CNC Machining versus conventional machining
Conventional machining requires a
skilled operator to manipulate the machine tool handwheels to produce a determined
component. The Operator has to examine the drawing many times, during the
operation, to determine the dimensions that apply and must decide by how much
each handwheel must be turned to produce the desired result.
Many conventional machine tools
have speeds and feeds governed by mechanical design features such as
fixed-speed gearboxes. Thus the choice of feed or speed is a compromise
depending on the gear ratios built into the machine tool.
By contrast, CNC machine offer
complete control of all axes, under optimum cutting conditions. Extremely short
set-up times are possible since standard tooling is all that is required. The
good accuracy and repeat ability of the components produced by CNC machines
enables a greater uniformity of production. The quality of finished job is no
longer under the control of the operator but under the control of a
computer-run part program.
Adopting CNC
CNC provides for an automated
approach to manufacturing. To change from one type of component to another
requires only a minimum amount of set-up time and the provision of a part
program. The main reasons to adopting CNC can be listed as follows:
·
CNC
provides flexible automation, adaptable to many differing requirements, and
changeovers from one job to another are rapid.
·
The
Investment of time in producing part programs can be realised many times over
since repeat orders require no additional work.
·
CNC
offers reduced downtime, early production start-up, uniformity of production,
minimum machining times, and less scrap and re-work.
·
CNC
can reduce labor costs.
Drawback of CNC
The biggest single limitation is
probably the initial high capital cost of the equipment itself and its sub sequence installation. CNC equipment is also high technology equipment and
will require maintenance of the different nature to that conventional machine
tool.
The introduction of CNC machine
will inevitably lead to the loss of existing conventional machines and their
operators. Resistance to change may further hamper the introduction of CNC.
Planned alternatives for those members of the workforce unable to make the
transition into CNC operation must be carefully considered.
