Mousetrap Powered Vehicle: Mechanical Design and Development

This project focuses on the mechanical design and development of a mousetrap-powered vehicle. It begins with an executive summary and table of contents, followed by an introduction to product design specification (PDS) and its importance in analyzing products. The assignment details the steps involved in PDS, including customer requirement collection and technical requirement analysis, utilizing a House of Quality to correlate customer attributes with technical specifications. It explores manufacturing details, including 3D printing (FDM) for prototyping and injection molding for large-scale production, covering materials like ABS plastic. Assembly and quality control procedures are also discussed, along with a cost analysis of the initial prototype. References are provided to support the design and manufacturing processes.

Mousetrap powered vehicle
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Mechanical design and development

Mousetrap powered vehicle
Executive Summery
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Contents
Introduction......................................................................................................................................4
Product Design Specification..........................................................................................................4
Steps for PDS and House of quality................................................................................................4
Requirement collection from customer.......................................................................................5
Technical requirement collection from customer........................................................................5
Relative importance of customers attributes................................................................................5
Technical requirement based on customers attributes.................................................................6
Assigning correlation between CAs and TR...............................................................................6
Building house of quality.............................................................................................................7
Manufacturing details......................................................................................................................8
Moulding and Wood cutting............................................................................................................9
Assembly & Quality........................................................................................................................9
Conclusion.....................................................................................................................................10
References......................................................................................................................................12
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Introduction
Product Design Specification
Product design specification is crucial procedure in analysing product which is going to be
launched in market. It is the combination of basically two parts one is requirement from
customers and another one is availability of engineering technique to satisfy the requirement of
customer, both are analysed simultaneously to improve the product which is going to be
launched, a mouse trap in this case. The process flow is occurring as per the following flow chart
for product design specification (Shetty, 2016).
Steps for PDS and House of quality.
Generally, the PDS process start with focussed group customer review, but our case especially
for the case of mouse trap, is not a type of product which can be shown in a large number of
group, because manufacturing a prototype is itself a costly and time taking procedure, the other
option is that we make one prototype and give provide it to someone’s home, and advice to use
it, give time for 1 or 2 days and collect the feedback from that home. Repeat the process as much
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Figure 1 PDS Flow Chart (Sources - (Shetty, 2016)

Mousetrap powered vehicle
data you want to collect. This may be time taking job but not costlier. We can also use 2 to 5
prototypes and give it to five different home and collect the data, doing this we can save the time
also (Houser, 2017).
Requirement collection from customer
As said earlier the feedback is collected from customer, generally two members of team from
product side are collecting the data in one from production and one for customer requirement and
one for technical requirement. Both the member should strive for answer for the questions like
what a good mousetrap should have? this answer is called as customers attribute, or in short form
CA. The CA for mousetrap could as follows but not limited to these the following requirements.
Easy in operation, easiness in setting the bait, luring the mouse to the bait, quick killing, and easy
to dispose of, life of the mousetrap, corrosion problem in metals etc (Shetty, 2016).
Technical requirement collection from customer.
From technical point of view the same question has been asked but team should record the
answer according to the technical requirement, the collection of data for technical team should as
follows, Quality of rubber band, fatigue life of rubber band, mechanism of operation of mouse
trap, process of opening the trap, manufacturing problem as per customer requirement. The force
applied by spring for one shot kill, force required to open the trap, life cycle for product as
whole, technique use in disposing dead mice. Therefore, the mind of the technical team should
work towards technical solution of collecting information from customer requirement, in some
other cases like mobile phone PDS or electronic item PDS, a team from marketing and sales also
have interface with customers (Hurst, 2007).
Based on the above collected requirement of customers we categorise the requirement of
customer on one to 5 scales, form technical team they analyse the number of component used for
requirement of customer from total number of components by using the following formula,
which is termed as design of efficiencies.
Design of efficiency ( η )= Number ofcomponents
Total numbers of component
Relative importance of customers attributes
Customer attributes Rating from customer
Easiness in operation 5
Setting of bait easily 4
Luring the mouse (Ability) 3
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Killing of mouse (One shot) 2
Disposing the killed mouse 1
Technical requirement based on customers attributes
Based on above requirement the efficiency of design can be calculated according to above given
formula, and result is tabulated below
Customer attributes Rating from
customer
Component
Used
Total
Component %
Rubber band fatigue life and
quality 5.00 4 12 33
Easiness in opening 4.00 4 12 33
Manufacturing easiness 3.00 3 12 25
Killing force of rubber band
(One shot) 2.00 1 12 8
Disposing techniques 1.00 2 12 17
Assigning correlation between CAs and TR
The correlation between two attributes is very important parts in PDS, some experience is
required in this analysis, most of the time we are going through certain rules and equation to
follow the procedure, but in this case only five attributes is given their, we will use only
analytical correlation. Which can be presented as,
Easiness in operation and opening is related to rubber band fatigue life and quality of rubber
band.
Manufacturing easiness is related to simplification in mechanism and device attachment which is
used to dispose the dead mice.
