Multi-Disciplinary Engineering Design Conference

Kate Gleason College of Engineering Rochester Institute of Technology

Rochester, New York 14623

Copyright © 2012 Rochester Institute of Technology

Project Number: P12712

WEGMANS SWIRL CAKE PROCESS IMPROVEMENT

Ryan Norris / Project Manager Arwen Sharp / Electrical Engineer

Benson Yu / Electrical Engineer Aaron Delahanty / Mechanical Engineer

Kenyon Zitzka / Mechanical Engineer

ABSTRACT

The primary goal of the Swirl Cake Process Improvement project was to design, build, and install an automated machine to aesthetically swirl marble cakes at the Wegmans bakery center. This project was implemented to improve the current manual swirling process which is labor intensive, ergonomically risky, and insufficient at providing adequate aesthetic. Several stages of swirl prototyping were performed in order to improve swirl aesthetic while maximizing the simplicity of the design to maintain low cost and provide ease of maintenance. Due to the large scope of the project and various uncontrollable hold-ups in the design and construction phases, the final result did not completely meet the initial goals. Instead, only a prototype of the swirling components was developed to serve as a proof of concept. This prototype consisted of (4) independent swirl modules that were driven by gear motors. These modules were fastened to a chassis mechanism that provided vertical motion for the swirl modules to enter and exit the batter. Concepts for other mechanisms, including a cart and pan stopping mechanism, were designed, but were not able to be implemented before the end of the project. The assembly was synchronized to the bakery line activity using a programmable logic controller and various sensors. The control portion of the project accomplished all tasks required for the completion of the project.

INTRODUCTION

Wegmans is a rapidly expanding, local

supermarket chain that is owned and operated in Rochester, NY. Wegmans owns and operates 79 stores in New York, Pennsylvania, New Jersey,

Virginia, Maryland, and Massachusetts (Wegmans, 2012). Despite the size of the chain, all baked goods are still produced in one facility in Rochester, NY. Therefore, in order to keep up with growing demand, Wegmans has been taking on various projects to expand capacity and increase efficiency at the facility. The Swirl Cake Process Improvement Project was one such project. The goal of the project was to design a fully automated machine that swirls vanilla and chocolate cake batter for marble swirl cakes, a process that is currently done by hand. The current process was identified by Wegmans, the customer, as an inefficient allocation of personnel and an ergonomic risk considering the complex motion required to complete the task. The implementation of an automated device would allow resources to be allocated to other parts of the facility, resulting in overall increase in production capacity and significant cost savings for the customer. The elimination of the manual task would also remove the possibility of any repetitive motion injuries associated with the process.

Swirl cakes from Wegmans are produced using a

mostly automated process using several reconfigurable machines. Empty cake pans are loaded into a pan greaser by bakery staff. After greasing, the pans travel on a conveyor to the batter dispenser. Vanilla batter is first dispensed and then chocolate batter in dispensed on top of the vanilla batter. The swirling process occurs after the batter has been dispensed. Two employees utilize wooden sticks to quickly swirl the chocolate batter into the vanilla as they travel down the bakery line. Since cake pans remain in motion, the swirl process must be completed hastily. Figure 1 shows the cakes

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exiting the batter dispenser and in the process of being swirled.

Figure 1 – Swirl station on bakery line

Once the swirling process is complete, the cakes

travel to the oven queue to wait for baking. If a cake gets through the swirl station un-swirled, an employee must travel down the line and swirl the cake before it enters the oven. Due to the rapid nature of this process, cakes are often inadequately and inconsistently swirled. Figure 2 shows the finished product. Close observation shows that the dobs of chocolate batter remain mostly intact and large areas of un-swirled vanilla are prevalent.

