Group 20 CR

Coordination Review

The main purpose of the Coordination Review is to have the group analyze the components of the printer in order to see what works well, what could be improved, and what further forms of analysis can be completed in order to get a better understanding of the product. The Component Summary lists all of the components of the printer, including what they are made of as well as their manufacturing process, while the Component Summary Reflection further discusses what was found inside the printer. Using these components, Solid Models can be made to show how part of the printer is assembled in sequence, while Design Revisions can be made by the group based on total analysis of the product. Finally, Engineering Analysis can be used in order to show how further testing and analysis can be done on the HP Deskjet 960c Printer.

Component Summary

After disassembly of the printer, 57 components with important functions were found and documented. The full listing of these components can be found below, in Table 3: Components of the Printer.

Table 3: Components of the Printer

Part #	Part Name	Quantity	Function	Material	Manufacturing Process	Image
1	3/4" Torx 10 Screw	2	Hold top casing on printer	Steel	Machining
2	Outer Casing	1	House internal components of printer; protect printer from dust	Plastic	Injection Molding
3	Power Cable	1	Provide power to the printer	Plastic outside, copper inside	Injection Molding, Insertion of wire into cord
4	Ink Cartridges	2	Provide ink to be used for printing	Plastic	Injection Molding
5	Back Panel	1	Allow access to back of printer in case of a paper jam	Plastic	Injection Molding
6	Paper Guide	1	Guide paper out of printer as documents are printing	Plastic	Injection Molding
7	LED and Button Assembly	1	Allow user to turn printer on and off, cancel a print job, and show when ink in printer is low	Plastic, Silicon for buttons	Injection Molding
8	Parallel Port and USB Cover	1	Protect the main circuit board from outside damage from connecting cables	Plastic	Injection Molding
9	Thin Silver Bar	1	Pulls print head assembly into a vertical position	Steel	Die Casting
10	1/8" Round Head Torx 10 Screw with Ridge	2	Hold thin silver bar in place on top on printer	Steel	Machining
11	Large Motor	1	Provides power necessary to move ink cartridges back and forth across print head assembly	Steel	Machining
12	3/16" Flat Topped Torx 10 Screw	2	Hold large motor in place	Steel	Machining
13	Power Port and Circuit Board	1	Takes power from the power cable and uses it to run the motors in the printer	Epoxy Resin, Solder, Polytetrafluoroethylene	Board is molded; Individual components attached to board
14	Power Port and Circuit Board Case	1	Houses power port and circuit board	Plastic	Injection Molding
15	3/16" Flat Topped Torx 10 Screw	1	Hold power port and circuit board in place	Steel	Machining
16	Small Circuit Board	1	Send information to small motor located near the rollers	Epoxy Resin, Solder, Polytetrafluoroethylene	Board is molded; Individual components attached to board
17	Black Plastic Clip	1	Protect small circuit board near small motor from moving parts	Plastic	Injection Molding
18	3/16" Round Edge Torx 8 Screw	1	Hold small circuit board in place	Steel	Machining
19	Small Motor	1	Provides power necessary to move rollers	Steel	Machining
20	3/16" Round Edge Torx 8 Screw	2	Hold small motor in place	Steel	Machining
21	Ribbon Cable	1	Sends information between main circuit board and print head assembly	Copper, Plastic	Molding
22	Heavy Silver Bar	1	Provides sturdy track for ink cartridges to move on	Steel	Die Casting
23	1/2" Torx 10 Screw	2	Hold heavy silver bar in place	Steel	Machining
24	Transparent Band	1	Provides additional support for ink cartridges to move on	Plastic	Injection Molding
25	Ink Cartridge Carriage	4 pieces	Holds ink cartridges and circuit board in place	Plastic	Injection Molding
26	Ink Cartridge Circuit Board	1	Provides information that tells print head assembly what to do	Epoxy Resin, Solder, Polytetrafluoroethylene	Board is molded; Individual components attached to board
27	Pink Torx 10 Screw	6	Hold ink cartridge carriage together	Steel	Machining
28	Print Head Assembly Belt	1	Moves ink cartridges along print head assembly	Rubber	Molded into shape with pressure
29	Print Head Assembly Frame	1	Holds print head assembly together	Steel	Die Casting
30	Paper Tray	1	Stores paper for printing	Plastic	Injection Molding
31	Plastic Covered Spring	1	Pull rollers and print head assembly closer together	Steel	Coiling
32	Main Circuit Board	1	Sends information to all parts of the printer with instructions for printing	Epoxy Resin, Solder, Polytetrafluoroethylene	Board is molded; Individual components attached to board
33	Wire Harness	1	Transfers information from circuit board to all parts of the printer with instructions for printing	Copper	Individual wires braided together
34	Roller Cover (1)	1	Protects rollers from accidental ink spills from cartridges, guides paper	Plastic, Steel	Injection Molding, Die Casting
35	Rollers (1)	1	Pulls paper through printer	Plastic, Steel	Injection Molding, Die Casting
36	Small cover for front right of printer	1	Houses wires	Plastic	Injection Molding
37	Spittoon	1	Catches excess ink from cartridges	Plastic	Injection Molding
38	Spittoon Cover	1	Ensures ink stays inside spittoon, unless a massive ink spill occurs	Plastic	Injection Molding
39	Spittoon Roller	1	Slides print head cleaner along the bottom of the ink cartridges	Plastic	Injection Molding
40	Print Head Cleaner	1	Cleans excess ink off of the bottom of the cartridges after printing	Plastic, Steel	Injection Molding, Investment Casting
41	Spittoon Sponge	1	Soaks up excess ink	Plastic Polymers	Materials mixed in a mold
42	Spittoon Motor	1	Powers print head cleaner	Steel	Machining
43	Small Gear from Spittoon	1	Transfer movement from motor to Spittoon	Plastic	Injection Molding
44	Large Gear from Spittoon	1	Transfer movement from motor to Spittoon	Plastic	Injection Molding
45	Pink Torx 10 Screw	3	Hold Spittoon together	Steel	Machining
46	Small Metal Block	2	Provide a spot for screws from the print head assembly to securely attach to	Steel	Die Casting
47	Wings	2	Guide paper as it leaves the printer	Plastic	Injection Molding
48	Small Spring	2	Allow slight movement of black plastic wings as paper goes through printer	Steel	Coiling
49	Wing Holders	2	Support Wings as paper goes through printer	Plastic	Injection Molding
50	Rollers (2)	1	Pulls paper through printer	Plastic, Steel	Injection Molding, Die Casting
51	Roller Cover (2)	1	Protects rollers form accidental ink spillage	Plastic	Injection Molding
52	Medium Spring	1	Allow slight movement of gears and plastic pieces so pieces do not snap under pressure	Steel	Coiling
53	Large Blue Gear	1	Transfer energy from roller motor to rollers	Plastic	Injection Molding
54	Large White Gear	1	Transfer energy from roller motor to rollers	Plastic	Injection Molding
55	Black Plastic Cover	1	Protect thin moving plastic pieces from breaking	Plastic	Injection Molding
56	Paper Lifter	1	Lifts paper from tray so rollers can make contact with paper	Plastic	Injection Molding
57	Frame	1	Provides a base for all of the printer parts to be placed in	Steel, Plastic	Die Casting, Investment Casting, Injection Molding

