Multi-Disciplinary Engineering Design ConferenceKate Gleason College of Engineering

Rochester Institute of TechnologyRochester, New York 14623

Project Number: 07501

DEVELOPMENT OF A FUSER TEST BED

Justin McMillan/Industrial Engineer Damon Peters/Mechanical Engineer

Chris Fink/Industrial Engineer

Kevin Duffus/Electrical Engineer

Joe McGrath/Electrical Engineer

Robert Northrup/Mechanical Engineer Ruben Caballero/Electrical Engineer

© 2005 Rochester Institute of Technology

ABSTRACT

This paper will describe the inception and development of the laser fuser test bed. The laser fuser test bed project set out to develop an experimental test bed to determine the effects that a set of parameters have on the fusing of toner to paper. Different from the standard fuser test bed, the aim of this project was to look at how to implement a method of individually varying the temperature, pressure, and dwell time to better understand how each of these parameters affects the fusing of different toners on different media. The long range goal is to use the test results obtained from the test bed to develop the next generation of laser fuser printing technology. The current state of the test bed and an outline will be provided in the following text for the future development of this project. Issues that will potentially be encountered pertaining to these suggested improvements will be addressed.

INTRODUCTION

Currently, copier development is coming to a proverbial fork in the road. As customers demand faster printing speeds, the limits of temperature and pressure that can be instantaneously applied to the toner molecules is being approached. Constraints arise within the NIP (non-impact printing) area of the toner fusing process, where the actual fusing of the toner to the paper through temperature and pressure application occurs. As the speeds of printers increase, the dwell time within the nip decreases. As a result of this decreased exposure to temperature and pressure, the toner particles must be exposed to increasingly higher levels of the these two variables to compensate for the lost dwell time. There is a foreseeable limit of the speeds at which the current roller fuser set-ups will be able to provide the pressures and temperatures need to produce quality prints.

Along with printer speed concerns, industry has worked to produce the very best gloss possible for their printed images. A fundamental understanding of the relationship between temperature, pressure and dwell time and its effect on dry toner is essential to facilitate production of the best possible image.

The aforementioned needs of industry and research personnel were the high level motivators for the development of a laser printer fuser test bed, otherwise known as the LFTB project. This fuser test bed will provide a means to research the relationship between temperature, pressure, and dwell time as it applies to toner fusing and ultimately to the gloss of the image produced during printing.

The current test bed is merely the first iteration in the life of the mechanism. A 5 year project program is in place to facilitate continuous improvement on the current test bed configuration.

OBJECTIVE

The purpose of this paper is to tell the story of the development of this laser fuser test bed. The justifications for concept selection, sub-system selection, and purchased parts will be provided as development milestones. This project,

although determined to produce a functioning test bed, worked under the premise that this was the first step and the outcome may not be exactly the desired experimental tool needed. The paper will, along with the steps in development, give a detailed description of the test bed capabilities as well as engineering specification metrics as a measure of success.

CUSTOMER NEEDS & ENGINEERING SPECS

The Customer was interviewed upon the outset of the project and the overreaching results of the interview confirmed the goals of the project. The ability to independently and accurately control pressure, temperature, and dwell time were the most important deliverables set forth by the customer. The sampled parametric values must be passed to a computer in a closed loop data acquisition and control system. Sample size requirements, of 2cm x 2cm, as well as heating and change over time were also defined as critical customer needs. All determined customer needs were then given a ranking to help quantify their relative importance to the customer. A ranking system of 1-10 was employed, 1 being not very important and 10 being critical. The ranking metric is shown below:

Structural Drawings 9

Electronic Schematics 3

Make it safe 9

Durability 3

Cost Effective 1

Adaptability (pressure profile variation, media type) 3

Plug into standard wall outlet 9

Good functional user interface 9

Real-time data acquisition 3Accuracy of temperature, pressure, and dwell time data acquisition 9Accurate controlling mechanisms (temp, press, dwell time) 9