Figure 2 – Finished cakes leaving oven

The bakery line used for swirl cake production is also utilized to create a variety of other Wegmans products. Swirl cake is usually only produced for two or three shifts each week. The process requires approximately (4) employees (2 at the greasing station and 2 at the swirling station). Automating the swirling station would make the process down line from the greaser fully automatic and allow employees from the swirling station to be utilized elsewhere in the facility. This is the end goal of the customer. DESIGN PROCESS

Project Needs The initial step in the design process was to

assess the customers’ needs. The project readiness package assembled by the team guide, John Kaemmerlen, and interviews conducted with the customer provided the needs of this project. These needs and their designated specification are documented in Table 1.

Table 1 – Customer Needs

Additionally, it was required that the machine be

easy to service, integrated with the bakery line without major modifications, and limit/avoid change-over time between ¼ sheet (9”x13” cake foil) and ½ sheet (18”x 26” cake foil) pan operation. The final product should also improve the overall aesthetic appearance of the swirl cakes. Many of the customer needs listed above are qualitative and subjective in nature. This made creating quantifiable specifications difficult.

Project Specifications

Food safety played a large role in defining machine specifications. The material used in the construction of the machine is dictated by FDA and other food industry standards. As a result, the primary material used in the construction of the swirling machine was alloy 304 or 316 stainless steel. A list of food safe lubricants and plastics were also provided by the customer. Additionally, the design was required to avoid small parts and provide appropriate shielding to prevent small components from falling into food product.

Since there was no pre-established condition for complete swirl, Wegmans artisan, Sharon Penta, deemed that a piece of cake must have both vanilla

CN# Desription

CN1 Change over time; 15 minutes or not interfere with operations

CN2 Swirl 6.69 sheets per minute

CN 3 Stay within $2500 Budget

CN4 Machine needs to withstand sanitizing/cleaning

CN5 Machine must be food safe

CN7 Limit excess batter drip onto conveyor

CN8 Use 120 v, 240 v or 440 v power

CN9 Easy to maintain, service and obtain parts (limit downtime)

CN10 Maintenance and service documentation provided.

CN11 Moving parts must be contained to avoid injury

CN12 Chocolate batter must be swirled to aesthetic completion

CN13 Machine must be capable of switching between 1/4 and 1/2 pans

CN16 Limit machine size

CN17 Limit use of small hazardous parts

CN18 Limit machine weight

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Copyright © 2012 Rochester Institute of Technology

and chocolate batter present to be considered swirled. A piece of cake was further defined as a 3”x3” slice.

Table 2 - Specifications

The artisan also specified that the chocolate batter should penetrate through the entire thickness of the cake. This meant that post bake; the swirl pattern must be visible on both the top and bottom surfaces.

The cycle time of the swirling machine is also another very important specification considered. To avoid creating a “bottle-neck” in the bakery line, the swirling machine should take no more than 8 seconds to complete the swirling process. This is based on the oven’s limited rate of 6.69 sheet pans per minute (Starve rate). If the machine operated more quickly that the oven, it would not be a threat to production.

The budget was left open ended as it was not a priority. The customer specified a starting value of $2,500 that was open for expansion as the project progressed.

Noise limit and machine weight were standard OSHA (Occupational Safety and Health Administration) limitations. Noise was not expected to be a concern and weight was only relevant if the machine required lifting.

Concept Development

The concept development for the project was

split into three major phases of consideration: Overall process function, swirl process, and facility operation. The primary goal of the concept development was to meet the customer’s needs while creating as simplistic a design as possible.

The device’s overall process function related to how it would interact with the current cake making process. One consideration for this included whether the cakes would be processed while they remained in motion on the conveyor or if they would be temporarily paused for processing. The current manual operation allowed for the sheet pans to remain in motion while they were swirled and guaranteed that the oven would never be starved. Although processing the pans in motion would be

ideal, stopping each pan was determined to be the best decision. It required that extraneous devices (stop gate, etc.) be designed, but this was viewed as a far less complicated task than synchronizing with inconsistently paced, moving pans. This solution aligned well with the overall goal of creating a simplistic solution to the problem.

