Continuous improvement: PDCA, Kaizen and Lean.

Continuous improvement is not a project with a start and end date: it is a way of running the business that turns every problem into an opportunity and every data point into a lever for progress. In this guide I present the three most effective methodologies (PDCA, Kaizen and Lean) with a practical lens for the reality of Spanish SMEs, plus a real anonymised case, an actionable checklist and a comparison table.

The Deming PDCA cycle: the foundation

The PDCA cycle (Plan-Do-Check-Act) is the fundamental engine of continuous improvement and the framework on which the entire ISO 9001 structure is built. It is as simple as it is powerful.

Plan means identifying what you want to improve, analysing the current situation with data, determining the root cause of the problem and designing the solution. Do means implementing the solution in a controlled way, preferably at small scale first (pilot). Check means measuring results obtained and comparing them with expected results, analysing deviations. And Act means standardising the improvement if it worked, or going back to planning if it did not produce the expected results.

The key to PDCA is that it is a cycle, not a linear process. Each turn produces a higher level of performance, and every problem solved opens the door to the next improvement.

A practical PDCA example in an industrial SME

Imagine a machining workshop with 28 operators whose final-inspection reject rate exceeds 4% (internal target 1.5%). Applying PDCA: in the Plan phase a Pareto analysis reveals that 70% of rejects come from three specific part numbers; in Do, the tooling jigs are adjusted and two operators are retrained; in Check, six weeks of measurement show the rate drops to 1.8%; in Act, the work instruction is updated and the change is replicated across the other nine affected part numbers. A three-month cycle, with no investment in machinery, and a direct return in avoided rework hours.

Kaizen: thousands of small improvements

Kaizen literally means "change for better" in Japanese, and rests on the idea that many small, constant improvements generate a greater cumulative impact than occasional large transformations.

The Kaizen approach is implemented through several complementary tools. Kaizen events or improvement workshops are 3-to-5-day sessions where a cross-functional team analyses a process, identifies waste and designs and implements concrete improvements. They are especially effective for processes with visible problems.

The suggestion programme invites all employees to propose improvements at their workstation. The best companies receive between 10 and 50 suggestions per employee per year. The key is that suggestions are evaluated quickly, the viable ones are implemented without excessive bureaucracy and the author is recognised.

Daily stand-up meetings of 10-15 minutes at the start of each shift identify problems, share learnings and coordinate immediate improvement actions.

The seven basic quality tools

The seven classic quality tools remain extraordinarily useful for analysis and problem solving:

• Ishikawa diagram (fishbone): identifies potential causes of a problem by category (the 6Ms: Man, Machine, Method, Material, Measurement, Environment).
• Pareto diagram: visualises the 80/20 rule to prioritise the most frequent causes.
• The 5 whys: drill down to the root cause by asking "why" repeatedly until reaching the real origin.
• Histogram: shows the distribution of a dataset.
• Scatter diagram: reveals correlation between two variables.
• Check sheet: standardises data capture.
• Control chart: monitors a process to detect variations outside acceptable limits.

Lean: eliminating the 8 wastes

Lean thinking identifies eight types of waste every company should eliminate:

1. Overproduction: producing more than the customer needs.
2. Waiting: time lost between process stages.
3. Unnecessary transport: moving materials or information without need.
4. Over-processing: doing more than the customer values.
5. Excess inventory: holding stock above what is needed.
6. Unnecessary motion: staff movement that adds no value.
7. Defects: products or services that do not meet specifications.
8. Underused talent: not leveraging people's capabilities.

5S as a starting point

5S (Seiri, Seiton, Seiso, Seiketsu, Shitsuke — translated as Sort, Set in Order, Shine, Standardise and Sustain) is the simplest Lean tool to implement and the one that produces visible results fastest. A 5S project in a workshop, warehouse or office is completed in a week and produces immediate improvements in productivity, safety and team morale.

