Esign and fabrication of a shearing machine for glass fiber sleeves using ste...
CapstoneFinalReport-McHugh
1. School of Engineering
University of California, Merced
Engineering Capstone Design- Spring 2016
Nicholas Balaban, Bernie Gabriel, John Leung,
Edgar Lozano, Josh McHugh
13 May 2016
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2. Contents
Section Page
1: Abstract 3
2: Introduction 4
2.1: Problem Description
2.2: Mission Statement
3: System Design 5
3.1: Mechanical System
4: Design Analysis 10
4.1 Stress Analysis
4.1.1 Loads
4.1.2 Constraints
4.1.3 System Tolerances
4.1.4 Analysis
5: Costs 11
6: Risk Assessment 13
7: Results and Recommendations 14
8. References 16
Appendices
Appendix A: Bill of Materials and Data Sheets 17
Appendix B: CAD Drawings 23
Appendix C: User Guide 35
E.1: Mechanical Installation/Operations Instructions
E.2 Maintenance and TroubleShooting Guide
Appendix D: Stress Analysis 39
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3. 1 Abstract
Integrated Design aims to design a cheap and effective solution for integrating a working clutch
that gives the turntable the ability to disengage the worm gear from the motor. Integrated
Designs has successfully redesigned the CobraTurn Digital Turntable, manufactured by MK
Products, system by implementing a dog clutch that gives the ability to detach the worm gear
from the turn table. The solution consists of a lever assembly which includes a shifter fork, shaft,
machined plate, a pin, detent ball,spring and a bolt. After incorporating both the dog clutch and
lever assembly, Cal Weld workers will be able to successfully disengage and engage the
turntable by hand. As a result, it solves the issue of the electromagnetic interference experienced
by turning on the motor.Throughout this report, we discuss how our mechanical system operates,
design and stress analysis, constraints, cost to implement our design and our results through our
prototype testing. More importantly, we demonstrate the effectiveness, reliability and feasibility
of our solution.
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4. 2 Introduction
Universal Calweld is a manufacturer
of high purity equipment,
subsystem, and components that is
located in Fremont, California. The
business has been serving other
industries that makes products such
as semiconductors, nanotech,
defense, alternative energy, etc. for
over 30 years. Customer satisfaction
and service of excellence allows
Universal Calweld to grow into one
the Industry leader in welding
technology and peaked their interest
in partner with one of the world
class research university UC
Merced.
Welding, assembly, and testing is a
time consuming process that require
patience and precision. In order to
increase the quality of the weld, the
usage of the turntable is critical. The
process of using the rotation of the
table and the gas emission from the
pipes has to be consistent without
any interference, such as stopping in
the middle of the welding procedure.
The amount of skill and experience
needed to use a turntable without
causing any damage to the system
has to be used by a committed
employee.
2.1 Problem Description
Currently at Cal Weld, they operate with turntables that do not have a clutch or mechanism that
allows welders to freely rotate a part or assembly without the use of the stepper motor associated
with the CobraTurn Digital Turntable. This is an issue because the high frequency electric motor
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5. causes electromagnetic interference with the TIG welding equipment which ultimately lowers
the effectiveness of the weld and the quality of the product. Industry standards require wetted
surfaces to maintain a high surface polish between 5 to 10Ra and maintain a weld integrity of
leaking gas no greater than In order to achieve these industry standards, Cal Weld0 cm /s.1 −9 3
workers must utilize precision equipment such as variable speed turntables to properly, quickly
and accurately weld components. For that reason, it is imperative for Integrated Solutions to
design a solution for the CobraTurn Digital Turntable that will allow the skilled workers at Cal
Weld to successfully rotate the part without the use of the motor.
Universal CalWeld has approximately 30 Cobra Digital Turntables that would require
modification, therefore, our solution must be cost effective while being easy to implement and
maintain. More importantly, it must not interfere with the system dynamics such as the gear
ratios, the gas going through the turntable and the TIG Welding equipment. Integrated Solutions
aims to provide a solution that is minimally invasive to the current system and that allows the
skilled welders to provide quality products to their customers.