Component Summary Reflection

Materials used in the Printer

Many of the components inside of the printer, as well as the printer housing, were made out of plastic. Plastic was chosen because it is cheap, lightweight and easy to form. Pieces like the small gears, spittoon, and roller covers did not need to be strong; they needed to be small, light and durable- roles which plastics fill easily. The frame of the printer, however, needed to be strong enough to support all of the components without major deformation, so it was made out of metal, as were the rod and back board supporting the print head assembly. The service station absorber was made out of a fibrous spongy material because its job is to hold as much as possible of excess ink cleaned from the print head.

Forces Applied to the Components

Few components in the printer are meant to handle strong forces. The notable exceptions to this observation are the two larger springs and the frame. Two tiny springs on the wings exert very small forces, not more than an ounce, but the two larger springs exert larger forces. We would estimate the the smaller spring exerts 0.5 pounds of force and the large plastic covered spring exerts 1 pound of force. The frame of the printer is subjected to the force of the weight of the printer’s many components- all told, probably about five to ten pounds of force.

Affects of the Material Choice on the Manufacturing Process

The prevalence of plastic materials in the printer makes the manufacturing process much easier. There were quite a few screws in the printer, but there were also many places in which pieces snapped into place. This is much easier to accomplish with plastic components than it is with metal and made assembly much quicker, and saved money as the cost was not driven up by more screws, as well as the cost of machining holes for the screws.

Affects of the Shape of the Components on the Manufacturing Process

Certain processes must be used for pieces with complicated shapes or thin pieces such as die casting or machining. Investment casting is used for very intricate metal pieces, injection casting for intricate plastic pieces. Injection molding was used for all of the plastic components, such as the gears, wings, and the smaller roller cover because of their complicated shapes. Die casting was used to create the precise configuration of the print head assembly frame and the thin silver bar that pulls the print head into a vertical position.

