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PART THREE SYSTEM DESIGN
Feasible
Less expensive and
therefore preferable
Avoid undercuts and reentrant
angles in the cross section of special
cold-finished-steel stock if possible,
since these are more costly to produce.
Design rules for size and spacing of holes
in metal stampings.
Not this
Machined
casting
This
Sheet-metal
stamping
Stampings are often less costly
than machined castings.
Feasible
Better
Minimize the number of fasteners by
incorporating lips or other hooking elements
in the basic parts. (Design for assembly.)
Profile
milling
cutter
Specified radius
Radius allowed to be the
same as that of the cutter
Cutter
Specified radius
Radius allowed to be
the same as that of the cutter
Not these
These
Product design should permit the use of the
radii provided by the cutting tools in milling machines.
Draft
angle
Crumbling and patching
of mould necessary
(a)
(b)
(a) Poor stripping from the mould results when no
allowance is made for draft.
(b) Ample draft permits easy and safe stripping for
castings made in sand moulds.
Stock
thickness
Less than T
T or greater (2 T or greater
for alloy or stainless steel)
Not this
This
Not this
This
Less than 2 T
Stock
thickness
2 T or 3 T or greater
Allow a straight length between bends in tubes.
No distance
between bends
D
D or 2 D
between bends
Not this
This
Examples of design for manufacturing and assembly
Source: J. G. Bralla, Design for Manufacturability Handbook, 2nd ed., New York: McGraw-Hill, 1999.
Summary :
(Design for assembly.) Profile milling cutter Specified radius Radius allowed to be the same as that of the cutter Cutter Specified radius Radius allowed to be the same as that of the cutter Not these These Product design should permit the use of the radii provided by the cutting tools in milling machines.
Tags :
design,cutter,radius,less,between,bends,draft,greater,stock,specified,feasible,milling,stripping