifications have been proposed. These modifications are based on specific user considerations (people with disabilities or special needs), problems discovered during role playing, input from other users, and other ideas that would facilitate use. The top modification possibilities are as follows:
- Add rotary blade to further refine confetti, which will increase security
- Add a ramp at the bottom of the basket to facilitate disposal
- Add a feeding device where a large stack of papers can be left and fed reliably and continuously into the shredder without user input
- One large blade to replace one hundred smaller blades
One or more of the proposed modifications will be implemented. Further detail is enclosed in the following report.
Product Study and Dissection
The following section is comprised of a complete analysis of the product. The concepts that are covered are:
- Why one would use the product
- General inputs and outputs of the product during operation (if the product were a black box, the things that go in and come out)
- Who the stakeholders are, and what are their needs
- What special considerations should be given to people with disabilities or abnormalities
- How one would normally use the product
- How the product functions
- User based research into understanding the product more
- Focus groups
- Asking people to comment on the product
- Role playing
- Pretending to be a user in various types of situations
- Observation
- Watch general users use the product
- Focus groups
- Component break-down
- Complete list of all components in the product
- Component function
- Component makeup
Conventional and Unconventional Purposes:
The standard purpose of a paper shredder (specifically this one) is to shred paper or credit cards placed properly into the correct feeding slot. However, this is not the only use for a paper shredder. There are many other possible functions a paper shredder can have. Below are some examples.
- Increase security - not able to easily retrieve information from shredded items
- Facilitate disposal - reduce volume of garbage
- Substitute for a recycling bin - provide a separate container for paper wastes
- Produce confetti - save money on party decorations
The foregoing unconventional purposes give more room for thought in possible design modifications. From this analysis it can be concluded that it is not enough to only consider modifications based on the standard use of a paper shredder.
Inputs/Outputs:
In this analysis, the paper shredder is viewed as a "black box". The three types of inputs and outputs are material, information, and energy based. Material inputs and outputs are physical items that go into the system and come out respectively. Information inputs and outputs are data that go into and out of the system respectively. Data can be anything from a user input, for example a keyboard, to an automatic sensor picking up information from the surroundings. Examples of data output are information on a screen, deliberate sounds, and LEDs. Energy inputs are anything that cause functionality, for example electricity, heat. Sometimes material inputs can also be energy inputs, for example gasoline in an engine. Energy outputs can be biproducts of a system, such as heat, or driving outputs such as rotational energy in a shaft from an engine. The inputs and outputs of the paper shredder are as follows:
- Material Inputs: Paper, Staples, Credit Cards
- Information Inputs: Direction of motor rotation
- Energy Inputs: 120V AC
- Material Outputs: Shredded material inputs
- Information Outputs: Operation status
- Energy Outputs: Heat, Noise, Light
Stakeholders:
Stake holders are entities that have some sort of dependency on the product, i.e. a defective product or ailing manufacturer effects the stakeholder causing negative effects such as loss of money, loss of jobs, and/or anguish. Stakeholders in the paper shredder are:
- Possible outsourced companies (computer chips, bulbs, motor)
- Raw materials suppliers
- Retail stores
- Transportation workers
- Stock holders
- User
Needs and Requirements of Stakeholders:
The following section contains some necessities for the stakeholders to be effected positively. Should these needs be met, all parties will be satisfied.
Stakeholder Needs (non-user):
- Light-weight for transportation
- Small size for reduced inventory requirements
- Stackable boxes
- Good profit margin
- Ease of assembly
User Needs:
- Quiet operation
- Low power consumption
- Light-weight shredder to facilitate disposal of shreds
- Ensured safety
- High degree of difficulty for anyone, especially children, to insert extremities
- High degree of difficulty for unintended items to fall into shredder, e.g. ties
- Secure housing to contain any detrimental failure
Product Requirements:
Due to insufficient information, Product Requirement data will be generated within the next month.
Specific User Considerations:
Below are some design concerns that consider people with abnormalities, disabilities, or special needs.
