Quality Assurance Process at Japanese Plants: 8 Steps
You make parts for a Japanese customer, or you work at a Japanese-owned plant in the US, India, or Southeast Asia. Before the first production order, their quality team may ask for a hinshitsu keikaku-sho (品質計画書, quality plan) and a QC kotei-hyo (QC工程表, QC process chart). Later they talk about the ryosan iko hantei (量産移行判定, go/no-go decision for mass production). When a defect reaches them, they want a quick initial report that separates "why it happened" from "why it got out."
Each of these requests belongs to one step in a single workflow. Quality work at a Japanese manufacturer can be laid out as an eight-step cycle that starts before the first part exists and continues after the product reaches the customer. Once you know which step a request comes from, you can tell what the customer is trying to protect and what a good answer looks like.
This guide walks through the eight steps in three stages (before mass production, during mass production, and after shipment). For each step, it covers the documents and tools used, who is involved, and common mistakes. It ends with a list of questions to ask the Japanese side at each stage. For who does what in a Japanese quality department, and how quality assurance (QA) differs from quality control (QC), see QA vs QC in Japanese Companies: Who to Contact for What.
- The workflow has eight steps in three stages: quality plan, design review and risk assessment, and the mass production decision; then incoming, in-process, and outgoing quality control; then complaint response and quality audits.
- Quality work has the greatest impact upstream. A problem caught on the drawing may need one line changed. Caught after launch, it can mean reworking molds and equipment or recalling shipped products.
- Inspection is meant to catch process problems early, not only to sort out bad parts. Defects should be stopped in the process, not at the final check.
- When a customer reports a defect, expect to separate the occurrence cause (why it happened) from the escape cause (ryushutsu genin, why it was not caught), and to show interim action, permanent action, an effectiveness check, and yokoten (rollout to similar products).
- Mass-produced and build-to-order products follow the same flow with different emphasis, and the customer's industry decides which standards apply.
Contents
The Quality Workflow at a Glance
Quality work follows the product's life cycle in this order:
Quality plan → Design review and risk assessment → Mass production decision → Incoming inspection → In-process quality control → Outgoing inspection → Complaint response and recurrence prevention → Quality audit and improvement
The work falls into three stages: before mass production, during mass production, and after shipment.
Step names and boundaries vary by company and product. Work during mass production and after shipment runs in parallel.
A simple way to remember the three stages: before mass production, you build quality in; during mass production, you keep quality stable; after shipment, you fix what went wrong and feed the lessons into the next product.
The terms below are the ones you are most likely to hear from a Japanese customer or parent company. If you work with automotive customers, the flow will look familiar: it is close to the five phases of APQP (Advanced Product Quality Planning). Companies outside the auto industry may never use APQP labels, but the mapping can still help you place a request.
| Step | Japanese term | What you may be asked for | Closest APQP phase |
|---|---|---|---|
| Quality plan | 品質計画 (hinshitsu keikaku) | Quality plan, list of key characteristics, check schedule | Plan and define program |
| Design review | 設計審査 / デザインレビュー (sekkei shinsa, DR) | FMEA, design review comments and actions | Product design and development |
| Mass production decision | 量産移行判定 (ryosan iko hantei) | Capability data (Cpk), inspection standard, QC process chart | Process design and development; product and process validation |
| Incoming inspection | 受入検査 (ukeire kensa) | Inspection certificates from suppliers | — |
| In-process control | 工程内の品質管理 (kotei-nai hinshitsu kanri) | Control charts, change notices | — |
| Outgoing inspection | 出荷検査 (shukka kensa) | Inspection records, inspection certificates | — |
| Complaint response | 不具合対応・再発防止 (fuguai taio, saihatsu boshi) | Initial report, investigation report with countermeasures | Feedback, assessment, and corrective action |
| Quality audit | 品質監査 (hinshitsu kansa) | Records for internal and supplier audits | Feedback, assessment, and corrective action |
The QC process chart covers much the same ground as a control plan: each process step with its control items, methods, and frequencies. Treat it as the closest equivalent, not an identical document. Columns and level of detail vary by company, so ask for the customer's template.
Before Mass Production: Building Quality In
At this stage, no production parts exist yet, only prototypes at most. Every problem fixed here means fewer defects and claims later.
Engineers generally agree that the later a problem is found, the more it costs in time and money to fix. On the drawing, the fix may be one changed line. After launch, the same problem can mean reworking molds and equipment, or even recalling products that have already shipped. In short, quality work pays off most upstream.