Reasons why each Manufacturing Process was used

• Injection Molding- Cheap to produce, ideal for producing large quantities of one part, low labor cost, and little wasted material.
  

• Die Casting- Produces smooth surfaces; thinner surfaces can be cast than by sand or permanent casting.
  

• Machining- High precision for metal pieces; can produce complicated shapes and edges.
  

• Coiling- Best way to produce springs.
  

• Investment Casting- Good surface finish, high dimensional accuracy, intricate small parts possible.
  

Particular Shapes of Certain Components

Many of the printer’s components have a distinct shape that allows them to fulfill their purpose. The rollers that draw paper up into the printer are round, some of the screws have flat tops so that they do not get in the way of other components while other screws have rounded tops to make them easier to remove, and the paper tray is exactly the right size to hold 8.5” by 11” paper.

Purpose of the Components- Functional, Cosmetic, or Both

Very few components in the printer serve a cosmetic purpose. The outside casing, and a few pieces such as the back panel that allows paper jams to be easily accessed and fixed, and the paper guide which holds printed sheets until they are dry serve both a cosmetic and a functional purpose. All other components inside of the printer are there because they fulfill a needed function. These functions include transferring data from one part of the printer to another, holding parts of the printer together, or moving parts of the printer.

Component Complexity

All of the components of the printer can be ranked on a complexity scale of 1 to 5, with each of the values outlined below.

1. Component is solid, consists of one piece, composed of one material and has a simple shape.

• Examples of Components with a complexity of 1 are the gears, spittoon casing, wings, print head assembly belt, the heavy silver bar of the print head assembly, springs, and the spittoon sponge.
  

2. Component consists of one piece, is composed of one material and has a complex shape.

• Examples of Components with a complexity of 2 are the wing holders, paper lifter, screws, wires, ribbon cable, top casing, and the back panel of the printer.
  

3. Component consists of three or less pieces, may be made of different materials.

• Examples of Components with a complexity of 3 are the print head cleaner, and the print head assembly frame.
  

4. Component consists of four or more pieces made of different materials.

• Examples of Components with a complexity of 4 are the rollers and the frame of the printer.
  

5. The component is electronic in nature, such as a circuit board.

• Examples of Components with a complexity of 5 are the 4 circuit boards of the printer and the 3 motors..
  

Analysis of Ten Major Components

Printer housing

• Plastic was chosen because it is cheap and lightweight.
  
• Injection molding was chosen to manufacture this part because little material is wasted and there are low labor costs.
  
• The housing serves both a functional and cosmetic purpose- it protects the parts inside from most outside forces, as well as hiding the inside components from view.
  
• The printer housing was given a complexity rating of 2.
  

Spittoon Casing

• Plastic was chosen because it is cheap and lightweight.
  
• Injection molding was chosen to manufacture this part because little material is wasted and there are low labor costs.
  
• The spittoon casing serves functional purpose- it is not meant to be seen, it's only function is to hold discarded ink.
  
• The printer housing was given a complexity rating of 1.
  

Large Blue Gear

• Plastic was chosen because it is cheap and lightweight.
  
• Injection molding was chosen to manufacture this part because little material is wasted and there are low labor costs.
  
• The gear serves a functional purpose- it conveys work from the roller motor to the rollers.
  
• The printer housing was given a complexity rating of 1.
  

Rollers

• Plastic was chosen for the wheels as it is cheap and lightweight and grips the paper well. Steel was chosen for the rod for its strength.
  
• Injection molding was chosen to manufacture the wheels of the rollers because little material is wasted and there are low labor costs. Die casting was chosen for the rod because it can produce thinner parts than other casting methods and because it creates a smooth surface finish.
  
• The rollers serve a functional- they move the paper through the printer.
  
• The rollers were given a complexity rating of 4.
  

Paper Tray

• Plastic was chosen because it is cheap and lightweight.
  
• Injection molding was chosen to manufacture this part because little material is wasted and there are low labor costs.
  
• The paper tray serves both a functional and cosmetic purpose- it holds paper until the printer needs it, but it also must look attractive as a large part of it is visible at all times.
  
• The paper tray was given a complexity rating of 3.
  

Heavy Silver Bar

• Steel was chosen for it's strength.
  
• Die casting was chosen for the rod because it can produce thinner parts than other casting methods and because it creates a smooth surface finish.
  
• The bar serves a functional purpose- it supports and guides the print head assembly.
  
• The bar was given a complexity rating of 1.
  