Kill switch 1

Documentation (operators manual) 9

Monitor Energy Consumption 3

Minimum sample size must be 2cm x 2cm 9

Table 1: Customer Needs and Rank form 1- 10

From these customer needs, engineering specifications were derived. It was determined necessary for the unit to run on a 110V outlet; accurate within 3% of measured temperature, 5% of measured pressure, and 6% of determined dwell time; have a change overtime of less then 3 hours; it must be able to accommodate a minimum 2cm x 2cm paper sample. The test bed was also required to be able to test a range of temperatures from room temperature up to 400 degrees Fahrenheit, a range of pressures from 0 to 3 atmospheres, and to test these parameters over a time of 10 milliseconds. These were the corner stone engineering specifications used as design drivers upon the outset of the project.

Customer Needs Rank

SUB-SYSTEM DEVELOPMENT

Being able to independently vary temperature, pressure, and dwell time on un-fused toner became the focus of the team as the project moved forward into initial sub-system brainstorming. A brainstorming session was then performed by the team in an effort to determine what sub-systems would be necessary to satisfy the customer needs. The session determined the primary sub-systems to be the heating system, the control system, the sensing system, and the pressure application system. Once critical subsystems were agreed upon, investigation of the best means of accomplishing the goal of each sub-system ensued. The needs of the heating system to instantaneously raise the temperature of the toner during pressure application were addressed with suggestions of radiation coupling or conduction from media or structure. Conduction quickly became the decided upon choice due to the fact that it is more accurate to the actual method by which toner in a printer is fused to paper. The pressure application system was a bit more complicated of a decision. There was no clear way to be able to apply pressure to the toner evenly. The nearly instantaneous nature of the pressure application system, much less then a second, made for some interesting suggestions. One team member suggested that a cannon be used as a possible means of applying pressure over the short period of time. Motors on a rail system and servo motors also came up during discussion as possible solutions. Ultimately a combination of motors would be the determined best solution. The sensing and controlling aspects of the system presented their own set of problems. With such a short period of time to work with, what kind of DAQ (Data acquisition) system would possess the ability to sample at an extremely high rate. The software that was determined as the optimum for our application was LabView. Due to its versatility and availability, LabView was really the only software given serious consideration. The DAQ board was researched and the National Interments cDAQ-9172 8-slot USB 2.0 Chassis, US(120 VAC) chassis with analog and digital cartridges was determined to provide the functionality and expandability required for the future of the test bed. Thermal couple wire is the most versatile and accurate temperature sensor found by the LFTB team. It is able to be placed and record temperatures any where the wire can be fastened. The Pressure could be measured accurately through the use of a piezoelectric load cell. The load cell would sense an applied force and transmit that force to the DAQ system at a conversion of 5mV/lb.

CONCEPT DEVELOPMENT

With best sub-system decisions made the team proceeded to the concept development stage. During concept development the best sub-system solutions were combined together in differing configurations in an effort to come up with the best over all system as outlined by our customer needs. The results of the brain storming sessions are shown below. Pugh’s matrix was used to select the best concept. A vote was then taken to determine the best concept. The selected concept was a two roller system in a metal housing. The two rollers would be able to be press against one another through the use of pneumatic cylinders. Where the cylinders met the paper and

toner pressure would be applied. One of cylinders would have a current running through it to heat it. The pressure would be controlled by LabView. Laser temperature guns would be aimed at the place where the two rollers and toner would come together. A digital pressure sensor would be installed in the air lines to determine the pressure applied to the mechanism. The positive aspects of this set up were that, it closely mimicked the standard fuser set up so results could be related directly to the industry fusers, it would be fairly easy to control the pressure applied to the sample, dwell time could be derived from the speed of the rotation through the rollers. The draw backs to this concept were the inability to determine nip width accurately and therefore the inability to determine dwell time accurately, the inability to evenly disperse and sense pressure due to the inherent flexibility with in a roller, and the inability of the laser temperature gun to be accurately aimed at the exact place where the tone, media, and two roller meet. The sub-systems and sub-systems solutions applied for the first top concept selections are shown in the table below:

System need addressed Sub-System SolutionConvert electrical to thermal energy OhmicTransfer thermal energy to toner Conduction from media / structureControl temperature signal electrical relaysApply and release pressure pneumaticControl pressure signal DAQ boardSense temperature in toner Laser temperature gun (IR)Sense pressure Digital pressure gaugesEnergy Transfer modelingTransfer thermal energy to media Conduction from media / structureSense media temperature Laser temperature gun (IR)Sense input energy Monitor power inputSense how much energy gets to toner ModelingSense dwell time A function of the pressure sensorControl dwell time pneumatic

Table 2: Overall system needs and Sub-sustem solutions

Sketches of the concept were then done and the system was outline prior to moving forward to the parts order and fabrication stages.

FINAL CONCEPT

Just prior to moving forward with the selected best concept, it was put through extreme scrutiny by the team to make sure it was going to fill all the customer needs prior to moving forward. Unfortunately, the chosen concept had some major short coming when the “reality check” customer needs were looked at closely. Sensing the temperature at the toner was still not determined to be possible; determining the pressure profile (curve) on the toner was still up in the air as far as accuracy of measurement; and determining nip width was deemed to be a nearly impossible task. This step back allowed for a new direction to be revealed. A cam can have a curve directly related to its shape through cam design, and the magnitude can be adjusted through linear position change of the cam itself. This was a better solution to the pressure application system needs. Then the idea of the equilibrium temperature was presented to the group by customer and team member Dr. J. Arney. This seemed to be the ice breaker that the team needed, and when HP bought into this idea of bringing the toner to equilibrium temperature prior to applying pressure,

the path to success was illuminated. The temperature in the toner could accurately be determined due to the fact that the entire space would be at an equilibrium temperature, thus the toner would also be at that measured temperature. The force on the toner could be sensed by a load cell located directly below the toner itself and rigidly connected the impact area. This force could then be translated to pressure through the use of the formula p=f/a, knowing the area of the impact surface area. Finally the concept that would satisfy all the customer needs was determined, and the process could move to the research and production stage. The first rough sketch of this new and improved final concept is shown below:

*/-

Image 1: Initial final concept sketch

MECHANICAL ASPECTS

The main objectives were to be able to apply and read pressure, apply and read temperature, and apply and read a dwell time. The challenge, as previously stated, was not the application of the magnitudes but being able to apply these magnitudes and read them accurately. In order to apply the pressure the cam was implemented. Based on simple calculations we were able to generate a conceptual cam that allows for a basic pressure curve. Following this we needed a good way of holding the paper and being able to read the true pressure applied within one percent. A flexure design was implemented that was analyzed using finite element analysis in ANSYS. The key to understanding the finite element results was to look at not the stresses, but the displacement caused by the loading. The following results show that there was uniform displacement (less than about 50 millionths of an inch) over the area where the pressure was applied.

Image 2: ANSYS pressure analysis

ANSYS was also used for modal analysis. This was done to prevent natural frequencies from being reached during the impulse from the cam actuation. The goal was to have a system that could cycle within about 20 milliseconds. This would imply a cycle of about 50 Hz. The ANSYS results show that the first three modes are 34.5, 41.0, and 58.6 Hz. This was only acceptable because the true excitation was not in the same direction as the first three modes. The following shows the first mode:

Image 3: Frequency analysis

However, we did add more mass and stiffer flexures to prevent these modes, and still allow for the same loading characteristics. Then a transient heat transfer was performed over one and five minutes. This was done to determine if uniform heating would occur. These analyses also confirmed our initial material choices of 6061 aluminum for the main plate and steel mounting between the load cell and plate, and between the plate and flexures. We needed to be sure that the load cell would not reach 250ºF. For safety and to better control the heating gradient in the test bed from creating unwanted convection insulation was also added.