- Certain tasks difficult for people with a neural disorder and/or coordination difficulty
- Feeding tasks
- Switch control
- Bending over to feed items difficult for individuals with orthopedic (e.g. back) and/or balance problems
- Inconvenient and inefficient for large corporate tasks
- Main shredder assembly is heavy and possibly difficult to lift for weaker individuals
- Main shredder assembly must be lifted when emptying basket and setting up
- Main shredder assembly may often be moved depending on storage preference
Operation Procedure:
The following is a step by step procedure to using the product based on the most likely scenarios: storing the shredder without the power cord plugged into the electrical wall outlet, storing the product plugged in and in the off position, and storing the shredder in the "auto" position which keeps the shredder off until a sensor is triggered by feeding an item which turns on the motor. This process does not take into account where the shredder is stored, for example if it is unplugged it does not matter if it is stored under a desk or in a cabinet- these factors effect other design considerations such as weight. From the list below, it can be seen that the basic operation of the product is straight forward and there are not many modifications that can be made to make it easier.
Functional Operation:
There are three switches in the electrical circuit that must be activated to begin shredding. First, the shredder must be properly resting on the waste bin to toggle the safety switch, and then the off/auto/reverse switch that allows power to go to the shredder must be moved to "auto". Finally, the paper being put into the shredder compresses an air damper which trips the third switch and sends power to the AC motor. The damper slowly depresses and when it is fully extended the switch is released, terminating the shredding process. The AC motor drives a gear train that reduces the speed of the shaft rotation and increases the torque. The first two gears are helical gears in order to reduce noise. At the end of the gear train, two spur gears are meshed and attached to individual shafts with cross-hatching blades. The blades are in a wave shape that cuts paper into the desired diamond shaped shreds. The blades spin in opposite directions and the paper is fed in between the spinning blades. The shredded paper falls into basket.
The following video is a clip of the shredder operating without the top cover on. This video shows how the gears spin, how the shreds are dispensed, and the basic working operation of the product. http://www.youtube.com/watch?v=G7R82fCtcRc&feature=PlayList&p=501153C70A89F93B&index=3
The following video is a demonstration of how the on/off sensor works. There is a trigger that is depressed by the paper when it is inserted, which in turn compresses an air valve. While the trigger is down the motor is on. The motor stays running while the air valve slowly fills up with air, consequently slowly lifting the trigger. This ensures that the paper will pass through entirely before the trigger is reset and the motor turns off. http://www.youtube.com/watch?v=07vDsKt7tHU&feature=PlayList&p=501153C70A89F93B&index=5
Below are pictures of the system partially disassembled. See below in the components section for pictures that are labeled for clarification.
Angular Velocity Calculation and Free Body Diagram
Gear Train
Free Body Diagram
Given:
- Feed Speed = 7.22 ft/min
- Blade Radius = 0.5 in
- N = number of teeth on gear
Find:
- Angular velocity of motor shaft
Solution:
7.22 ft/min = 1.44 in/s
Circumference of Blade = (2)(π)(0.5 in) = 3.14 in
ωBlade Shaft = (1.44 in/s)(1 revolution/3.14 in)(2π rad/revolution) = 2.89 rad/s
ωShaft 2 = (2.89 rad/s)(31/6) = 14.93 rad/s
ωShaft 3 = (14.93 rad/s)(25/7) = 53.32 rad/s
ωMotor Shaft = (53.32 rad/s)(36/4) = 479.89 rad/s
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.
Research:
Role playing:
The design team performed various trials in which the shredder was tested in different situations.
In the following video, one tries to use the product normally. Notice the difficulty for an experienced user to even shred a single page. This highlights an area that can be improved. http://www.youtube.com/watch?v=ZJsL37RSc_U&feature=PlayList&p=501153C70A89F93B&index=0
In the following video the same expert user shreds two credit card, which is noticeably easy. http://www.youtube.com/watch?v=j1troZx-K_M&feature=PlayList&p=501153C70A89F93B&index=1
In the following video the team decides the optimal way to jam the shredder. After successfully causing a malfunction, the user then tries to fix the problem in two ways. First, the user just pulls straight up on the paper, opposing the direction of feeding. This attempt is unsuccessful. The second solution is to put the motor in reverse, which fixes the problem easily. http://www.youtube.com/watch?v=qkPbcWVmai0&feature=PlayList&p=501153C70A89F93B&index=2
These videos highlight many important notes, most importantly, that even for a normal user it is significantly difficult to shred one page.
Components:
As part of the first stage of disassembly, we documented the inner workings prior to removing each individual component. The first image shows the shredder with the top removed and certain key components labeled. The second is a detailed close-up of the gear train. Refer to the table below for more details on individual components identified in these pictures.
