Literature Review: Parameteric Design and Validation of Push-Fit Plumbing Connectors Manufactured via Fused Filament Fabrication (FFF)

Notes to Reader[edit | edit source]

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Background[edit | edit source]

Search Strategy & Terms[edit | edit source]

Key words terms (KWT)

1. "pipe" AND "fitting"
2. "pipe fitting"
3. "pipe fitting" AND "3D print"
4. "pipe fitting" OR "pipe fit"
5. "push fit pipe"
6. "push fit" AND "pipe"
7. "pipe fit" AND "CAD"
8. "pipe fit" AND "3D"
9. "pipe fitting" AND "CAD"
10. "pipe" AND "coupling"
11. "plastic" AND "pipe" AND "fitting"
12. "additive" AND "Manufacturing" AND "pipe" AND "fitting"

Strategies

1. Searched KWT 1-5 on duckduckgo
2. Searched KWT 6 & 7 on
   1. thingiverse
   2. grabcad
   3. yeggi
   4. printables

What are Push-Fit Plumbing Connectors?[edit | edit source]

Push-fit plumbing connectors, widely recognized for their ease of installation, are universal fittings that secure pipes without soldering, crimping, or gluing. Utilizing an internal mechanism, these connectors lock the pipe in place, leveraging the pressure within the plumbing system. Among the various brands, Sharkbite is noted for its popularity and reliability for both temporary and potentially permanent installations. These fittings are compatible with multiple types of pipes, including CPVC and copper, and are appreciated for their versatility, reusability, and the longevity they offer, often coming with a 25-year warranty. However, despite their benefits, they are generally more expensive than compression fittings and are considered not as robust as soldered connections^[1]​​.

Theoretical Framework[edit | edit source]

The theoretical framework for the design and validation of push-fit plumbing connectors through Fused Filament Fabrication (FFF) involves the use of OpenSCAD for modeling and an open-source desktop 3D printer, such as a Prusa, for production. This approach leverages the principles of parametric design, enabling customization and optimization of connector geometry based on specific requirements. Additionally, the framework incorporates material science to select appropriate filament types for durability and water tightness, and mechanical engineering principles to ensure the connectors can withstand the pressures and stresses encountered in plumbing applications. The use of open-source tools and hardware democratizes the manufacturing process, allowing for rapid prototyping and iterative testing to validate the performance of the connectors.

Significance and Importance[edit | edit source]

The significance and importance of researching and developing parametric design and validation of push-fit plumbing connectors manufactured via Fused Filament Fabrication (FFF) lie in the potential to revolutionize the plumbing industry by introducing customizable, easily producible, and potentially more sustainable plumbing solutions. Utilizing FFF and parametric design enables rapid prototyping and testing, reducing development time and cost. This approach also aligns with the growing trend towards digitization and customization in manufacturing, offering the possibility of producing connectors tailored to specific requirements, enhancing installation efficiency, and promoting the use of environmentally friendly materials.

Current State of the Art[edit | edit source]

The current state of the art in push-fit plumbing connectors has seen significant evolution and acceptance in the plumbing and HVAC industries, largely driven by the introduction and advancement of PEX (cross-linked polyethylene) and the development of push-to-connect technology. Over the past two decades, these innovations have transformed plumbing practices, offering a time-saving alternative to traditional methods such as soldering, gluing, or using specialized tools for pipe connections.

Push-to-connect technology, particularly when used with PEX, has become increasingly popular due to its flexibility, ease of use, and the efficiency it brings to connecting different types of pipes. This has been crucial for new construction and retrofitting projects, where the need for quick and reliable connections is paramount. PEX-based potable water systems, for instance, have been widely used in Europe since the 1980s, and their adoption in North America has grown substantially, now being used in over 70% of new residential constructions​^[2].

The advantages of push-to-connect fittings include not only time savings but also fewer requirements for fittings than rigid piping, the ability to curve around obstacles without elbow fittings, and a reduction in the water hammer effect. Furthermore, these systems are particularly useful in water heater installations and can facilitate the transition from water heater nipples to PEX as well as connect PEX to existing copper or CPVC lines​.^[2]

Despite their growing popularity, some skepticism remains among professionals regarding the reliability and durability of push-to-connect fittings. However, advancements in the technology have addressed these concerns, with next-generation push fittings showing significantly improved strength and reliability. These newer fittings have been engineered to withstand higher pressures and are backed by extensive warranties, reflecting confidence in their long-term performance​^[3].

