Design for Maintainability

Understanding Design for Maintainability: A Critical Engineering Principle

In the competitive landscape of product development, engineers often focus intensely on initial performance specifications, manufacturing costs, and time-to-market metrics. However, one of the most consequential factors determining a product's long-term success frequently receives insufficient attention during the design phase: maintainability. Design for Maintainability (DfM) represents a systematic engineering approach that considers the entire lifecycle of a product, ensuring that inspection, servicing, repair, and component replacement can be performed efficiently, safely, and cost-effectively.

For industries across Atlantic Canada—from offshore energy operations to fish processing facilities, from forestry equipment to marine vessels—the implications of maintainability extend far beyond convenience. In our region, where harsh environmental conditions, remote operational locations, and seasonal workforce availability present unique challenges, a well-maintained piece of equipment can mean the difference between profitable operations and costly downtime.

Research from the Society of Automotive Engineers indicates that approximately 70% of a product's lifecycle costs are determined during the design phase, yet maintenance considerations often represent only a small fraction of early engineering discussions. This disconnect creates substantial financial burdens for end users and can ultimately damage manufacturer reputations and market position.

The Core Principles of Design for Maintainability

Effective Design for Maintainability rests upon several foundational principles that guide engineering decisions throughout the product development process. Understanding and implementing these principles requires a shift in perspective—viewing the product not just as a new creation, but as an asset that will require ongoing care throughout its operational life.

Accessibility and Ergonomics

The physical accessibility of components requiring regular maintenance represents perhaps the most fundamental consideration in DfM. Engineers must analyse how technicians will access inspection points, wear components, and serviceable parts. This analysis should consider:

• Minimum clearance requirements for hand tools (typically 50-75mm for wrench access)

• Sight lines for visual inspection of critical components

• Body positioning requirements for maintenance personnel

• Weight limitations for components requiring manual handling (generally under 23kg per CSA standards)

• Environmental conditions during typical maintenance windows

For equipment operating in Maritime conditions, accessibility takes on additional dimensions. Maintenance personnel may be working in cold temperatures, wearing heavy gloves, or dealing with ice accumulation. Components that are easily accessible in a controlled factory environment may become virtually unreachable when covered in salt spray corrosion or frozen condensation.

Standardisation and Interchangeability

The selection of fasteners, fittings, and consumable components dramatically impacts maintenance efficiency. A piece of equipment requiring fifteen different socket sizes for routine service creates unnecessary complexity and increases the probability of errors. Effective DfM strategies emphasise:

• Minimising the variety of fastener types and sizes

• Selecting common, readily available components over proprietary alternatives

• Ensuring interchangeability of similar components across the product

• Specifying standard lubricants, filters, and consumables available through multiple suppliers

In Nova Scotia and throughout Atlantic Canada, supply chain considerations amplify the importance of standardisation. Remote operations on Cape Breton Island or along the Fundy coast may not have immediate access to specialised components, making standard, widely-available parts essential for minimising downtime.

Quantifying Maintainability: Metrics and Specifications

Engineering disciplines thrive on measurable parameters, and maintainability is no exception. Several established metrics allow engineers to quantify and compare maintainability characteristics during the design process.

Mean Time to Repair (MTTR)

MTTR represents the average time required to restore a failed system to operational status. This metric encompasses fault diagnosis, component access, repair or replacement, and verification testing. Industry benchmarks vary significantly by sector:

• Consumer electronics: 15-30 minutes

• Industrial machinery: 2-8 hours

• Heavy mobile equipment: 4-24 hours

• Marine propulsion systems: 8-72 hours

Design decisions directly influence MTTR. For example, modular component design can reduce repair times by 40-60% compared to integrated assemblies requiring complete disassembly for component access.

Maintenance Labour Hours per Operating Hour

This ratio provides insight into the ongoing human resource requirements for equipment operation. Well-designed industrial equipment typically achieves ratios between 0.1 and 0.3 maintenance hours per operating hour. Products exceeding 0.5 maintenance hours per operating hour often indicate fundamental design deficiencies that should be addressed before production.

Accessibility Index Scoring

Many organisations employ numerical scoring systems to evaluate component accessibility during design reviews. A typical five-point scale might assess:

• Score 5: Component visible and accessible without tools or cover removal

• Score 4: Accessible with removal of one cover using common tools

• Score 3: Accessible with removal of multiple covers or adjacent components

• Score 2: Requires partial disassembly of primary structures

• Score 1: Requires major disassembly or specialised equipment for access

Components requiring frequent maintenance should target scores of 4 or 5, while even components with extended service intervals should achieve scores of 3 or higher.

Practical Implementation Strategies

Translating maintainability principles into tangible design features requires systematic approaches integrated throughout the development process. The following strategies represent proven methods for embedding maintainability into product designs.

Modular Architecture Design

Modular design partitions systems into discrete, replaceable units with well-defined interfaces. This approach offers multiple maintainability advantages:

First, fault isolation becomes more straightforward when systems comprise distinct modules with clear functional boundaries. Diagnostic procedures can systematically test each module, rapidly identifying failed components without extensive troubleshooting.

Second, module replacement typically requires less skill and time than component-level repair. A technician can swap a failed module in minutes, restoring system operation while the failed unit undergoes detailed repair at a properly equipped facility.

Third, modular architectures facilitate technology upgrades without complete system replacement. As improved components become available, individual modules can be updated while maintaining overall system compatibility.