The most critical portion of the concept development was designing a mechanical system to swirl the cakes. The swirling process involved many complex motions and the customer’s aesthetic requirements were open ended. In order to come up with a solution that would satisfy the customer’s desires, three iterative prototype experiments were performed. The overall goal of these rapid prototype phases was to design a device that would provide a satisfactory swirl aesthetic, using as simplistic a mechanism as possible.

Phase 1 of the prototype experiment involved the modification of common kitchen utensils and small scale testing to gain an understanding of the physical swirling process and how different objects interact with the batter (See Figure 3). This phase was quick and dirty, but it was useful in highlighting the strong potential concepts while eliminating others. The next phase would continue to narrow the list of potential design solutions.

Figure 3 – Phase 1 Prototyping

Phase 2 was a full scale experiment that focused

on the motion required to achieve a sufficient swirl. It also examined if the task should be completed with many small swirlers or a few larger swirlers. The results showed that there was no benefit from using a larger number of swirlers and combining the motions of rotation and translation provided the most pleasing aesthetic performance. Although the best result was produced with a rotating swirler that translated across the batter, two, non-translating, interlacing swirlers provided a seemingly comparable performance. Since avoiding translation simplified the design, a purely rotational concept was tested in the final swirl

Specification (description) Unit of

Measure Marginal

Value Ideal Value

Change-over time mins 15 10

Overall Process Time (to prevent oven starve)

sec/sheet 8 4

Cost USD 2500 1500

Noise limit dB 80 70

Un-swirled gap in 0.5 0

Machine Weight lb 40 30

Adhere to FDA & American Meat Packing Industry Standards

yes/no yes yes

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experiment. Figure 4 illustrates an example of the testing performed in this phase.

Figure 4 – Full scale prototype with motion

diagram

The third and final experiment (Phase 3) utilized a custom constructed, reconfigurable test device that would serve to examine the appropriate position, size, quantity, and angle of the swirl “fingers” (Physical devices that interact with the batter). This experiment was performed using the customer’s batter and proportions to best match the automated batter dispensing that occurs on the bakery line. The results were reviewed by the customer the input was used in constructing the final swirl device design. Figure 5 & Figure 6 show the experimental swirling device and an example of the results, respectably.

Figure 5 – Reconfigurable Swirling Device

Figure 6 – Sample Result (Phase 3)

The last part of the concept development

involved what was described as “facility operation”. This included how the overall device would interact with employees and the bakery line. One key decision was whether the device should be permanently fixed to the bakery line or if it should be a mobile entity. Creating a permanent fixture ensured that the device would stay aligned and would require minimum setup time, but due to infrequent use food safety considerations, it was decided that the device should be mounted on a cart. This meant that a dock with an alignment fixture and power/communication plugs would be required. This was extra design work, but it provided a more sensible approach based on the customer’s needs.

DETAILED DESIGN Overview

Prior to designing the mechanical and electrical subsystems, the design team first considered the sequence of operations that must take place in order to produce a properly swirled cake. By laying this out early in the detailed design phase the remaining design tasks were streamlined and allowed for design decisions to be made. The sequence of operation is detailed in Figure 7.

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Copyright © 2012 Rochester Institute of Technology

Figure 7 - Sequence of Operation

Mechanical System

The mechanical system design utilized an approach that began by first designing the swirling devices and moving upward to drive train, chassis and support structure. Overall, careful consideration was taken throughout the design to avoid small parts/components and utilize food-safe materials to greatly minimize any hazards to consumers.

The swirling devices were designed to provide maximum coverage of both ¼ and ½ sheet pans while avoiding mixing (vice swirling) the two types of batter. The swirling device consists of (3) arms that have (2), 0.25” fingers each, that are mounted at varying radii. The (3) arms are mounted 120 degrees apart so that complete interlacing can be achieved between two separate swirl devices. To make removal and sanitation of the swirl devices easy, a spring loaded quick-connect device was designed. A representation of a swirl device is depicted in Figure 8.

