There are many contents of CNC lathe
machining, including many aspects, especially in CNC precision parts machining
and checking fixture machining, these words are often used. These are precautions when machining,
and we need to be familiar with them.
1. Precautions on CNC precision parts machining
(1) When the workpiece is too high, it
should be cut with different lengths. After using a large knife for roughing,
use a small knife to remove the remaining material.
(2) Use flat-bottomed knives to process
planes. Ball knives are used less in order to reduce machining time. If there
is a slope and it is an integer, a sloped knife should be used for machining.
(3) Reasonably set tolerances, so that the machining
accuracy and computer calculation time are balanced with each other, and more
procedures are performed to reduce the empty tool time;
(4) The rough material has high hardness,
so choose upside down milling; the rough material has low hardness, choose down
milling. Rough machining up-milling, finishing machining down-milling;
(5) The tool material has good toughness
and low hardness for rough machining, and the tool material has poor toughness
and high hardness for finishing.
2. Notes on fixture machining
(1) Part clamping method and fixture
selection
The clamping method of the cnc machined parts
on the CNC lathe should also reasonably select the positioning datum and
clamping scheme. In the selection of the fine datum, the two principles of
"unification of the reference" and "reference coincidence"
are generally followed. We need to consider this principle:
a. Try to complete the machining of all
surfaces in one positioning clamp, so choose a positioning method that is
convenient for each surface to be processed;
b. When the workpiece is clamped at one
time, it should be able to complete the machining of all surfaces of the
workpiece;
c. When determining the placement position
of the workpiece on the workbench, consideration should be given to the effects
of machining at each station, the length of the tool and the rigidity of the
tool on the machining quality;
d. Fixtures used in controlled machining
should be selected as much as possible by assembling universal components and
can be adjusted to shorten the production preparation cycle.
(2) Arrangement of fixture machining
sequence
When arranging the machining sequence, the
basic principles must be followed, including "face first, then hole",
"rough first and then fine", etc. In addition to these basic principles,
we should also follow the following principles, as follows:
a. According to the centralized machining
of the tool, avoid the repeated use of the same tool multiple times and reduce
the number and time of tool changes;
b. For the hole system with high coaxiality
requirements, after one positioning, the machining of the hole system should be
completed, and then the hole system at other coordinate positions should be
processed. This can eliminate the errors caused by repeated positioning and
improve Concentricity of the hole system;
c. Select and determine the tool point and
the tool change point. Once it is determined, it should not be replaced.
The above are the matters needing attention
about CNC precision parts machining and fixture machining. For more information
on this, you can consult Dongguan PTJ Cnc Machine Shop.