What factors do designers need to consider when selecting materials and components?
- Availability
- Functional need
- Cost
How is availability considered when choosing a material or component for a design?
- Are the chosen materials available in stock forms?
- Are expensive or rare materials needed that are harder to source?
- Does the supply of materials affect the production flow?
- Have the materials been sourced from a renewable supply?
- Have the raw materials been processed without causing environmental damage?
How is functional need considered when choosing a material or component for a design?
Functionality is vital in product design. Designers need to consider:
- Will the selected material function as expected?
- Is it strong enough? Will it resist wear and tear?
- Does it need to be weatherproof or chemically resistant?
- Is the product safe?
- What standards does it need to conform to?
How is cost considered when choosing a material or component for a design?
- Does the cost of manufacturing meet the expected budget?
- Does the selected production method (mass, batch or one-off) impact the cost of materials?
- Are bespoke sizes required?
What is the difference between quality assurance (QA) and quality control (QC)
QA - Procedures to manage all functions that affect quality. (Checks manufactureing processes)
QC - Check against the manufacturing Specification. (Checks the product itself)
What is quality assurance (QA)?
Quality Assurance does not check the quality of the final product, but the quality of all systems on the production line, staff training and quality monitoring.
What is quality control (QC)
The process of inspecting products to ensure that they meet the required quality standards.
It may take part in any part of the production.
What is tolerance?
Tolerance is the amount of error allowed for a given task.
It is applied to distance measurements and weights such as in fabric, paper or card.
There will be a specified measurement range which is an acceptable difference in size between an upper limit and a lower limit.
How does tolerance vary between different products and components?
- During a making activity, it may not be possible to achieve 100% accuracy.
- An appropriate degree of tolerance needs to be considered for a given product.
- This could vary from a fraction of a millimetre to a few millimetres.
- A narrower tolerance is usually required for more technical elements. (metalwork, wood joints, 3D printed or laser-cut components, or specific levels of voltage required in a circuit)
What is a go/no-go gauge? (Accurate working)
A go/no-go gauge is used to check dimensions are within specified tolerances.
The expected dimensions and tolerances will be pre-set.
For instance, when checking a drill hole, if the go gauge fits but the no-go gauge does not, the hole is within tolerance.
What is a depth stop? (Accurate working)
- A depth stop ensures a hole will be drilled to the correct depth.
- The limit is set to control how far the drill bit enters the workpiece.
- This can be used in a pillar drill or can be in the form of cap added to a power or hand drill.
- Metal band saws can also be fitted with an adjustable stop to ensure a blade only cuts to a pre-set depth.
How are a laser cutter’s settings changed when changing the material being cut?
The speed, power and dimension settings must be set according to the material.
What is a seam allowance?
A seam allowance is the area between the line of stitching and the edge of the fabric.
Commercially, a seam allowance may only be 10mm to save on fabric.
The tolerance is very small, so accurate stitching is needed otherwise pieces will not fit as intended.
How can patterns on textiles be checked for inaccuracies?
Although many checks are made by eye, machine vision systems are being introduced to scan and detect physical or pattern defects.
This automated process is extremely fast, but the computer equipment is costly, so it is only used by large scale factories at present.
What is photo etching and how is it used for printed circit boards?
- Printed circuit boards (PCBs) can be made using the photo etching process.
- This process corrosively etches away selected areas of sheet metal.
- It is a precise process which can produce complex circuits with fine detail.
- Commercially finished etched boards are inspected both visually and by machine.
Exam style question:
Explain the purpose of ‘quality control’.
[2]
Quality control checks or tests a product to ensure that it meets pre-set standards, tolerances or specification criteria.
It guarantees the accuracy of a part or component and that it is fit for purpose, and of an acceptable standard for sale
What is done during the ‘Marking out’ stage?
Marking out transfers a design or lines from a plan onto a workpiece in preparation for the next step.
It provides the guidelines for cutting, bending, shaping or drilling
Templates, patterns and jigs are used to ensure repetitive ________ when marking out and cutting out materials.
accuracy
What is a template and how is it used to increase accuracy when marking out and cutting?
A template is a specific shape that can be drawn or cut around.
For a one-off production, a paper template may be used.
When batches of identical shapes are needed, a template would be made of a more durable material to withstand repeated use.
What is a pattern and how is it used to increase accuracy when working with textiles?
- A sewing pattern is a template, often made of paper or a lightweight cardboard for repeated use.
- It is made up of several pieces which represent the different sections of a garment.
- The outline is marked onto the fabric which is then cut out and assembled.
- The outline may be traced by hand or with CAM.
What is a pattern and how is it used to increase accuracy when casting?
- A pattern can also be a replica mould of an object to be cast.
- The patterns can be made in metal, plastic resin or wood.
- Allowances must be built into the cast to allow for the different characteristics of the casting material.
- For example, metals contract when they cool, so there must be allowance for shrinkage or distortion.
What is a jig and how is it used to increase accuracy?
- Jigs keep material positioned in the same place whilst being machined or drilled.
- They can be made into a particular shape for a specific process.
- Jigs are used for guiding a cutting tool or drill, to ensure the hole or cut is made at the correct place every time.
- Jigs increase production rate, improve accuracy and reduce wastage.
Exam Style Question:
A hole punch creates holes in sheets of paper.
Describe how a tool can be used in order to ensure that the holes are always cut in exactly the same place on each individual punch.
[2]
A jig is commonly used which is slid into the correct position for the size of sheet and held against the edge of the paper.
The punch is then pressed to create the holes.
What are some different pieces of equipment used for marking out?
- Scriber
- Tailor’s chalk
- Engineer’s blue / layout stain
- Centre punch
- Marker pens, pencils, chinagraph
- Pattern or tracing wheel
- Marking gauge
- Engineer’s / combination square
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Section A - Core Technical Principles1
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1.1 - New and Emerging Technologies57
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1.2 - Energy Generation and Storage39
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1.3 - Development in New Materials35
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1.4 - Systems Approach to Designing18
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1.5 - Mechanical Devices43
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1.6 - Materials and their Working Properties104
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Section B - Specialist Technical Principles1
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2.1 - Selection of Materials or Components11
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2.2 - Forces and Stresses12
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2.3 - Ecological and Social Footprint22
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2.4 - Papers and Boards0
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2.5 - Timbers73
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2.6 - Metals57
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2.7 - Polymers48
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2.8 - Tools, Processes, Shaping and Forming of Timbers, Metals and Polymers26
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2.9 - Textiles0
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2.10 - Electronics and Mechanical Systems0
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2.11 - Scales of Production10
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2.12 - Specialist Techniques and Processes8
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Section C - Designing and Making Principles1
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3.1 - Designing Principles79
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3.2 - Making Principles43
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3.3 - Design Companies9
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3.4 - Notable Designers6
