1. College of Engineering and Computer Science
Department of Mechanical Engineering
ME 330
Dr. Mike Kabo
The Crank Slider Crusher
Cynthia Sosa
Joseph Sarhadian
Due: July 07, 2015
Submitted: July 07, 2015
2. 1
Executive Summary
The use of a can crusher enables the manual working of a machine with less outsourced
power. The input force of the crusher is 30lbs. Other than the high efficiency realized from this
concept, the safety of the user is assured. The modified design used the Crank Slider Mechanism
where the shape, materials, and some equipment used to manage the process were altered to
create a new mechanism for crushing the cans. Here five consecutive designs were applied. The
complexities, maintenance, manufacturing, performance, safety measures, and servicing of all
designs were analyzed and compared.
Four alternative designs have been analyzed alongside the original design. There
is intended to withhold the cans with a circular base. When using this design, the process of
crushing is carried out inside a shield. In the second method, there are two sections involved in
the process that is carried out in a sequential manner. In this method, a cylinder and a piston
work jointly in crushing the can. This process is relatively safe as it takes place inside the
machine. The third method, on the other hand, involves a long track that acts as a passage for
cans. The width of the track can only allow one can pass. This prevents cans from jamming the
track. Besides, the track is surrounded by a column preventing cans from falling off. The
process is carried out in a place surrounded by boundaries. This boundary is meant to protect the
operator from the moving parts. This, in turn, makes it safe to operate. The fourth method
presents an advanced application of the can-crushing mechanism. In this respect, automated arms
are used in the process. One arm inserts the can inside the crusher while the other crushes it.
Once the can has been crushed, it slides out of the exit that is designed by the user. Since the
process is carried out by an operating system, the safety of the operator is assured.
3. 2
For all the designs a load of 600lbs was applied. There were no injuries reported
in all the tasks. The modified version was noted to have numerous advantages. Notably, the high
efficiency, coupled with a reduced risk of injury, is a major improvement over the older version.
Original Design Thoughts
The Mounted Crusher:
The can crusher concept was intended to make a safe human-powered can crusher
(Mau’s). This concept helped in designing the Mounted Crusher, which works on the lever
mechanism by the application of an axial load to crush the can or bottle. The complexity of use is
reduced to zero as the machine uses a lever only. The lever is lifted for the bottle or can to be
placed and then lowered to crush it. The drawer facilitates pulling out the bottom surface and
transferring the can or bottle to the disposal container. The lever has a concave surface cover that
protects the operator from injuries while crushing cans. The mounted crusher sits on the storage
container. The storage bin has a door to allow for easy collection.
We modified the design by shifting from a lever mechanism to a slider crank mechanism.
The change was aimed at increasing the efficiency of the machine. The Crank Slider mechanism
would result in a greater output force given the same input force of 30lbs. The linkages are
designed to convert the rotational motion into reciprocating motion. This was done using a crank
that rotates about a center. The crank is connected to the connecting rod with hinge support that
moves in the translation and angular direction. A connecting rod was attached to a piston using a
piston rod with a hinge support between them. This resulted in a reciprocating motion of the
piston. However, the mechanical advantage of the lever in the mounted crusher was not enough
4. 3
to crush the largest plastic bottle. The mechanism was fixed over a rectangular box of size 24’’x
36’’x 46’’ because the length of the crusher is long and narrow. As such, it would be hard to fit it
over a cuboid. Given this limitation, a rectangular prism was found to be a better alternative for
this crusher. The prism also serves as the container for collecting the crushed items.
Design Alternatives
Design 1 – Clash of Cans and Bottles:
Design 1 is a copy of the mechanism used for holding parts in the machine vise
(Johnson). Using that mechanism with modification as per project requirements to crush the cans
helped in reaching the goal. The design has a plate attached to a long threaded screw. The screw,
on the other hand, has a handle to rotate. The design is also fitted with a hollow rectangular box
with an opening on the top to place cans and bottles. Rotating the screw pushes the plate forward
and crushes the inserted item. Once the can has been crushed, it falls into the storage container
through the thin gap between the surface where the bottle is placed and the back of the machine.