2.2 Mission Statement
Integrated Designs aims to create a functional and viable solution to Cal Weld’s position welder
by incorporating a system to engage and disengage the turntable. Our project plans to assist the
welders for a more comfortable and efficient way of working to provide their consumers with
quality products.
3 System Design
The current Cobra Turn Digital Turntable is being controlled by an electric motherboard that is
located in the back of the housing assembly parallel to the axle of the turntable. The turntable is
active when the button located on the front control panel is pushed causing the motor with the
worm to drive the worm gear attached to the axle of the turntable. Our solution needs to modify
the existing housing design that will give the ability to rotate the turntable manually with or
without the motor being active.
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6. Exploded View of Original Turntable Design
Furthermore, the chosen solution has to take into account of a few constraints and requirements.
The solution requires the following: disengage and engage the gears that are connected with the
worm gear and the axle of the turntable, a system design to be easily maintained, and cost
effective. The solution cannot interfere with other parts surrounding the housing such as the gas
pipes and electrical wiring due to safety concerns. The solution was also constrained by how the
structure was set up, which space is limited in certain areas and the motor with the worm cannot
be moved due to a fixed hole.
Constraints Requirements
Worm hole has diameter of 12.30 mm (Fixed
Position for motor with worm)
Design must be to implemented within the
spacing limits of 21.77mm
21.7 mm spacing between the worm gear and
axle wall to work with
Ability to disengage and engage the gears in
connection with turntable and motor
Gas pipe and electric line surrounding housing Doesn’t pose a danger to welders with new
design
The first proposed solution was to use a sliding mechanism for the motor. The sliding
mechanism would have four steel rods on each corner of the housing box with the motor hooked
onto the rods. The worm hole where the motor would fit into would be redesign to create a trail
path for the motor to shift in different direction to disengage the worm with the worm gear. Also,
the motor sliding on the rods would be lubricated or put on rollers to minimize friction that
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7. would cause wear on the metal. The components needed for this solution are four smooth rods,
flat plate, lever and four nuts. Also, some parts would require machining to fit specifications.
Overall cost would be around $145.00. Although, this was an option, it was quickly discovered
that the orientation of how the motor is placed and how the structure of the design was different
from the CobraTurn Digital Turntable. The motor that is placed in the wormhole cannot be
moved from that position because of the gas pipe and electrical wiring that’s surrounded.
Moving the worm would cut into these components thus creating a hazard for the user.
Initial Concept Design
The second proposed solution was to implement a dog clutch. The dog clutch is used to
disengage and engage the drive between a gear spinning freely (worm gear) on the splined shaft.
Arrangement will be used in synchro-mesh. Essentially, the dog clutch is another gear that is
splined onto the shaft which will rotate with the turntable. Meanwhile, the original worm gear
will have grooves machined into it which will allow the dog clutches teeth to mate with the
worm gear. When the two gears are not meshed together then the turntable will not be rotated by
the motor, allowing the user to rotate it manually. Required components, would be one
redesigned worm gear, a dog clutch, lever fork, rod for lever fork, lever housing, pins, and c
-clips. This design will also require machining splines onto the shaft of the turntable to
implement the dog clutch. This design was the chosen desired option because of its simplicity to
disengage and engage the motor connected with the turntable. This option would not require the
movement of the motor and the user would only have to shift the lever to give the option of
rotating the turntable manually.
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8. Dog Clutch Disengaged with lever Dog Clutch Engaged with lever
During the initial CAD design of this system, the worm gear had circular grooves that would
mate with the teeth of the dog clutch. During our prototype simulation we experienced that due
to the capabilities of the 3D printer, the tolerance of the system has increased. The dog clutch if
not aligned perfectly would require extra force to mate and could eventually lead to the system
being unoperational. To solve this issue, we redesigned the grooves on the worm gear to be
slightly larger than the teeth of the dog clutch and also to be in the shape of an oval which also
increased the tolerance of our system.