Print Head Assembly Frame

• Steel was chosen for its strength.
  
• Die casting was chosen for the rod because it can produce thinner parts than other casting methods and because it creates a smooth surface finish.
  
• The frame serves a functional purpose- it supports the print head assembly, as well as the main circuit board and a motor.
  
• The frame was given a complexity rating of 3.
  

Medium Spring

• Steel was chosen for its strength.
  
• Coiling was chosen because it is the best way to produce springs
  
• The spring serves a functional purpose- it allows slight movement of the gears and plastic pieces so pieces do not snap under pressure.
  
• The spring was given a complexity rating of 1.
  

Large Gear from Spittoon

• Plastic was chosen because it is cheap and lightweight.
  
• Injection molding was chosen to manufacture this part because little material is wasted and there are low labor costs.
  
• The gear serves a functional purpose- it transfers movement from the motor into the spittoon.
  
• The gear was given a complexity rating of 1.
  

Black Plastic Cover

• Plastic was chosen because it is cheap and lightweight.
  
• Injection molding was chosen to manufacture this part because little material is wasted and there are low labor costs.
  
• The cover serves a functional purpose- it protects this plastic pieces inside from outside forces.
  
• The cover was given a complexity rating of 3.
  

Solid Model Assembly

Our group chose to model the Spittoon portion of the printer for a couple a reasons. First, no one in our group had extensive knowledge of solid modeling, so we decided to model a relatively simple portion of the printer. Second, while the Spittoon itself is simple, the same important processes are used in all three sections of the printer that require a motor (Spittoon, Rollers, and Print Head Assembly). Thus, while we are modeling a simple part of the printer, the more complicated systems use the same basic components to complete their tasks. These basic components include a motor, gears or a belt to transfer the energy, and the final component that uses the energy (the rollers, ink carriage, or print head cleaner). Without any of these basic components, none of the three systems would work correctly, and the functionality of the printer would be greatly compromised. Due to the reasons outlined above, our group felt that modeling a portion of the Spittoon would be very beneficial to our understanding of the printer and its more complicated systems. As for the CAD package, our group decided to use Autodesk Inventor because the program was easily available to students on the Autodesk website, and because no one in our group had a 3D Cad package already available on their personal computer.

• The parts of the Spittoon that we modeled are shown below in Table 4: Solid Model Figures
  

• Solid Model Figure 1 is the Spittoon itself
  
• Solid Model Figure 2 is the inner Spittoon gear that moves the Print Head Cleaner
  
• Solid Model Figure 3 is the Spittoon Motor, which provides the power necessary to run the inner Spittoon Gear and in turn the Print Head Cleaner
  
  

Table 4: Solid Model Figures

Spittoon	Solid Model Figure 1: Spittoon
Spittoon Gear	Solid Model Figure 2: Spittoon Gear
Spittoon Motor	Solid Model Figure 3: Spittoon Motor

The Spittoon works by using energy provided by the Spittoon Motor (Solid Model Figure 3), which arrives at the motor from the power port. The motor then turns three gears, two on the outside of the Spittoon, and one on the inside of the Spittoon (Solid Model Figure 2). The final gear is connected to the Print Head Cleaner, which slides back and forth inside the Spittoon and cleans excess ink off of the ink cartridges after each use. The exploded assembly of the Spittoon can be seen by clicking the link below.

View Exploded Assembly of Spittoon

Design Revisions

While the HP Deskjet 960c Printer is very well put together, the group has come up with 4 design changes that we feel would improve the printer a great deal.

• To ease the maintenance and to increase the reliability of the printer, a new compartment should be made in the case. This compartment should be placed in a location that would allow the end user of the printer to remove the spittoon. If the sponge inside the spittoon was to overfill, the ink could leak out of the box, potentially ruining the printer. Currently the entire printer has to be disassembled to remove the spittoon. If a compartment was made to allow the direct removal of the spittoon then the owner would be able to clean it occasionally, prolonging the life of the printer. Though we do not know how long this printer was in use, the amount of ink filling the spittoon was significant. The sponge at the bottom of the spittoon was fully saturated and a layer of gel-like ink lay on top of it. The nozzle cleaner at the top of the spittoon was covered; even the gear inside of the spittoon was so coated that it's shape was no longer distinguishable.
  

• Along the same lines as the previous revision, a spill proof spittoon could have been used in the printer since there is no easy way to clean it. A spill resistant spittoon has higher walls, preventing the ink from spilling when the printer is moved. This would allow the printer to be transported by the owner without fear of spillage. This revision would also be relatively cheap because the spittoon is made of plastic.
  