The following table contains each individual part present in the product. A brief description of each part and its function will help determine whether any of the components can be refined for future designs to make it less expensive or possibly remove it all together. The current design contains many injection molded plastic parts, so their dimensions are quite important because any reductions will save significantly off the cost of materials. It can be also be seen that a large, important part of the system is purchased (the motor and electronics).
| Part # | Part name | QTY | Function | Materials | Dimensions | Manufacturing Process | Picture |
|---|---|---|---|---|---|---|---|
| 001 | Top Cover | 1 |
| Plastic | 12" x 5" x 1" | Injection Molding | 
|
| 002 | Switch Housing | 1 |
| Plastic | 3" x 1" x 1" | Injection Molding | 
|
| 003 | Base | 1 |
| Plastic | 12" x 5" x 3" | Injection Molding | 
|
| 004 | Feeder Lip Top | 1 |
| Plastic | 8" x 2" x 1" | Injection Molding | 
|
| 005 | Feeder Lip Bottom | 1 |
| Plastic | 8" x 2" x 1" | Injection Molding | 
|
| 006 | Child Safety | 1 |
| Plastic | 2" x 1" x 1" | Injection Molding | 
|
| 007 | Electrical & Motor Sub-assembly | 1 |
| N/A | N/A | Purchased | 
|
| 008 | Helical Gear | 1 |
| Plastic | 1" x 1" | Injection Molding | 
|
| 009 | Large Spur Gear | 1 |
| Plastic | 3" x 1" | Injection Molding | 
|
| 010 | Small Spur Gear | 1 |
| Plastic | 1" x 1" | Injection Molding | 
|
| 011 | Output Spur Gear | 1 |
| Plastic | 1" x 1" | Injection Molding | 
|
| 012 | Light Bulb Reflector | 1 |
| Plastic+Aluminum | .5" x .5" x 1" | Injection Molding and Sheet Foil | 
|
| 013 | Delay Trigger Housing | 1 |
| Plastic | 3" x 1" x 1" | Injection Molding |
|
| 014 | Cutoff Switch Time-Delay Trigger | 1 |
| Plastic | 1" x 1" x .5" | Injection Molding | 
|
| 015 | Spring for Child Safety Switch | 1 |
| Spring Steel | 1/8" x .5" | Winding | 
|
| 016 | Bow-Tie Washer | 1 |
| Plastic | 1" x 1" x 1/8" | Injection Molding | 
|
| 017 | Main Shaft Base Plate | 1 |
| Plastic | 3" x 3" x 1/4" | Injection Molding | 
|
| 018 | Cover Plate for Shaft Alignment | 1 |
| Plastic | 2" x 2" x 1/4" | Injection Molding | 
|
| 019 | Gear Train Housing Base Plate | 1 |
| Metal | 4" x 2" x 1/4" | Stamped | 
|
| 020 | Gear Train Housing Top Plate | 1 |
| Metal | 3" x 1" x 1/4" | Stamped | 
|
| 021 | Attachment Aligner for Motor Base Plate | 1 |
| Plastic | 1" x 1" x 1/4" | Injection Molding | 
|
| 022 | Screws | 31 |
| Steel | #10-20 | Machined |  In the background
|
| 023 | Helical Blade | 104 |
| Steel | .5" x 1\32" | Stamped | 
|
| 024 | Flat Blade | 8 |
| Steel | .5" x 1\32" | Stamped | 
|
| 025 | Paper Aligners | 54 |
| Plastic | 1/2" x 1/4" x 1" | Injection Molding | 
|
| 026 | "Paper Aligner" Aligning Rod | 2 |
| Metal | 1\4" x 8" | Extrusion |  Gold rod
|
| 027 | Long Main Shaft | 1 |
| Steel | 10" x 1/4" | Machined | Center rod
|
| 028 | Short Main Shaft | 1 |
| Steel | 9" x 1/4" | Machined |  Center rod
|
| 029 | Basket | 1 |
| Steel | 12" x 12" x 5" | Stamp |
|
| 030 | Tab | 1 |
| Steel | 1/2" x 1/2" x 1/2" | Stamped | On the basket
|
FMEA: Failure Mode and Effects Analysis
The following table contains our analysis of the most serious failures we predict the current design could experience. In this analysis, we explain how various parts may fail and what the consequences of those failures would be. By addressing the more important possibilities, future designs of this product may be made more reliable. 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.
