DT OCR A level (product design)
How can we measure tolerance?
'go' or 'no go' gauges' e.g bolt fitting a hole
Why do we have tolerances?
- so components are the correct size to fit another component - set up parameters for quality control checks - so components aren't made too accurately saving money and time
How does compression moulding work?
1. mould heated 2. piece of plastic placed into mould 3. plastic is heated by the mould and becomes all droopy 4.hydraulic press time 5. plastic removed
What is a mitre gear?
A bevel gear but both parts are the same dimensions
What is a ferrous metal? e.g
A metal that contains iron e.g Steel
What is a non-ferrous metal? e.g
A metal that does not contain iron Aluminium, brass, copper
What is NACERAP?
A quality assurance term used in the fashion and textiles industry
What is Six Sigma?
A quality control programme
What is Kaizen?
A strategy whereby all employees work together to achieve continuous improvement
What is a thermoplastic? Examples
Can be reheated, melted and remolded into new shapes Polypropylene HIPs Polyethylene, HDPE and LDPE
What type of improvement does Kaizen aim to achieve?
Continuous
What does the ISO do?
Create standards for products ➢ safety ➢ quality
What approach do Six Sigma practitioners follow?
Define the problem ⇒ measure the problem ⇒ analyze the problem (cause) ⇒ improve and verify a solution ⇒ control situation (put into place)
Characteristics and uses of: Polyamide
E.g. Nylon ➢thermoplastic ➢ high melting point ➢ self lubricating ➢ cable ties ➢ washers ➢ cooking utensils ➢ string
What is used to join metal to plastic?
Epoxy resin
Characteristics and uses of: HDPE
High Density Polyethene ➢ Thermoplastic ➢ fairly stiff ➢ chemical resistance ➢ milk crates ➢ bleach bottles
Characteristics and uses of: HIPS
High impact Polystyrene ➢ thermoplastic ➢ easy to process ➢ low cost ➢ heat resistance ➢ high impact strength at low temperatures ➢ electrical components ➢ paper trays ➢ toys
What are thermosetting plastics? Examples
Plastics which cannot be reheated into new shapes Urea Formaldehyde Melanime Formalydehyde
What gases are used in brazing?
Oxy-acetylene, butane or propane can all be used
What form do Kaizen events often take?
PDCA Plan → hypothesis, set goals Do → run experiment Check → review the results Act → fix what doesn't work, refine the experiment
Characteristics and uses of: Polymethyl methacrylate
PMMA ➢ Acrylic ➢ thermoplastic ➢ clear, glossy ➢ car rear lights
Characteristics and uses of: Polypropylene
PP ➢ thermoplastic ➢ stiff, hard, chemical resistance, food safe ➢ child car seats ➢ garden chairs ➢ packaging ➢ bank notes ➢ rope
Characteristics and uses of: Polystyrene
PS ➢ thermoplastic ➢ low cost ➢ easy to mould ➢ easy to process ➢ trays ➢ boxes ➢ disposable cups
Is Kaizen an action plan or philosophy? How?
Part action plan, part philosophy 1. Action plan = organizing events to improve specific areas in the company • Involving all levels of employees 2. Philosophy = Building a culture where employees are actively engaged in suggesting and implementing in the company
What is Quality Control
Part of the achievement of Quality Assurance Involves actual activities inspections, testing
What is a UV stabilizer?
Polymer additive ➢ extent the products lifespan ➢ absorb UV radiation ➢ garden chairs
Characteristics and uses of: PVC
Polyvinyl Chloride ➢ Thermoplastic ➢ Can be both flexible and rigid ➢ Chemical resistance ➢ drain pipes ➢ hose pipes ➢ window frames
What is Total Quality Management (TQM)?
Quality assurance system
What is the British Standards Institute?
Quality standard award
What is Conformité European?
Safety standard
Gear ratio → 1:3 slowing down or speeding up?
Slowing down
Gear ratio → 4:3 slowing down or speeding up?
Speeding up
What is Quality Assurance?
Systems of planned activities used from design to manufacture stage to monitor the quality of the product
What are the disadvantages of implementing Total Quality Management?
➢ Additional costs of developing new ways of working ➢ Additional costs of training staff ➢ Benefits take time to filter through ➢ Some Staff may be reluctant to embrace change
Disadvantages of worm and wheel gears?
➢ Many turns of the shaft required to turn the wheel
What is a spur gear?
➢ Most common type of gear ➢ straight teeth ➢ parallel to the axis of rotation
Disadvantages of spur gear?
➢ Noise ➢ Light impact duty only ➢ Cannot be highly stresses
What are the benefits of a company implementing Total Quality Management?
➢ Staff feel more valued ➢ better working conditions ➢ Increased job satisfaction ➢ Less staff absentees ➢ Fair pay ➢ Better company reputation ➢ Increased customer satisfaction
Where is a rack and pinion gear used?
➢ car steering ➢ marine hoists ➢ pillar drils
Advantages of spur gears?
➢ cost effective ➢ durable ➢ can be made from a variety of materials
Advantages of a rack and pinion?