Killing force of mice is related to strong force generated by rubber band give a one shot on head.
Based on the above correlation we can move towards house of quality which is final step for
PDS. In this HOQs table we are specifying the correlated requirement based on Level of
importance, which is shown by dark circle which is very important, Empty circle, which has
average importance, and Importance of low level which is shown by triangle (Hurst, 2007).
It shows Most important
Show average importance
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Low importance
Building house of quality
The house of quality can be given as below
Rubber band fatigue life and
quality
Easiness in opening
Manufacturing easiness
Killing force of rubber band
(One shot)
Disposing techniques
Customer attributes
Easiness in operation 5
Setting of bait easily 4
Luring the mouse (Ability) 3
Killing of mouse (One shot) 2
Disposing the killed mouse 1
Importance Rating 33 33 25 8 17
From above house of quality, it is clear that easiness in operation is having customer weightage 5
and its technical efficiency is about 33%, in this condition, primary concern form customer point
of view, but its technical solution is that we have to implement such type of rubber band which
has enough force to kill mice in one shot. It was also seen that using heavier rubber band in any
component provides extra life and fatigue resistance to the product; therefore one secondary
concern is omitted by taking care of one primary concern from technical attribute (Palermo,
2013).
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Setting of bait easily has customer weightage 4 and its technical requirement is easiness
operation, the solution for this problem can be fixing the rubber band close to the hinge as close
as possible. Fixation of rubber band near to hinge, will provide extra moment of Inertia during
hit and during opening it can be opened easily. Use of some extra metal on top of bait can give
better shot than hitting with open bait only.
Disposing the killed mice is only related to technical attribute, in which there is only one
solution, and this solution is to provide some disposing technique in the mousetrap, but initially
it was instructed in assignment that we do not have to the original design given in photograph.
One important point about product design specification is that the primary concern also related to
the secondary concern, it means that if we take care of one primary requirement of our attributes,
there may be possibility of some other secondary or tertiary concern is also omitted
automatically. There vital few is dependents on useful many.
One problem with this model is that, this does provide the priority of action for technical person,
for this purpose, we are infusing one more thing in this house of quality, and it is Kano’s model,
this model also provide higher customer satisfactory attributes, but for this assignment Kano
model is out of scope, so we are limiting it up to house of model (Versace, 2013).
Manufacturing details
The manufacturing of mousetraps material starts with two sections, the first section will tell
about the prototype of mousetrap, which will manufactured through 3D printing technology, and
in second stage when product design specification the selection and house of quality will be
completed, then we will go to the main manufacturing process. Which will utilised for large
scale production (Zheng, 2009).
The manufacturing process in first stage, as said earlier, done through Focussed deposition
modelling, short form is FDM. It is one of the kinds of 3D printing which used ABS
(Acrylonitrile Butadiene-Styrene) plastic material in coil form. The ABS plastic material
filament is supplied to the printer through extrusion nozzle, which is heated and melts the
plastics. The nozzle is attached with the mechanism which controls the flow of melted ABS
material on sequence given by computer. The nozzle with flow mechanism is fully mounted on
mechanical stage which is free to move in horizontal and vertical direction (Palermo, 2013).
The movement of nozzle as per required geometry deposits the melted ABS to the plane layer by
layer and finally 3D object we obtained as per our requirement. The immediate cooling of plastic
making difficulties to bond with the layer of which is deposited previously, to solve this
problem, the whole system is kept heated just below the melting point of plastic. FDM is one of
the most widely used rapid prototype technology, we cannot establish the production instantly,
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but prototype is necessary for customer survey program used for product design specification.
The prototype can also be completed through stereolithographic, but it is quite expensive as
compared to FDM technology. Another advantage is that we are having Zortrax 3D printer at the
university’s maker’s space. So finally we can say that we will manufacture our mousetrap
prototype with the help of FDM 3D printer (Demaria, 2014).
But for second stage i.e. for large scale manufacturing we have to establish a setup, because 3D
printing is not meant for large scale. We have to start with injection moulding machines, which
can provide the same product at quite large scale with fraction of time as compared with 3D
printing (Yohanes, 2017).
The large scale manufacturing process will proceed as follows
Moulding and Wood cutting.
The ABS available for market to use in moulding machine is much cheaper than filament. For
large scale production, so many companies using this ABS as a raw material for their product.
Such form of plastic is also available which is biodegradable. The AusPlas is a company who is
providing inbuilt injection moulding machine which melts the ABS and inject it into the
moulding machine of desired shape and produce it. In the same time we have to establish wood
equipment so that long term cost benefit can be obtained through the use of supplied woods for
our purpose.
Other miscellaneous materials such as bearing and wire etc. can be directly procured from
market either it is online or offline, based on the cost and quality consideration (Shah, 2016).
Assembly & Quality
The assembly of the different parts has to be done manually through workforce. If the entire
different components are gathered at one place, this can be assembled easily with one person.
Initially we have to build the material on the basis of build to order. But if production increases
we have to increase the station for assembly, the tools that can be use in assembly line will have
flathead screw drive, metric size nut wrench, hammer and super glue. Later on quality can be
check through another person and if necessary finally packed it for despatch (Mmereki, 2016).
