Design Guidelines

Key Aspects

1.0 Modularity
2.0 Standardisation
3.0 Construction
4.0 Accessibility
5.0 Safety

0.1 Preface

The guidelines presented here are a synthesis of insights gathered from various online sources and real-world experiences. Their purpose is to offer designers precise yet easily digestible information that can be effectively integrated into their practices. While striving to implement many or all of these guidelines is commendable, it's worth noting that even adopting one or more can positively contribute to creating a more repairable product.

Considerable effort has been invested to ensure that these guidelines are neither too numerous nor overly complex. Consequently, this is not an exhaustive compilation, but a thoughtfully curated set aimed at conveying the essence and intent of designing for repairability.

0.2 Terminology

To promote universal interpretation of the following guidelines, key terms used are defined below.

Repairer: The person who is seeing to the product repair.
Part(s): Encompasses any of the following categories without specificity: assembly, sub-assembly, module, or component.
Assembly: The highest level of part grouping within a product, consisting of sub-assemblies, modules and components that form a functional system.
Sub-assembly: An intermediate group of parts, consisting of modules and/or components that serve as a smaller functional unit within an assembly.
Module: A self-contained unit of strategically grouped components, usually designed to be easily replaceable.
Component: A single part within a product, generally serving a very specific function.
Inherent hazard: A product safety risk integral to the functionality of specific parts, unavoidable by design.
Design-addressable hazard: An existing product safety risk that could be mitigated or minimised through intentional design choices.

1.0 Modularity

1.1 Establish a part hierarchy

Categorize the parts of your design into assemblies, sub-assemblies, modules, or individual components, considering their complexity and role within the product. Establishing this updateable hierarchical structure helps indicate the relative scale and functional importance of each part throughout your design process. This awareness is critical for effective modularity planning, as parts will vary in their modularity depending on their position within this hierarchy.

1.2 Design modules for ease of extraction and replacement

In the contemporary repair landscape, it is generally more cost-effective to engage in and design for module-level part replacement instead of component-level part repair. Form module units within your product by strategically grouping the smaller and less-costly components. Design these units to be easily extractable and replaceable with features like quick-release mechanisms, clear mounting points and low-friction connectors.

1.3 Design assemblies for ease of access and service

Given that assemblies and sub-assemblies within products are often large, heavy, or complex, cost-effective repairs are best achieved without complete disassembly from the rest of the product. To facilitate ease of access, modularly segmenting parts based on their functionality or role within the assembly is key. This strategy may involve establishing dedicated compartments for modules, employing sliding or hinged access points, or utilising easily removable panels or covers.

1.4 Create a disassembly map for your product

A disassembly map is a visual guide that outlines the sequential steps required to dismantle a product. Evaluating each stage of disassembly can help identify redundant steps, such as unnecessary component removal or complex sub-assembly disconnections. This provides designers with valuable insights for optimizing disassembly efficiency and highlights potential design improvements that could be achieved through further modularisation.

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2.0 Standardisation

2.1 Physically label and number parts as much as possible

Physically labelling and numbering parts within your product enables repairers to more easily locate and reference specific parts during repair processes. This practice establishes a standard of communication that enables repairers to interpret repair information more reliably. Clear labels and numbering are particularly crucial in visually distinguishing similar parts from each other.

2.2 Ensure required repair tools are simple and common

Design your product so that the required repair tools are simple and commonly available. This increases the likelihood that repairers already possess these tools, thereby significantly streamlining the repair process. Additionally, simple and common tools are easily borrowed or affordably purchased by repairers who may lack the required equipment.

2.3 Utilise tool-less interfaces

Minimizing the number of tools required for product repair improves repair efficiency and accessibility. Furthering this concept, tool-less interfaces eliminate the need for tools entirely, leveraging our natural human tools – hands. These interfaces, including knobs, toggles, buttons, sliders, and magnetic connections, offer unparalleled standardisation for tooling requirements in repair processes and should be utilised wherever practical.

2.4 Utilise parts common within model or family

In selecting parts for your product design, prioritise parts shared across existing product variations or models. For instance, in designing a kettle, aim to use parts identical to those found in existing kettle designs, or at least parts shared within the broader kitchen suite product category. By fostering standardisation in this way, the parts in your design are made more readily available in the supply chain, more familiar to repairers, and more affordable due to economies of scale.

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3.0 Construction

3.1 Utilise reversible joining methods

Avoid designing irreversible or semi-permanent joining methods like rivets, press-fit connections, adhesives, or crimps into your product design, as they can be difficult and time consuming to separate during disassembly for repair. Instead, make assembly and disassembly processes more accessible and efficient by utilising reversible joining methods like bolts and nuts, toggle clamps, bayonet fittings, and snap-fit connectors.

