Rugby School Thailand Design & Technology Senior School

17 Quality Systems

Content

• Quality assurance (QA) checks to be used in the production of a product. (Quality assurance checks are

made at every stage of the production process to meet the quality standards set.)

• Quality control (QC) checks to be used on a made product. (Quality control checks are made to a

finished product to see if it meets the quality standards set.)

• The benefits of introducing Total Quality Management (TQM) to a production process. (Total Quality

Management involves applying quality assurance procedures at every stage of the production process.)

• The benefits of quality systems to the manufacturer and the consumer.

• Product testing methods that can be used before or during the manufacturing of products, such as:

– material testing

– dimensional checks

– joining/assembly checks

– visual checks.

• The organisations that are responsible for quality standards within the candidate’s country such as the

International Organization for Standardization (ISO).

• The quality standards concerned with testing products, components and materials against external

quality standards, e.g. ISO 9013 (thermal cutting) or ISO 34257 (wood adhesives).

Planning for accuracy and efficiency

When producing a prototype product, it is essential that you plan for accurate production.

A detailed product design specification (PDS) is one essential element in the process, but the development of the design must allow the concept to be tested against key specification criteria prior to final production or prototype.

The proposed manufacturing procedures must be evaluated for suitability and the achievable level of accuracy - For example, a tolerance of + or – 0.0001mm when machining on a lathe will likely require outsourcing to a company with the necessary equipment and skill to achieve that level of accuracy.

The successful manufacture of a product on any scale requires a clear schedule of production, with deadlines and Quality Control inspections factored in.

Ensuring accuracy of prototype designs - Pre-production:

accuracy in prototype development relies heavily on a UCD approach (see previous units for more on UCD) with client feedback playing a major part in the success of the prototype. This list covers some of the pre-production Quality Assurance (QA) procedures used to ensure accuracy:

CAD simulations
working drawings with tolerances
mock-up models and mechanical systems/test rigs
client feedback/approval
peer review

Ensuring accuracy of prototype designs - Production:

during production of a prototype, product accuracy is ensured using a range of QC checks. These are used in conjunction with client feedback to ensure visual aesthetic checks

appropriately accurate dimension checks
machine tooling and alignment checks
assembly checks of multiple components
quality checks of the manufactured finish

The definition of small, medium and large scale production is very subjective and testing procedures will also vary based on the cost analysis to ensure profitability.

Ensuring accuracy in various scales of production - Pre-production phase:

during product development, a wide range of techniques are used to ensure that the product going into production is accurate compared to the PDS. The cost of rectifying errors during pre-production is considerably less than during production.

Techniques used include:

CAD including simulations and costings
working drawings with tolerances
sample prototypes
templates, jigs and fixtures
focus groups and surveys
NDT (Non Destructive Testing) and destructive testing

Ensuring accuracy in various scales of production - Production phase:

when manufacture of the final product begins, accuracy is assured using a range of QC checks to compare the products against the PDS. Some of the types of checks used include:

visual aesthetic checks during regular sampling
sample dimensions using flexible measuring equipment
tolerance dimension checks such as a go/no go gauge
machine tooling and alignment calibrations
specific sampling regularity set by legal requirements
checks of the quality of the manufactured finish

Quality assurance (QA) & Quality control (QC)

quality assurance (qa)

Quality assurance, or QA, refers to the procedures and policies put in place to reduce waste, and to ensure manufactured products are produced accurately within set tolerances. By using effective QA procedures, a manufacturer is aiming to produce products ‘right first time and every time’.

To check that products being produced conform to the tolerances set, QA and QC checks must be included within the production process. Examples of QA include:

only sourcing materials from suppliers that hold ISO 9001 Quality Management Standard
setting specific temperature ranges for moulding to ensure effective filling of cavities and speeds of cooling
setting rigid maintenance schedules for machinery to ensure cutters are machining within tolerances.

As the effectiveness of QA procedures increases, the number of QC issues and waste products will inevitably decrease.

Using CAD software the following tests can be carried out....

components can be modelled and assembled virtually to review any possible conflicts.

FEA can be used to analyse the stresses that a component will face during its working life, although this may still be tested on a real product.