*The Resulting RPN is an estimate.
| Item & Function | Failure Mode | Effects of Failure | S | Causes of Failure | O | Design Controls | D | RPN | Recmd Actions | Responsibility & Deadline | Actions Taken | S* | O* | D* | RPN* | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Motor
| Electrical failures: Short circuited | Product ceases to function reliably. Shredding no longer possible. | 8 | Intense heat and/or vibrations loosen connections, resulting in intermittent operation. | 4 | Run under extreme working conditions | 3 | 96 | Add solder to strengthen connections. Add dampening to decrease effect of vibrations | Motor manufacturer prior to purchase | - | 8 | 3 | 3 | 72 | |
| Mechanical Failures: Wear. Fatigue. Fracture. | Inoperative. Noise. | 8 | Gear train shears helical gear. Thermal deformation from heat generation. Shredding unapproved items | 3 | Test at high rpm with strain gage and thermocouple | 5 | 120 | Treat motor axis to add strength | Motor manufacturer prior to purchase | - | 8 | 2 | 5 | 80 | ||
| Main shafts | Mechanical Failures: Thermal. Creep. Corrosion. | Depending on degree of failure, blades may begin to clash or will function at a reduced capacity. Noise. Unstable. | 7 | Heat. Applied load from gear train. Shredding unapproved items | 2 | Feed solid items. Run under extreme conditions | 6 | 84 | Treat rod to increase strength. Increase diameter | Machinist(s) prior to installation | - | 7 | 1 | 6 | 42 | |
| Helical gear | Mechanical Failures: Shearing. Thermal. Wearing. Plastic deformation to out of spec | Under complete mechanical failure, gear train will not be connected to the motor. Under partial failure, will have possible slippage which will result in inefficient operation and noise | 7 | Heat from motor. Vibrations. Forces from gear train. | 4 | Drive gear at high rpm and/or under intense working conditions | 3 | 84 | Thicker injection mold to make gear larger. Use stronger plastic. | Injection molder(s) prior to installation | - | 7 | 2 | 3 | 42 | |
Shredding cutoff time-delay
| Electrical failures: Short circuited | Product ceases to function reliably. Shredding no longer possible. | 8 | Intense heat and/or vibrations loosen connections, resulting in intermittent operation | 4 | Run under extreme working conditions | 3 | 96 | Add solder to strengthen connections. Add dampening to decrease effect of vibrations | Switch manufacturer prior to purchase | - | 8 | 3 | 3 | 72 | |
| Mechanical Failures: Creep. Fatigue. Deformation. Shear. | 8 | Flat metal spring fatigues leading to fracture. Thermal deformation from heat generation. Plastic deformation from shredding unapproved items | 4 | Compress and expand spring repeatedly and under extreme conditions | 3 | 96 | Treat metal to strengthen. Increase thickness of spring. | Switch manufacturer prior to purchase | - | 8 | 2 | 3 | 48 | |||
| Helical Blade | Mechanical Failures: Shearing. Fatigue. Thermal. Wearing. | Fracture of blade will result in inefficient, but continued, function. Bending of blade can result in wear against other blades, which can also result in a chain reaction leading to complete failure. | 7 | Bending and shearing can result from shredding unapproved items. Fracture and malfunctions can also result from malfunctions of other components such as the main shaft or gears. | 4 | Shred unapproved items. Work at high rpm. Shred lots of paper and/or credit cards | 5 | 140 | Thicker blades for strength. Smaller opening so unapproved items are harder to fit. | Blade stamping department | - | 7 | 2 | 5 | 70 |
DFX: Design for 'X'
In this section, all the relevant factors to consider during the design of this product will be addressed. Each subsection will focus on one particular element, such as the environment, manufacturing, or safety. By analyzing the design process from each of these angles, where the most important changes need to be made to improve the product will be determined.
DFE: Design for Environment
The DFE analysis takes into account all possible environmental issues with the product, both big and small. From what is known about the product it can be concluded that there are no grave environmental issues, however some possible solutions to the recognized problems are proposed below the listed issues.
Possible Environmental Problems:
- Power usage
- Possible harmful byproducts of manufacturing processes
- Pollution from production
- Leftover materials
- Odd shapes make it difficult to transport product pre-packaging, which uses more fuel and resources to transport fewer items.