➢ durable ➢ high load applications
Advantage of bevel and mitre gears?
➢ ideal for high load applications
disadvantages of compression moulding
➢ limited complexity of shapes produced ➢ low production rates ➢ limited to flat of slightly curved shapes ➢ secondary operations required e.g removing excess resin around the edge
Disadvantages of rotational moulding
➢ longer cycle time than blow moulding and injection moulding ➢ material must be spun slowly enough to coat and dry evenly, takes time
advantages of compression moulding?
➢ low intial set up costs ➢ good surface finish, smooth ➢ heavy plastic can be moulded
Advantages of rotational moulding
➢ produces little waste plastic, as the required weight of plastic is placed into the mould ➢ can produce complex hollow shapes ➢ high quality surface finish ➢ low production costs
Advantages of worm and wheel gears?
➢ smoothest of gears ➢ quiet ➢ high precision ➢ small input force = large output force ➢ self locking ➢ cost effective ➢ large gear ratio
Characteristics and uses of: Epoxy resin
➢ thermosetting plastic ➢ high temperature resistance ➢ good insulator ➢ high chemical resistance ➢ furniture frames
Characteristics and uses of: Melamine Fomaldehyde
➢ thermosetting plastic ➢ opaque ➢ good chemical resistance ➢ stain resistance ➢ heat resistance ➢ cups (the ones at home) ➢ plates ➢ buttons
When is a compound gear train used?
➢ when large changes in speed or power are needed ➢ small space between input and output gear
Where are worm and wheel gears used?
➢ winches ➢ musical instruments
Characteristics and uses of: ABS
Acrylonitrile butadiende-styrene ➢ thermoplastic ➢ opaque ➢ high impact strength ➢ electrical plugs ➢ lego
What companies follow Six Sigma?
Amazon, Lenovo, eBay, HSBC
What is the filler material typically made from in brazing and soldering?
An alloy of silver → silver brazing, silver soldering
What is ISO?
International Organization for Standardization
How might a team define a faulty process using Six Sigma? Who leads the team?
Lead by a champion 1. team measures the initial performance of the process and make a list of potential inputs that might be causing it 2. the team analyse the process by isolating each component 3. then identifies reason for the process error through analysis 4. work to improve the system's performance 5. the add controls to the system to ensure it doesn't happen again
Characteristics and uses of: LDPE
Low Density Polyethene ➢ Thermoplastic ➢ flexible, soft ➢ chemical resistant ➢ Bin liners ➢ zip lock bags
Who developed Six Sigma?
Motorola
What does NACERAP stand for?
Name the fault Appearance of the fault Cause of the fault Effect the fault has on the quality of the product Repair the fault Action to be taken to correct the fault Preventing the fault from reoccurring
What is torque measured in?
Newton meters
How many manufacture defects does Six Sigma accept? No more than....
No more than 3.4 per million products made
What are the generally accepted procedures for a company implementing Total Quality Management (TQM)?
No required actions but generally accepted procedures: ➢ Customer satisfaction ➢ Effective communications ➢ Continuous improvement ➢ Decision based on facts ➢ Listening and acting on customer requirements ➢ Fair pay to workers ➢ Improving work conditions
Gear Ratio equation
Teeth on driven ------------------ Teeth on driver
How to join plastic and plastic?
Tensol cement
What materials are used in compression moulding?
Thermoset plastics Urea Formaldehyde Melamine formaldehyde
What is flux used for in brazing and soldering?
To clean the material being joint
Equation for torque
Torque (T) = Force (f) x perpendicular distance from pivot
Characteristics and uses of: Urea formaldehyde
UF ➢ thermosetting plastic ➢ hard ➢ brittle ➢ high melting point ➢ inexpensive ➢ resin form + water = wood glue ➢ electrical plug cases sockets switches
What does the CE symbol ensure?
the product has met the minimum standard of safety
Characteristics and uses of: Phenol formaldehyde
thermosetting plastic ➢ heat resistance ➢ saucepan handles
What is a bevel gear used for?
transition of power and motion between right angle shafts
What is an idler gear used for?
When both the driven and driver gears have to turn in the same direction.
What is a rack and pinion gear?
a bar or rectangular gear having straight teeth perpendicular to the axis of motion
What is a worm and wheel gear?
a shaft with helical threads on the surface perpendicular to the axis of rotation
What is a compound gear train?
at least one shaft has two gears
What is a polymer additive?
chemicals added to a polymer to enhance its properties
What does Six Sigma emphasize?
improving cycle time Reducing manufacture defects
What is a processing additive?
polymer additive ➢ added to enhance the processablility of the polymer ➢ lubricants ➢ heat stabilizers to PVC is common as it is a heat sensitive material
What is an optical property modifier?
polymer additive ➢ pigments ➢ dyes ➢ give colour
Where are bevel and mitre gears used?
printers, elavtors
Gear ratio → 5:6 slowing down or speeding up?
slowing down
Gear ratio → 3:1 slowing or speeding
speeding up
