UnCanIt!

ME 74 – Senior Design – Mechanical Engineering Capstone Project

Many craft breweries have cans with intricate art on them that patrons enjoy. Currently, once the beer is finished, there is no good way to preserve the art on the can. Most people just throw the cans away or recycle them.

Our goal is to create metal art memorabilia from 16-ounce cans for bar patrons in exchange for money. The collectible “license plate” style design will allow people to create pocketable metal art commemorating their evening. Each design will highlight the art on the can and imprint a fun logo that the brewery chooses. Our solution must be purely mechanical, easy to use, and safe for patrons.

This concept could also link breweries by providing a consistent collectible item at various breweries. It could encourage beer enthusiasts to try new breweries as a motivation to collect more license plates.

CLICK HERE TO SEE FULL FINAL REPORT

UserS & Key Needs

Bar Patron:

Enjoyable, simple/easy, and interactive experience

Aesthetically pleasing and artistic product
Safe product
Pocketable size

Machine Owner:

Customizable design
Safe machine and product
Durable and repairable machine
Can earn money

Engineering Requirements

Clean product: Design is cleanly imprinted (without punctures) and edges are fully blanked.
Safety: user does not have access to blades, memorabilia is safe to handle
Easy-to-use machine: < 100 lbf force needed to operate machine, 6" clearance around interactive elements
Positive experience & lasting art: quick, easy, interactive process; product is durable and something users want to keep
Monetary transaction: must facilitate monetary exchange between patron and owner

Competitive Benchmarking

There are currently no commercial solutions that use a machine to recycle cans into flattened decor. However, there are machines that take other objects and produce art (e.g. penny press, or Art-o-Matic machine), and “do-it-yourself,” hand-powered techniques that turn aluminum cans or sheet metal into art (e.g. using a can opener, or a 3D printed can holder & cutter).

CONCEPT GENERATION & FIRst prototype

When presented with the prompt, the concept below, to the left, is the general process that we first developed for turning a can into flattened art. To summarize, this process is designed to take off and discard the top and bottom of the can, cut a slit in the side, flatten the sheet of metal, round the corners, and then imprint a design onto the metal. The end design is meant to reference a license plate motif.

However, after doing extensive testing on this process—and other ideas—we decided to change the overall flow to the second image, to the right. The can would be rotated 180˚ against two sets of stationary blades to cut off the top and bottom of the can. Then, a slit would be cut in the side of the can, and the metal sheet would be flattened. A blanking and embossing punch with a die would then come down on the metal and create the final art product.

To implement this process, we decided to focus on the two main categories: cutting and blanking/ embossing. The following designs were the prototypes developed in this first stage:

Cutting Mechanism

Blanking / Embossing Mechanism

Due to mechanical issues, and time/material constraints, both mechanisms ultimately did not function as desired. However, through this process, we learned a lot about the material and structural properties of the can.

The can cutting mechanism had a lot of issues with the cam system (the cams kept getting stuck and were not able to move the blade bar up and down in the desired fashion), and the blanking/embossing mechanism had a weak point in the design, and ended up fracturing upon use. In light of these circumstances, new designs were generated.

Redesign Process

We went through multiple redesign phases and prototypes, as seen in the images below. We shifted from a rotating then blanking mechanism to a puncture-pull-blank-emboss process. The full writeup describes these processes in (a lot of) detail.

Instron Machine Testing

We were curious about was how much force was needed to blank and emboss the metal, but we first needed to figure out how much clearance we needed for the die and punch.

To do so, we ran some tests using the arbor press using an existing ⅛” thick aluminum blanking punch and die in NOLOP. Using Onshape, we designed dies of different sizes, and cut each of them out of the aluminum. We kept the punch size the same. Then, we tested each of the punch-die pairs, which led us to the conclusion that the 0.5mm offset was optimal for shearing the can. With this knowledge, we fabricated a full-sized model of the punch and die for use in Instron machine (Instron 5800R Tensile and Compression Test System) testing.

Results of Blanking Tolerance Testing with ⅛” Aluminum on Arbor Press and Instron Machine Testing Results

The first test using the Instron machine used the 0.5mm clearance blank and punch. From this test, we determined that we needed 500 lbs of force to successfully blank the aluminum can.