- Noise production (office environment)
- Disposal of product at end of life
Possible Environmental Improvements:
- Use alternative energy sources (solar power)
- Use less power if possible
- Use recyclable/recycled materials
- Reduce amount of material used
- Add noise dampening materials to inside of shredder
- Make parts shaped such that as many stamped parts as possible can be stamped on one sheet
- Make stackable parts
- Use leftover materials for other parts
DFMA: Design for Manufacturing and Assembly
DFMA is a strategy used to determine how to simplify a design and/or manufacturing process to achieve cost savings. It can improve supply chain cost management, product quality, product manufacturing, and communication between all branches of the production process- design, manufacturing, purchasing and management.
Design for Assembly (DFA):
Design for Assembly aims to optimize the manner in which products are assembled, which is desirable since assembly costs money. Some examples of how assembly can be optimized are: containing fewer parts (snaps instead of screws), use a base piece for locating other parts, and design components for handling and mating. Below is a list of how it is believed DFA was applied to the design of the Ativa™ DQ81M.
- Clear Subassemblies (Modularity)
- Stacked gears (two gears that are on top of each other, teeth not meshing) are molded as one solid piece
- Reduces number of components
- Blades and paper aligners have grooves that match extrusions on the main shaft which facilitate nesting and assembly
- Prealigned
- Plastic housing used as base for other components
- Pieces fit together and mate without fasteners
- Base has nesting features
- Base webbed to increase rigidity
- Electrical assembly is held between the top and bottom covers, which speeds up assembly by eliminating fasteners
From the foregoing it can be concluded that the DQ81M has been designed well for assembly. It is assumed that during the assembly process no unnecessary rotation is necessary. Furthermore, there is little room for improvement. It is hypothesized that the reason there are still a few screws instead of all snaps is primarily for maintenance and disassembly. A strong DFA design must optimize DFA with respect to other considerations; it is believed that the DQ81M does that.
One possible modification that can be made with respect to DFA is to have the feeder lips be one part (which would eliminate one part). In addition, the product would be easier to assemble if there was one large blade instead of fifty individual blades.
Design for Manufacturing (DFM):
DFM is the process of optimizing the design of the system for ease and efficiency in manufacturing while still producing acceptable parts. An acceptable part is one that meets the design requirements as intended. One concern in DFM is specifying the optimal manufacturing process for the part in question. An optimal manufacturing process is dependent on cost, environmental impacts, waste, product quality, and time. As one can see, the aforementioned dependencies are not all independent. Below are some examples of how it is believed DMF was used in the design of the Ativa™ DQ81M.
- Blades
- Due to demand number, they are stamped for cost efficiency with respect to time, waste, and personnel (opposed to machined, extruded, or forged for example)
- Design of blade allows for only one design in which the helical blades nest inside each other, causing the diamond-cut shred
- Plastic parts are made by injection molding for cost efficiency in mass production
- The tolerance between the main shafts and the components that rest on it (blades and aligners) does not have to be tight because grooves machined into shaft and blade for good fit
- Allows more parts to "go", i.e. fewer parts discarded for not fitting specifications- "go" vs "no go"
- Do not have to change manufacturing bits as often
- The tolerance between the "paper aligner" aligning rod and the paper aligners is loose because the main shaft keeps the aligners together; aligning rod simply keeps them vertical
- Allows more parts to "go"
- The mold for the stacked gears (when two gears run off the same shaft and are next to each other, teeth not meshing) causes the two gears to be manufactured as one piece
- Allows for fewer parts to be made (also an assembly consideration)
- Only have to worry about tolerances on one part instead of two
- There are no complex metals or plastics that are difficult to work with
From the aforementioned it can be concluded that the DQ81M is well designed for DFM. The raw materials and manufacturing processes (when applied to bulk) are cost efficient, the components are designed to mitigate excessive actions (e.g. stamping processes), and the tolerances are loose enough to have a low out-of-spec percentage. One main improvement that can be made to the DQ81M’s DFM is to have, again, one large blade. Having one large blade would only require two parts to be manufactured vs. the 104 that exists now.
Possible Areas of Improvement
Though it can be concluded that the design of the Ativa™ DQ81M has accounted for DFMA well, there are still improvements that can be made, especially with regards to assembly. Below are two possible improvements.
- Blades
- The 50 separate blades which need to be put onto a shaft should be joined together first
- Possible to coalesce all the blades to form one large rotary blade with small serrations periodically
- The feeder lips can be made from one piece instead of two
Design for Maintainability:
Design for maintainability is primarily concerned with designing the product so it is easy to maintain, which consequently increases the first life span. As one can see, all of the above DFXs are not independent, in some way or another they overlap. For example, increasing the first life span benefits the environment.