Prior to production, designers and engineers can model production procedures using CAD and CAE (Computer Aided Engineering) to ensure that products are produced accurately first time.

specific forms of CFD (Computational fluid dynamics) such as MFA (Mould Flow Analysis) can be used to check the flow of materials within moulding machinery.

Along with these pre-production checks, the design of components can be modified to help QC checks such as having multi-part moulds so just one part can be replaced if errors are found.

Quality control (QC)

Quality control (QC) refers to the monitoring, checking and testing of materials, components, equipment and products throughout production to ensure they conform to acceptable tolerances specified within the QA policies within the company.

QC inspection checks take place throughout the production process and are performed in conjunction with the strict guidance documentation produced by the company and the client.

Material checks

At the beginning of any production process, the materials must be checked for their compliance with the manufacturers specification. These can consist of:

simple visual checks on the materials supplied
chemical analysis on small volumes of the material
colour matching for polymer pigments of paint finishes

Dimensional accuracy checks

have been covered in the previous units and are carried out as part of a QC system.

Digital measuring devices

These were also covered in more detail in the previous unit but it is worth a reminder of some of the digital tools used for measuring accurately. These include digital vernier calipers and micrometers.

Co-ordinate measuring machinery

The use of co-ordinate measuring machinery (CMM’s) such as a probe scanner, allows a manufacturer to check a range of predefined measurements on finished components.

CMM can be used to check tooling for dimensional accuracy during maintenance, and the results may be used to update QA procedures such as setting the regularity of tool changes.

Go/no go gauge

When checking dimensional accuracy on a production line, a specific measuring instrument is often used such as a go/no go gauge, which checks whether a single measurement fits within a tolerance range, giving a simple pass/fail reading. This is quicker than using a vernier or micrometer because the operator does not have to check for an accurate reading. It also requires little training to perform this task.

A go/no-go gauge is a precision measuring tool used to verify whether a workpiece meets the specified dimensional tolerances or not. Here are some specific applications where a go/no-go gauge is commonly used:

Machining industry: Go/no-go gauges are widely used in the machining industry to ensure that parts are manufactured to precise tolerances. They are used to check the dimensions of threaded components such as bolts, nuts, and screws.
Automotive industry: In the automotive industry, go/no-go gauges are used to check the dimensions of critical components such as engine parts, transmission gears, and brake components.
Aerospace industry: In the aerospace industry, go/no-go gauges are used to check the dimensions of components that are critical for safety, such as turbine blades, fuel system components, and hydraulic components.

Two reasons why a go/no-go gauge would be used:

To ensure product quality: Go/no-go gauges are designed to verify whether a workpiece meets the specified dimensional tolerances or not. By using these gauges, manufacturers can ensure that their products meet the required quality standards and avoid costly rework or scrap.
To improve efficiency: Go/no-go gauges are quick and easy to use, which makes them ideal for high-volume production environments. By using these gauges, manufacturers can quickly check the dimensions of parts and identify any out-of-tolerance parts before they are assembled, which can help to improve production efficiency and reduce waste.

This is an example response to an exam question about go/no-go gauges:

List some specific applications where a go/no-go gauge is commonly used and give two reasons why it would be used.

Go/no-go gauges are precision measuring tools used to verify whether a workpiece meets the specified dimensional tolerances or not. They are widely used in various industries, including the machining industry, automotive industry, and aerospace industry. Here are some specific applications where a go/no-go gauge is commonly used:

In the machining industry, go/no-go gauges are used to check the dimensions of threaded components such as bolts, nuts, and screws. In the automotive industry, these gauges are used to check the dimensions of critical components such as engine parts, transmission gears, and brake components. In the aerospace industry, go/no-go gauges are used to check the dimensions of components that are critical for safety, such as turbine blades, fuel system components, and hydraulic components.

Two reasons why a go/no-go gauge would be used are to ensure product quality and to improve efficiency. These gauges are designed to verify whether a workpiece meets the specified dimensional tolerances or not. By using these gauges, manufacturers can ensure that their products meet the required quality standards and avoid costly rework or scrap. Additionally, go/no-go gauges are quick and easy to use, which makes them ideal for high-volume production environments. By using these gauges, manufacturers can quickly check the dimensions of parts and identify any out-of-tolerance parts before they are assembled, which can help to improve production efficiency and reduce waste.

