Product, Service and Process Design

Introduction

Industrial engineering begins before production starts. Decisions made during product, service, and process design determine much of an organisation’s cost, quality, flexibility, safety, environmental impact, and ability to satisfy customers. In many industries, most life-cycle cost is committed during design, even though expenditure occurs later during purchasing, manufacture, distribution, use, and disposal.

Product design concerns what an organisation offers. Service design concerns how value is created and experienced by customers. Process design concerns how inputs are transformed into outputs. These decisions are interdependent: a complex product may require an expensive process; a service promise may require additional capacity; and a process constraint may require redesign of the product.

This chapter develops an integrated approach based on life-cycle thinking, the voice of the customer, quality function deployment, value engineering, standardisation, modularity, design for manufacture and assembly, concurrent engineering, process selection, process mapping, and make-or-buy analysis.

Learning Objectives

After studying this chapter, you should be able to:

1. Explain product and service life cycles and their implications for design decisions.
2. Translate customer needs into measurable technical requirements using the voice of the customer and QFD.
3. Apply value engineering, standardisation, modularity, and design for manufacture and assembly.
4. Explain how concurrent engineering improves design decisions.
5. Select an appropriate process type using volume, variety, flexibility, and technology considerations.
6. Construct and interpret process maps.
7. Evaluate make-or-buy decisions using relevant costs and strategic criteria.
8. Critically assess environmental, ethical, safety, and digital issues in design.

1. Product, Service, and Process Design as a System

A product is a tangible output whose physical characteristics can be specified and inspected. A service is an activity or experience delivered to a customer, often involving simultaneous production and consumption. Many modern offerings are combinations: an industrial machine may be sold with installation, software, maintenance, and remote monitoring.

A process is an organised sequence of activities that transforms inputs into outputs. Inputs include materials, information, labour, energy, equipment, and capital. Outputs include products, services, information, waste, emissions, and customer outcomes. Design therefore must consider not only the intended output but also variation, failure modes, resource consumption, and end-of-life consequences.

A useful systems perspective is:

Figure: Product and process design form an integrated, feedback-driven system.

2. Life-Cycle Thinking

The product life cycle describes the stages through which an offering passes: concept and development, introduction, growth, maturity, decline, and retirement. This market model is different from a physical life-cycle assessment, which examines raw-material extraction, manufacturing, distribution, use, maintenance, and end-of-life.

At introduction, design priorities commonly include functionality, reliability, market acceptance, and speed of launch. During growth, capacity, supplier capability, and standardisation become important. At maturity, cost reduction, process improvement, differentiation, and maintainability dominate. During decline, the organisation may simplify the product, serve a niche, harvest remaining value, or withdraw it responsibly.

Life-cycle costing evaluates costs over the relevant life rather than focusing only on purchase price. In its simplest undiscounted form:

where C_d is development cost, C_p purchase or production cost, C_o operating cost, C_m maintenance cost, and C_e end-of-life cost. All terms must be expressed in the same currency and time basis. For investments spanning several years, discounted cash flow is more appropriate:

Here C_t is the net cash flow or cost in period t, r is the discount rate per period, and n is the final period. This expression assumes that cash flows occur at discrete period ends and that a constant discount rate is suitable.

Life-cycle thinking also supports circular design. Designers should ask whether materials can be repaired, upgraded, remanufactured, reused, or recycled; whether hazardous substances can be eliminated; and whether product data can support maintenance and recovery. Environmental claims should be supported by evidence and should not shift impacts from one life-cycle stage to another.

3. Voice of the Customer and Requirements

The voice of the customer (VOC) is a structured representation of customer expectations, problems, preferences, and constraints. Sources include interviews, observation, complaint records, warranty data, market research, field studies, online reviews, and regulatory requirements. Customers may be external users, purchasers, maintainers, operators, distributors, or internal departments.