Precision was another concern with the system due to the fact that the load cell had a very high spring constant (6lbf/in). Due to this a heavy duty in-line spring was introduced. This spring created a direct link between the stamp and the roller follower that the cam rotated against. Since the spring compressed more than the load cell, it allowed for the cam to displace the roller follower further with the same load as otherwise would happen. This removed the necessity of high precision control of the cam shape and position. Also, to allow for more variations of the pressure curve, a linear slide was introduced to move the cam position up and down. This slide can make an accurate step of .004”. This displacement is well within the range to allow for accurate load prediction of 1% with thought given to other parts of the system that remove load accuracy.

SENSOR SYSTEM CONTROLLING

The thermal couples work as advertised by National Instruments due to their packaged integration with the DAQ system. The heating elements work due to their max temperature ratings. The whole system comes together to work in a type of on/off switching feedback system. The on/off functioning is achieved through the solid-state relay and is controlled by a 5V DAQ digital output. Heating the plunger works on the same feedback system, but using a different type of heating element. This heating element will be inside the plunger, in order to effectively heat the plunger evenly.

The linear slider and cam shaft motors come in packages that interface with complimentary computer control software, but was then implemented into LabView. The control algorithm that determines the step motors positioning was developed by the same manufacture of the motors and we have excellent control of the parameters to assure high precision.

The thermocouples output voltage needs to be conditioned with which the DAQ has the required instruments to do this. Conversion between voltages to degrees is done automatically by a previously calibrated LabView block element along with the required DAQ card. The output of the load cell is analog and within the input range resolution of the DAQ.

TESTING

Prior to completion of the manufacturing and assembly, the entire system was tested on a sub-system basis. The control of the heating elements, load cell, thermocouples, stepper motor, and linear slide were tested individually. The stepper motor and linear slider were tested using the complimentary software from Anaheim Automation and Velmex respectively. The load cell was calibrated by PCB piezoelectric prior to the team’s acquisition of it. Further testing could be done to truly know the load cell’s accuracy integrated into the overall test bed. The cartridge and heating strips were tested for performance using an Infrared temperature gun. Along with the heating elements the thermocouples were tested for consistency with the IR temperature gun. Both performed well under individual testing. Once the system was assembled, multi-component testing commenced. Control of these components was assembled into LabView.

The test for calibrating the pressure system was originally set out to be accomplished through the use of a thin pressure sensing film. The necessary film was not acquired during the senior design II, but may be a useful future calibration device. Instead of the pressure sensing film, an object of know weight and surface area was placed on the impacted plate, above the load cell. The load cell produces results in milli volts per pound. When a 1 inch diameter, 1Kg test load was placed on the impacted plate, the load cell read out changed from 0mV to 22.27 mV. This read out should have been 22.05mV per pound according to the 1 Kg weight applied to the load cell. The displayed load on the load cell was in error by approximately 1% much less then the customer allotted 5% error. The error in the measurement is expected to decrease as increased loads are applied due to the larger forces overcoming the spring flexures and eliminating some system noise.

Figure 4: LabView data acquisition front-end

The temperature application system was to be calibrated through the use of thermocouple wire. The wire would be placed in side the test bed and would be used to determine weather or not the heaters, either strip or cartridge, were actually reaching the temperatures set forth by LabView. When this procedure was performed the thermocouple wires

through LabView determined that indeed the system was reaching the temperature entered into LabView to within .5 degrees Celsius. Although not in the original procedure, a laser temperature gun was also used to check the actual temper inside the test bed “oven” as opposed to the readings of both the thermocouple wire and the desired temperature. When an input temperature of 60 °C was set as the desired temperature in LabView, after approximately 5min, thermocouple wires were reading a temperature of between 59.8°C and 60.7°C. When checked with the laser temperature gun the reading on the instrument varied from 58°C to 61°C due to movement in aiming of the device. The necessary accuracy as set forth by the customer for temperature control and sensing was to be with-in 3% of measured temperature. In this case the thermocouple wire measurements are well within the 1.8°C acceptable variance window. The measurements taken by the laser temperature gun were within the + 3% window, but did fall 0.2°C below the minimum acceptable tolerance level. This variation can be attributed to the in accuracy of the infrared (IR) temperature gun due to movement of the operator. The IR gun did provide a level of comfort that the thermocouple wires were accurately reading the temperature.