Crushing requires the operator to apply torque. One of the major strengths of this design is user
safety. On this note, crushing takes place inside the machine. As such, the risk of getting pressed
by the machine is eliminated. For higher efficiency, lubrication of the screw should be done
weekly. Lubrication is aimed at reducing the friction force of the threaded screw. Also, it reduces
wear and tear. As explained by Bynoe-Arthur, the lubrication of the moving parts in a machine is
essential to ensuring higher efficiency and longevity of the machine. These benefits are realized
from reduced wear and tear, as well as the little force required to operate the moving parts
(Bynoe-Arthur 116).
5. 4
Design 2 – The Pedal Crusher:
This crusher design is derived from the Finkelstein Fred invention, the dumpster lid
opening system. The concept of the dumpster lid opening system is then modified to fit the can-
crushing context. This results in a “pedal crusher”. The mechanism consists of two systems: a
sewing system and a reciprocating system. The main component of the sewing is a pedal. The
operator of the machine applies force on the pedal. With the help of the linkages in the machine,
the sewing motion is transferred to the wheel of the reciprocating system. The wheel converts the
rotary motion into reciprocating motion. The conversion is enabled by the piston rod, connecting
rod, and linkages. The piston is responsible for crushing cans. On this note, the operator applies
force to the piston, which in turn crushes the can. Similar to the case in the first design, the safety
of the operator is enhanced, as the components of the machine – cylinder, piston, and mechanism
– are located inside a box.
Design 3- Can Squeezer:
The Can Squeezer design is derived from the concept of the pedal crusher as explained
above. Although the design works in a similar fashion as the pedal crusher design, fewer
mechanisms are involved in the process. The design works best when the machine is mounted on
a wall. Bottles and cans are placed on top of one another in a manner that the can being crushed
is at the bottom of the pile. On this note, the can crusher is made up of a column, plunger, and a
lever. Cans are placed in the column on top of each other. Once a can is crushed, it drops into the
storage container, thus giving room for other cans to be crushed. A long column gives ample
room for placing many cans at once. Besides, it prevents the cans from falling off in the case of
uneven force application. This design presents several benefits. First, the operator is safe to
6. 5
operate the machine, as the moving parts are not exposed. Second, the can crusher operates
efficiently. The operator does not need to place a can repeatedly.
Design 4 – Jack Crank:
The Jack Crank design is derived from the idea and working of the scissor-type jack used
in automotive. The jack has two arms attached to a crank. A screw is used to move the arms up
and down. The lower arm of the jack crank is attached to a ramp that is responsible for crushing
the cans or bottles kept below the ram on the surface of the container. The jack crank is fixed in
the container and has a door at the base to remove the crushed objects. It consists of a scissor
jack, bearings, a container, and a ramp. The maintenance requires the inspection of the crank and
periodic lubrication. As noted earlier, lubrication is necessary for reducing the friction between
moving parts.
Analysis of the Alternative Designs
To summarize the relative effectiveness of the alternative designs, an analysis has been
carried out. The analysis seeks to address the major characteristics that define a good machine.
Six characteristics have been identified: safety, complexity, maintenance, performance,
manufacturability, and serviceability. Each feature was evaluated for the five machines and their
average scoring determined. Machines with a higher score have high effectiveness. The first
feature to be determined was safety. Safety was evaluated based on the frequency and severity of
injuries to the operator. On the other hand, the complexity feature was measured by evaluating
how easily the operation of the machine could be understood. Third, maintenance scores were
based on how often each machine required undergoing maintenance procedures. The
7. 6
performance component was measured based on the efficiency of each model to crush the cans.
Assigning scores for the fifth feature, manufacturability, entailed assessing the complexity of the
components required to make the machine. Machines requiring simple components were
accorded higher scores. Lastly, serviceability was measured based on the time and effort required
to operate a machine, including the retrieval of crushed cans.
Scores of one to five were assigned to each of the features under consideration. It is
assumed that each feature is of equal importance when determining the effectiveness of each
design. Since all the features were accorded equal weights, the relative effectiveness of each
design was determined by calculating the mean score of the cumulative score. High scores were
associated with better models. Based on the analysis, the Mounted Crusher design attained the
highest score while the Jack Crank design scored lowest among the alternative designs. Safety
was the only feature that had three machines scoring the highest attainable score. On the other
hand, the designs scored lowest in the maintenance feature, as two designs scored 2, and none
scored 5.