Good VOC practice distinguishes a need from a proposed solution. “Easy to clean” is a need; “use stainless steel” is a possible technical response. Needs should be clarified, grouped, prioritised, and translated into measurable requirements. A requirement should ideally be specific, observable, testable, and linked to a stakeholder.

Typical requirement categories include:

• performance and functionality;
• reliability, maintainability, and availability;
• safety and regulatory compliance;
• ergonomics and accessibility;
• appearance and user experience;
• cost, delivery, and serviceability;
• environmental and ethical performance.

Conflicting requirements are normal. Increasing strength may increase mass; reducing cost may reduce durability; improving speed may increase energy consumption. Trade-offs should be made explicitly rather than hidden in late-stage compromises.

4. Quality Function Deployment

Quality Function Deployment (QFD) translates customer requirements, often called “WHATs,” into technical characteristics, or “HOWs.” The central tool is the House of Quality. It normally contains customer importance ratings, relationships between customer needs and technical characteristics, correlations among technical characteristics, competitive comparisons, and target values.

A basic weighted-priority calculation is:

where P_j is the priority score for technical characteristic j, w_i is the importance weight of customer requirement i, r_ij is the relationship score between requirement i and characteristic j, and m is the number of customer requirements. Relationship scores are often assigned as 0, 1, 3, or 9 for none, weak, moderate, and strong relationships. The scale is ordinal; therefore, the result is a prioritisation aid, not a precise physical measurement.

Worked Example: QFD Priorities

Suppose three customer requirements have importance weights 5, 4, and 3. Two technical characteristics are response time and battery life. The relationship matrix is:

Response-time priority is (5 × 9) + (4 × 3) + (3 × 3) = 66. Battery-life priority is (5 × 1) + (4 × 9) + (3 × 9) = 68. Battery life receives the slightly higher design priority. The team must still check feasibility, cost, and technical correlation before setting targets.

QFD is not simply a matrix-filling exercise. It is a cross-functional discussion mechanism. Poorly defined customer needs, biased ratings, excessive detail, and failure to update the matrix can make QFD misleading. Its value lies in traceability: each important design decision can be connected to a stakeholder need.

5. Value Engineering and Value Analysis

Value engineering is a systematic method applied during design to achieve required functions at the lowest total cost without reducing necessary performance, quality, safety, or environmental responsibility. Value analysis applies similar reasoning to an existing product or process.

A useful conceptual relationship is:

This is not a universal financial valuation formula. It is a comparative design concept: value improves when required function increases for a given cost, or when cost decreases without loss of required function. “Cost” should include relevant life-cycle costs where appropriate.

The value-engineering study typically involves information gathering, function analysis, creative generation of alternatives, evaluation, development, and implementation. Function analysis uses a verb–noun description, such as “support load,” “transfer heat,” or “protect user.” The team distinguishes primary functions from secondary functions and identifies unnecessary features, over-specification, and avoidable complexity.

Cost reduction must not become indiscriminate cheapening. Removing a safety margin without engineering justification, selecting an unsafe material, or transferring work to poorly protected labour is not value engineering. Design alternatives must be verified against standards, reliability requirements, maintainability, and user expectations.

6. Standardisation and Modularity

Standardisation reduces unnecessary variety by using common dimensions, interfaces, materials, components, procedures, or data formats. Benefits include lower purchasing cost, simplified inventory, easier training, interchangeability, and more consistent quality. Excessive standardisation can reduce differentiation or prevent adaptation to legitimate customer needs.

Modularity divides a product or service into relatively independent modules connected by defined interfaces. A modular design may allow a common platform with different engines, control systems, enclosures, or software options. Modularity can delay final configuration until customer demand is clearer, reduce engineering repetition, and simplify maintenance.

Two design principles are particularly important:

• Interface control: mechanical, electrical, software, information, and human interfaces must be clearly specified.
• Coupling management: changes in one module should have limited unintended effects on others.

