What does Machine Designing stand for? What is the main work of Engineer in Machine designing?

macchine designing stand for gearbox junction that we should test it after assembly for viberation , nois and testing load  ,and we should test after operation and befor operation , and to reduce the noise

the main work of engineering in machine engineering  is that means adesigner engineering is the most important person in the company with helping the varios disciplines including(elec,mech,chemical,civil system ..................) design eng tend to work in products , system that involve the use and adaption of complex scientific and mathimatic techniqes