Quality Plan
Once a new product is approved for development, the quality team reviews customer requirements, regulations, and past defects, then sets quality targets. The hinshitsu keikaku-sho (quality plan) records which characteristics count as key items and when and how each one will be checked.
Design, production engineering, and sales take part. The job of this step is to translate customer requirements into internal language: tolerances, test conditions, and inspection items that the plant can act on. A misread requirement causes major rework later, so the team clears up anything ambiguous now.
The plan also sets the schedule: when prototypes and evaluations happen, and who approves at each stage. Laying the quality checkpoints over the development schedule keeps checks from being missed or pushed back.
Design Review and Risk Assessment
When drawings or prototypes are ready, the quality team gives input from a quality point of view in a design review (DR, sekkei shinsa). Using methods such as FMEA (Failure Mode and Effects Analysis), the team identifies where the design is likely to fail and what happens if it does, then ranks the fixes by priority. Related: DRBFM vs FMEA: Design Review Steps, Template & Example.
The quality assurance engineer's main contribution is experience from past defects and claims. A common mistake is letting the FMEA become paperwork. An FMEA is useful only when it leads to actual countermeasures and testing.
In the review, quality engineers deliberately question points the designer considers fine. Some of these comments are unwelcome. Still, debating an issue at this stage costs far less than dealing with the same defect after launch.
Mass Production Decision
When the line is ready, the team measures prototype and first-production parts to confirm that the process can make parts within specification consistently. They also confirm that these documents are in place:
- Process capability index (Cpk) and similar indicators
- Inspection standard (kensa kijunsho, 検査基準書)
- QC process chart (QC kotei-hyo)
For automotive parts and similar products, the supplier compiles these documents and gets the customer's approval before starting mass production. If schedule pressure pushes a product into mass production before the checks are complete, defects tend to cluster right after launch. That is why the decision criteria should be set in advance. Ask the customer which Cpk value and which documents they require before the decision, rather than assuming.
Design, production engineering, manufacturing, and quality meet for the decision and go through each open issue and its response one by one. Quality assurance may run the meeting or make the final call.
If the team launches with issues still open, it sets conditions: which item is closed by when, and tighter inspection until then. A conditional go is common in practice. A related term you may hear is shoki ryudo kanri (初期流動管理, early production control): a set period of tightened checks right after a launch.
During Mass Production: Keeping Quality Stable
Once mass production starts, the goal is to produce consistent quality every day. Inspection happens at three points: incoming, in-process, and outgoing.
The shop floor leads this stage. Quality assurance and quality control engineers set the inspection criteria, analyze the data collected, and get the right departments moving when something goes wrong.
Each one checks a different thing for a different purpose.
Incoming Inspection
Parts and materials from suppliers are checked against the specification and the supplier's inspection certificate for dimensions, appearance, material, and so on. The usual approach is to sample from each lot rather than check every piece.
In practice, inspection intensity is set supplier by supplier: lighter for suppliers with a stable record, heavier for those with frequent problems. Quality shares this information with purchasing and, when needed, coaches the supplier. If you are the supplier, your quality record decides how closely your parts are checked.
When incoming inspection finds a defect, the lot goes on hold and the supplier is asked to sort or remake the parts. The customer then requests a report on cause and countermeasures. The loop closes only after later deliveries show the fix is working.
In-Process Quality Control
During production, operators and inspectors measure and record set items. Quality control engineers chart this data, for example on control charts, and watch for spread and shifts in trend.
When they find an abnormality, they investigate the cause with manufacturing and production engineering, then revise the equipment or work procedure. A common failure is a plant where data gets recorded but nobody looks at it. Quality control includes looking at the data and acting on it.
Changes need control too. A change in equipment, material, operator, or method can change quality. Japanese plants call these points henkaten (変化点, points of change). By identifying them in advance and checking quality before and after each change, the plant prevents unexpected defects. Many Japanese customers also ask suppliers to notify them before making such changes, so check the rules in your quality agreement.
Problems spotted in the process are solved together with shift leaders and team leaders on the floor. Quality engineers who see production staff regularly, and make it easy for them to raise small concerns, find problems earlier.
Camera-and-AI visual inspection and automatic collection of quality data from equipment sensors are also spreading.
Outgoing Inspection
Finished products get a final check against the criteria agreed with the customer. Besides dimensions, appearance, and functional tests, the inspection covers labels, quantities, and packaging.
