The document provides an engineering report for the design, manufacture, and testing of a chocolate bar wrapper stamping machine (CBWS) created for Denman Island Chocolate. It describes the prototyping process, including developing a suction cup system to separate wrappers and a hot stamping method to imprint dates. The report outlines the CBWS design, including its motion, control, and stamping systems, as well as its user interface. It concludes with next steps to further develop the design into a commercial product.

1. Engineering Report
Denman Island Chocolate CBWS
Oliver Terry, Mike Viala
9/7/2015
Engineering report for the design, manufacture, and testing of the CBWS Chocolate Bar Wrapper
Stamper designed and constructed for Denman Island Chocolate.

2. 1
Table of Contents
Executive Summary.......................................................................................................................................3
Introduction ..................................................................................................................................................4
Prototyping and Concept Development .......................................................................................................5
Design Description........................................................................................................................................6
Overview...................................................................................................................................................6
Detailed Description .................................................................................................................................7
Motion...................................................................................................................................................7
Control ................................................................................................................................................11
Stamping .............................................................................................................................................14
User Interface .....................................................................................................................................15
Use ......................................................................................................................................................15
Evaluation ...................................................................................................................................................16
Overview.................................................................................................................................................16
Design Issues...........................................................................................................................................16
Next Steps...............................................................................................................................................16
Conclusion...................................................................................................................................................17

3. 2
Table of Figures
Figure 1: Prototype Wrapper Hopper...........................................................................................................5
Figure 2: The CBWS.......................................................................................................................................6
Figure 3: Cylinder Valve Manifold.................................................................................................................7
Figure 4: Suction Head..................................................................................................................................8
Figure 5: Suction Head Suction Cups ............................................................................................................8
Figure 6: Hot Stamper Pancake Cylinder ......................................................................................................9
Figure 7: Vacuum Generator.........................................................................................................................9
Figure 8: Input Hopper Platform.................................................................................................................10
Figure 9: Linear Screw and DC Gearmotor..................................................................................................10
Figure 10: Pneumatic Reed Cylinder Switches............................................................................................11
Figure 11: Upper Platform Limit Microswitch.............................................................................................11
Figure 12: Lower Platform Limit Microswitch.............................................................................................12
Figure 13: Photoelectric Sensor..................................................................................................................12
Figure 14: Photoelectric Reflector ..............................................................................................................13
Figure 15: Click PLC .....................................................................................................................................13
Figure 16: Hot Stamping Machine ..............................................................................................................14
Figure 17: Hot Stamping Dies......................................................................................................................14
Figure 18: CBWS Control Panel...................................................................................................................15

4. 3
Executive Summary
The Denman Island Chocolate CBWS (Chocolate Bar Wrapper Stamper) is an automated hot-stamping
machine for encoding dates onto the outer paper wrappers of their chocolate bars. Its design status is
that of a late-stage prototype, and can be used as-is in their production line. Several recommendations
have been generated based on the construction and operation of this prototype that will lead to a more
complete design that can be advanced to a commercial product.

5. 4
Introduction
Denman Island Chocolate is a small chocolate company located on Denman Island, BC. While some of
their production line is automated, most notably with a 1950’s-era machine which wraps the chocolate
bars in foil, as well as an automated foil-cutting machine, many tasks are done by hand.
Due to changing regulations and requirement by vendors, Denman Island Chocolate is now adding best-
before information to their wrappers. Due to the dynamic nature of the best-before date of the
chocolate bars produced, these cannot be added to the wrappers during printing, but must be added on
an ongoing basis during production.
Previous solutions to this problem included using a laser printer, which did not work due to the
minimum paper size requirements of most printers and the tendency of the wrappers to stick together
and their slickness; a roller-based hot stamping machine, which did not function as advertised and had
to be returned; and finally, manual stamping using a TRODAT date stamper.
In order to do away with the tedious and time-consuming process of manually stamping the dates onto
each wrapper, several commercially available options were explored in order to do this task, including
the purchase of a hot roller stamping machine from Dalemark, which did not function as advertised and
was returned.
After further research revealed that no commercially available, non-custom machine was suitable for
this task, we were commissioned to build such a machine. This machine would be fully automatic, low
maintenance, and would be capable of stamping 1000 wrappers per hour.