Next, we conducted tests on different embossing plates. We brought in half-samples of the embossing design for testing purposes, with the top plates having various widths and heights of letters, and the bottom plate being the same throughout. These tests led us to conclude that a letter depth of 0.75mm, with thin letters, and 500 lbs of force successfully embossed the metal without tearing it. Given that we were only testing a quarter of our design and recognizing that the force required for embossing is proportionate to the surface area being embossed, we scaled up this force to 2000 lbs for effective embossing.

Second Prototype

This new design was significantly better than our previous design. And, most importantly, both the cutting and blanking/embossing mechanisms actually worked!

To use this device, the patron would first put the can in the can holders, and then slide the held can under the knives. The can holders would then be secured by a knob on each side. The patron would then move the knife rod down through the tracks, to puncture the can, by holding the handles on each side of the machine. Next, the knives would be moved back up, and stored in the top horizontal holding slot, and then the paddle would be moved down to the can, again using the rod and the tracks, to enter the slit on the side of the can. The paddle would then rotate 90˚, pulling the metal and laying it flat underneath the arbor press. This would allowing the ram of the arbor press to come down through the cutout of the paddle and blank and emboss the metal, when the arbor press handle was rotated.

CAD of Second Prototype

Second Prototype Build

STRUCTURE

PROS

Much more sturdy

CONS

Arbor press wasn't secured relative to the 80/20

CUTTING MECHANISM

The blades effectively sheared the can, the can holders held the can securely and prevented rotation, and the paddle fit around the blanking mechanism well

The blades were not securely stored, it was sometimes hard to puncture the can on the can holder nails, and the paddle track needed to be redesigned to more easily pull down the can wall

BLANKING / EMBOSSING MECHANISM

Adjustability of design improved alignment, and the ram and the ram adapter were very secure

The metal needed to be taut to effectively and cleanly emboss, and the ram adapter could be attached at an angle, if not careful

Final redesign

With these thoughts in mind, we continued redesigning. The first major change that we made was eliminating the tracks. We wanted to make something more easily maneuverable, user friendly, and simple. Therefore, we decided to attach the blades directly to the arbor press. This would facilitate ease and smoothness of the cutting process.

However, this design caused some initial concerns. How could we avoid cantilevered stresses on the 80/20 beams? Where should the can be located, to ensure both the cutting and blanking/embossing mechanisms worked properly and had enough clearance? After ideating in CAD and rapid-prototyping in real life, we developed the "Rooster" design, as seen in the images to the right.

Initial Ideation

CAD Prototyping

Final Outcome

Next, we redesigned the can holders. This redesign was fairly simple, but time consuming. Some modifications included:

The nail holes on the top holder were moved such that they punctured the flat wall of the can, rather than the slanted bit.
Can holders that wrapped around the top of the can were designed
Holes for hinges were added to the sides of the can holders
The curvature of the top can holder was adjusted so it fit the can better
Holes were added to the bottom of each can holder to attach to a baseplate to the can holders

Due to time constraints, and wanting to focus on getting the cutting mechanism, can holders, and blanking / embossing mechanisms working effectively, we decided to forgo the paddle, and tear the can using tongs. We found that tongs work surprisingly effectively, and maintain a safe distance between the user and the blades.

The next largest change in the final redesign was to the ram adapter. We made the sleeve slightly taller and adjusted the placement of the set screws to improve stability, and we added a spring-loaded clamping mechanism (SLCM) that attached to the ram.

We took inspiration from existing industrial blanking systems: as we lowered the ram, the bottom plate of the SLCM pressed down on the sheet of metal and held it firmly in place. Due to the nature of the springs, the ram could continue lowering—and as this happened, the bottom plate clamped even harder against the base of the arbor press. The ram could then lower until the blanking and embossing processes were completed. This helped to limit motion of the sheet metal during the entire process, reduced the number of points of interaction required by the user, and allowed the blanking/embossing process to be one-handed (so if you’re still holding a drink in the other hand, you could still do it!).

We also made some modifications to help with ease of use (wider clearance of blanking pocket, ejector holes), to improve the embossing (recessed top plate so blanking pocket would hit metal first, extruded letters further, etc.)

Spring-Loaded Clamping Mechanism

Acrylic Fracture

Our first SLCM was built out of acrylic. This provided a great proof of concept, but eventually fractured with excessive pressure.

