Manufacturing part II

what happens with faster cooling

finer grains, more boundaries, distribute strain

what do fillet radii do in casting

reduce stress concentration

what does delaying the solidification time do

increase hot tear risk

what metals can be used in casting

non-ferrous

what is in gelation phase

gel phase insoluble

sol phase soluble

difference between amorphous and crystalline

amorphous are translucent and low shrinkage and have no melting point

what is the pressure equation

$$p=\sigma\left(a+b\ln\left(\frac{1}{1-r}\right)\right)$$

how do you find the force from pressure

$$P=pA$$

what does isotropic mean

the properties are the same in every direction

what to know about ferrite

BCC, low carbon, low temp, coexists with cementite

what to know about martensite

BCC/BCT, lots of carbon, austenite rapidly cooled

what is solid-state sintering

occurs when powder densly packed in only solid state

what is liquid state sintering

liquid fuses particles together, usually large discreptancies in their melting temperatures

which sintering type is faster

liquid

what happens when you have a low clamp force in injection moulding

flash or leakage can occur

what is cavity pressure affected by in gates

number of gates, gate size, location

what do large gates do to flow

they reduce flow

which processes need higher temperatures

long, small ones to avoid preemptive solidification

what is dwell time

time to apply force during packing process

how do burn marks form

trapped superheated gasses

how do sink marks form

insufficient polymer/material

what are the different steps in injection moulding

plastification, injection, packing/cooling, ejection

which is more prone to shrinkage, amorphous or crystalline

crystalline as they pack more tightly together

what are the process parameters for injection moulding

melt temp, temp of mould, injection pressure, fill rate/time, dwell time, freeze time, ejection time

what can cause sink marks

insufficient polymer, flow back into runner system, temp too high, too hot

what can cause knit lines

slow injection, under-packing of part, polymer too cold, multiple gates