Whether to sample or check every unit depends on how critical the product is and on its defect history. Safety-related characteristics and items the customer specifies often get 100% inspection. Setting those criteria in an inspection standard is part of quality control.
Outgoing inspection is the last gate, but relying on it too much raises inspection workload and still lets defects slip through. Defects should be stopped in the process. When outgoing inspection finds one, the team traces it back to where in the process it could have been prevented.
Outgoing inspection records also prove what condition a product was in when it shipped, if a problem appears later. Many customers also ask for inspection certificates, so keeping accurate records is a core part of this step.
After Shipment: Complaint Response and Feedback
Quality assurance work continues after the product reaches the customer. How the supplier responds at this stage has a major impact on the customer's trust.
Information after shipment is not limited to defect reports. Customer questions and data on how the product is used in the field also feed into the quality of the next product.
Complaint Response and Recurrence Prevention
When a customer reports a defect (Japanese teams often call this a kureemu, from the English "claim"), the team first examines the actual defective product and the production records to judge the scope of impact. They check whether products made in the same period are affected and, if needed, stop shipments and sort inventory.
Next, they dig into the cause with tools such as a cause-and-effect (fishbone) diagram and naze-naze bunseki (なぜなぜ分析, why-why analysis), and build countermeasures for two questions: why it happened and why it got out. The investigation and countermeasures go into a report explained to the customer. The job ends only when the countermeasure has been shown to work. For the report format itself, see How to Write an 8D Report: D0–D8 and the Toyota 8-Step.
Many customers agree on a deadline in advance for the first report after a defect is reported. Check that deadline with your customer before a defect ever occurs. Showing the scope of impact and the interim action quickly is what keeps the customer's trust in the first days.
How to keep a countermeasure from being a one-time fix.
A common mistake is to blame "operator carelessness" and stop there. Countermeasures that rely on people paying attention do not last, so the basic approach is to prevent the defect with jigs, equipment, or procedures. A report that stops at "we retrained the operator" is unlikely to satisfy the customer.
The investigation needs many records: production records, inspection records, and equipment operating data. Well-organized records speed up root-cause analysis, so the speed of a complaint response reflects how well the plant is managed day to day.
Quality Audit and Improvement
A quality audit checks, on a regular schedule, whether the systems that support daily quality actually work. The quality team checks each department through internal audits under ISO 9001, and also visits supplier factories to check processes and records.
Audit findings and the year's defect and claim data are shared in a meeting with top management, then built into the next year's quality targets and improvement themes. Feeding post-shipment information back into the next product's quality plan closes the loop.
In a supplier audit, the auditors walk the process, check work and records, and pass on concerns as improvement requests. They sometimes go with purchasing to gather input for deciding whether to keep doing business with the supplier. For what a Japanese customer checks and how to prepare, see Supplier Audit Checklist: How Japanese Customers Audit You.
How the Workflow Changes by Product and Company
The flow above is common to most manufacturers, but the emphasis shifts a lot with the type of product and the size of the company.
Production volume changes how quality is protected.
One company can use both approaches, depending on the product.
Mass-Produced vs. Build-to-Order Products
In industries that make the same product in large volumes, such as automotive, process stability is the core of quality. Teams control processes with statistical methods and watch for even small changes in the defect rate.
In build-to-order work such as industrial machinery, every unit has different specifications. Much of the time goes into finished-product tests, witness inspections, and inspection records, and quality is confirmed with each customer individually. For how witness tests run with Japanese equipment makers, see FAT and SAT with Japanese Suppliers: Steps & Free Checklist.
The required standards also differ by industry. These add industry-specific requirements to ISO 9001:
- Automotive: IATF 16949
- Aerospace: JIS Q 9100 (the Japanese counterpart of AS9100 in the Americas and EN 9100 in Europe)
- Medical devices: ISO 13485
Your customer's industry decides how detailed the work has to be.
Large Companies vs. Small and Midsize Companies
At large Japanese companies, the quality assurance department is often split into customer quality, process quality, supplier quality, and quality systems, and each person covers one area in depth. Customer quality handles the customer interface and claims, for example, while supplier quality handles supplier audits and coaching. Many companies rotate people through these roles so they gradually see the whole picture.
At small and midsize companies, a few quality staff usually cover everything from inspection to customer contact and ISO system administration. They see the whole workflow early, but each person carries a wide scope.
Company size changes who covers what.
Even at the same size, structure varies with company policy and products.
