2.7-Accuracy in Design and Manufacture Flashcards
Name some tools used for measuring and marking out
scriber
dividers
beam compasses
callipers
knife
pencil
marker pen
steel rule
cross line levels
surface/angle/gauge plate
marking gauge
try square
combination square
What is engineer’s blue?
an ink used to make the scratched lines from a scriber easier to see
What is a combination square?
like a try square but allows for 45 degree angles and has a spirit level
Explain some very high precision measurement machines
micrometres
vernier callipers
co-ordinate measuring machines (CMMs)
profile projector
digital test gauge
Explain the digital test gauge
a single axis measuring device that is used extensively for precise measurement. It has largely taken over the role of the mechanical dial indicator because it has an easy to read display
What is a profile projector?
used to inspect the dimensions and shapes of small parts. It works by projecting the shadow of a part onto a screen, allowing for precise measurements without physical contact. This makes it ideal for checking the accuracy of complex shapes and fine details.
What is a go/no go gauge?
used to check whether a part’s dimensions are within specified tolerances. It has two ends: the “go” end, which should fit into or around the part, and the “no-go” end, which should not fit. This simple pass/fail test helps ensure parts meet design specifications and quality standards without the need for detailed measurements.
Name some measuring aids used to improve speed, accuracy and consistency
jigs
fixtures
templates
What are jigs?
devices used to control the motion of a tool relative to a workpiece. The most common type is a drilling jig, used to ensure that holes are drilled in the correct location every time. They are normally locked onto the workpiece using clamps; and replaceable, hardened bushes guide the drill. Using a jig means that the need for marking out is removed, and the work does not require high skill levels
What are fixtures?
robust frames with holding points and clamps that are used to hold workpieces firmly in place while machining, welding and other manufacturing operations take place. It is essential that every component or assembly is held in exactly the same position each time the manufacturing process is carried out, to ensure consistency.
What are templates?
consists of a rigid shape or pattern, often made of thin manufactured board or sheet metal, which is used to transfer a design onto a workpiece. It is normal practice for a template to be held securely in position while the outline is traced onto the material below with an appropriate marking tool.
What is tolerance?
the acceptable upper and lower limits of accuracy of a measurement
What is accuracy?
how close the measurement is to the required value
What is datum?
a surface or edge used a reference from which measurements are taken to improve accuracy