3.2 Avoid technical assembly requirements

Improve repair efficiency by eliminating the need for specialized assembly techniques and tools, such as specific torque ratings and proprietary diagnostic equipment. Specialized tools and assembly requirements unnecessarily increase costs and cause delays in repairs. Simplifying repair procedures by standardizing tools and specifications promotes accessibility and removes barriers within product repair processes.

3.3 Design for repeat assembly and disassembly cycles

When selecting materials and designing specifications, anticipate the need for your product to endure numerous disassembly and reassembly cycles during its lifespan. Just as you might design for anticipated usage stresses, consider the unique stresses of repair operations, and ensure your product is robust enough to withstand them. For instance, select fasteners resistant to corrosion and stripping to maintain functionality over use and time.

3.4 Prefer bolts over screws in selecting fasteners

Bolts are designed to fit smoothly into uniform pre-formed threads, and they enable the connection and separation of product parts with minimal force. In contrast, screws forcefully carve threads into the material they penetrate, and require more operational force. Screw threads degrade significantly faster than those of bolts, and so increase the risk of repair delays or interruptions, particularly during reassembly.

3.5 Utilise threaded inserts instead of integrated threads

As fastener threads undergo multiple fitting cycles and endure stress from general product use, they can deform and require repair or replacement over time. When threads integrated into larger parts become worn or damaged beyond repair, the necessity of replacing the entire part can result in a costly repair. In contrast, being able to replace a threaded insert or nut is often a more economical and straightforward solution.

3.6 Include built-in wear indicators where possible

A wear indicator is typically an external device that visually signals or measures the progression of wear and tear on a part. A built-in wear indicator achieves this same function but is seamlessly integrated into the design of the part, eliminating the need for an additional assessment device. By incorporating built-in wear indicators into your product's design, you enable anticipatory repair planning for parts that need to be replaced more regularly.

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4.0 Accessibility

4.1 Reduce product complexity

Simplify your design by minimizing unnecessary intricacies and complexities. A straightforward product structure supports maintenance and repair by reducing the likelihood of errors during disassembly and reassembly and facilitating quicker identification of faulty parts. This allows repairers to navigate and address issues with greater ease.

4.2 Apply the Principle of Least Astonishment in shaping your design

The Principle of Least Astonishment is all about minimising user surprise, encouraging intuitive design that aligns with repairers’ expectations and makes interactions straightforward and user-friendly, therefore astonishing them the least. Leveraging this principle to guide your design can enhance the overall repair experience by ensuring a smooth and predictable repair interaction.

4.3 Highlight points of interaction for repair

Facilitate easy repair navigation within your design by incorporating visual cues that emphasize essential points for interaction during repairs. Utilise various design elements, such as colour, shape, pattern, contrast, and light, to highlight interactive parts like handles, dials, panels, construction tabs, and more.

4.4 Position vulnerable parts for easy repair access

Improve repair efficiency by aligning accessibility with the anticipated repair frequency of parts in your design: the more likely a part will need to be replaced, the more accessible it should be. Strategically position parts accordingly so to streamline the repair process by ensuring that common faults can be swiftly addressed.

4.5 Integrate spare parts into the product's design

Integrating common spare parts into a products design simplifies the repair process by providing immediate access to essential replacement parts. Proactively anticipating potential issues, this strategic inclusion ensures that more frequently replaced parts are on-hand when required, reducing downtime and mitigating delays associated with external supply chains.

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5.0 Safety

5.1 Identify and classify hazards

List and evaluate the potential hazards that repairers may encounter in repairing your product. Classify these as either inherent or design-addressable hazards. Inherent hazards are those typically associated with the core functionality of a design, and while minimally alterable, are predictable in terms of their occurrence during repairs. On the other hand, design-addressable hazards generally involve specific features, and offer higher alterability but less predictability in most cases.

5.2 Manage inherent hazards

Visually signal the inherent hazards within your product using industry standard colours, patterns, and symbols, aligning with best practices for each specific hazard type. It is crucial to safeguard repairers from exposure to inherent hazards by implementing comprehensive insulation and isolation measures. Employ protective elements such as guards, enclosures, shields, covers, and screens to effectively prevent any direct physical contact between the repairer and these hazards.

5.3 Minimise design-addressable hazards

Improve your design by carefully examining the design intent behind each of these hazards. In minimising or mitigating each hazard, keep in mind the functional and aesthetic aspects they feature, and ensure these are appropriately replaced. If you encounter challenges in this process, it may help to seek inspiration from comparable designs, engage in discussions with peers, and/or brainstorm alternative solutions that maintain the intended outcome without introducing hazards.

5.4 Minimise required force for repair procedures

Optimize safety during disassembly, replacement, and reassembly procedures by minimising the force and mechanical advantage required to be exerted by the repairer. Designing parts and connections with minimal force or leverage requirements reduces the risk of tool slippage and lowers the likelihood of accidental damage to the product or injury to the repairer.

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