3.1 Mechanical System
The current mechanical system has a worm
gear that is pinned to the turntable shaft that
is driven by the worm which implies the
system is always engaged. Our solution of
implementing the dog clutch would allow us
to control when the system is engaged or
disengaged. First, we will begin by
removing the material that allows the gear
to be pinned to shaft which will create the
space needed to add the dog clutch. The
worm gear will then be supported by
c-clips. Once the pin is removed from the
worm gear, this will cause the worm gear to
have a slip fit around the turntable shaft,
allowing the worm gear to freely rotate
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9. around the turntable shaft. Next, the turntable shaft will need splines which will act as keys for
the dog clutch. The turntable shaft is 20 mm in diameter and the gas line is 8mm in diameter
which allows the splines to be a maximum of 6 mm deep without interfering with the gas line.
Our design has the shaft splines to be 2 mm deep which will give it more than enough strength as
the turntable rotates at a max of 10 revolutions per minute. Now the dog clutch is able to be
implemented, however, it still lacks a lever that allows the user to be in control of engaging and
disengaging the turntable. In addition, it also lacks a mechanism that prevents the dog clutch
from sliding down and mating with the worm gear due to the effects of gravity. Subsequently,
our design adds an additional plate in which it will house an additional shaft that will have a
shifter fork pinned onto it. The shifter fork will be attached to the dog clutch in such a way that it
will be able engage and disengage the turntable by moving the lever up and down but also
remain static while the dog clutch is rotating. Along the shifter fork shaft will be two grooves
separated by 6mm which is the distance required to move the dog clutch to either engage or
disengage. By using a spring and detent ball lock mechanism, we will be able to lock the dog
clutch into place until a sufficient force is applied. In summary, with the dog clutch not engaged,
the worm will rotate the worm gear but since it is free to rotate, it will not rotate the shaft. When
the dog clutch is engaged, it will allow the transfer of energy between the worm gear and the
shaft which will then cause the turntable to rotate.
Exploded view of the turntable assembly
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10. 4 Design Analysis
Analysis was performed on the mechanical system of the design solution. Stresses were analyzed
on the mechanical components and the results were shown through the simulation from Pro E.
We examined the von Misses stresses the the fork will exhibit when put into action under the
given load of the system.
4.1 Stress Analysis
The stress experienced was analysed through the CAD software of Pro E. Our team was mainly
concerned with the forces on the fork since it will be the part that will experience the most usage.
Detailed below are the loads and constraints used for the analysis.
4.1.1 Loads
The load seen by the fork shift due to the system is made up of several variables. The load used
accounted for the weight of the dog clutch, the force of the user moving the lever, and the force it
takes to move the detent ball. The minimum force required to actuate the system was calculated
to be around 5 N/m2
. This force was calculated based on the amount of force required to release
the detent ball from the locked position. To account for other unforeseen forces the actual load
examined for analysing the stresses was 10 N/m2
.
The load of the dog clutch resting on the shift fork and the force of the user moving the dog
clutch was represented by a uniform load in the Pro E simulation. Furthermore, the fork was
restrained to be fixed to the rod on the Pro E software. This would mean that the fork will
experience some bending forces at the point fixed to the rod.
4.1.2 Constraints
To fully analyze the actual stress seen throughout the system several constraints are required. To
account for the material, dimension, and attachment to the rod we set all these constraints in the
Pro E software. Stainless steel was assigned as the material for the fork. This material was used
because of it’s durability and strength. The dimensions used are specific to the the dog clutch
that is mated to the fork to ensure that there is a slip fit in order for the dog clutch to rotate freely
with the attachment of the fork. Moreover, the fork was constrained to be fixed to the rod to
reflect the actual setup of the design.
In order to determine if dimensions such as the selected length, width, and thickness for our fork
shifter satisfy our reliability constraints, we as a group decided to calculate deflection on the
shifter fork using the weight of the dog clutch as the acting force. Next, we then added design
factors of safety values of 1.2 and 1.5 to our deflection calculations. We found that all three
deflection values were negligible, meaning our selected dimensions for our fork shifter satisfied
our reliability constraints.
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11. 4.1.3 System Tolerances
In order to regularly replace parts, we needed to decide a tolerance fit for our prototype design.
The lever rod and fork shift will have a clearance fit. This means the fork shift will loosely fit
within the shifter fork. A pin will also be inserted through the lever rod and fork shift to ensure
the fork shifter stays in place while actuating the dog clutch. This tolerance will be ±0.1mm to
ensure a proper clearance fit.