Comparison: PDCA vs Kaizen vs Lean Six Sigma

Criterion	PDCA	Kaizen	Lean / Lean Six Sigma
Origin	USA (Deming, 1950s)	Japan (Toyota, post-war)	Toyota + Motorola (1980s-90s)
Approach	Structured improvement cycle	Small, continuous improvements	Waste elimination + variability reduction
Typical project length	1-3 months	3-5 day events	3-6 months (DMAIC)
Initial SME investment	Low (8h training)	Low to medium	Medium (training + data collection)
Best for	Solving specific problems	Daily improvement culture	Processes with quantitative data
Fit with ISO 9001	Total (engine of the standard)	High	High
Recommended to start with	Yes, always	Yes, in parallel with PDCA	Once process maturity exists

Real case: an 18-employee labour-law advisory firm

A professional services firm in Valladolid with 18 employees ran a combined 12-month programme: launched 5S in offices (week 1), implemented daily stand-ups of 10 minutes per team (month 1), introduced a suggestion box with a 15-day response commitment (month 2) and ran four PDCA projects on invoicing, document management, client onboarding and payroll (months 3-12). Client-reported result: average new-client onboarding time fell from 9 to 4 days, and recurring billing incidents dropped 60%. Investment: 24 hours of internal training, no additional software.

Continuous improvement indicators

To prove that continuous improvement works (and to comply with ISO 9001), you need indicators that measure it. The most relevant ones are:

• Number of improvements implemented per period.
• Economic savings generated by improvements.
• Reduction in defects or non-conformities.
• Improvement in process times.
• Staff participation in suggestion programmes.
• Evolution of customer satisfaction.

Mini-glossary

• PDCA: Plan-Do-Check-Act improvement cycle, the structural foundation of ISO 9001.
• Kaizen: Japanese philosophy of continuous improvement through small, sustained changes.
• Lean: approach focused on eliminating everything that does not add value for the customer.
• Six Sigma: statistical methodology for reducing process variability.
• Gemba: the real place where work happens (shop floor, office, warehouse).
• Muda: Japanese term for waste.
• 5S: workplace organisation methodology (Sort, Set in Order, Shine, Standardise, Sustain).
• Kanban: visual system for workflow management and stock replenishment.

Checklist: 10 steps to start with continuous improvement

1. Get explicit management sponsorship (not just an email: time on the agenda).
2. Train the leadership team on PDCA and 5S (4-8 hours).
3. Choose a small, visible pilot area to start.
4. Roll out 5S in that area (1 week).
5. Establish a 10-minute daily stand-up in the pilot area.
6. Launch a suggestion box with a 15-day response commitment.
7. Select the first PDCA project with quantifiable impact.
8. Train an internal facilitator as the continuous-improvement reference.
9. Measure and publish results (visual posters, not just spreadsheets).
10. Publicly recognise the people involved and replicate to the next area.

Want to embed a real culture of continuous improvement in your company, not a paperwork system? Let's talk and I will help you select the right tools and train your team.

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By Ángel Ortega Castro · independent consultant in strategy, quality and digitalisation for SMEs.

Frequently asked questions

Where do I start if I have never done continuous improvement?

Start with 5S in a specific area (a warehouse, an office, a reception) and by implementing 10-minute daily stand-ups. These are the two practices that produce visible results fastest (1-2 weeks) and build the culture on which you can later layer PDCA and Kaizen. Do not try to implement everything at once.

Do I need an external consultant to get started?

It is not essential, but it helps a lot in the first three months to avoid two typical mistakes: over-documenting (building a bureaucratic system that suffocates operations) and giving up at the first obstacle. If you go it alone, assign someone as internal facilitator with recognised part-time dedication (15-20% of their time).

How much does it cost to launch a continuous improvement programme in an SME?

The minimum cost is the initial team training (an internal course of 8-16 hours on PDCA, 5S and basic tools, between €1,000 and €3,000 if delivered by an external consultant) plus the time people dedicate to the first projects. You do not need specific software, Black Belt certifications or large investments.

How do I prevent the programme from dying after six months of initial enthusiasm?

Three practices make the difference: monthly review with leadership where indicators are reported and resources unblocked, public and specific recognition for people who propose and implement improvements, and clear connection between the improvements made and the company's strategic objectives.

Does continuous improvement work in services companies or only in industry?

It works perfectly in services. In fact, the improvement potential is often greater in services because processes are less standardised than in industry. Advisory firms, professional practices, agencies, clinics and consultancies can apply PDCA, 5S, Pareto, Ishikawa and Kaizen events with exactly the same rigour as a factory.

How is real success measured?

Not only with activity indicators (number of suggestions, meetings held) but with outcome indicators: attributable economic savings, reduction in defects or complaints, improvement in lead times, customer satisfaction and employee satisfaction (eNPS). If you have a year of many meetings but no quantifiable result, the approach needs review.