A platform strategy combines common underlying architecture with configurable features. It can create economies of scale, but it may also produce a platform that is over-engineered for simple variants. The appropriate level of modularity depends on demand variety, volume, technology change, service requirements, and the cost of managing interfaces.

7. Design for Manufacture and Assembly

Design for Manufacture (DFM) aims to make parts economical and reliable to produce. Design for Assembly (DFA) aims to simplify, speed, and error-proof assembly. Together they are often called DFMA.

DFMA principles include:

1. Reduce the number of parts where functions can be combined without compromising maintenance or safety.
2. Use standard, readily available components.
3. Design parts for easy orientation, handling, insertion, and fastening.
4. Provide access for tools, inspection, and maintenance.
5. Avoid unnecessary tight tolerances and surface finishes.
6. Select processes compatible with material, geometry, volume, and required capability.
7. Design mistake-proof features such as asymmetry, keyed connectors, and visual identification.
8. Consider worker ergonomics and safe manual handling.

A simple assembly-time estimate is:

where t_a is total assembly time, t_k is the time for assembly task k, and N is the number of tasks. This estimate assumes tasks are sequential and excludes parallel work, waiting, and learning effects. In practice, standard-time systems, observations, or predetermined motion systems may be used, but the method must match the purpose and accuracy required.

DFMA should be applied early. Redesigning tooling, fixtures, suppliers, or production layouts after design freeze is expensive. However, a design that is easy to assemble but difficult to repair may increase total life-cycle cost; manufacturability must therefore be balanced with serviceability and sustainability.

8. Concurrent Engineering

Traditional sequential development passes work from marketing to design, manufacturing, purchasing, quality, and service. Concurrent engineering involves these functions early and in parallel. The aim is not merely to work faster but to prevent late discovery of constraints.

A concurrent team may include customers, designers, manufacturing engineers, quality specialists, procurement personnel, operators, maintainers, suppliers, safety professionals, and environmental experts. Digital product definitions, shared bills of material, simulation, rapid prototyping, and design reviews support collaboration.

Concurrent engineering can reduce time to market, engineering changes, rework, and launch problems. Its limitations include coordination overhead, data-management complexity, premature convergence on weak concepts, and conflict between functional objectives. Effective governance requires clear decision rights, configuration control, documented assumptions, and escalation of safety or compliance concerns.

9. Process Selection

Process selection links product or service characteristics to an appropriate transformation system. The classic volume–variety relationship is useful:

Service processes also vary. Professional services generally have high variety and customer contact. Service shops have moderate variety and standardisation. Mass services handle high volumes with standardised activities. Digital services may decouple delivery from physical location but still require capacity, cybersecurity, support, and failure recovery.

Selection should consider:

• expected volume and demand variability;
• product variety and customisation;
• required flexibility and lead time;
• capital availability and automation;
• labour skills and safety;
• quality capability and traceability;
• environmental performance;
• supply-chain resilience and technology maturity.

Automation is not automatically superior. A highly automated line may have low unit cost at stable high volume but poor economics when demand is uncertain or products change frequently. Process capability, maintainability, cybersecurity, and the availability of skilled personnel must be assessed.

10. Process Mapping and Analysis

A process map represents activities, decisions, flows, queues, information, and responsibilities. Common forms include flowcharts, cross-functional swimlane maps, value-stream maps, service blueprints, and business process models.

A useful process map identifies:

• the start and end points;
• inputs, outputs, customers, and suppliers;
• activities and decision rules;
• inspection, rework, transport, and waiting;
• ownership and handoffs;
• information systems and records;
• risks, controls, and performance measures.

The map should describe the actual process before proposing improvements. Direct observation is essential because written procedures often omit interruptions, informal workarounds, and rework.