Overall, the adoption of push-to-connect fittings represents a significant shift in plumbing practices, emphasizing the industry's move towards more efficient, reliable, and flexible installation methods. This evolution reflects a broader trend in construction and maintenance towards adopting technologies that save time and labor, address skilled labor shortages, and meet the demands of modern building practices​^[4].

Relevant Stakeholders[edit | edit source]

1. Plumbing Industry Professionals: This group includes plumbers, engineers, and contractors who are the primary users of push-fit connectors. Their expertise and feedback are vital for refining the design and functionality of these connectors to meet industry standards and practical needs.
2. Regulatory and Standardization Bodies: Organizations responsible for setting safety and performance standards for plumbing components play a significant role. They ensure that push-fit connectors manufactured via FFF meet all required certifications for use in plumbing systems, affecting market acceptance and usage.
3. Manufacturers of 3D Printers and Filaments: Companies that produce 3D printers capable of FFF and the filaments used in the printing process are crucial stakeholders. Their innovation and development of materials suitable for plumbing applications directly affect the viability and quality of push-fit connectors.
4. Research and Development Institutions: Universities and research centers conducting studies on new materials, 3D printing technologies, and innovative plumbing solutions contribute to the advancement of knowledge in the field. Their research can lead to breakthroughs in the performance and reliability of push-fit connectors.
5. Construction and Building Sector: Developers and construction companies are key stakeholders, as they decide on the plumbing solutions for new buildings and retrofitting projects. The adoption of innovative connectors by this sector can drive demand and influence market trends.
6. Environmental and Sustainability Advocates: With a growing focus on sustainable and eco-friendly construction materials, stakeholders advocating for environmental conservation have a vested interest in promoting the use of materials and technologies that reduce waste and carbon footprint, including FFF-manufactured push-fit connectors.
7. End-users and Homeowners: Ultimately, the individuals and businesses that use buildings with plumbing systems incorporating these connectors are stakeholders. Their satisfaction with the reliability, cost, and performance of the plumbing system affects the reputation and adoption rate of push-fit connectors.
8. Open-source and Maker Communities: Enthusiasts and hobbyists engaged in the open-source movement and DIY projects contribute to the innovation and dissemination of knowledge regarding FFF technologies and their applications, including plumbing connectors.

Applicability and Context[edit | edit source]

1. Residential Plumbing Systems: Push-fit connectors can be used in home water systems for repairs, modifications, or upgrades. Their ease of installation makes them ideal for DIY projects or professional plumbing work, especially in tight spaces where traditional soldering is difficult.
2. Commercial Buildings: In offices, retail spaces, and other commercial environments, push-fit connectors offer a quick solution for plumbing maintenance and changes, reducing downtime and facilitating easier modifications as tenant needs evolve.
3. Industrial Applications: In factories and industrial settings, where reliability and quick repairs are crucial, push-fit connectors manufactured with FFF technology can offer a durable solution compatible with a variety of piping materials.
4. Emergency Repairs: The simplicity of push-fit connectors makes them highly suitable for emergency repairs, allowing for quick restoration of water supply without the need for extensive plumbing experience or specialized tools.
5. Retrofitting and Renovation Projects: For updating older plumbing systems or retrofitting buildings with new water supply lines, push-fit connectors can significantly reduce labor costs and project duration, minimizing disruption to occupants.
6. Temporary Water Systems: For events, construction sites, or temporary facilities, push-fit plumbing connectors offer a flexible and reusable solution for establishing or modifying water supply systems quickly and efficiently.
7. Sustainable Building Projects: In the context of green construction and sustainability-focused projects, the use of FFF to manufacture push-fit connectors aligns with the goals of reducing waste and using more environmentally friendly materials.
8. Education and Training: Educational institutions and training centers can use push-fit connectors as teaching tools for plumbing students, demonstrating modern plumbing techniques and the integration of 3D printing technology in practical applications.
9. Remote and Rural Areas: For communities in remote locations, the ability to produce push-fit connectors on-demand using FFF technology can reduce reliance on distant suppliers and improve the resilience of water infrastructure.
10. Space Exploration and Remote Habitats: In extreme environments such as space stations or research bases in remote areas like Antarctica, the ability to manufacture push-fit connectors onsite can be crucial for maintaining life-supporting infrastructure with limited supply chain access.