So, after much discussion about materials, top vs. bottom plate travel distance, and ram adapter positioning within the SLCM, we developed a metal version.

However, with this new addition, we started having conflicts between the clamping mechanism and the can holders, and between the clamp and the can itself. We considered cutting the can holders, and also attempted to design a new, shorter clamping mechanism, but decided to keep everything as it was, in the end, and instead move the blades slightly further from the arbor press.

Furthermore, with this new setup, as we unfurled the wall of the can, the sheet of metal was not quite long enough to fully reach the blanking/embossing mechanism. To fix this, we decided to get rid of the nails that prevented the can from rotating inside the can holders. Now, when pulling the flap of metal out with tongs, the can rotated, and allowed even more metal to be ripped off from the top and bottom of the can.

Final build

The final product contained five major components: the structure, the can holding mechanism, the cutting mechanism, the blanking/embossing mechanism, and the tongs.

The structure around the arbor press was made out of 80/20 aluminum beams and clear acrylic protectors. For fun, we also added lights!

The arbor press was also bolted down onto pieces of wood. The wood was planed to create a level surface, cut on the miter saw to the same length using a stop block. Additional pine was attached to the end of the pieces as a bracket using wood screws.

The can holding mechanism was made of 3D printed PLA, and each end has two parts, connected by hinges on one side, and bolts on the other.

The cutting mechanism included the blades in a 3D printed PLA holder, the 80/20 hanging structure, and then the top 80/20 to ram adapter.

The blanking/embossing mechanism included a 3D printed nylon ram adapter with a blanking punch and 3D printed nylon top embossing plate. The blanking/embossing mechanism also included a waterjetted aluminum spring-loaded clamp, an aluminum baseplate, and a 3D printed nylon bottom embossing plate.

Finally, the tongs were standard BBQ grill tongs.

How to Operate the Machine

Remove the tab from the can.
Place the can in the can holders, such that the top of the can is in the left-most can holder.
Secure the can holders closed by screwing the nuts onto the bolts at the front of the can holders.
Loosen the knobs on either side of the can holders, and slide the can toward the arbor press until the can holders cannot move any further.
Tighten the can holders onto the structure using the big plastic knobs on either side.
Rotate the arbor press handle clockwise on the right side of the machine to cut the can. Move the blades down until the can is completely cut (until the base of the yellow tape is just above the metal of the can).
Rotate the handle counterclockwise to lift the blades away from the can.

8. Use the tongs to grab the wall of the can closest to the arbor press, through the slit that was just cut. Pull the can wall away from the can holders, until the metal is fully under the clamping mechanism of the arbor press.

9. Rotate the arm of the arbor press clockwise again. This allows the clamp to press against and hold the metal sheet, and the ram adapter to first blank and then emboss the metal.

10. Release the clamp by rotating the arm of the arbor press counterclockwise.

11. Take the souvenir from under the ram using the tongs.

Use by machine owner

While the main focus of this project was to provide the patron with a piece of art and a fun experience, we also wanted our design to have modular and accessible features to allow the machine owner to more easily maintain and personalize the device.

The blanking/embossing system features many adjustable and interchangeable parts. For example, the owner can unscrew the set screws on the ram adapter, and switch out the plates inside the ram adapter to allow for a new logo using an M3 allen wrench. Furthermore, the knife holder is attached to the 80/20 using bolts, and the owner can replace the blades if the get dull. Ideally, the UnCanIt! business would supply pre-made knife holders (blades securely glued to the 3D printed knife holder).

Finally, if the owner is comfortable with using OnShape, they can open the plate template and create their own design for the embossing plates. The design should be extruded to the UnCanIt! specified and tested values. Once the 3D files are ready in OnShape, the producer simply exports the STL file and can start the print. The plates can be printed on any standard (or higher) quality 3D printer with material close (or greater) in hardness to PLA or Nylon. Depending on the printer, printing a set of top and bottom embossing plates usually takes a mere 2-4 hours (2 for Prusa MK4 with PLA material, 4 for Markforged Onyx with Onyx Nylon material).