8. 7
Table 1: An analysis of the can four designs:
Design 1:
Clash of Cans
and Bottles
Design 2:
Mounted
Crusher
Design 3:
The Pedal
Crusher
Design 4:
The Can
Squeezer
Design 5:
Jack
Crank
Safety 5 5 5 4 3
Complexity 3 5 3 3 2
Maintenance 3 4 2 3 2
Performance 3 4 3 3 3
Manufacturability 4 5 3 3 4
Serviceability 4 5 3 3 3
Average 3.7 4.7 3.2 3.2 2.8
Design Matrix Rubric:
Safety:
1- Person operating machine is severely wounded
3- Person operating machine receives minor injury
5- No one was injured while operating machine
Complexity:
1- Person does not know how to operate the machine; extreme confusion
3- Person needs to read instructions
5- Person operating machine understands how it is used; straightforward
9. 8
Maintenance:
1- Daily attention
3- Routine check
5- Long lifespan
Performance:
1- The machine does not crush the can or bottle at all
3- The machine somewhat crushes the can or bottle
5- The machine crushes the can or bottle without any problem
Manufacturability:
1- Mostly complex components
3- Some simple components and some complex components
5- Mostly simple components
Serviceability:
1- Time consuming and a lot of effort
3- Some time and effort required
5- Serviceman can easily access can or bottles without any obstacles
10. 9
Design Selection
Since the last update, a few modifications have been made in order to optimize the Crank
Slider Cracker design. The shape of the container housing the piston has changed from a hollow
rectangular box to a hollow cylinder. Ball bearings have been added to smoothen the back and
forth movement of the piston through the piston housing. Bhatnagar explains that ball bearings
enhance the efficiency of a machine by reducing the friction force. On this note, rolling friction
is considerably lower than sliding friction. When using ball bearings, less input force is required
to move an object (Bhatnagar 68). A needle was also included in the latest design. Material
properties have also changed from stainless steel 304 to stainless steel 301(AISI 301). AISI 301
is one of the most common and affordable stainless alloys. It has a high tensile strength and
exhibits good resistance to corrosion (Peninsula Spring Corporation).
11. 10
The Crank Slider Crusher can crush a can or bottle (up
to 59oz.) by a human powered mechanism. The user will open the small door located on the top
face of the cylinder to load the can or bottle. Once the can has been loaded, the operator should
rotate the handle 180 degrees in the clockwise direction. A minimum force of 30lb is required to
create a torque of 150lb-in. This torque will transfer the force from the axle to the crankshaft,
then to the connecting rod, and lastly to the piston rod. The piston, which is welded to the end of
the piston rod, will move forward to crush the can or bottle. A needle welded to the crushing face
of the piston allows air to escape from plastic bottles. A 3-inch gap between the end of the
cylindrical surface and the back surface allows the can or bottle to fall in once it has been
crushed. Two springs attached to the back surface of the piston and the front face of the
12. 11
cylindrical container will return the piston and handle back to their initial position. The door
located on the side of the unit will allow the collection of the crushed cans and bottles. For
machines intended for crushing a large volume of cans, the compartment should be enlarged. The
door in front of the unit is a complementary area for more storage.
The operation of the Crank Slider is simple. In this regard, the input force is applied to
the handle and the circular rotation causes the pins to rotate. This, in turn, makes the connecting
rod move forward. As the piston moves forward, it crushes the can in the compartment. The
piston connected to the connecting rod can move forward and backward through the cylindrical
housing with five times the force applied. Thus, the machine has a mechanical advantage of five.
The piston applies the crushing force on the can or bottle, which compresses them to a width of
three inches. Given the 3-inch gap between the cylindrical surface and the back surface, the
crushed object falls freely into the storage bin once the 3-inch width has been attained.
The selection of dimensions of the parts were done with a consideration of the maximum
bottle or can size that will fit in the cylinder for crushing. These dimensions also took into
account the factor of safety of 4 and the load of 150lbs, which is the minimum necessary force to
crush the largest bottle.
