accuracy in design and manifacturw

Question 1

measuring and marking out equipment

Answer 1

marking metal usually requires the use of a high carbon steel scrubber which is harder than the metal that is being marked so can scratch surface
if difficult to see ink is used called engineers blue to be applied
if circles or arcs are required dividers are used which have two points
beam compasses called trammels can be used to larger radii

Question 2

measuring and marking out material 2

Answer 2

timber is usually marked out with a marking knife or pencil called carpenters pencils with thicker lead to avoid breakages
marker pen on polymer sheet

Question 3

measuring

Answer 3

cross line levels
large complicated fabrications are being undertaken
perfectly horizontal vertical reference line
marking decide needs to be glued in some way as can’t be free hand
- surface plates, gauges with angle plates and V blocks

Question 4

high precision work

Answer 4

micrometers, vernier callipers and coordinate measuring machines are tools used for precise measurements involving fine tolerances
profile projector and digital test gauge- single axis measuring device that is used extensively for precise measurement
accuracy of 0.01mm

Question 5

impact of CNC controlled machinery

Answer 5

doesn’t need marking out as the G codes control the coordinate path
needs optimum layout for all of the parts to avoid wastage
all situations where decisions must be made

Question 6

importance of accuracy

Answer 6

level of conformity of a measurement to a required value
important feature of modern product design
ensure parts fit and function correctly
designer has to determine suitable range of accuracy known as the tolerance
may vary depending on material size and function
watch gears need a fully functional accuracy

the components outside the tolerance have to be rejected as part of the QA and QC measures
geometric dimensioning and tolerance
standardised system of symbols and figures used on CAD model or engineering drawings that express the ideal distance and angular dimensions required along with variation

Question 7

testing and the elimination of errors

Answer 7

1. hand forged iron or steel decorative scrolls for a bespoke gate
   - no need for good accuracy
   - handmade bespoke look
   2 a rectangular piece of MDF for mounting a picture to be cut form a board
   measure ohotogpra make as close as possible +_ 0.5mm no working parts so not critical with rigid ruler + larger tri square
   3 mass produced glass bottles
   - fit screw top
   - no sagging
   - correct volume
   checks needed
   camera and computer scanning systems
   profile projector for the screw top fitting +_ 0.015mm
   tolerance checks with go/no go gauge
   weight +_ 5g

4 mould for blow moulding a glass bottle
electrical discharge machining that can achieve an tolerance of +_0.002 mm
highly trained engineers check
vernier callipers