Conclusions & Future Work

Strengths of design

Cutting Mechanism

The blades in the cutting mechanism were quite effective. Their design allowed the user to puncture the can and create a linear, continuous slit in the side without having to apply too much force. The amount of flat can which was the canvas for the blanking and embossing was more than enough to fit reliably and support a clean cut. The can holders worked well; the can holders effectively hugged the shape of the can, but allowed it to easily rotate with little interference.

Tongs

The tongs were surprisingly effective at gripping and ripping the wall of the can to place it underneath the arbor press. The motions needed to do so were also generally simple and accessible to users. Furthermore, the tongs kept the user’s body at a safe distance from both the blades and from the arbor press.

Blanking/Embossing Mechanism

The blanking/embossing system is effective, modular, and easy to put together. The spring loaded clamp that we added as our last piece of the cutting and embossing system completely revolutionized how our embossing performed. Because of this addition, we were able to consistently blank through the metal.

Also, because we were using a low quality arbor press, we were initially having issues with the ram being very shaky in the track. However, after packing the track with frictionless tape, the ram stopped wiggling—and then securing the arbor press to the wooden base further ensured that the device was very precise.

Finally, the embossing plates are easy to install, and because they are 3D printed, they are also easy to make. This allows for endless plate customization options for future clients.

Limitations of Design

While we made great progress throughout this design project, there are certainly a number of limitations to the design. A few important ones are noted below, but a thorough analysis is detailed in the Final Report.

Cutting Mechanism

PROBLEMS:

As soon as we started moving the blades away from the arbor press, we started increasing the cantilever and getting unwanted forces and deflection. We therefore wonder if there are any improvements or additions to be made to the rooster that would still allow the blades to be placed at the necessary distance away from the arbor press while minimizing the cantilever and deflection of the device.

We also noticed that the ram cap cracked after extended use. This most likely happened when we were testing the extent of the cantilever; the deflection of the 80/20 parts could have stressed the part to failure.

PROPOSED SOLUTIONS:

We could potentially connect the blades to the ram adapter. This likely would involve making them one piece, or creating an overlapping design so they fit together and both fasten to the base of the ram.

To fix the ram cap issue, we propose making the cap out of a stronger material, like Onyx, or a reinforced 3D printed material. We could also make it out of metal.

Can Holders

PROBLEM:

The decision to remove the nails from the can holders was a last minute decision. When testing without the nails, if we ripped too far or too hard, the force would make the top and the bottom of the can pop out of the holders. We also think that securing the ends of the can at a fixed distance helped to make the rip more uniform; the sheet of metal that we pulled out was often trapezoidal, rather than rectangular, with an unsecured can.

PROPOSED SOLUTION:

There are a couple of options to fix these issues. First, both the can holders and the clamp could be sized down slightly, to allow the can to move closer to the arbor press. This would allow us to keep the nails in the can holders. Second, we could redesign to better integrate the cutting and blanking/embossing mechanisms.

Tongs

PROBLEM:

Loose, BBQ-style tongs are not the ideal solution for unfolding the can wall to lay beneath the arbor press, as they could easily get misplaced. However, due to time constraints, this is the solution that we had to go with for our final product.

PROPOSED SOLUTION:

Throughout our design process, we threw out many different ideas for how to rip and move the can wall beneath the arbor press, including a paddle, an arm with hooks, and clothespin style clamps. While we pretty effectively ruled out the arm with the hooks, we still believe that the paddle and the clothespins are potentially viable options. Both worked well, but had a lot of usability issues, when integrated with the rest of the design. We therefore believe that spending more time on ideation, redesign, and testing for this step in the process would be valuable in the future.

Blanking/Embossing Mechanism

PROBLEM:

The edges of the embossed design were successfully imprinted, but the center of the design was often not visible.

The main limitation of our current system was that aligning the die with the punch and attaching the die to the arbor press was difficult. Because the tolerance between the punch and the die had to be so tight, it meant the placement of the die needed to be precise and robust.

PROPOSED SOLUTION:

We did attempt to increase the height of the center of the design on the top embossing plate in an effort to combat the uneven embossing, but there was not enough time to properly test to determine if this was effective. We would like to study this problem more to improve the embossing system.

On the day of the showcase, we taped the die down. However, this is not suitable for a real-world application of the device. Therefore we designed a 3D printed plate to sit on top of our arbor press that would secure the die to the arbor press. We were not been able to test this design due to time constraints, but think it is a promising concept.

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