Lead time can be decomposed conceptually as:

The terms must refer to the same unit of work and observation boundary. This identity is a classification framework rather than a law of nature; activities may overlap, and inspection may occur during processing. A process with 20 minutes of processing and 180 minutes of waiting has a flow efficiency of:

Thus, 20 ÷ 200 × 100% = 10%. The result indicates substantial potential in reducing waiting, but it does not by itself prove that all waiting is waste: some buffers protect against variability or enable economic batch sizes.

Process mapping supports bottleneck analysis, standard work, error-proofing, layout improvement, capacity planning, and digital transformation. A map should be validated with process users and updated when the process changes.

11. Make-or-Buy Analysis

Make-or-buy analysis evaluates whether an organisation should produce internally or purchase from an external supplier. The decision combines quantitative relevant-cost analysis with strategic, technical, and risk considerations.

If fixed costs differ between alternatives and variable unit costs are constant, the break-even volume is:

where F_m and F_b are avoidable fixed costs for making and buying, v_m and v_b are relevant variable costs per unit, and Q* is the volume at which total relevant costs are equal. The denominator must be non-zero, and the result is meaningful only over the range where the cost assumptions apply.

Worked Example: Make or Buy

A factory can make a component for a variable cost of $18 per unit and avoidable annual fixed cost of $24,000. A supplier offers it for $24 per unit. The make-cost equation is 24,000 + 18Q, while the buy-cost equation is 24Q. Therefore:

Q* = 24,000 ÷ (24 − 18) = 4,000 units.

Below 4,000 units, buying is cheaper because the supplier avoids the internal fixed cost. Above 4,000 units, making is cheaper, provided capacity, quality, and supply assumptions remain valid. A cost that will continue regardless of the decision is not relevant to this short-run comparison.

Strategic issues may reverse the numerical recommendation. These include intellectual property, supplier dependence, quality capability, delivery reliability, labour conditions, cybersecurity, geopolitical exposure, environmental obligations, future capacity, and the opportunity cost of constrained internal resources. Total landed cost should include transport, duties, inspection, inventory, coordination, warranty, and expected disruption costs where they are reasonably estimable.

12. Integrated Applied Case: Modular Electric Pump

The following is an illustrative case, not a report of a specific company.

Background

A manufacturer of industrial water pumps is developing a compact electric pump for small factories. Customers request lower energy use, easy maintenance, reliable operation, short delivery time, and several flow-rate options. The initial concept contains many unique housings, fasteners, seals, and control boards.

Problem

Prototype cost is high, assembly is slow, and service technicians report that replacing a control board requires removing the entire housing. Marketing also proposes six variants, although forecast demand is uncertain. The organisation must choose a design and process before committing to tooling.

Analysis

The team collects VOC data from operators, maintenance technicians, purchasing staff, and distributors. QFD identifies energy consumption, uptime, and maintenance access as high-priority needs. The team defines measurable characteristics: motor efficiency, mean time between failures, access time to the control module, and spare-parts availability.

Value analysis shows that several decorative covers perform no required function. Standard fasteners replace three proprietary types. A modular architecture separates the motor, pump head, control module, and mounting frame. A common frame supports three flow-rate variants, while different impellers provide the principal capacity change.

DFMA review reduces part count, provides one-direction insertion for the control module, and adds a keyed electrical connector. Designers consult manufacturing and service personnel concurrently. A supplier is considered for the control board, but the make-or-buy review includes not only price but also firmware ownership, cybersecurity, repairability, and supply continuity.

Process mapping reveals that functional testing was performed after final packaging, so failures caused costly unpacking and rework. Moving an intermediate leak test earlier prevents defective units from reaching final assembly. A batch process is selected for pump heads, while final assembly uses a paced cell because demand is moderate and product variants remain significant.

Outcome

The revised design uses a common platform, fewer component types, accessible modules, and earlier testing. It retains variant flexibility without creating six unrelated products. The organisation also establishes design-change control, supplier quality requirements, service documentation, and end-of-life recovery instructions.