The selection of the material is essential in ensuring high system performance. Crushing
requires a material that is both stiff and strong. Materials that can easily break or bend would
lead to increased maintenance costs given the higher frequency of breakdowns. Given these
factors, Stainless Steel 301 was selected as the most appropriate material for making the
connecting rod. The selection of this material was done due to its stiffness and strength. Besides,
the material has demonstrated better performance over a wide range of temperatures when
13. 12
compared to other materials (Stainless Steel 301). Also, Stainless Steel 301 was selected as the
most appropriate material for making the piston. The material was preferred for its weight, yield
strength, non-corrosive nature, and heavy load bearing capacity (Peninsula Spring Corporation;
Materials). The use of this material is aimed at reducing the cost and frequency of maintenance.
On this note, the intense movement of these parts may lead to breakages or bending if the
material used is fragile or of low strength.
Prior to the selection of the materials to be used in making the different components of the
machine, an analysis of different factors was conducted. In this respect, the safety and yield
strength of the material used were evaluated. The analysis included mathematical calculations,
which are included in the appendix.
On visualizing the forces exerted on the parts of the Crank Slider, we realized the connecting rod
undergoes maximum stress in compression and tension. We thus contended that the first avenue
for failure was the connecting rod. A spreadsheet is made to calculate the factor of safety by
analyzing the connecting rod’s strength under various loads. The spreadsheet takes the input as
the load and the modulus of elasticity of the material and calculates the safety factor based on the
diameter of the rod. For a load of 600lbs, a factor of safety of 246 was achieved. This implies
that the design is strong enough to bear the load of 600lbs. The rest of the machine parts will thus
have a higher strength as per the load bearing condition. Thus, they cannot fail, as the connecting
rod has been found to withstand the force applied to it.
14. 13
Challenges and Avenues for Improvement
At first, we had problems calculating the stresses involved in the whole mechanism and
judging the first part failure. Since the failure first takes place in the hinge or the bolt, it was very
challenging to make the stress analysis around the circumference of the hinge and to find out its
failure. This challenge was solved when we resolved that the connecting rod was the first part to
fail. This was essential in understanding how the machine fails when various loads are applied.
The equation for the buckling derived for the connecting rod and the calculation made
based on the load and deformation of the connecting does not concur with the analysis of the
cosmos SolidWorks. Further analysis requires the crank slider parts undergoing forces to be
analyzed in the software to minimize the error by obtaining a more accurate calculation.
SolidWorks cosmos allows you to analyze the parts based on the given load and defined fixture
of the part(s) or assembly. The hand calculations need to be done by considering the stresses
generated in the hinge, piston rod, and the bolt so that they match with the results from the
SolidWorks cosmos static or buckling analysis.
15. 14
Work Cited
1. Anderson, P S L and Patek S N. "Mechanical sensitivity reveals evolutionary dynamics
of mechanical systems." Proceedings B 282.1804 (2015).
2. "Mechanical Advantage of Simple Machines." CPO Science. n.d. Web. 18 January 2016.
3. Aspen Fasteners. "Stainless Steel Fasteners." Aspen Fasteners. n.d. Web.18 January
2016.
4. Bhatnagar, V. P. The Art of Comprehension. New Delhi: Pitambar Publishing Company
(P) Ltd., 1999.
5. Bynoe-Arthur, Donna. Integrated Science: A Concise Revision Guide for CXC.
Cheltenham, U.K: Nelson Thornes, 2004.
6. Johnson, F. Vise grip. United States: Patent 1439822 A. 7 May 1920.
7. Mahadevan, K. and K. Balaveera Reddy. Design Data Hand Book: For Mechanical
Engineers. New Delhi: CBS Publishers & Distributors, 1984.
8. Azo Materials. "Stainless Steel - Grade 301 (UNS S30100)." Azo Materials. 11 April
2014. Web. 18 January 2016.
9. MatWeb. "Tensile Property Testing of Plastics." MatWeb. n.d. Web. 18 January 2016.
10. Mau’s, Karl Heinz. Can Crusher. United States: Patent 0293944 A2. 7 December 1988.
11. Peninsula Spring Corporation. "Stainless Steel." Peninsula Spring Corporation. n.d.
Web. 18 January 2015.
12. Rajput, R K. Strength of Materials. New Delhi: S. Chand & Co., 2006.