6. 5
Prototyping and Concept Development
Our initial step was to identify the main challenges inherent in this design. These were paper
handling/destacking (singly separating) the wrappers, which have a tendency to stick together, and
stamping the dates on the wrappers. We undertook research into commonly used technologies in these
areas in existing packaging systems.
After extensive testing of the wrappers, we determined that this tendency seemed to stem from the
cutting process used during the printing of the wrappers, and was therefore beyond our control. A
roller-based destacking system, such as that used in the unsuitable Dalemark machine, and in laser
printers, did not seem able to overcome the tendency of the wrappers to stick together. We explored
various other forms of paper separation, including those used in bank note counting, and finally settled
on a method using suction cups to separate one wrapper at a time from a stack, which overcame the
problem of the slickness of the wrappers. Preliminary testing of this idea using drinking straws and the
vacuum produced by the human lung yielded favourable results.
For stamping the dates, we settled on a hot stamping system, similar to other machines on the market,
including the unsuitable Dalemark machine. Other methods of stamping dates, including laser printers,
generally used water-soluble or other slow-drying ink. The ink used in these methods tended to smear,
rendering imprints from this method illegible. Hot stamping machines melt a layer of ink on a ribbon
using a heated die. After removal of this ribbon and die from the surface, the ink quickly dries and
becomes permanent. Tests undertaken using an inexpensive hot stamping machine verified these
results.
In order to avoid both mechanical and heat damage to the bars, we chose to stamp the wrappers before
their application the chocolate bars. This also simplified the task due to the more uniform dimensions of
the stacked wrappers as opposed to the wrapped bars.
We also prototyped a method of restacking the wrappers, as the
wrappers would have to be in a relatively neat pile in order to be
useful in the packaging line at Denman Island Chocolate. After
exploring various options involving chutes and ramps, we found that
a rectangular vertical hopper provided good stacking, as the air
escaping around the sides of a falling wrapper naturally caused the
wrappers to fall in a neat stack. A picture of the prototype hopper is
show below in Figure 1.
Overall, preliminary tests were favourable, and showed that
construction of a machine to fulfil the design requirements of
automation, low maintenance, and sufficient speed was possible,
while overcoming the problems particular to the wrappers. Figure 1: Prototype Wrapper Hopper

7. 6
Design Description
Overview
The Denman Island Chocolate CBWS (Chocolate Bar Wrapper Stamper) is a fully automated date coding
machine, using pneumatics and a ball screw linear guide for machine movement, a PLC and various
sensors for control, and a hot stamping machine to physically stamp the wrappers.
It features simple and intuitive controls, and is self-resetting at the end of each stamping run. The input
and output hoppers can accommodate approximately 2000 wrappers.
Figure 2: The CBWS

8. 7
Detailed Description
Motion
The CBWS uses pneumatic cylinders to control its motion; these are powered by a Makita MAC-700 air
compressor and controlled by valves attached to a manifold, as shown in Figure 3 below.
Figure 3: Cylinder Valve Manifold

9. 8
The motion of the suction head is provided by a dual-rod guided pneumatic cylinder, as show in Figure
4; the vertical motion of the suction cups on the suction head is provided by two pancake pneumatic
cylinders, as shown in Figure 5. One more pancake pneumatic cylinder controls the actuation of the hot
stamper, as show in Figure 6. All of these cylinders are supplied with air from the compressor, limited to
60 psi with an external regulator, and feature meter-in fittings to allow fine-tuning of the cylinder speed.
Figure 4: Suction Head
Figure 5: Suction Head Suction Cups

10. 9
Figure 6: Hot Stamper Pancake Cylinder
The vacuum cups on the suction head are powered by a vacuum generator, which is shown in Figure 7.
This vacuum generator is supplied with air at the pressure of the compressor.
Figure 7: Vacuum Generator

11. 10
The motion of the input hopper platform, shown in Figure 8, is achieved using a ball screw linear
actuator powered by a 24VDC gear motor, both shown in Figure 9.
Figure 8: Input Hopper Platform
Figure 9: Linear Screw and DC Gearmotor

12. 11
Control
Motion control of the pneumatic components of the CBWS
is achieved by on-cylinder reed switches actuated by the
magnetic pistons of each cylinder. An example of these,
shown on one of the suction cup cylinders, can be seen in
Figure 10 below.
The input hopper platform advances automatically, with a
roller lever microswitch sensing the level of the paper, as
shown in Figure 11. A second microswitch controls the
maximum lower position of the platform, to prevent
overloading the motor and burning out the windings, as
there is no current protection elsewhere in the circuit; this
switch is shown in Figure 12. All switches are configured in
such a way as to disable their outputs in the case of a fault
in the system, which prevents mechanical component
overload and breakdown.
Figure 11: Upper Platform Limit Microswitch
Figure 10: Pneumatic Reed Cylinder Switches

