A two-phase QFD approach on the design of a two-wheeled bag type grocery handcart
Date of Publication
Bachelor of Science in Industrial Engineering
Ergonomics | Operations Research, Systems Engineering and Industrial Engineering
Gokongwei College of Engineering
Defense Panel Chair
Jose Edgar Mutuc
Defense Panel Member
One of the latest design alternatives for grocery shopping is the grocery handcart. It is a small handcart that is used for bringing groceries from one place to another. One of the benefits of this design is the pulling mechanism, wherein instead of lifting the grocery items, which is often to be heavy, the shoppers would only require to store them inside the cart and pull it to the designated location. This design prevents people from getting harmful injuries such as lower back pain. Currently, handcarts are still not very popular in the country, as many shoppers can still be seen using paper bags and eco-bags. However, the researchers found an opportunity to improve the current handcarts available in the market.
This study only focuses on the two-wheeled bag-type grocery handcart sold in Amazon, eBay, and Alibaba. The difference of this type of handcart to the other types is that the material used for storing the items is fabric bag while the others are plastic or metal. Moreover, this handcart makes use of a stand to help the handcart balance and usually the design of the handle is not adjustable unlike the other handcarts. Through data collection such as observations, FGD, and survey as well as biomechanical analysis, the current bag-type handcart provides dissatisfaction to users in terms of ease of sorting items, size, and item security. Aside from that, based on the biomechanical analysis, the users experience an additional 30.6N of force to keep the cart titled and an additional 27.94N of force to pull it. As such, this study aims to improve the current design of bag-type handcart by minimizing the 1-S ratings as well as the exerted force to the handcraft.
Concept selection was performed wherein brainstorming was conducted to come up with a good design. Concept classification tree was first utilized to narrow down the possible concept design after which concept screening was done. The team combined the concepts and obtained three alternative designs. Based on the concept scoring conducted, the second concept is best design according to the criteria. Furthermore, in order to create a product that would be suitable for all Filipinos, relevant anthropometric measurements are considered for the dimensions of the prototype. The 5th percentile of women, which is 23.23 inches, is considered for the arm length. In the 95th percentile, 4.33 inches is considered for the hand breadth. From those considerations, the handcart's dimensions are 16 inches by 13 inches by 38 inches (LWH) while the large bag's dimensions are 16 inches by 13 inches by 20 inches and the insulated bag is 15 inches by 10 inches by 8 inches.
Material selection was conducted wherein different experts were asked to rate down the alternative materials for the prototype development. For the frame, the best material is stainless steel. For the bag, ballistic nylon is the suitable material based on the criteria. Lastly, for the wheels, rubber wheels are the best.
FMEA was done to determine which part of the prototype should be given higher priority and consideration when revising the prototype. A total of 23 failure modes were assessed in the FMEA, but the major ones, with an RPN of more than 300 was the priority. The major failures are from the design of the bags.
In addition, various prototype testing were conducted to determine the improvements of the prototype including leak test, walk test, volume test, and user survey. The evaluation results of the prototype were compared to the original handcart in the market using a t-test. Based on the t-test, the problem of size, item protection, and easy to sort items were resolved with a new 1-S rating of zero. However, the new design provides dissatisfaction in terms of its usability, storage, and aesthetic aspect. Aside from that, other customer requirements have significantly increased due to misunderstandings between the researchers and the suppliers. The poor coordination with the supplier truly affected the satisfaction rating of the users to the final prototype. As such, it is recommended to further improve the product by increasing the satisfaction of the customer requirements.
Lastly, there are various improvements which can be made in terms of the methodology of the study. For the user surveys and focus group discussion, it is recommended to have larger pool size to saturate the data. This would ensure a more accurate representation of the demographic of users. Another improvement is for the selection of the concept designs wherein it would be better to incorporate the perspective of the expert designers instead of relying on pure research and brainstorming. This in effect would eliminate bias in choosing the concept design for the product and improve the chance of feasibility of the prototype. Lastly, it is recommended to conduct further research on possible materials rather than listing down the materials that are only available from the suppliers.
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Ampil, M., Castillo, A., & Lim, E. (2018). A two-phase QFD approach on the design of a two-wheeled bag type grocery handcart. Retrieved from https://animorepository.dlsu.edu.ph/etd_bachelors/18667