The initial cost of prototype is given below.
Item Description Qty. Cost (AUD)
Zortrax ABS Filament The raw material for 3D printing parts 138 gm $8.50
MR83(3x8x3 mm)
Deep-groove ball bearing Global
trade365, 2017) 1 pc $0.10
DIN 625ZZ (4 x 13 x 5)
Deep-groove ball bearing Global
trade365, 2017) 3 pc $3.00
4 mm dia wooden dowel The raw material for vehicle axle 2 pc $2.30
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Fishing Line For vehicle pulley system 5.0 m $0.00
Fishing line protector
turbing For vehicle pulley system 300 mm $1.00
Rubber bands 100 pc pack at $2 2 pc $0.00
During manufacturing at the overall cost of above material will drastically reduce. We can also
introduce continuous improvement program later, in which we are taking suggestion form shop
floor people and implementing it accordingly. The use of rubber band in place of spring also
reduces cost effectively (Bilgili, 2011).
Conclusion
From the above designing idea of making mouse trap powered vehicle, we have analysed several
possible idea and tried to simulate the design through Solidwork. It was possible to design the
mousetrap powered vehicle. The running the vehicle is found to be successful except some
turning problem, the sue of spring in place of spring has provided extra power to the front wheel
and provide turning the vehicle, finally the prototype was printed in 3D printing and assembled it
and send for customer review.
After customer review we have tried to analyse the product design specification through
specified tools of PDS. From PDS analysis it found that the movement of mousetrap doesn’t
effect to the customer, but if it is a mousetrap and it should solve its purpose. The major
requirement was found about longevity of product, the product should last longer and serve its
purpose for what it is made for, the technical attributes found in the analysis is stronger rubber
band and generation of killing force to the from the bait. One extra requirement provide by
customer is not fulfilled in this design, because of limitation of design change as per assignment
requirement. Manufacturing easiness found on average scale because, it is also one of the
attributes in which there is not concern for the customer. But it may be our major concern. The
house of quality suggests that rubber band fatigue becomes most important thing as a
manufacturer which also satisfies the major attributes for customer requirement. It was also
found that if we implement it we can omit one or two secondary and tertiary requirement of
customer. Two major technical attributes has been covered which has total about 67% of
efficiency in house of quality model
The last but not least is the manufacturing process adopted on the basis of prototype developed
through 3D printer with ABS material. After PDS the manufacturing process is suggested on the
basis cost and future requirement. Primary we have to install injection moulding machine which
will meld ABS material and provide shape according to the requirement, in parallel we have to
install wood cutting system in which wood requirement could be completed. Further requirement
of material is going to procured from market and feed to the assembly line, in this place
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assembly will takes place with the help of portable tools and by one person. There requirement
of person in assembly line will be based demands in the market, initially it is better to
manufacture the material on built to order basis.
References
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Bilgili, B. (2011). Kano model application in new product development and customer
satisfaction. Procedia, 24(1), 829 - 846.
Demaria, C. (2014). Fused deposition modelling. Centro piaggio, 1-50.
Evans, B. (2016). Practical 3D Printers: The Science and Art of 3D Printing. London: Apress.
Goodship, V. (2009). Practical Guide to Injection Moulding. Shropshire: Rapra Technology.
Heim, H. P. (2016). Specialized Injection Molding Techniques. Oxford: Elsevier.
Houser, J. (2017, 10 23). The House of Quality. Retrieved from https://hbr.org/1988/05/the-
house-of-quality: https://hbr.org/1988/05/the-house-of-quality
Hurst, K. (2007). Engineering Design Principles (2nd ed.). New York: Elsevier Science &
Technology.
Mmereki, D. (2016). The Generation, Composition, Collection, Treatment and Disposal System,
and Impact of E-Waste. International Research of Low Carbon and Green Buildings, 1-
12.
Palermo, E. (2013). Fused Deposition Modeling: Most Common 3D Printing Method. Live
Science, 1-5.
Qin, Y. (2015). Micromanufacturing Engineering and Technology. London: Elsevier.
Rosen, I. G. (2015). Additive Manufacturing Technologies: 3D Printing, Rapid Prototyping, and
direct digital printing. London: Springer.
Schmid, S. K. (2013). Manufacturing Processes for Engineering Materials. New York: Perason
Education.
Schmid, S. K. (2016). Manufacturing Engineering and technology. New York: Prentice Hall.
Shah, N. (2016). Maximising value addition in indian mobile phone manufacuring.
Counterpoint, 1-61.
Shetty, D. (2016). Product design for Engineer. Washington D.C: Cengage learning.
Versace, C. (2013). What Do Consumers Want In A New. Forbes Contributors, 1-3.
Yohanes, A. (2017). Improvment of sleeping bag. Dinamika Technique, 1-12.
Zheng, X. (2009). EXTENDING QUALITY FUNCTION DEPLOYMENT TO ENTERPRISE.
CEAI, 7(2), 42-49.
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