Learning Points

The case demonstrates that product design, process design, supplier decisions, and service design cannot be optimised independently. QFD clarified priorities; value engineering removed unnecessary cost; modularity controlled variety; DFMA improved production and maintenance; concurrent engineering exposed problems early; process mapping revealed hidden rework; and make-or-buy analysis required both financial and strategic judgement.

13. Challenges, Ethics, Regulation, and Contemporary Practice

Design decisions affect workers, communities, customers, and the environment. Engineers must comply with applicable product-safety, machinery, electrical, chemical, accessibility, labour, environmental, and data-protection requirements. Compliance is a minimum obligation, not a substitute for professional judgement.

Ethical design requires honest performance claims, transparent limitations, protection against foreseeable misuse, inclusive usability, and respect for worker safety. Cost pressure must not justify unsafe working conditions or deliberate reduction of product life without disclosure. Engineers should document assumptions and raise concerns when commercial targets conflict with safety or law.

Digital tools and artificial intelligence can support requirements analysis, generative design, simulation, inspection, demand forecasting, and process mining. They do not eliminate the need for engineering verification. AI-generated designs may reproduce biased data, violate intellectual property, expose confidential information, or produce non-obvious failure modes. Human accountability, traceability, validation, access control, and cybersecurity are essential.

Contemporary best practice increasingly combines design thinking, systems engineering, lean methods, digital twins, additive manufacturing, mass customisation, circular-economy principles, and resilient supply-chain design. These methods should be selected because they solve a defined problem, not because they are fashionable. A technically advanced solution that is unaffordable, unmaintainable, insecure, or environmentally harmful is not a successful design.

Chapter Summary

Product, service, and process design establish the foundation for operational performance. Life-cycle thinking considers development, production, use, maintenance, and end-of-life rather than isolated purchase cost. The voice of the customer converts stakeholder experience into prioritised requirements, while QFD links those requirements to measurable technical characteristics.

Value engineering improves required function relative to life-cycle cost. Standardisation reduces unnecessary variety, and modularity manages product options through controlled interfaces. DFM and DFA reduce manufacturing and assembly difficulty, while concurrent engineering brings relevant functions into early design decisions. Process selection must match volume, variety, flexibility, technology, capability, and risk. Process mapping exposes activities, waiting, handoffs, and rework. Make-or-buy decisions require relevant cost analysis together with strategic, ethical, quality, resilience, and environmental judgement.

The central professional lesson is integration. A good design satisfies customers, can be produced and supported safely, performs reliably, and remains responsible across its life cycle.

Key Terms

Voice of the customer: Structured information about stakeholder needs, expectations, and problems.

Quality Function Deployment: A method for translating customer requirements into technical design characteristics.

House of Quality: The central matrix used in QFD to relate customer needs to technical responses.

Value engineering: Systematic improvement of required function relative to total cost during design.

Value analysis: Value-engineering study applied to an existing product or process.

Life-cycle costing: Evaluation of costs across development, ownership, operation, maintenance, and disposal.

Standardisation: Use of common components, dimensions, methods, or interfaces to reduce unnecessary variety.

Modularity: Division of a product or process into relatively independent units with defined interfaces.

Platform: Common underlying architecture supporting multiple product variants.

Design for Manufacture: Designing products for economical, capable, and reliable production.

Design for Assembly: Designing products for efficient, safe, and error-resistant assembly.

Concurrent engineering: Cross-functional and overlapping development of product and process decisions.

Process selection: Choice of a transformation system suited to volume, variety, flexibility, and technology.

Process map: Visual or structured representation of activities, decisions, flows, and responsibilities.

Flow efficiency: Processing time divided by total lead time, expressed as a percentage.

Make-or-buy analysis: Evaluation of internal production versus external purchase.

Relevant cost: A future cost that differs between decision alternatives.

Modular interface: Defined connection through which modules interact mechanically, electrically, digitally, or organisationally.

Circular design: Design that supports repair, reuse, remanufacture, recycling, and responsible resource use.