13. 12
Figure 12: Lower Platform Limit Microswitch
When the input wrapper supply is exhausted, a photoelectric sensor, shown in Figure 13, detects a
reflective disc fixed to the platform, shown in Figure 14. This causes the platform to reset to its initial
position.
Figure 13: Photoelectric Sensor

14. 13
Figure 14: Photoelectric Reflector
The machine is controlled by a Koyo Click PLC, which runs off 24VDC; the PLC, along with the system
wiring, can be seen in Figure 15.
Figure 15: Click PLC

15. 14
Stamping
The stamping of the wrappers is achieved using a hot stamping machine purchased as a unit. This
machine feeds a hot stamping foil ribbon over a heated die, which can be seen in Figure 17. When the
die is pressed against the wrappers, it sandwiches the ribbon between the two. The ink melts, adhering
to the paper, and remains when the die is removed from the wrapper. The hot stamping machine as
modified for use with the rest of the machine can be seen in Figure 16.
Figure 16: Hot Stamping Machine
Figure 17: Hot Stamping Dies
As the ink must be melted onto the wrappers, the dies must heat up before the machine can be used.
This takes some time and must happen before system readiness can be achieved.

16. 15
User Interface
The CBWS has three user inputs, and two outputs. The inputs are a power on/off switch, an emergency
stop switch, and a button which starts the program. The outputs are a red and green light, used to show
machine readiness and unreadiness/malfunction respectively.
Figure 18: CBWS Control Panel
Use
In order to use the CBWS, one must first power up the machine, and load wrappers into the input
hopper. Once the green light starts flashing, indicating machine readiness, the machine button is
depressed. This will prompt the machine to advance the input hopper platform to bring the paper stack
into the correct position for the stamping cycle, with the paper flush with the top edge of the input
hopper. Once this has happened, the machine button is depressed again to begin the stamping cycle.
The stamping cycle will complete and repeat automatically, until the stack of wrappers is depleted.
When this occurs, the stamping cycle will stop, and the input hopper platform will return to the starting
position.

17. 16
Evaluation
Overview
Overall, the Denman Island Chocolate CBWS stamping machine exceeds the requirement of being able
to stamp 1000 wrappers per hour with minimal outside intervention, in fact being able to stamp 1200
wrappers per hour.
As this machine is essentially a late-stage prototype, some design issues remain. In order for it to be
manufactured as a marketable product, the information learned in prototyping, testing, and running this
machine will have to be incorporated into future design revisions.
Design Issues
A few of the components chosen for this prototype machine would not be wholly suitable for
production use or would require a design revision for improved function or compatibility:
 The hot stamping machine uses rigid dies which require a flexible medium which they are
stamping. In terms of machine performance, this translates to a decreased amount of wrappers
that can be loaded into the input hopper; rather than loading 2000 all at once, they must be
loaded in stacks of 500.
 The ribbon used by the hot stamping machine may become misaligned, resulting in an
incomplete stamp or premature filling of the output spool.
 The air compressor used, while inexpensive and quiet, has a low capacity and flow rate; the
machine requires a higher flow rate than anticipated, resulting in continuous operation of the
compressor and a high rate of water condensation within the tank and input air line.
Next Steps
A few recommendations detail the pathway to take the CBWS from a prototype to a piece of
commercially available production equipment:
 Replace the hot stamping machine with a superior, custom hot stamping assembly, and feed the
paper wrappers in singly; this could be done as part of an integrated packaging line which also
puts the wrappers onto the chocolate bars.
 Replace the hot stamping machine with a rubber stamp type date stamper, which would allow
large stacks of wrappers to be stamped with no outside intervention. This solution might require
further engineering and research to ensure stamper ink suitability and integration with existing
machine infrastructure.
 Accurately measure the air consumption of the CBWS, and select a suitable compressor based
on this data. This data could also be used to correctly integrate future machines with existing
production lines.
 Refine the COTS (components off the shelf) bought, to improve suitability for final CBWS design.
 Improve the cosmetic appearance of the CBWS, to guard against misuse, injury, or damage
against the machine, and to improve perception of the CBWS as a technically mature product.

18. 17
Conclusion
The Denman Island Chocolate CBWS is a successful late stage prototype, can be used in Denman Island
Chocolate’s existing packaging line, and is the first step in the road towards commercialization of similar
products. Information gained in constructing this machine has proved invaluable in generating
recommendations to increase the success of future designs and to more fully address design
requirements.