Non-destructive testing (NDT)

refers to methods used to check the internal structure of materials, often after joining through processes such as welding. The two main methods are X-ray and ultrasound analysis.

The material is subjected to radiation or ultrasound waves to check for refraction of the signal which would indicate an internal fault not visible to the naked eye.

Ultrasonic testing is safer than X-ray testing because it uses sound waves rather than radiation. The test records defects where the reflecting signal indicates something other than solid material.

Such testing is necessary for components such as turbine blades and jet engines where failure due to a fault in the welded joints could be catastrophic.

Ultrasound

X-Ray

Case Study

Allied Glass is a world producer of high quality glass containers. Its success over the last 150 years is largely down to its ability to facilitate a wide range of varying designs.

It currently produces in excess of 600 million containers per year for the premium drinks market. To ensure that these containers meet the high level of standards expected by it’s customers, it employs a wide range of QA procedures and QC controls.

Stage 1: customer specification

The initial design of a glass container is developed closely with the prospective customer who will give clear and specific criteria that Allied Glass must follow. These details will include aesthetic elements such as the type and clarity of glass to be used, maximum sizes, details of the market where the product will be sold and the volume of liquid to be held within the container.

stage 2: concept development

Design development is done in-house. This means that the lead time (from initial concept to final production) is reduced because the new product development (NPD) team employs a concurrent approach, guiding the customer through the production limitations during concept generation.

Concepts are modelled in solid forms using 3D CAD software which is used to drive two rapid prototyping machines.

Prototype models are produced as full-size visual representations using PLA polymer, allowing the customer to hold and critique the form of the container.

Stage 3: mould design and sampling

Using 3D CAD software, the mould for the container is developed to fit with the existing production equipment. The testing regime is thorough with some of thes main stages:

working drawings: specification drawings with tolerances used to adjust the production equipment for the specific job
sample prototypes: a sample sets of moulds is used to produce a batch of container for QC testing
sample dimensions checks: measuring equipment is used to check the relatively low volume of sample containers
visual aesthetic checks: sample bottles are checked visually for faults in the forming process such as ‘shorts’ where glass has not filled the mould.
machine tooling and alignment calibration: to maintain accuracy
NDT: samples checked for internal faults and stress to prevent shattering
templates jigs and fixtures produced: as every container is different

stage 4: production

Combined with the QA procedures employed for each individual container, Allied Glass must monitor the overall quality of the glass being used during the production of all containers.

Raw materials are checked before being stored in a silo. Main ingredients are sand, soda ash, limestone and cullets of recycled glass. One issue is the colour of the glass. The higher the iron content, the greener the glass.

As the materials enter the furnace, the temperature is tightly controlled within pre-determined tolerances.

Once glass enters the production line, it is formed through a glass blow moulding process and then fed into an annealing oven to reduce the internal stresses and prevent brittleness.

During production, numerous QC checks continue. These are covered in more detail on the next slide.

When full scale production begins, the new container moulds are installed on a production line and the report from sampling is used to calibrate all machinery and tooling.

qc testing

Every container is checked, using camera analysis, for glass imperfections, which records the individual mould where that container was produced. Any issues with specific moulds will be fed back to the forming end of the production line and investigated.

Every hour, each production line provides a sample for the QC department to check volumes, stresses within the glass, dimensional accuracy and other QC specs. Random sampling also take place using specific gauges. Any faults are recorded with the results feeding back to relevant points on the production line.

summary

When producing a prototype product, it is essential that you plan for accurate production.

The development of the design must allow the concept to be tested against key specification criteria.
Modelling strategies may include virtual CAD simulations.
Effective QA should ensure products are made correctly ‘first time’.
Effective project management is essential in all design and manufacture activities.
QC inspections take place throughout the production process.
Dimensional accuracy is vital for components to be assembled effectively
NDT refers to methods used to check the internal structure of materials, often after joining processes such as welding.

