Proceedings of the KGCOE Multi-Disciplinary Engineering Design Conference Page 7

Project Number: P09711

wEGMANS MINI-COOKIE SEPARATION SYSTEM

Stephanie Rager/ Project Manager / Bruno Coelho/ Chief Engineer
Brian Duffy/ Electrical Engineer / Ben Powell/ Electrical Engineer
Chukwuma Morah/ Industrial Engineer / Mark Voss/ Mechanical Engineer

Proceedings of the KGCOE Multi-Disciplinary Engineering Design Conference Page 7

Abstract

The objective of Wegmans Mini-Cookie Separation System Project is to create a prototype that will separate Wegmans’ Mini-Chocolate Chip Cookies by the correct weight for packaging. Customers are charged one price for all packages of mini-cookies but often employees are putting too many cookies in packages. This miscalculation leads to a loss for Wegmans. A fourth of the full design that was developed was built and tested in order to prove the concept, which consisted of funneling the cookies down the conveyor towards the drop chute which would rotate between weigh stations and once the correct weight was reached the push rod would move the cookies off the weigh scale. After testing, it was proven that the prototype met the needs and specifications developed with Wegmans and proved the concept for separating and packaging the correct amount of all types of mini-cookies.

introduction & Background

Wegmans has 72 stores located in New York, New Jersey, Pennsylvania and all the way down to Maryland and Virginia. Each of these stores has a bakery section which provides bread, cakes, pies and a wide array of cookies. These products are all baked and packaged in the Wegmans Bakery which is located on Brookes Avenue in Rochester, NY.

One of Wegmans high volume cookies is their mini-cookies. Each package should have 397 grams of cookies. Currently to package the mini-cookies about six or seven employees stand around a conveyor and pull the cookies into their clam-shell package. The employees estimate how many cookies should be put into the package to reach the 397 gram mark. Later down the conveyor is a check-weigher, which at the Wegmans facility only rejects packages that are under the 397 gram mark. Because of this Wegmans is over-packaging their mini-cookies. Employees usually put in about 450 grams of cookies instead of the 397 grams that the package calls for, causing Wegmans to lose money because customers are receiving more cookies than they are paying for.

In the beginning, the main product that this project was aimed at was Wegmans’ Mini-Chocolate Chip cookies. The mini-chocolate chip cookies have the highest volume of all the mini-cookies and would provide the highest savings when implemented. This project has a very high economic potential. By eliminating all of the excess mini-chocolate chip cookies that are packaged, Wegmans can save approximately $125,000 in a year. Although this project was to be mainly focused on the mini-chocolate chip cookies, through testing it was extended to all mini-cookies, which made the potential annual savings approximately $208,000.

Due to the volume of cookies produced by Wegmans and the constraints of a food environment and scheduling, this project develops a prototype that is one fourth of the final design. This prototype is not production floor ready in order to save on the cost of materials and time.

Design process

Customer Needs

The cookie line project was created in order to satisfy the needs of Wegmans and two of the company’s employees. Scott Young is the Manufacturing Engineer Manager and Chris Isaacson is an Industrial Engineer at the Wegmans bakery.

Through interviews and meetings, multiple categories of needs were developed. These categories included: separating product by weight, separating product by count, waste reduction, long term solution, labor/employee use, food environment restrictions and budget. These categories were broken down further into specific needs which were then given an importance rating.

The most important needs that this project should satisfy include separating specifically the mini-cookies by weight, reducing the amount of excess mini-cookies in a package which both came from the separating product by weight and waste reduction categories. The developed system should also not substantially slow down the current process which is from the long term solution category. It should also be less than $10,000. And finally, the system should be easy for employees to use and must not create a substantial extra amount of work for the employees.

It should be noted that the food environment restriction needs were not rated with a high importance because the final deliverable of this project is a prototype. Therefore, the prototype and the materials it is made out of do not need to follow these restrictions.

Engineering Target Metrics

Using the needs that were gathered from the Wegmans contacts, a set of eight metrics were developed in order to measure the performance of the final prototype. Marginal and ideal values were developed for each metric. The metrics can be seen in Table 1.

These metrics were also given an importance rating like the customer needs. The importance rating determined whether or not the metric would be a requirement of the prototype. The most important metrics are the main focus of the project, while the less important metrics were a secondary focus. Metric numbers 1, 2, 6, 7 and 8 were given a high importance rating and are the main focus of the prototype.

It should be noted that metric one was created through data collection. Currently 95% of the mini-cookie packages have at least two or more extra cookies in them which equates to approximately 25 grams or more. Some packages have four, six, eight or all the way up to ten extra cookies in them. Reducing the current value of 95% to the marginal value of 60 % would be eliminating the packages with at least six or more extra cookies which is 75 grams or greater.

It should also be noted that the throughput metric’s marginal and ideal values are representative of the full design and not the prototype. For the final prototype the marginal value of the throughput is 375 +/- 2.5% and the ideal value is 425 +/- 2.5%. These values are one fourth of the full design’s marginal and ideal values because the prototype is one fourth of the final design.