Initially procedure for determining the accuracy of a mathematical model of the test beds operation was to be tested. The mathematical modeling was later determined to be less unnecessary at this point due to the fact that information about the operation of the test bed can be determined through real world experimentation. The fact that the test bed systems are functional makes it more reasonable to use experimentation rather then theoretical modeling.

There was a customer need of being able to determine dwell time of pressure and temperature on toner. In order to determine this dwell time the was a need for a mechanism that could sample enough times in a second to capture enough data points out put by the load cell to accurately represent the duration of time that force was being applied to the toner. Although this sample rate was unable to be defined exactly due to the versatility of the system regarding angular velocity of the cam, the shape of the cam, and the magnitude of the pressure profile applied experiments were run to determine if the DAQ system could sample enough times per second. When the samples were written to a spreadsheet with a capacity of 65,536 cells available to house samples, the spread sheet was full in less then 3 seconds. This represents a sample rate of more then 21,000 samples per second. Currently the DAQ system is set to record at 1kHz (frequency) and 100 samples pre frequency, meaning that every .001 second the DAQ system takes 100 samples. This has been more then enough to provide the user with sufficient samples to display a relatively smooth force curve which was the customer requirement. The motor can reach an angular velocity in a range from 600 to 10,000 steps per second currently. At 600 steps per second the force curve is over a 250 millisecond period. The DAQ system is capable of expanding to 14kHz and to as many samples as required, only limited by the sampling capacity of the theremocouple wire which is 14kHz. The system has plenty of capability to run the stepper motor as fast as necessary and to record the applied

temperature and force through the real-time, closed loop, DAQ system.

Currently there is no bare wiring exposed on the test bed. All wire connections are capped and the relays are isolated with electrical tape. No exposed wiring was a customer requirement and this has been accomplished. The visual inspection of the system was performed by the electrical engineers on the team. Further housings may be developed to better conceal wiring, but the test bed is currently safe from all exposure to shock from bare wires.

A kill switch for the system was a requirement from the outset of the project. The engineering specification was that the kill switch should stop all system function within 2 seconds of being engaged. A system kill switch is located on the power strip in which all power cables from the system are plugged. During experimentation, the kill switch was able to cease all system functions in a time frame of less then 1 second. This time of less then one second meets the pre-determined engineering specification for the kill switch.

A major customer need was the ability to be able to plug the test bed in to a common wall 120V wall socket. System design allowed for this need to be met and the current test bed configuration can run solely off of a common 120V wall socket. This specification was visually verified.

The monitoring of the energy consumed by the system as a whole was determined to be necessary by the customer. A transducer was purchased through which the power strip cord could be placed in an effort to determine current drawn by the test bed. To verify the accuracy of the transducer a cord from a computer monitor with a known power need of 168 watts was run through the transducer. The Current read by the transducer when the monitor was plugged in was 1.4 Amps; this current multiplied by the known voltage coming from the wall of 120V equaled a value of 168 watts. The calculated value matched that of the expected value, leading the team to conclude that the transducer is indeed accurate in its measurement of current.

All drawings done for test bed components met the requirements set forth by ISO standard ISO/IEC 11518-1:1995. Proper dimensioning, sectioning, and notation were used to convey the requirements of the part depicted in each drawing.