Literature[edit | edit source]

TODO[edit | edit source]

• Create lists and sub-lists of topics that need to be further reviewed.

Push-Fit Plumbing Connectors[edit | edit source]

Paper/Website/Source Title[edit | edit source]

Zotero citation field with the URL (DOI preferred).

• Each top-level point should be a clear and concise key item from the source (methodology, info, design, gap, etc.)
  • Sub points are to be concise explanations of critical aspects of the key item
  • Should not be a copy and paste of info but rather an interpretation of what parts are relevant and why, selective copy & paste of relevant snippets is fine.

Fused Filament Fabrication (FFF) for Plumbing Applications[edit | edit source]

EcoPrinting: Investigation of Solar Powered Plastic Recycling and Additive Manufacturing for Enhanced Waste Management and Sustainable Manufacturing[edit | edit source]

DOI: 10.1109/SusTech.2018.8671370

• Abstract

In this article we propose the EcoPrinting technology, which aims at a near zero carbon foot print means of recycling waste polymers into functional, working products. To achieve this goal, we demonstrate a nanogrid device by which solar energy can be stored in a modest sized battery system and use this to power instrumentation for melt extrusion of waste polymers into 3D printer filaments. We then use this filament in a modified 3D printer system to manufacture functional humanitarian aid components such as water seals and pipe connectors. We investigate the feasibility of the EcoPrinting principal using ABS and HDPE plastics, while evaluating and optimizing enabling device energy consumption and manufacturing performance. We conclude that the EcoPrinting principal is possible and functional devices can be manufactured with mechanical integrity equivalent to commercially available components. We finally demonstrate that EcoPrinting can be used as a tool for humanitarian use, realizing a manufacturing paradigm that is self-sufficient and potentially capable of addressing challenges of plastic proliferation in developing nations.

• Introduction
  • Near zero carbon footprint
  • Importance in remote habitats
• Materials and Methods
  • Uses recycled ABS and HDPE plastics
  • Designing a low power renewable system to recycle and print plastic
  • Used Lulzbot Mini, Aleph Objects
  • Printed ABS at 220 C and bed temp at 95 C and speed of 60 mm/s
  • Printed HDPE at 200 C and bed temp at room temperature and speed of 7mm/s
  • all the prints are 100% infill
  • pipe connector and stem washer were designed using Inventor software
• Results
  • design is based on the outer diameter of the pipes
  • the parts were printed larger than commercial fittings to provide more strength
  • it takes 9 hours to print one pipe fitting and each fitting uses 700g of ABS

Design and Fabrication of Industrial Components Using 3D Printing[edit | edit source]

DOI: https://doi.org/10.1016/j.matpr.2018.03.036

• Abstract

In the product design and development process, prototyping or model making is one of the necessary steps to finalize a product, which helps in realization of a conceptualized design. The 3D Printing, as a prototyping method, has been used widely since the 2000s, once it became popular as an additive manufacturing method. This paper aims at revolutionizing the previous method further, to 3D print final components, instead of just prototypes, in all areas applicable, using some industrial components as samples. This paper provides the further scope of research into the possibilities of replacing metallic parts with non-metallic ones, due to the rising costs and dwindling resources, so as to sustain the same utility of product without any compensation on durability and quality.

• Introduction
  • Importance of replacing metallic parts with non-metallic
  • cost of casting, machine works, assembling of traditional pipes and fittings
• Materials and Methods
  • Specifications of the 3D printer is given
  • Materials used: ABS, and ABS-FR (blend of ABS and PVC)
  • ABS can be utilized from -20 to 80 degrees C
  • ABS-FR is Fire resistance, and has poor thermal conductivity
• Design Considerations
  • Component size
  • physical and thermal stress
  • durability
  • chemical reactivity
  • economic feasibility
  • difficulty of manufacturing
• printed a three way flow split working similar to a commercial one

Methods and Considerations for Parametric Design[edit | edit source]

An open source toolkit for 3D printed fluidics[edit | edit source]

DOI: https://doi.org/10.1007/s41981-020-00117-2

• Abstract:

As 3D printing technologies become more accessible, chemists are beginning to design and develop their own bespoke printable devices particularly applied to the field of flow chemistry. Designing functional flow components can often be a lengthy and laborious process requiring complex 3D modelling and multiple design iterations. In this work, we present an easy to follow design workflow for minimising the complexity of this design optimization process. The workflow follows the development of a 3D printable ‘toolkit’ of common fittings and connectors required for constructing basic flow chemistry configurations. The toolkit components consist of male threaded nuts, junction connectors and a Luer adapter. The files have themselves been made freely available and open source. The low cost associated with the toolkit may encourage educators to incorporate flow chemistry practical work into their syllabus such that students may be introduced to the principles of flow chemistry earlier on in their education and furthermore, may develop an early appreciation of the benefits of 3D printing in scientific research. In addition to the printable toolkit, the use of the 3D modelling platform – Rhino3D has been demonstrated for its application in fluidic reactor chip design modification. The simple user interface of the programme reduces the complexity and workload involved in printable fluidic reactor design.

• Design and 3D printing
  • Used Siemens NX, and OpenSCAD softwares
  • coupling consists of a male screw, a connector (cross-junction, T-piece, union or Y-piece), and a gasket
  • Fused Deposition Modeling (FDM) is used
  • commercial 1/4"-28UNF thread is modeled
  • a detailed explanation of the parametric design of all the parts is provided
  • used PLA for the male nut and the connectors because it has a high flexural (3150MPa at 23 degrees C)
  • used PEEK for printing the parts wetted bu the working fluid (high tensile strength, resistant to many laboratory solvents) - Polypropylene is an alternative
  • designed and printed a ferrule using PP material to prevent the leakage between connectors and the screw
  • pressure test was conducted uzing an AZURA P4.12 HPLC pump, and the flow rate was 1 mL/min
  • the highest pressure tolerated is reported to be 53 bar
  • the cost of material and the printing time is reported to be 1.43 pounds and 9h 49min (due to the small size of the connector)

Mechanical Properties and Performance Validation[edit | edit source]

An experimental investigation on mechanical performances of 3D printed lightweight ABS pipes with different cellular wall thickness[edit | edit source]

DOI: https://doi.org/10.15282/jmes.15.2.2021.16.0641

• AbstractIn recent years, cellular structures have attracted great deal of attention of many researchers due to their unique properties like exhibiting high strength at low density and great energy absorption. Also, the applications of cellular structures (or lattice structures) such as wing airfoil, tire, fiber and implant, are mainly used in aerospace, automotive, textile and biomedical industries respectively. In this investigation, the idea of using cellular structures in pipes made of acrylonitrile butadiene styrene (ABS) material was focused on and four different pipe types were designed as honeycomb structure model, straight rib pattern model, hybrid version of the first two models and fully solid model. Subsequently, these models were 3D printed by using FDM method and these lightweight pipes were subjected to compression tests in order to obtain stress-strain curves of these structures. Mechanical properties of lightweight pipes like elasticity modulus, specific modulus, compressive strength, specific compressive strength, absorbed energy and specific absorbed energy were calculated and compared to each other. Moreover, deformation modes were recorded during all compression tests and reported as well. The results showed that pipe models including lattice wall thickness could be preferred for the applications which don’t require too high compressive strength and their specific energy absorption values were notably capable to compete with fully solid pipe structures. In particular, rib shape lattice structure had the highest elongation while the fully solid one possessed worst ductility. Lastly, it is pointed out that 3D printing method provides a great opportunity to have a foresight about production of uncommon parts by prototyping.
• Materials and Methods
  • AutoCAD software was used for mechanical design
  • ABS filament was used
  • highest amount of error was reported 1.7% between the inner wall thickness of the design and the printed parts
  • three different lightweight designs introduced and there is around 74% weight reduction using the lightest design compared to fully solid pipe
  • compressive strength, elasticity modulus, and energy absorbed are measured for all of the pipes
  • fully solid pipe provides highest Compression strength (suitable for applications in which deformation is not acceptable)
  • Rib-shaped pipe has the highest elongation value (having highest flexibility before breaking)

Standards and Regulatory Compliance[edit | edit source]

Paper/Website/Source Title[edit | edit source]

Zotero citation field with the URL (DOI preferred).

• ...

Bibliography[edit | edit source]

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