Metric # / Metric / Units / Marginal Value / Ideal Value
1 / % of packages w/ excess (25 g) cookies / % / 60 / 0
2 / Weight of cookies in package / g / 422 +/- 5 / 397 +/- 5
3 / Follows Wegmans’ sanitation standard / Y/N / N / Y
4 / Requires training that takes X minutes / Mins / 60 / 15
5 / Change over time / Mins / 20 / 5
6 / Accurately separates product for packaging / Y/N / Y / Y
7 / Throughput / Avg pkgs per hr / 1500 +/- 2.5% / 1700 +/- 2.5%
8 / Cost / $ / < $10,000 / < $5,000

Table 1: Engineering Target Metrics

Concepts

In order to develop different concepts for the prototype, the team used a brainstorming technique. All ideas were listed and then combined into three different concepts.

This first concept was a multi-speed weigh concept. This concept used conveyors that moved at multiple speeds to create separation between the cookies.

The second concept was a drop-hole concept. For this concept cookies were guided into funnels and then dropped through a hole. A laser would be used to count how many cookies dropped.

The third concept was a chute-weigh concept. This concept uses a funnel to guide the cookies into a chute which drops them down onto a scale for weighing.

Table 2 shows the concept selection matrix that was utilized to determine what concept should be chosen to develop and design. To develop this matrix the team rated each concept against the engineering target metrics that were developed.

The main issues for the multi-speed concept were that it would require a lot of training for employees to learn how to use it and using the multiple conveyors would increase the cost.

The drop-hole concept used count for determining how many cookies should be packaged. This is a problem because there is a lot of variability in the weight of each individual cookie. So by using count it would only be an estimate of the weight of the package and would most likely lead to the same result produced by the current way of packaging the cookies.

The chute-weigh concept was ranked the highest in the concept selection matrix. It was rated high for the most important engineering target metrics, such as throughput, reducing the percentage of excess cookies and accurately separating the product for packaging.

Concept: / Multi-Speed / Drop Hole / Chute Weigh
Selection Criteria / Import-ance / Rating / Rating / Rating
Reduces percentage of excess cookies / 9 / 5 / 3 / 9
Follows Wegmans’ sanitation standard / 3 / 5 / 5 / 5
Little training / 5 / 3 / 5 / 5
Changeover time / 5 / 5 / 5 / 5
Accurately separates product for packaging / 9 / 9 / 5 / 9
Throughput / 5 / 5 / 3 / 9
Cost / 9 / 3 / 9 / 5
Total Score / 233 / 233 / 317
Rank: / 2 / 2 / 1

Table 2: Concept Selection Matrix

Selected Concept

Due to it being the highest ranked concept, the chute weigh concept was selected for designing. The first main aspect of this concept is the conveyor. In this concept the system is built on a conveyor which would then be connected to Wegmans’ current conveyor when the final system is implemented. However, for this project since it is only a prototype, the concept will be designed and built on a smaller conveyor provided by Wegmans.

The mini-cookies come down the Wegmans conveyor randomly and not in any uniform lines. To accommodate this, the concept uses a sifter bar. This bar has slots in it which should be wide enough for a mini-cookie to pass through. The bar moves back and forth in order to put the cookies into straight lines.

The next portion of the concept is a funnel. This funnels the cookies towards the next portion of the concept, which is the drop chute. This drop chute is like a slide which the cookies move down into a weigh station. The drop chute moves between two weigh stations. The weigh station is where the cookies are collected and when the specified weight is reached, the drop chute rotates to the second weigh station.

The weigh station also has what is called a push rod system. When the specified weight has been reached the push rod will move the cookies off of the weigh station and onto Wegmans’ original conveyor. It will then move back to its original position and wait for the drop chute to rotate back with more cookies.

PROPOSED PROTOTYPE DESIGN

Mechanical Design

Figure 1: Proposed Design of Prototype

The overall prototype design of the concept was created on a conveyor donated to the project by the customer, straight from their plant. This conveyor is not only large enough, but also gives the group a sound machine on which to test the prototype. The assembly is composed of five major subcomponents: the sifter bar, the funnel, the drop chute, the weigh station, and the table.

The major objective of the sifter bar is to create some spatial separation of the product. This is an important factor in the design because the scales will otherwise not be able to achieve a settled weight. By moving the sifter bar back and forth, the cookies will have increased separation, and hence help the scale settle.

Using the motor, the sifter bar will rotate at a constant speed in a direction perpendicular to the flow of product on the conveyor, hence causing the spatial separation. A basic image of the sifter bar system is shown in Figure 2.

Figure 2: Sifter Bar System

The second subassembly is the funnel, located on the conveyor in gold in Figure 1. The major objective of the funnel is to condense the rows of cookies into a single-file line of product. This also assists in improving the spatial separation, and preventing any settling time issues. With this single-file line of cookies, the drop chute can switch once the last cookie is dropped onto the scale, and therefore will reduce the variance of the weight in each group of cookies.

The third subassembly of the prototype is the drop chute, which transfers cookies from the conveyor onto the scale. In order to account for the pushing out of cookies, the chute must be able to rotate thirty degrees in order to rotate in between each scale. Also, for testing purposes, the vertical angle must be adjustable, in order to determine the optimal angle height for the flow of product. A basic design of the drop chute subassembly is shown in Figure 3.

Figure 3: Drop Chute Subassembly

The fourth subsystem, the weigh station, is the major subcomponent of the assembly which weighs product with little variance and sorts out separate groups of cookies. With accurate separation of cookies, variance in product will be reduced, and hence throughput will increase in a plant implementation scenario.