Condition Monitoring Integration

Modern product designs increasingly incorporate sensors and monitoring systems that provide early warning of developing problems. Effective condition monitoring reduces unplanned failures and enables maintenance scheduling that minimises operational disruption. Key parameters for monitoring typically include:

• Vibration signatures indicating bearing wear or imbalance

• Temperature trends suggesting lubrication breakdown or overloading

• Electrical parameters revealing insulation degradation or contact wear

• Fluid analysis data identifying contamination or component wear debris

For equipment operating in Atlantic Canadian industries, condition monitoring proves particularly valuable. Seasonal operational patterns in fishing, agriculture, and tourism create natural maintenance windows, but only if developing problems are identified sufficiently in advance to plan corrective actions.

Documentation and Diagnostic Support

Even the most maintainable hardware becomes problematic without adequate documentation. Design for Maintainability extends beyond physical characteristics to encompass the information systems supporting maintenance activities:

• Clear, accurate maintenance procedures with appropriate safety warnings

• Diagnostic flowcharts and troubleshooting guides

• Exploded assembly drawings identifying part numbers and relationships

• Torque specifications, clearance measurements, and adjustment procedures

• Maintenance interval schedules with clear criteria for condition-based adjustments

Industry-Specific Considerations for Atlantic Canada

The economic landscape of Nova Scotia and the broader Maritime region presents unique maintainability challenges that engineers must address when developing products for local markets or operations.

Marine and Offshore Applications

Equipment destined for marine service faces accelerated corrosion, salt contamination, and constant vibration. Maintainability features for these applications should include:

• Corrosion-resistant fasteners (316 stainless steel or better) for all external applications

• Sealed enclosures with IP66 or higher ratings for electrical components

• Sacrificial anodes or cathodic protection provisions

• Maintenance access points positioned to minimise water ingress

• Non-slip surfaces and secure handholds adjacent to maintenance locations

Cold Weather Operations

With winter temperatures regularly reaching -20°C and below across Nova Scotia's interior regions, cold weather maintainability becomes essential. Design considerations include:

• Material selection avoiding cold-brittle failures (impact-tested steels, appropriate polymers)

• Fastener sizing accommodating heavy gloves (M10 minimum for critical external connections)

• Hydraulic systems designed for low-viscosity cold-weather fluids

• Electrical connections using cold-rated insulation and strain relief

• Heating provisions for maintenance areas or component compartments

Remote Location Support

Many Atlantic Canadian operations occur in locations distant from major service centres. Equipment design should facilitate local maintenance capabilities through:

• On-board diagnostic systems reducing dependence on external expertise

• Spare parts kits containing high-probability failure items

• Design simplicity enabling repair by operators with basic mechanical skills

• Remote monitoring capabilities allowing expert consultation from distant locations

Economic Benefits of Maintainability Investment

While incorporating maintainability features may increase initial product costs, the lifecycle economic benefits typically provide substantial returns on investment. Quantifying these benefits helps justify maintainability investments during product development budget discussions.

Studies across multiple industries consistently demonstrate that every dollar invested in maintainability during design returns between $5 and $15 in reduced lifecycle costs. These savings derive from:

• Reduced maintenance labour hours (typically 20-40% improvement)

• Decreased spare parts inventory requirements

• Extended component life through proper service access

• Reduced unplanned downtime and associated production losses

• Lower warranty claim rates and associated costs

• Improved customer satisfaction and repeat purchase rates

For capital equipment with 15-25 year service lives—common in marine, industrial, and infrastructure applications throughout Atlantic Canada—these accumulated savings can exceed the original equipment purchase price several times over.

Integrating Maintainability into Your Development Process

Successfully implementing Design for Maintainability requires organisational commitment extending beyond individual engineers. Companies achieving maintainability excellence typically employ several organisational strategies:

Early stakeholder involvement brings maintenance technicians, service managers, and end users into design discussions from the concept phase forward. Their practical experience identifies maintainability challenges that desk-bound engineers might overlook.

Design review checklists ensure maintainability receives explicit attention at each development milestone. Without formal checkpoints, maintainability considerations often yield to schedule pressures and cost-reduction initiatives.

Prototype maintenance trials subject development units to realistic maintenance scenarios before design finalisation. These trials reveal access problems, tool interference, and procedural difficulties while changes remain economically feasible.

Lifecycle cost modelling quantifies the financial impact of design alternatives, enabling informed trade-off decisions between initial cost and long-term maintainability.

Partner with Experienced Engineering Professionals

Design for Maintainability represents a multidisciplinary challenge requiring expertise in mechanical design, human factors, reliability engineering, and lifecycle cost analysis. Developing these capabilities internally requires substantial investment in training, tools, and organisational processes.

Sangster Engineering Ltd. brings decades of product development experience to clients throughout Nova Scotia and Atlantic Canada. Our engineering team understands the unique operational challenges facing Maritime industries and incorporates maintainability thinking into every project we undertake. From initial concept development through detailed design and production support, we help our clients create products that perform reliably and maintain efficiently throughout their operational lives.

Whether you're developing new equipment for marine operations, industrial processing, or infrastructure applications, our team can help you achieve maintainability targets that reduce lifecycle costs and enhance customer satisfaction. Contact Sangster Engineering Ltd. today to discuss how our product development expertise can support your next project.

Partner with Sangster Engineering

At Sangster Engineering Ltd. in Amherst, Nova Scotia, we bring decades of engineering experience to every project. Serving clients across Atlantic Canada and beyond.

Contact us today to discuss your engineering needs.