Total Quality Management (TQM)

International organization for Standardization (ISO)

Effective project management is essential in all design and manufacture activities to ensure they are completed within budget and to agreed time scales.

For products to be commercially successful, they must conform to strict national, European and international standards. These standards cover a wide range of areas.

Certification with standards such as ISO9001 (Quality Management) is not compulsory, but can be essential when working with other companies that are ISO 9001 certified.

Such standards may become obsolete, updated or replaced over time so its good practice to keep up to date with any standards that are relevant to product design.

The following page looks at legislation and standards that you should be familiar with as a design student.

Total Quality Management (TQM) is an approach to project management that has been used since the 1950’s, gaining popularity in the 1980’s and beyond. The main aim stems from QA with the ambition to remove waste and produce products ‘right first time’.

Companies that use TQM strive for continual improvement. They value the views of their workforce and encourage them to participate in teams where individuals can problem solve and contribute to the overall effectiveness of the production process.

Project management systems

Scrum (agile manufacture)

is a method of project management first used within software development. The main focus of Scrum is to work in a team to reach goals in short timescale ‘sprints’.

The team works on the specified team goal, and attends daily 'scrum' updates where individuals feed back their progress towards the team goal, as well as any issues that are stopping them progressing.

The distribution of tasks can be updated based on these issues and the team can quickly respond to changing customer demand due to the regularity of feedback meetings.

Six Sigma

In the 1980’s, Motorola introduced the Six Sigma system; a set of techniques and tools for process improvement which is designed to minimise defects. The aim of the system is to reduce the number of defective products produced to less than 3.4 in every million!

The system requires the implementation of a DMAIC procedure (define, measure, analyse, improve and control) to assess each stage of the design and manufacture activity.

The five key stages of Six Sigma:

Define: what is the issue within the process?

Measure: take steps to measure the extent of the issue

Analyse: determine where the issues measured occur

Improve: introduce procedures to rectify the issues identified

Control: ensure the modified procedures are implemented and maintained through effective QA.

Lean manufacturing

Six Sigma is primarily aimed at reducing the number of defective products through monitoring. Lean manufacture, however, is a systematic approach to production which aims to eliminate all waste from product production.

Waste is identified as anything that does not benefit the client and is given the name ‘muda’. There are seven forms of muda which are given the acronym TIMWOOD:

Transport: rick of loss and damage when transporting goods
Inventory: using JIT to reduce the inventory on site at any time
Movement: employees and their equipment, time wasted in production
Waiting: hold ups in production while others catch up
Over production: making more products than there Is demand for means wasted inventory and storage space (see JIT)
Over processing: investment in machinery to mass produce must be justified by the demand for the product and level of precision
Defects: faulty products must be removes, This is key to Six Sigma and relies on effective QC and quality QA procedures

Lean Six Sigma

The DMAIC approach of Six Sigma is a structured framework that can be applied to all areas of the workplace to reduce variation in performance.

The TIMWOOD waste reduction strategy of lean manufacture gives clear guidance on the forms of inefficiency that need to be addressed. By combining both strategies, companies aim to improve operational and manufacturing excellence that has maximum benefit for the customer.

BSI is a national organisation formed to devise agreed standard procedures for performing a wide range of tasks. The range of current standards in the BSI portfolio exceeds 30,000 as of 2017.

If a British Standard has been accepted it will carry the prefix BS EN.

Examples include:

BS EN71-1: 2014 Safety of toys

BS EN 62115: Electrical toys. Safety

BS EN 50361: 2001 Basic standard for absorption rate of electromagnetic fields from mobile phones!

international standards organisation

BSI is one of over 150 national standards bodies that are part of the International Standards Organisation (ISO) where internationally recognised standards are agreed and put in place.

Standards for management services, such as ISO 9001, are applied worldwide with many companies only dealing with others that conform to the standard.

Key international standards include:

BS EN ISO 9001 quality management

BS EN ISO 14000 environmental management

BS EN ISO 50001 energy management

BS EN ISO 31000 risk management

The presence of a CE mark on a product means a product conforms to all relevant European safety standards and its presence is mandatory for all items sold in the EU.

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