Cost analysis was to be done according to the customer needs. The customer required that a bill of materials be produced, materials costs be recorded, and that a comparison of the overall cost be compared to the budget limit at the conclusion of the project. The final bill of material, complete with part description, vendor name, and material costs is available at https://edge.rit.edu/content/P07501/public/LFTB%20DOCUMENTS/LFTB/Spreadsheets/FINAL%20BILL%20OF%20MATERIALS.xls .

Different medial types are needed to do a variety of experiments with the test bed. This led to another customer need, of adaptability to many types of media. Three paper samples were tested for feasibility with in the test bed,

a .003”, .006”, and a .012 “ thick paper sample. Each of the paper samples went in to the test bed and the bed was able to operate normally. No common paper weight or thickness will impede the functionality of the test bed.

To determine the ease of use of the GUI (graphic user interface) a survey was conducted on 10 test subjects all with equivalent LabView experience. The survey test the usability of each of the interface functions to include temperature setting, cam angular velocity setting and the clarity of data out put. Subjects were asked to rate the clarity and ease of use on a scale from 1 to 7, 1 being easy and 7 being difficult. A paired T-test was then performed on the collected data. The test revealed a statistically significant ease of use of the interface according to the 10 surveyed subjects.

Cam change over time was a concern for the customer and a maximum changeover time of 3 hours was set for cam removal and change-over. This procedure was performed by a team member and the tasked was accomplished in less than twenty minutes. The customer maximum change over time is much higher than any necessary time for system change-over.

In order to test the effects of temperature on toner the customer required that the temperature on the toner to be able to range from room temperature, approximately 60°C, to 400°F or 204°C. When set to 204°C the test bed, using only the strip heaters, was able to reach this temperature in approximately 30 minutes. This experiment fulfilled the customer expectation of the ability to reach a toner temperature of 400°F is desired. The cartridge heaters heat up to this same temperature in approximately 15 minutes due to the reduced volume of material being heated.

The need for dwell time calculation was an expressed customer need from the beginning of the project and is successfully displayed on the current test bed GUI. The dwell time is shown by the duration of time between when the force curve applied to the toner leaves the zero point on the Y-axis and then returns to the zero measurement. The dwell time varies with the angular velocity of the can and with the vertical position of the cam shaft.

Area of testable toner sample was a customer concern as well. A need for a minimum 2cm x 2cm sample to be accommodated by the test bed was required. Currently the test bed can apply temperature and pressure over a 2in x 2in surface this was verified by calipers.

Initially, during full system integration, the sampling rate within LabView was not complete enough to give an accurate impact curve. However, this issue has been corrected, and LabView can be seen to give an accurate impact curve in Figure 1 above.

RESULTS

Upon successful completion of testing the now integrated system was determined to have met all critical customer needs and engineering specifications. The temperature was able to be sensed accurately to within 2% of

the actual temperature as well as being controlled to within 2% of desired temperature. The Pressure application system can create a desired pressure profile through the use of appropriate cam design. The applied pressure curve’s magnitude can be varied easily through the use of the linear positioning motor on top of the test bed. The pressure can be indirectly sensed through the use of the load cell, located under the impact plate, which can sense the force impulse applied directly to the toner. The force curve that is displayed on the LabView front end is set versus time to display the duration of time the toner sample spent in the nip, in other words how long the heat and pressure were applied to the toner. With the successful completion of the systems integration, the team accomplished all the critical goals set forth in the original customer needs and engineering specifications.

FUTURE ADJUSTMENTS

Even with all the initial success, there is still a lot of room for improvement. The current heating system is not fully understood. Thus more analysis into a proper understanding of this system is necessary to gain the full benefit of temperature control on the toner. This can be achieved by researching the thermal properties of the heating cartridges and strip heaters inside the system. From this it will be possible to calibrate how long it takes the air around where the toner will be, and the plates that the paper will be mounted on to reach the desired temperature. Also, a better understanding of any convection could allow for a more thorough understanding of heat loss control. In addition to the standard materials of the system, a better understanding of the toner’s heating properties would be beneficial. An improved heating algorithm could then be implemented as a result of this information.