- Easy to assemble and disassemble
- Facilitates changing parts
- Facilitates thorough cleaning
- "Paper shredder oil" is available to keep the blades and rods well lubricated
- A piece of paper dipped in mineral oil
- Liquid lubricant that can be poured into feeder lips
- Blades are coated to resist corrosion
- Screws are used instead of rivets or snaps which are easier to take in and out
- Design is modular, parts are easily accessible
- Overall design of product is simple
For increased DFM, the manufacturer could use less components, thus less parts would need to be replaced.
Design for Reliability:
Design for reliability takes into account designing the product so it can have an increased first life span with minimal maintenance as well as operating without failure. Some ways the product was designed to operate reliably are:
- White paper aligners ensure that paper is fed straight through blades
- Blades have notches on them that catch the paper to feed it through consistently
- The gears are very well lubricated to ensure consistent, quiet meshing
- Tolerances in the manufacturing of parts for proper alignment
- Blades appear to be corrosion resistant
- Small slots in feeder lips prevent user from inserting most unapproved items
- Motor shuts off once product runs for extended period of time
Another way the product can be made more reliable is to increase the torque in the gear ratio. This will ensure that there is enough force to pull the paper through. Again, one large blade would satisfy this requirement.
Design for Safety:
Design for safety is used to address any safety concerns that can occur due to unforeseen, unconventional use or failure. This is a very important consideration because the welfare of the user is held most paramount at all times.
- The on/off/reverse switch is "child-proof"
- The user must press a button and slide the switch in order to move it
- There is a protective cover over the blades so that fingers cannot fit inside the paper slot but paper and credit cards can
- Electrical components are housed inside of the shredder
- Shredder has a safety switch that does not allow shredding to occur unless the shredder is on basket
- Prevents access to blades while running
- When shredder is on for a prolonged period of time, it shuts off automatically for a fixed amount of time for motor to cool
- All components are housed, so any failure will not result in personal injury, just performance issues
- Warning labels printed into top case, so always visible when using
The design for this product addresses the safety issue very well. One possible improvement, though, would be a warning noise when the system malfunctions.
Design for Usability / Ergonomics:
Design for usability and ergonomics is concerned with designing a product that is easy and comfortable to use. Considerations do not only have to be functional, they can also be aesthetic.
- Shredder mounts easily on top of basket
- On/off/reverse switch is on top of shredder for easy access and is well shaped for easy control
- Shredder has convenient slot for paper and convenient slot for credit cards
- Basket height is such that it can hold a lot of paper but still fit under the user's desk
- Lightweight and portable for average users
- LED informs user of status of system
Regarding average users, the ergonomics are terrific and the product is easy to set up for use. However, the product is not well designed for users with special needs, as has been addressed previously. The basket is too heavy and the switch is hard to manipulate. The paper is hard to feed regardless of user, which is a major concern for design for usability.
Modification:
This section contains our suggestions for improvements that could be made to the current design to overcome its shortcomings. Our recommendation for the most significant improvement would be to add a feeding mechanism to the shredder. We found some users had trouble feeding the paper manually, plus sitting around shredding large quantities is an inefficient use of time. Both these issues would be remedied by adding an automatic feeding mechanism. The user could easily load the paper, not having to struggle with it trying to get the teeth to grab it, plus they could load large stacks and move on to other tasks.
Areas of Possible Improvement:
Although, the paper shredder has many design elements geared toward safety, efficiency, security, and ease of use, there are many areas that can be improved.
- Improved shredding capability for added security
- Rotary blade in which confetti is funneled into
- Pulp making apparatus
- Water jet (maybe acetone)
- Stirrer
- Decrease heat generation (when shredder overheats, safety mechanism kills motor till it has cooled significantly)
- Fan and vents
- Way to empty basin without taking off top
- Wall-mounting capabilities
- Weight issues of shredder assembly which affect portability, storage, and emptying waste basket
- Use a lighter material than machined steel for main rods
- Titanium
- Plastic
- Composite
- Smaller motor
- Lighter blades
- Composite
- Titanium
- Use a lighter material than machined steel for main rods
- Decrease noise pollution of system
- Line shredder with sound-dampening material
- Foam
- Line shredder with sound-dampening material
- Improved feeding capabilities
- Large queue where can position multiple sheets that will automatically feed
- Examine a printer and fax feeder