Figure 8 - Swirling Device w/ Quick-connect

Coupling

Each motor module was designed to actuate (2)

swirling devices in order to swirl one ¼ sheet pan cake (2 modules per ½ sheet pan). This was accomplished by utilizing one 60 RPM gear motor to operate a pair of gears that are coupled to the swirling devices. An illustration of the motor module is shown in Figure 9.

Figure 9 - Illustration of a Motor Module

The motor modules were mounted to a box

frame chassis in a 2 by 2 pattern to obtain coverage of an entire sheet pan of swirl cakes. Contained on the box frame chassis were embossments for fastening the motor modules and linear bearings. These embossments prevented the need for small fasteners on the bottom side of the chassis frame (food safety threat). The linear bearings aligned the swirl chassis to the support structure and ensured that the swirl chassis could actuate up and down consistently and align properly with sheet pans. The swirl chassis was actuated using a pneumatic cylinder with a 1 ½” bore size. Shown below is Figure 10. It illustrates the swirl frame chassis assembly, support structure, and pneumatic actuator.

Figure 10 – Complete Chassis Assembly with

Support Structure

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To position the swirl machine over the bakery line, a cart was designed with a vertical mast and bracket system. Mounting the machine on a cart allowed the machine to be moved out of the way when it is not in use or moved to a location to be sanitized. Locking casters and a quick release pin alignment system are used to maintain the machine’s position over the bakery line. Implementing a cart eliminated lifting hazards that would have been present if the machine had to be carried away.

To stop the sheet pans directly underneath the swirl machine, a gate mechanism was designed. It consisted of a flat plate attached to a 4 bar link that is mounted underneath the bakery line. A pneumatic actuator raises/lowers the gate to stop/release the sheet pans. Figure 11 shows the complete swirl machine assembly mounted to the bakery line along with the gate mechanism.

Figure 11 - Complete Swirl Machine Assembly

Electrical and Control System

The controls portion of this project was integral

in synchronizing the mechanical function with the bakery line. An Allen Bradley Micrologix PLC (Programmable Logic Controller) was selected to process the inputs from the sensors and provide output control signals to the swirling machine.

The numerous input signals to the PLC were provided from an array of sensors that were implemented to ensure consistent and safe operation of the swirl machine. Contact switches were mounted to the swirl frame so that position of the swirl chassis (up/down) could be monitored. Similarly, a reed switch was implemented on the gate actuator.

A mixture of photo-electric, optical sensors and inductance driven proximity sensors were used for indicating the presence and alignment of pans respectively. The customer noted that occasionally sheet pans are sometimes skewed and go down the conveyor the wrong way. It was important that the

system logic not only check for the presence of a pan, but also check for proper alignment.

Since the designed system stops each sheet pan, there was a potential risk that a queue of sheet pans could build up behind the sheet being processed. This introduced a problem because separation between pans was required for the gate mechanism to actuate up into a space between pans. Fortunately, the customer had a pre-existing clamp mechanism for creating pan separation. An optical sensor was implemented to detect the presence of a pan in the queue. This input was then used to actuate the pan clamp.

The pneumatic actuation of both the gate and the chassis were triggered using 4-way solenoid valves that default to all ports closed. This means that if power were lost, all pneumatically operated devices would remain in their current position. This was done to avoid damaging equipment or potentially causing injury to an employee. Control buttons were implemented to allow for restart.

The system functions are started and stopped using 4 control buttons that make up the user interface. There were three buttons for regular operation: start, stop, and reset. An emergency stop button was also implemented to meet facility protocol.

Since the PLC has a limited amperage output, all (4) motors (1 on each motor module) for actuating the swirl could not be directly powered from it. A motor starter with an amperage overload protector was used to act a relay for powering the motors. The PLC only needed to supply a low current signal voltage

Using signals from the various sensors and other input devices, the PLC controlled the operation of the device. When a sheet-pan arrived at the pan present/aligned sensors, the solenoids engaged the pneumatics which lowered the swirlers. Then the motors turned on for the cake to be swirled. The PLC then triggered the solenoid valve to raise the swirlers up, and the gate mechanism lowered to release the sheet pan.