The linear positioning motor could be replaced by a sturdier device, like the Velmex Inc., MB9000 motor. This motor has a maximum allowable thrust of 400lbs which would easily hold up under the maximum desired test of 4 atmospheres, as required by the test bed customers. This new device would allow the linear positioning system to operate while the cam is being engaged. Stiffer springs could be implemented in the stamp plate to ensure better contact with the cam during pressure application.

Along the same lines as the linear slide, a more thorough study of the rotational stepper motor would greatly increase the versatility of the pressure application system. For instance, if a graph similar to the following was desired:

Pressure Impulse

0

0.2

0.4

0.6

0.8

1

1.2

1.4

0 0.005 0.01 0.015 0.02 0.025

Time (sec)

Pres

sure

(atm

)

Graph 1 : Pressure profile exampleInstead of trying to move the linear slider, if it were possible to move the cam to a certain position, move it back a few steps, and then move it forward again with the stepper motor a whole new set of curves will be available. Also, with this method of doing the different pressure curves no new components would be needed.

However, it would be beneficial to add a position feedback system to more accurately know where the stamp is relative to the toner at all times. This brings up another point of the stamp. In an attempt to be more versatile the system was designed to have fairly easy changeover of the stamp. However, the final prototype was found not to have this characteristic. This leaves room to modify or change the stamp to enable quicker changeover, and to allow for the material that is to come into contact with the toner to be changed without hassle. The stamp also is in need of a heating analysis. Prior to actually designing the system to have the stamp heat up, no heat transfer analysis was done. Possibilities here include trying to understand where insulation will best help to control loss, if different/combination of materials could be used to direct the heat flow, and whether more thermocouples should be used to accurately measure the temperature.

With these added components and changes more investigation should be given to LabView integration and coding. A true future need would be to have LabView automatically send data to a file. At this point a good deal of testing different methods has been done, but could be greatly improved. Also, at this time only the speed of the cam is adjustable from the LabView interface. With a further understanding of the rotational stepper motor it will be of the utmost importance for ease of use to allow the user to select from a series of desired curves. Some suggestions include allowing the selection of a general shape, and selecting a magnitude. For the magnitude cam height would need to be changed by moving the linear slider. However, in addition to allowing for selection of these two parameters, an expected graph should also be available for viewing based on the parameters. It would be beneficial to knowing the true error and sensitivity of the system to see this simulation.

Eventually parts like the stamp and guide rods are going to wear, and replacement will be necessary. If these wear quickly, especially the rods, hardened steel would most likely be the best option. Other options include 7075 aluminum and ceramics for the stamp, and mild or stainless steel for the rods.

Also, if readings for pressure prove, upon testing, not to be consistent a thinner flexure might be a beneficial replacement.

CONCLUSION

With the ability of the test bed to successfully control and accurately sense pressure temperature and dwell time, all critical needs are met. The system can also apply any desired pressure profile through the proper cam design. Although the test bed has not reached its full potential as of yet, in a 22 week period it has gone from customer needs, to a functioning piece of test equipment, in lieu of some minor adjustments. Below on the left is the concept drawing done in solid works which was complete during wee two of senor design II. To the right is the actual laser fuser test bed that was delivered at the end of week 8.

Figure 5: Theoretical concept Vs. Delivered test bed

ACKNOWLEDGEMENTS

The laser fuser test bed team would like to thank all those who helped make the test bed possible. Our sponsor, Hewlett Packard provided an immense amount of technical support and guidance during the initial stages of the project. Thank you to Dr. J. Arney, Susan Farnard, and faculty guide Dr. M. Esterman who supported the team from the beginning and whose guidance was essential for team success. Dr. J. Cockburn and Dr. S. Paidy helped to set the team on the right path regarding the DAQ and controlling systems. The team would also like to thank the Brinkman Lab, John Bonzo and the lab assistants for all the hours of help during the machining of over 100 custom parts.