Another important tolerance that was decided would be how the groove on the shifter fork and
the groove diameter on the dog clutch will fit. The dog clutch must be able to freely rotate so the
turntable shaft can rotate, while also stay connected to the fork shifter in order to engage and
disengage the the dog clutch from the worm gear. The fork shifter and the dog clutch will have a
clearance fit, meaning one part fits easily into the other part. In this specific case, the groove on
the fork shifter will easily fit within the groove diameter for the dog clutch. This tolerance will
be ±0.25mm to ensure an easy fit amongst those two components. Although both of these
tolerances will be considered clearance fits, the tolerance must be larger for the dog clutch and
fork shifter compared to the lever rod and the fork shifter due to necessary rotation from the dog
clutch.
Our design of the turntable shaft splines are 3mm wide and 2mm deep and we recommend going
no further than 3mm deep as we do not want to interfere with the gas lines. The dog clutch
tolerance of the internal key that mates with the splines are designed to be relatively low to
ensure that the teeth of the dog clutch align perfectly with the worm gear. Subsequently, the
tolerance for the dog clutch’s width and depth is ±0.25mm.
4.1.4 Analysis
The analysis examined, after the constraints and loads were defined on the fork, showed that
most of the stress is experienced at the end of the fork that is attached to the rod. This stress is
due to the bending that the load causes the fork to experience while the fork is being applied to
the system. The stress is an indicator for the areas that will have the most wear over time.After
the stresses wear out the part, there are a couple suggestions to maintain the system as the fork
wears overtime. The first suggestion is the replace the fork entirely since the fork is relatively
inexpensive to buy and make. The second suggestion is to machine the cracks and wear from the
fork within the clearance of ±0.1mm. (See Appendix D for stress analysis pictures)
5 Cost
The initial cost analysis included all the materials needed to design the dog clutch system. In the
beginning of the semester, our team was given $1000 dollars to meet our requirements of
designing our system and can be asked for more later on. The final cost of one assembled
prototype ended up being $2114.33. The prototype cost included all the materials bought and
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12. machining services of outside vendors. The machining was for redesigning of the worm gear and
creation of the dog clutch to mesh with worm gear. Machining a worm gear as well as creating a
dog clutch ended up being the most expensive portion of this project. The total cost of the clutch
system for our prototype, including the modified worm gear and dog clutch, will end up being
$1950. This price includes the raw materials as well as the machining services. The total cost of
the lever system for our prototype will end up costing $164.33. This price includes the raw
materials for our prototype. The necessary machining needed for our lever system was done by
members of our group. It was decided that it would cost far more to have an outside source
machine our lever system versus machining the parts ourselves, due to the fact of how cheap the
raw materials were and the little machining actually needed.
Although designing and assembling one prototype went over the originally intended $1000
budget, the cost of raw materials and machining will go down significantly if we were to modify
more turntables with our design. Cal Weld has approximately 35 turntables at their facility, but
we were asked to look at the cost of modifying and assembling 1, 25, 50, and 100 turntables.
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13. The graph above represents our economy to scale analysis of modifying and assembling
additional turntables. As you can see, the price significantly decreases as more turntables are
made. The clutch systems prices drop at a large rate. Creating prototypes are expensive because
there is no mold to the dog clutch or worm gear, but once the mold is made then it becomes very
cheap to make these products. The prices for modifying and assembling turntables begins to cost
the same if 90 turntables or more are created. It would take approximately one day to assemble a
modified turntable by hand assuming all parts are made. CobraTurn digital turntables have lots
of components, so if an employee of Cal Weld were to do this task by hand, their responsibilities
would include disassembling a turntable, adding the modified components, and then
reassembling it while adding more lubrication to the newly assembled product.
6 Risk Assessment
Before, implementing the chosen design solution, there are factors that are needed to be taken in
consideration to eliminate any risk to the system and the user. The Risk factor are separated into
four categories. First, what may happen and the kind of hazards to look out for? Second, how
often can this occur? Third, if a problem were to occur how that would impact the production
line, time, cost, and safety? Fourth, how can we eliminate any risks that may occur?