RESCOPE Due mainly to a quickly approaching deadline, fabrication, assembly, and testing of the system components most critical for machine operation became the primary focus. Conversely, despite completing initial design, further development of the following system components was halted:

• Cart • Shielding • Gate Mechanism

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Copyright © 2012 Rochester Institute of Technology

Team resources were allocated to: • Assembly / calibration of machine

chassis • Development of a simulated

product line environment • PLC / Controls integration

FINAL SYSTEM PROTOTYPE The final completed prototype includes the entire machine chassis (as shown in Figure 11) with complete pneumatic actuation and functioning motor modules. The chassis is mounted on a temporary frame that allows the surface of whatever the test setup is located on to function as the conveyor surface. Additionally, an integrated test stand was developed that contains the PLC and all required sensors and actuators. The purpose of the prototype and test stand was to produce an environment that closely simulates the production environment. In order to test the functionality of the system only minimal human interaction is required; a pan must be moved under the chassis and upon swirling completion removed from the set-up* Initial set-up of the prototype test stand proved the concept promising but further testing is required. PLANNED TESTING

To assess the machine’s design’s ability to satisfy customer needs, a comprehensive final test plan was developed. The testing was divided into 3 phases to easily troubleshoot faulty components. Table 3, shown below, summarizes the final test plan and the test variable for each phase.

Phase one involves testing a single motor module and its ability to swirl a single 1/4 pan. Vertical motion is achieved through manually lifting the module in and out of the cake batter. Phase two tests 4 motor modules assembled as a complete chassis with functioning pneumatics to provide vertical motion. Phase three tests the entire process including complete chassis, actuation/sensing, and plc integration; simulating the production line environment. CONCLUSIONS/DOCUMENTATION PACKAGE

The end goal of this project was to not only serve as a proof of concept through the construction and testing of a prototype, but also to document a critical path to working successfully in cooperation with Wegmans. Working with such a large business was

Table 3 – Final Test Plan beneficial considering their vast resources, but accessing those resources proved to be a sometimes daunting task. The documented feedback from this project will act as a vital source of information that will provide details needed to work efficiently with Wegmans and allow future design projects to expand in both scope and complexity. ACKNOWLEDGEMENTS

The team would like to express its sincerest gratitude to those who have made invaluable contributions to this project. Thank you to advisor Professor John Kaemmerlen and to sponsor Mike Least, for their guidance and support. Additionally, the team would like to express thanks to all those involved who provided assistance - Gary Kittrell,

Tony Contrera, Dean Wight, Rick Norder and Professor Scott Bellinger.

*At the time of authorship of this paper. Test setup also required manual actuation of the gate mechanism pneumatics.

REFERENCES Wegmans. (2012, October 15). Retrieved October 15, 2012, from Wegmans: http://www.wegmans.com

TEST VARIABLE METRIC

Phase 1

Time to Swirl Completion time [s]

Batter Splatter N/A

Stopping Torque N/A

Swirl Quality N/A

Motor Fatigue Test - On/Off Cycle frequency[Hz] / time[s]

Swirler Misalignment/Interalacing N/A

Misalignment of Swirlers w.r.t. 1/4 Pan N/A

Phase 2

Length of swirl process time [s]

Pneumatics Fatigue Test frequency[Hz] / time[s]

Misalignment of chassis w.r.t. Sheet Pans N/A

Angular Misalignment of Guide Rails N/A

Phase 3

Length of Entire Process time [s]

Sensor / Actuation line simulation N/A

Process Repeatability N/A

Process Fatigue Test N/A

Process Noise Level [dB]

Sheet Pan Misalignment N/A