• A third revision involves the overall weight of the printer. The material used for the frame of the printer is very heavy for what it is. Being constructed of a heavy metal may help the printer’s durability; however, many of the outer components of the printer are made of plastic. The plastic is not very durable in comparison to the metal, so a lighter material could be used, making the printer substantially lighter. This would be beneficial not only for the end user, but also for shipping the printer out to stores. Depending on the chosen material the cost to manufacture the printer could also be cheaper.
  

• The fourth revision that the group has come up with has to do with the fasteners used in the printer. While only screws and molded plastic clips are used, there are two different sizes of screws used in the printer- Torx 8 and Torx 10 Screws. If only one size screw was used, the need to have a second screwdriver would be eliminated, as well as the hassle of switching tools throughout the assembly of the printer. Since the majority of the screws are of the Torx 10 variety, it would make sense that all of the Torx 8 screws be replaced by Torx 10 screws. This revision would make manufacturing less expensive, as only one type of screw size would have to be produced instead of two and, as mentioned, only one size screw driver would be necessary as well.
  

Engineering Analysis

Engineering analysis is an important part of the design process- it allows the product's functions to be modeled and optimized without the hassle or expense of a guess-and-check approach. It allows designers to have a decent understanding of whether a function is going to work or not without manufacturing anything and thus can save both time and money. Analysis is also helpful during the testing stages- if a component is not working, or even not working as well as need be, analysis can lead to the discovery of the root of the problem or even help to suggest a better solution.

A key functional part of the printer is the synchronization of the rollers and the print head assembly. Without this synchronization, the printer would produce incorrect print outs, which would severely limit the functionality of the printer. To prevent this problem from happening, tests could be done during the design phase of the printer to ensure that the rollers and print head assembly move at the correct speeds in order to produce proper print outs. To calculate the correct speeds that these parts need to move at, an engineering analysis problem such as the one below could be performed.

Problem Statement

• What speed, in passes per second, does the print-head assembly of the HP Deskjet 960c need to move at for a proper print out of a black and white text document?
  

Diagram

• Both Eng. Analysis Figure 1: Rollers, and Eng. Analysis Figure 2: Print Head Assembly, which are seen below in Table 5: Engineering Analysis Figures, must be moving in synchronization to produce proper print outs.
  

Table 5: Engineering Analysis Figures

Rollers	Eng. Analysis Figure 1: Rollers
Print Head Assembly	Eng. Analysis Figure 2: Print Head Assembly

Assumptions

• Black and white print speed of the printer is 15 pages per minute ^[1]
  
• Rollers move paper at print speed; therefore print-head assembly must keep up with rollers
  
• Printed document is single spaced
  
• Printed document has 48 lines of text with size 11 Calibri font
  
• One pass of the print-head assembly is equal to one cross of the page, or 10 inches
  
• One pass of the print-head assembly covers 5 lines with ink
  
• Page must be completed on a whole pass, not a partial pass
  

Governing Equations

• Seconds to print a page = ((1 minute)/(Pages per minute))*(60 seconds/1 minute)
  
• Passes required to cover page with ink = (Lines of text)/(Lines covered per pass of the print-head assembly)
  
• Passes required per second for proper print out = (Passes required/Seconds to print one page)
  

Calculations

• Seconds to print a page
  

seconds/page= ((1 minute)/(15 pages/minute))*(60 seconds)/(1 minute)=4seconds/page

• Passes required to cover page with ink
  

Passes= (48 lines)/(5 lines/pass)=9.6 passes=10 passes

• Passes required per second
  

Passes/second=(10 passes)/(4 seconds)=2.5passes/second

• Passes per second = 2.5
  

Solution Check

• The above answer of 2.5 passes per second is a reasonable answer to this problem, as a print-head assembly can generally be heard moving at a pretty quick pace to print out a document when using a home printer. Also, all calculations check with units, showing that the answer of 2.5 is indeed in the correct units.
  

Discuss and Interpret

• After calculations, it is found that 2.5 passes per second are required to properly print out a black and white text document based on the assumptions that were made. This means that every second, the print-head assembly passes over the document 2.5 times, all the while putting ink on the page. By associating the manufacturer’s specification of 15 pages per minute print speed with one specific part of the printer, (the rollers), the other main part of the printer used to print a document, (the print-head assembly), can be isolated and the speed required of this particular part can be calculated. While black and white text documents are by no means the only types of documents that are printed, they are very common, and a nice benchmark to calculate data for that can be used in most cases. By using these assumptions, the required speed of the print-head assembly can be calculated.
  

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References

^[1] Epinions.com