The Surface Treatment of Prototype Precision Machining
Overview : At
present, manual grinding and polishing is a mainly used method among surface
treatments of prototype in China.However , traditional machining is not
applicable to complex
cavity and curved surface of some slits. So it is
necessary to adopt other machining methods,
such as ECM (electrochemical machining) and ECMF
(electrochemical machining finishing) .
The surface
treatment of prototype precision machining can be mainly divided into two parts:
traditional and non-traditional finishing technology . The traditional
finishing technology includes
manual grinding and polishing and the newly
developed precision machining technology .
The non-traditional finishing
technology includes chemical polishing , electrochemical polishing ,
electrogrinding , ECMF , ultrasonic machining , MRF (magneto-rheological
finishing) , laser polishing
and spark polishing.
1. Manual
grinding and polishing . It is an adaptable method that doesn’t need special
equipment
and commonly rely on operators’ experiences and technological level .
But it is low efficiency(takes up
about 1/3 of whole prototype modeling cycle)
, huge labor intensity and instable quality , which have
restricted our
development of prototype modeling process to a higher level . Considering
present
development situation of social and economic technology , manual grinding
and polishing can
not be thoroughly eliminated temporarily.
2.Digital prototype
polishing machine . It adopts digital control , digital display and technical
control
parameter . It equipped with a
whole set of grinding heads , grinding
abrasives and semi-automatic
polishing machine . This machine has many
advantages like small volume,usableness , stable quality
and efficient
repeatability . Applied range/Range
of application:
A.material : prototype materials, such
as cast steel , forged steel , aluminum alloy and zinc alloy;
B: Surface
size : 100×100(mm)－1,500×3,000(mm).
3. Supersonic
prototype polishing machine . It is adopted the principle of high-frequency
electric
spark pulse power and ultrasonic rapid vibration grinding to polishing
. It can polish some winding
parts ,
such as narrow grooves , narrow slit , edge and angle , which can not be
accomplished
by normal polishing machines (electric grinding soft shaft) .
Moreover , the polishing process will
not ruin the corner angle and the
precision of prototype modeling . By using this machine ,
rough surface can be
shaped and polished quickly regardless of the restriction of part size and
hardness.
Because it has no requirement for the roughness of original surface
but has high efficiency .
Compared with EDM processing , HSM can save 25%~60% of processing time ; The surface milled
by HSM is great and can avoid fine lines (which will possibly appear in EDM processing) ;
HSM can process the surface hardness of 45~60HRC . And the roughness of fine milling surface
can reach to Ra=0.63mm which will help to reduce manual polishing time ; HSM can omit the step
of electrode manufacturing which assists to shorten moulding cycle .
based on the principle of electrochemistry anodic dissolution of metallic workpiece , which belongs
to the removal of ions . Furthermore , it is a kind of non-contact process method , so it will not
process deformed layer , metamorphic layer and residual stress ; The tools are anti abrasive
so that can be long-term applied ； It won’t cause trimming and burr.
