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clamping types are: s11_2, s11_3, s11_4; s12_2, s12_3, s12_4;
s13_1, s13_2; s2_1, s2_2; s3_2, s3_3, and s3_4.
In this notation, the last number means the number of clamp-
ing points.
3.4 Suitable surfaces of the workpiece for locating and clamping
3.4.1 Suitable surfaces for plane locating
The suitability of surfaces for plane locating depends on the
shape and dimension of the surface.According to the shape, the following surfaces are suitable
for plane locating: planar surfaces, intermittent planar surfaces,
group of planar surfaces in same plane, group of planar surfaces
in two different planes, cylindrical surfaces (with parallel axes),
and combination of cylindrical and planar surfaces.
The surfaces (features) so far identified are not equally suit-
able. The suitability decreases in the order of enumeration. In the
expert system prototype, only the first three features are built-
in. Next to the fair shape (feature), the plane locating surface
must be sufficiently large in order to be usable for plane locating.
Prismatic workpieces, according to their global structure, can be
pided into: cubical, flat and long workpieces.
Not all the faces of a workpiece are suitable for plane locat-
ing. In the case of flat workpieces, only the large faces, and in the
case of long workpieces, only the long faces are suitable.
The dimensions of candidate features for plane locating must
be compared with the three overall dimensions of the workpiece.
3.4.2 Surfaces suitable for side locating
Suitable features are established by each side locating type.
a) Suitable surfaces for side locating type p1. Side locating can
be pided into guide locating and endwise locating. Hence, suit-
ability tests are to perform separately for guiding and for endwise
locating.
Suitability for guiding must be tested from three aspects, i.e.,
shape of surface, dimension, and position of surface.
• According to the shape of the guide locating element the use-
able faces are: planar face, two planar faces, two cylindrical
faces, combination of cylindrical and planar surfaces, and
single cylindrical surface.• The typical dimension of a surface must not be less than 35%
of the longest dimension of the plane locating face.
• According to the position of the guide locating element, they
must belong to adjoining faces of the plane locating face.
Suitability for endwise locating must be tested from two aspects,
i.e., according to shape of surface and position of surface.
• According to the shape of the surface, planar or cylindrical
surface is useable for endwise locating.
• According to the position of the endwise locating elements,
they must be on the face, which is the adjoining face of both
the plane locating face and guiding face.
b) Suitable surfaces for side locating type p2. According to the
shape of surface there should be two holes on the plane locat-
ing face. The distance between the holes must not be less than
35% of the greatest length of the plane locating face. Suitable
surfaces for other side locating types are defined in a similar
way.
3.4.3 Suitable surfaces for clamping
Suitable clamping surfaces have been established for every
clamping type.
4 General solution concept of operation sequence
and clamping fixtures
Rectangular castings can almost always be machined on a ho-
rizontal machining centre in two operations. The operation in
which the functional surfaces, or most of them, are machined, is
called the main clamping, while the operation in which the rest of
the surfaces are machined is called additional clamping. Fixtures
for both the main and additional clamping make a clamping fix-