The implementation of our design solution may carry a few risks. The mechanical components
itself may wear down over time however, the system appears to already have proper lubrication
so it does not pose an immediate issue. In addition, there may be times that the gears do not mesh
smoothly as the dog clutch teeth must mate with the worm gear’s grooves. To account for this,
the Worm Gear’s grooves were made in the shape similar to an oval while the dog clutch has
teeth that are in the shape of a circle which increases the chances of them mating smoothly and
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14. also reduces any possible backlash felt into the system. Overtime the grooves may get worn out
but as long as the system is properly lubricated, our design should not affect the life of the
original product significantly. Using AGMA equations and assumptions, we approximate that
our design has a life time of 8 working years. In addition, with the addition of our design, it
simplifies the process of opening the turntable which allows easier access for maintenance. With
that in mind, maintaining the system properly lubricated should not be an issue.
The system conditions, electrical wiring, gas pipes, were the main factors to consider in our
design solution. The design was created to make sure it does not interfere with the surrounding
elements, so when activating the dog clutch by a lever, the user would not have to worry about
the gears meshing and cutting into any wiring or pipes.
The components used for the design assembly is all stainless steel. The stress analysis showed
the stainless steel would show positive results for the desired application. Our stainless steel
prototype functioned smoothly without any problems.
7 Results and Recommendations
On our design test, we validated our initial concept by 3D printing all the components needed to
create the dog-clutch and lever system. In the process of 3D printing our components and testing
to see if the gears mate, there were some problems that occurred in order to meet the
specifications of our design. The first problem we encountered was the dimensions from the
technical drawings sent to the technical specialist to have our models 3D printed were slightly
off which was seen from the difficulty of putting the components together. One example of this
was the gaps in the worm gear where the teeth of the dog clutch will mate. We originally had
circular shaped gaps in the worm gear, a similar shape as the teeth for the dog clutch. Once we
ran a simulation of engaging and disengaging the worm gear and the dog clutch, we found a
slight difficulty with these two components mating. We then decided to change the the shapes for
the gaps of the worm gears to be more of an oval shape, covering more surface area of the worm
gear. This oval shape for the worm gear gaps would make mating with the dog clutch much
easier when performing a simulation. A second example was creating a larger clearance fit
between the dog clutch and the fork shifter. This was necessary because a snug fit between these
two components would cause the shifter fork and dog clutch to rotate together, which would
ultimately cause the system to fail.
We were able to purchase materials for our lever system, machine the parts and assemble them
together. During the machining portion that was done, in order to create the lever assembly, there
were several discrepancies to consider. In the machine shop at the University of California,
Merced’s campus there wasn’t a drill bit long enough to machine the desired depth in the plate
for the shifter rod. A solution to this issue was milling out a larger diameter hole in the entrance
with an end mill so that the drill can plunge deeper into the material. Another consideration for
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15. machining the plate is the radius for the pocket of the fork are designed to mate with the original
housing. One corner has a different radius from the other three so this should be kept in mind.
The actual machining done made all of the radii the same since the 2-flute end mill didn’t have
the proper length for the smaller radius corners. Machining the rest of the plate was simple, since
all that was left was drilling the mounting holes. The fork for the system was also machined in
house by our team. The fork was machined by taking the CAD model and using software to code
the process for the CNC machine to machine the fork out of our solid plate of stainless steel. The
fork came out as expected. Overall the machining portion went well, meeting all of our
requirements. We believe that our design solution is feasible and realistic while being effective
and reliable.
.
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16. 8 References
[1] Bo, Li. "Study on Optimum Economic Shift Law of Automated Mechanical Transmission." 2015 ASABE
International Meeting(2015): n. pag. Benthanopen. Zhao Yiqiang, 9 June 2015. Web. 6 Apr. 2016.
[2] "SPRING-LOADED DEVICES, BALL PLUNGERS, Technical Information :: Carr Lane Manufacturing
Co." SPRING-LOADED DEVICES, BALL PLUNGERS, Technical Information :: Carr Lane Manufacturing
Co. N.p., n.d. Web. 06 May 2016.