For you, this decides who you talk to. At a large customer, the person who approved your launch documents may not be the person who handles a defect complaint, so ask who owns each stage. At a smaller customer, one contact often covers everything. For a contact guide by topic, see QA vs QC in Japanese Companies: Who to Contact for What.
Questions to Ask the Japanese Side at Each Stage
Use these questions at kickoff, or whenever a request arrives and you are not sure what it is for. Answers vary by customer, so get them in writing.
| Stage | Question to ask |
|---|---|
| Quality plan | Which characteristics do you treat as key (critical or safety) items, and how are they marked on the drawing? |
| Quality plan | Which evaluations and approvals do you need, and at which milestones? |
| Design review | Do you want to see our FMEA? Will you review it, or only receive it? |
| Mass production decision | What Cpk value do you require, for which characteristics, and with how many samples? |
| Mass production decision | Which documents must be approved before the first production shipment: QC process chart, inspection standard, anything else? Do you have a template? |
| Mass production decision | If we launch with open issues, what conditions apply, and how long does early production control (shoki ryudo kanri) last? |
| Incoming / outgoing | Do you need an inspection certificate with each lot? What format, and what sampling plan? |
| Outgoing | Which items require 100% inspection? |
| In-process | Which changes (equipment, material, operator, method, sub-supplier) must we notify you of before making them, and how far in advance? |
| Complaint response | What is the deadline for the first report and for the final report? Do you have a required report format? |
| Complaint response | Who is our contact for defect complaints, and is it the same person as for launch approval? |
| Audit | Do you plan supplier audits? How often, and what do you check? |
Limits of This Guide
- Step names, boundaries, and documents differ by company, industry, and product. Some companies merge steps; others add their own gates.
- Numbers such as required Cpk values, report deadlines, and sampling plans are set by each customer or by contract. This guide does not give default values. Confirm them with your customer.
- The APQP mapping in the table is a rough guide for readers who know automotive terms. It does not mean a Japanese customer follows the AIAG APQP manual.
- Industry standards (IATF 16949, JIS Q 9100, ISO 13485) add requirements beyond what is described here. Check the standard that applies to your customer.
FAQ
What are the main steps of quality assurance in manufacturing?
At Japanese manufacturers, there are eight steps in three stages. Before mass production: quality plan, design review and risk assessment, and the mass production decision. During mass production: incoming inspection, in-process quality control, and outgoing inspection. After shipment: complaint response with recurrence prevention, and quality audits that feed lessons into the next product.
What is a QC process chart (QC kotei-hyo)?
It is a table that lists each process step with its control items and how each is checked. It is close to a control plan in APQP and PPAP terms, but formats vary by company, so ask your customer for their template.
What is the difference between an occurrence cause and an escape cause?
The occurrence cause explains why the defect was made. The escape cause (ryushutsu genin, 流出原因) explains why inspection or the process did not catch it before shipment. Expect to show a countermeasure for each.
What does yokoten mean in quality?
Yokoten (横展) means rolling out a countermeasure to similar products and other processes, so the same problem does not happen elsewhere. It is a common item in a defect report to a Japanese customer.
Why is "operator retraining" a weak countermeasure?
Fixes that rely on people being careful do not last. A stronger fix prevents the defect through jigs, equipment, or procedures, with data showing that the fix worked.
Sources
- Job description (production and quality control engineers): Ministry of Health, Labour and Welfare, job tag "Production and Quality Control Engineer" (Japanese)
- Job description (inspectors): Ministry of Health, Labour and Welfare, job tag "Inspector (Industrial Products)" (Japanese)
- APQP phases: Advanced product quality planning (Wikipedia); Net-Inspect, What are the 5 Phases of APQP?
- JIS Q 9100, AS9100, and EN 9100: SGS, JISQ 9100 / AS 9100 / EN 9100
Original article in JapaneseThis guide is adapted from a MONOSCOPE article written for readers in Japan: 品質保証・品質管理の仕事の流れ｜品質計画から不具合対応までの各工程を実務目線で解説
About the editor
MONOSCOPE EditorFOUNDER & EDITORSpent about ten years at a plant equipment maker and a plant engineering company, proposing, designing, and commissioning equipment, then moved into web marketing. Now a web consultant for B2B manufacturers, helping them explain their products and technology. Licensed in Japan as an Energy Manager and a Third-Class Chief Electrical Engineer.
Has run an engineering blog since 2017 (500+ articles) and a Japanese YouTube channel with about 20,000 subscribers. Each English guide is written from the Japanese shop-floor point of view and checked against the cited standards.
