Development of Specifications
DEVELOPMENT OF SPECIFICATIONS:
The developments of the specifications are dependent on customer and economical requirements. Based on customer feedback, a product should be geared at fulfilling the wants and needs of the customer. Furthermore, for the product to be cost feasible, economics and design for manufacturability are used. The customer needs are typically taken and translated into engineering values. The House of Quality (QFD) matrix is used to determine the relationship between customer needs and the product capabilities (technical requirements)
Based on customer analysis, the customer needs were determined to be ease of operation, versatility, safety, low cost, ergonomics, durability, ease of development, and ease of loading. The technical requirements were determined by the engineering team as follows: cap dimensions, bottle dimensions, closure type, opening torque, applied pressure, number of motors, machine dimensions, machine weight, opening time, and loading time. The customer needs and technical requirements were related within the matrix, and scored based on relevance using a scoring scale of one, five, or nine. Nine would equate to a strong relation, five would be medium, and one would be weak. For example, in the QFD chart that is provided in the Problem Approach section, the customer need “versatility” and technical requirement “cap dimensions” are given a value of nine since it is important to the customer for the machine to be able to open a wide range of cap dimensions. Based on the scores, the technical requirements and customer needs were ranked. These results guide the specifications of the project.
Specifications (engineering characteristics) such as the cap and bottle dimensions and closure type were determined through researching the different types of medication containers that exist. The values were acquired from manufacturers of the medication containers. Specifications such as the machine dimensions, weight, opening time, and loading time were determined from feedback that was provided by the customers. The customer research showed that the consumers desire a product that is similar to conventional home devices such as a coffee maker or a microwave. The opening time must not exceed 30 seconds and loading time must not exceed 20 seconds. The remaining specifications such as opening torque, applied pressure, and number of motors required experiments and further engineering design to determine the necessary motions required to perform the operation.
To determine specifications for the project that will resolve the design of the product and the components that need to be purchased to fulfill the required functions, experiments needed to be conducted. These experiments help establish values that can be used as the basis for performing the required functions. The requirement of the machine is to disengage the safety mechanism, and turn the closure so that the closure is loose and can be easily removed. Experiments and tests were performed to attain these values
Safety Mechanism Compression Test:
In order to determine the amount of force required to depress the closure on a container so that the safety mechanism is disengaged, a non-destructive compression test was performed on a tensile test machine. The acquired value for the depression of the safety mechanism shows the amount of force that needs to be provided by the lowering mechanism, which lowers the top assembly onto the closure. The tensile tester located in the Stevens Institute of Technology Engineering Design II laboratory was used to determine the amount of force required to depress the safety mechanism. The setup used can be seen in the following picture:
The obtained results show that the amount of force required to depress the cap are approximately 11 lbs of force. This value is used to determine the type and size of motion device that will be utilized to provide the downward force to disengage the safety mechanism of the closure.
Closure Torque Experiment:
An experiment was created to determine the amount of torque required to twist the closure once the safety mechanism is disengaged. By using rudimentary tools, a shaft with a wrench attached to it was used to hang a tank where water was filled until the closure turned from the closed position to the open position. By weighing the amount of water required to twist the closure, the torque was calculated. The setup can be seen in the following pictures:
A second test was performed to show that the frictional force required to grip the bottle in place will fail before the closure or bottle will break. This was performed by applying as much force as necessary until either the bottle broke or the gripping mechanism slipped. The results showed that the bottle slipped from the gripping mechanism before breaking. The results of the amount of force required to turn the closure (“To Turn” section) and the force applied when the slipping occurred (“Fully Loaded Bottle” section) can be seen in the following spreadsheet.