Design change control: Formal management of modifications to approved product or process definitions.

Review Questions

Short Answer Questions

1. Distinguish product design, service design, and process design.
2. What is the purpose of the voice of the customer?
3. Explain the difference between standardisation and modularity.
4. State two principles of design for manufacture and assembly.
5. Why should make-or-buy decisions include strategic factors as well as cost?

Long Answer Questions

1. Explain how life-cycle thinking can influence material selection, maintainability, and end-of-life design.
2. Describe the structure and purpose of a House of Quality, including the limitations of weighted relationship scores.
3. Discuss the benefits and risks of concurrent engineering in industrial product development.
4. Compare project, job-shop, batch, repetitive, and continuous processes using volume and variety.
5. Explain how process mapping can reveal waste and improve operational control.

Analytical / Application Questions

1. A company has make costs of $30,000 fixed plus $12 per unit and a supplier price of $18 per unit. Calculate the break-even volume and explain what additional information is needed before deciding.
2. Design a QFD relationship matrix for a portable medical device with three customer needs and three technical characteristics. Justify the importance and relationship ratings.
3. A product has eight unique fasteners, three housing variants, and frequent assembly errors. Propose a standardisation and modularity strategy, and explain how you would validate its effects on cost, quality, and serviceability.

Multiple Choice Questions with Answers

Question 1

Which activity best represents the voice of the customer?

A. Selecting a machining centre before interviewing users

B. Collecting and structuring user needs from interviews and field observations

C. Assigning production workers to assembly stations

D. Calculating supplier invoice totals

Correct Answer: B. Collecting and structuring user needs from interviews and field observations

Question 2

In QFD, the technical characteristics are commonly called the:

A. WHATs

B. WHYs

C. HOWs

D. WHOs

Correct Answer: C. HOWs

Question 3

Using the chapter’s illustrative QFD method, what is the priority for a characteristic with relationships 9, 3, and 3 to requirements weighted 5, 4, and 3?

A. 48

B. 57

C. 66

D. 72

Correct Answer: C. 66

Question 4

Which statement best describes value engineering?

A. Reducing purchase price regardless of performance

B. Increasing required function relative to relevant cost without compromising essential requirements

C. Replacing all human work with automation

D. Increasing the number of product features

Correct Answer: B. Increasing required function relative to relevant cost without compromising essential requirements

Question 5

A modular product is best characterised by:

A. Undefined connections among interchangeable parts

B. A single permanent configuration

C. Relatively independent units connected by specified interfaces

D. A process with no inspection requirements

Correct Answer: C. Relatively independent units connected by specified interfaces

Question 6

Which process type is generally associated with high volume and low variety?

A. Project

B. Job shop

C. Batch

D. Continuous

Correct Answer: D. Continuous

Question 7

A process has 15 minutes of processing time and 135 minutes of waiting time, with no other time categories. What is its flow efficiency?

A. 5%

B. 10%

C. 15%

D. 90%

Correct Answer: B. 10%

Question 8

A make alternative costs $20,000 fixed plus $10 per unit. Buying costs $15 per unit. At what volume are the alternatives equal?

A. 2,000 units

B. 4,000 units

C. 5,000 units

D. 10,000 units

Correct Answer: C. 5,000 units

Question 9

Which cost is normally relevant to a short-run make-or-buy decision?

A. A fixed cost that continues unchanged under either alternative

B. A sunk cost already incurred

C. An avoidable cost that differs between alternatives

D. A historical cost with no future effect

Correct Answer: C. An avoidable cost that differs between alternatives

Question 10

The primary purpose of concurrent engineering is to:

A. Delay manufacturing involvement until design is complete

B. Involve relevant functions early and develop product and process decisions in parallel

C. Eliminate all design reviews

D. Maximise product variety without regard to cost

Correct Answer: B. Involve relevant functions early and develop product and process decisions in parallel