[3] The Owners’ Manual. St. Paul, MN: Office,
1979.Http://www.mkproducts.com/support/Manuals/091-0677D_CobratTurn_DigTurntables_Lores.p df. MK
Products, 1Aug. 2010. Web. 4 Feb. 2016
[4] Budynas, Richard G., J. Keith. Nisbett, and Joseph Edward. Shigley.Shigley’s Mechanical Engineering
Design. N.p.: n.p.,n.d. Print
[5] "Tolerance Definition,Tolerancing,Engineering Standards,ISO,ANSI,JIS,Fit,Shaft Limits,Hole Limits,."
Tolerance Definition,Tolerancing,Engineering Standards,ISO,ANSI,JIS,Fit,Shaft Limits,Hole Limits,. N.p., 6
May 2016. Web. 06 May 2016.
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17. Appendix A: Bill of Materials and Data Sheets
Bill of Materials
Item Description Quantity
Precision Ball 3/16” Diameter 100
Rod 316 SS. 3/8” Diam x 1’ L 1
Plate Stock 304 SS. 3/8”x6”x6” 1
Compression Spring 20.3 lb/in Rate 25
Plate Stock 6061 Al. 1”x6”x6” 1
Retaining Ring Shaft Diam 20mm 2
Bolt #8-32x1-¾” 4
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35. Appendix C: User Guide
E.1 Mechanical Installation Instructions
Materials
Mechanical Components
(1) Machined Worm gear (refer to technical drawing Pg. )
(1) Machined Plate for lever assembly (refer to technical drawing Pg. )
(1) Machined Turntable shaft (refer to technical drawing Pg. )
(1) 3/16 inch Detent Ball
(1) Compression Spring rated at 20.3lb/in
(2) Retaining Ring for a shaft diameter of 20mm
(1) 3/8 inch diameter and 1 ft. long shaft.
(1) Dog Clutch (Refer to technical drawing Pg. )
(1) Shifter Fork (Refer to technical drawing for it’s specifications)
(1) pin
(1) 1 #8-32x1-3/4in bolt
Mechanical Installation
Step 1: Housing Assembly
1. Open the housing plate of the turntable and remove the turntable shaft and worm gear
2. Refer to our technical drawings and machine the current turntable shaft and worm gear to
our desired specifications
3. Insert the dog clutch and worm gear into the housing assembly along with the retaining
rings(x2).
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36. Exposed View of Dog Clutch and Worm Gear
Figure 1-Modified Gear and Turntable with the Dog clutch inside the housing assembly
Step 2: Lever Assembly
1. Insert the 3/8 inch diameter shaft into the machined plate, leave enough clearance so that
there is enough room to also place the shaft through the shifter fork.
2. Insert the pin through the shifter fork and shaft, locking it into place.
3. Insert the detent ball and spring through the hole which is located to the right.
4. Compress the spring by fastening the bolt, thus sealing the hole.
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37. Shifter and Housing Assembly
Step 3 System Assembly
1. Begin by carefully mating the shifter fork with the dog clutch.
2. Place the lever assembly on top of the housing assembly while aligning the holes.
3. Fasten the 4 screws into place, connecting both of the assemblies.
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38. E.2 Maintenance Guide
Maintenance Plan:
As the design of our system is used it will experience some wear that will affect the overall
performance. Therefore, here is a guide to help maintain the system, highlighting the
maintenance of the worm gear, lubrication, and the maintenance of the fork.
Based on AGMA equations the worm gear will have a lifetime of 3 years when running nonstop
at the maximum RPM. The worm gear will last 8 years when running under a typical work
schedule, 5 days per week and 12 hours per day. It is suggested that the worm gear should be
replaced every 8 years.
The system will be in constant motion so it is important to keep the parts lubricated for optimal
performance. Furthermore, adequate lubrication will prevent heat transfer through friction.
As the fork experiences wear there are a couple of suggestions to keep the system running at an
optimal rate. The first suggestion is to replace the fork entirely as cracks propagate on the fork
and become apparent to the performance of the system. The second suggestion is to machine the
cracks from the fork within the tolerance fit of ±0.1mm.
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